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Command Technology Corporation Mountain Blvd. All you have to do is wait. Wait until mid- Oracle has it now. K i»«.. Applications that run faster. Applications that are easier to use and have more capability. Multi-user, networked applications. So stop writing dead-end dBASE code today. And stop writing cramped, limited-to-less-thanK applications.
Call DBMS today. Or use the rightmost coupon. Or mail one of the other coupons. And wait. I have every confidence your first attempt will be full-featured and bug-free. When you do, fill in the check amount. Hope to hear from you sometime in the next couple years.
I agree to use this license only for application development. I understand all prices include applicable taxes and postage. Tba otbar conpaniw montlonod own numtroui riglilorad tradamartt.
Evan tbo Viporwart it tradamartad. Hudson declined to say what the EDS agreement would entail or when it is expected to be concluded. Building net for GM? General Motors Corp. In his speech, Meyer said the company plans to streamline through plant closings during the next three to six months. And in the U. The HRX will reportedly have up to four processors connected to one bus. Jerome Meyer One problem with French development is that it takes time for Americans to learn about new products.
Equally powerful. Equally practical. You can read about them in the following pages of this magazine. But Compuware is more. Sound too good to be true? In Michigan As easy to read, as easy to understand, as the English you see here. Others agreed.
As a result, it may allow DB2 to query Dbase. West Coast correspondent Stephen Jones contributed to this report. Dell cut the prices on four of its Intel Corp. Additionally, Dell added an based PC for a monochrome system with a 40M-byte hard disk drive. Prices were also cut on two EGA s. Macintosh-compatible world. The program is scheduled for release in the fourth quarter.
At times you need to add it. Or rearrange it. Or change it. Or just even look at it. Because no other tool offers the versatility that this software utility does. It also has extensive logic selection capability. File-AID can manipulate any record structure or data format. We make it even easier with a training video, a convenient and complete guide for users. Case closed.
Within the U. Postal Service, a courier or telex. Compuware also takes the mystery out of databases by providing extensive support. Compuware takes the mystery out of databases by taking the guesswork out for you. Conversely, users retain connectivity to their host system.
Centaur II can contain between one! Ollerton, director of product marketing for Celerity. The , available with up to four scalar processors or up to two vector processors working in combination with two scalar processors, is the first Celerity to perform parallel processing by breaking down a problem to run simultaneously on several CPUs, according to Ollerton.
It is available with up to K bytes of cache, IG byte of memory and 44G bytes of disk storage. X Windows is a portable architecture for developing network-based windowing applications for workstations. MIT also announced that it is forming a consortium of industrial companies to continue X Windows development. Because as data processing evolves, the need to improve pro- ductivity becomes greater. And most recently, DB2. In Michigan Educational Resources Compuware offers, were developed to answer the growing needs of data processing.
A vision of how information management would evolve over the next several years. With new types of computer users and new computing needs. And our strategy for making our vision a reality was to build it upon the most aavanced technology we could find. And a 4GL that out-performs anything in the present.
The software, that is. The company is already taken. For more information call Debbie Cox at It is in this light that Judge Harold H. The technical effectiveness of most copy protection programs has improved to where there is virtually no legitimate argument against it.
Newbury Park, Calif. L, in a big way. The suit is also filed against Bridge Technology, Inc. Microvax II, and he knows nothing about either. I can tell you that I am one woman who j will not just stay and put up with it, and neither should anyone!
That is how we can bring j about a change — how unfortu- nate for all involved. Gilbert Jackson, Miss. Some of what was said was confusing. Thus, it was not clear if MIS graduates, as opposed to computer science graduates hired by MIS departments, also have the same deficiencies. Well, a lot happened in the subsequent two years.
The booming mainframe market of and turned into the doldrums of , and And IBM did such a good job convincing customers that the was a solid box that many bought inexpensive, used s instead of s. Aside from its intrinsic value. I expect to see knock-offs of both products shortly. So what is it? First of all, hypertext is a concept, dreamed up by Computer Lib author Ted Nelson. Consider a text file. However, the text file is still basically linear. You could examine it and then move on from there, or you could go back to where you were.
Documents are assembled from needs. For example, you could turn a reference or etiquette manual into hypertext, with links from soup spoons in the appetizers chapter to dessert spoons from the dessert chapter. In other words, hypertext allows you to structure text in many different ways and lets the user maneuver easily through it. Some systems control video monitors: Press the right button, and you get a video clip.
Instead of hypertext, you get HyperCard, with pointers between these cards, which are are basically screenfuls of data. These cards can also have fields and can be sorted, indexed and searched by the data in these fields. This program could also be copied, with the boilerplate of the letter altered, and attached to another form. HyperCard will use that name to search a card file for phone numbers, then automatically dial that number. HyperCard gives the user a sense of power and offers as much programming capability as he is prepared to use.
The possibilities are endless. It can do anything you want — if you think to tell it to. Will the assumptions that IBM is building into its mid-range processor strategy still hold true in ?
There is a moral to this story. To customers: All vendors, including IBM, change their strategic directions when market conditions change. I understand that the statistics I would prefer to see are not easy to compile. MIS professionals and educators know that the field is young and its direction unclear. Entry-level expectations, salary levels and the value of work experience must be different with educational status. Jill Smith, Ph. Hakenower Brockton, Mass. Computerworld welcomes comments from its readers.
Box , Cochituate Road, Framingham, Mass. Choose Realia. Imagine that. The power of Epson being put into millions of hands. Like the hands of Kate Grant. Give or take a few seconds. Equity is a trademark of Epson America, Inc. CA Most include 4GL tools. And they all claim to deliver performance. But once you get your hands on these products, the differences are dramatic. No wonder. INGRES has been designed from top to bottom to support developers of performance- critical applications.
And makes them easy to maintain. The most important thing about a DBMS is the way it performs for you. Just send this coupon or call us. When structured analysis and real-time and data modeling are done in the same data base, the different teams can validate the specifications they are using, Nastec officials claimed.
The diagramming interface provides pop-up menus and a mouse for moving symbols around the screen or changing them, Nastec spokesmen said. The option can check state- transition diagrams against flow diagrams and verify that events are consistent between them.
It is so resource efficient, it easily supports tens of thousands of users in the data base, with many hundreds concurrently on-line. Call for a free trial or more information. In Florida, call All rights reserved. To turn raw data into meaningful facts. To analyze, estimate, optimize, simulate. To produce custom reports and color graphs.
Whatever your information need, the SAS System delivers more from the data you store. Explore Your Data. Forecast sales and cash flow. Perform statistical analyses.
Build financial and planning models. Create spreadsheets of unlimited size. Schedule projects for best use of time and resources. Produce stacks of personalized letters. Generate calendars, charts, and many other formatted reports. Spot relationships and graph trends with powerful presentation graphics. Customize these applications any way you wish.
If You Know Data Bases. End users, even those who know nothing about data bases, have immediate access to the data they need. Update values in a data base directly from a SAS System application. All without risk to data security. The SAS System lets you choose which users browse or update specific files. Get the Facts Today. Bring the SAS System together with your data base.
For details, call or write today. SAS Institute Inc. Ridge Medical Supplies Inc. CuUinet Software, Inc. Printed in the USA. Tandem Computers, Inc. Digital Equipment Corp. Verimation is jointly owned by AB Volvo and L. Software Techniques, Inc. VMS systems. SPSS, Inc. Although the acronym-happy software industry rarely takes inspiration from housewares, Silden Software in Encino, Calif. A system that automatically signs off terminals after a preset time lapse during which they have remained idle is called EZoff.
Jim Wisdom can be a tough critic. Tough, but fair. Speaks his mind. Not many people can say that. Which is also nice to hear. The Next Dimension in 4th Generation technology.
Bohl, who resigned in April to join Digital Research, Inc. A story in the Sept. Infodata Systems, Inc. One powerful, accessible, responsive computer. When you do that, you get a different kind of computer. Then, the network the computer.
This screen shows what we mean. Other brand or product names are trademarks or registered trademarks of their respective holders. As you may have guessed, though, this is no ordinary screen. It belongs to the most powerful Sun workstation ever built.
In computer-ese, it delivers the performance of 10 MIPS. At a tenth the cost. Merely the latest. On the contrary. All three can coexist on the same network. I What it gives you is a compatible growth path 1 to the most cost-effective and powerful workstations m in the world. Software support for the Sun Living proof it's no empty box. Only Sun has all the pieces of the Open Systems Network in place.
Advanced network services. Across-the-board licensing of innovations and implementations. It's as though your company has just one computer. One computer with the power of many. And the network is that computer. And a long list of network management services for vendors and customers alike. Our strategy is paying off.
In other words, a network that works. For everyone. Or write Sun Microsystems, Garcia Ave. The proposed addition is designated X3. The X3 committee has also announced a review period through Oct. Unmatched installation and implementation program. Inc Masterpiece. CA-Accounts Poyoble. Software superior by design.
Changes during the final editing of X3. The standard facilitates the development and utilization of tape peripherals on computers by providing a common logical interface. Software is no longer a cottage industry. To be a leader, the drive to be inventive must be backed by substantial resources. The way programmers work. The way computer applications are written and managed. The way corporate infomiation is managed. And the r way future software systems will evolve.
Today, ADR continues to lead the industry. And will continue to answer the needs of business. But now in greater diversity than ever before. Unlock the potential. The feature is one of several that the small systems utility firm said it hopes will allow it to compete more effectively with the job scheduling packages offered by Computer Associates International, Inc.
Pools systems for scheduling Release 3. And sessions can be saved on the host. Make contact today with Trax for a free trial! TtaX Trax Softworks, Inc. Tymshare Inc. International Business Machines. Inc, IBM. Lcslic P. Marcia Feingold — Cap Gemini America m. The company has sold licenses for the product. Macros can be defined in separate files and included with one-line commands in the procedure source code file. It is said to take the place of more expensive mainframe security risk analyses.
Tata Engineering and Locomotive Co. Access Technology, Inc. SQL is key to taking advantage of future technologies. And ADR will fully support the industry standard. Wliich means choosing a DBMS is now a matter of choosing the system that satisfies your current needs best. Without the fear of being locked out tomorrow. The future may bring something new, but today, businesses like yours depend on computer-based online solutions built by professional programmers.
Only to find that any advantages are lost to an insurmountable learning curve or are offset by an extremely painful performance penalty. That is, until now. You can even utilize existing Cobol copybooks. You get a system that executes real instructions. From the simplest to the most demanding of programs. Call or write today for a free, no obligation trial and complimentary poster.
Perfect together. Cincom Systems, Inc. Hessinger said that rating is unofficial; the official one will have to come from the Codd and Date Consulting Group when it decides to make it public. Perhaps the danger here is not that we will ignore a new standard so much as allow it to become too confining once users start adhering to it.
IBM executives have said that a follow-on machine, code- named Silverlake, should arrive in the second half of [CW, Sept. Professional, powerful and quick. The only system with everything you need to build corporate applications on DB2. Including static and dynamic SQL functionality, an active dictionary tied to the DB2 catalog and a complete application development environment. Or in other words, everything you need to get the most from your investment in DB2.
It provides job log and listing information that the user can customize. Executive Assistant. Regional Sales Manager.
Departmental mini using data from PC. National Sales Manager. IBM PC off mainframe; data uploaded from mini. Corporate Graphics Artist. Created using Editor at graphics workstation. Vice President of Manufacturing. Departmental mini. Financial Manager. A single graphics package can make everybody in your company look good. Especially you. And file sharing capabilities so data can move freely throughout your company.
On a micro, mini or mainframe. All your people learn a single set of commands and menus, no matter where Impressionist is running. Best of all, data from your host computer can be shared throughout your company. To find out more about the one graphics package for everyone, call Chris Barkley at In Texas and Canada call Call for special introductory price on Micro Impressionist. Lotus and are registered trademarks of Lotus Development Corporation.
This module is integrated with Supertab, the I- Deas finite element modeler. If two users try to simultaneously open the same data set, the product guarantees that all update operations are serialized and protects the overall integrity of the data set. Enhanced Data Set Integrity operates in a stand-alone or integrated mode. On-Cue generates and submits a batch job request and returns it to the user. A hard copy can be routed to an available printer. Filled-in screens can be saved in a user library, and security for sensitive data is provided.
It emulates the deduetive reasoning of human experts and shows how to improve the performance of your system. In fact, it even gives the rationale for its advice.
And can tailor its recommendations to the requirements of your system. It is compatible with other versions of Plantrac. Computerline, P. Box , 52 School St. A version of the Mass word processing software for Digital Equipment Corp. Mass Version 7-A allows the fonts to be printed in outline form or in various shades from black to white, the vendor said. Users may change typefaces and point sizes anywhere within a document. Microsystems Engineering, Suite , W. Hassell Road, Hoffman Estates, Ill.
Other features include more than component library symbols, editing functions and the abiity to create parts from portions of a drawing. The software also allows definition of a pixel array with a color associated with each pixel.
Raster data from various sources can be merged. Versatec has also announced Veraplot 9. The software outputs raster data and was designed for VAX and Microvax computers. Versatec, Walsh Ave. The system, called Jcamms, runs on Wang Laboratories, Inc. VS minicomputers. Broadway, Hicksville, N. Version 1. DEC, Maynard, Mass. Louis A. Sharing DASD? Want to Improve Performance? System Devel.
Facility Info. You can use a telephone. Reply and it digitizes your voice to be replayed later. So now the company computer is just a phone call away.
Teltech, 39 Broadway, New York, N. But since we bought the C Supra from C. Itoh Digital Products, I never have a moment to spare.
I'm living life in the fast lane. It manages continuous forms, labels, letterhead and up to 6-part invoices with its rear or bottom feed paper paths. Sound investment The finance department says the Supra is a great investment since C.
Itoh Digital Products, Inc. It prints high volume data processing output, like invoices and spreadsheets, at speeds up to characters per second cps. And for word processing, the Supra prints sharp, clear, high-speed letter quality at cps. And they were right. Forms expert Our executives are really impressed with the Whether it's high volume spreadsheets and multi-part invoices or letter quality business letters and presentations, the Supra is fast and reliable.
MS-DOS-based systems. Software Research, Third St. Francisco, Calif. According to the vendor. Version 2. Updata, Holmdel Road, Holmdel, N. The Tapesaver Utility backs up and restores data by volume or by file. No system generation is required for installation. The utility can be run by an operator in interactive menu prompt mode or unattended under batch control.
And offers software designers a CASE system that works the way they do. A commitment that has made ADR the leader. Up to 16 watch points can also be set. Program statements can be traced as they are executed. Glenstone, Springfield, Mo. The system lets engineers and managers focus their efforts on software development, quality, and productivity, without having to supervise a complex computer facility.
A composite material made of graphite epoxy is ideal for use in space because it is stronger than steel yet lighter than aluminum. Unlike metal, it does not expand from exposure to heat or cold, and its reduced weight translates into lower costs and larger payloads. For example, saving just one pound in a space vehicle means a reduced launch cost of several thousand dollars or added fuel for longer operations. Until now, however, graphite composites have proved difficult to mold to shapes more complex than a simple cylinder.
But research and development by Hughes has opened the way for the fabrication of a variety of new forms, including tubes with integrated end fittings in a one-piece design, support beams, and ring structures up to seven feet in diameter. Air Force FE dual role fighters.
Unlike previous systems requiring software check-out after the completion of hardware, the Hughes Digital Software Integration Station DSIS can test and de-bug software while the hardware is being built, resulting in substantial development cost and schedule savings. It has ten times the software and six times as many test targets as its predecessor, the APG radar. The signal is then relayed to a Japanese ground station north of Tokyo and fed into the local NHK studio.
The daily broadcasts include segments of major US. An ultramodern facility spanning 1. S3, El Segundo, CA Ada is a registered trademark of the U S. Government Ada Joint Program Office. For more information write to: P. Development tools Cadre Technologies, Inc. Cadre Technologies, Richmond St. Smalltalk DE Version 2. Continued on paged? Postscript has clearly emerged as a standard, and Palo Alto, Calif. The Continued on paged? How do you plan to penetrate that market? Users report dramatic productivity improvements and more.
All these and more to improve productivity and produce quality applications. For the most efficient development of either your PC or mainframe programs, call us now. The company also unveiled a Holiday Clipart Library that users can incorporate into holiday correspondence, newsletters and other types of publications, according to a company spokesman.
They are compatible with Adobe Systems, Inc. Data integrity is key for such an application. Another reason for Follet to go with Baler was purely economic. The plan eventually calls for 60 copies of the model to be in place. According to Butler, compiling a spreadsheet with Baler was easy. At up to 1. SCO Xenix has proved to be a reliable operating system. It offers an excellent low-cost opportunity to get back up to speed on the current state of Unix.
Xenix vs. Even a little experience with the two systems is enough to show that both will have their place in corporate use. SCO Xenix is clearly the operating more professional, unified look. All of which means PageLaserl2 can meet the needs of any office worker. So if your business prospers on high volume, get the laser pnnter that does the same. The PageLaserl2. For more details, call for the name of theTbshiba printer and computer dealer nearest you.
Then see how well FhgeLaserl2 performs in your surroundings. Diablo is a reKistend track-mark of Xenix Corporation. Qunie is a ivgistervd trademark of Qume Corporation. LaserJet Plus is a a-gislemd trademark of Hewlett-Bickard. Inc, Infomuition Systems Division system of choice when more traditional, multiuser, multiterminal configurations are desired.
Control-C Software, Inc. We also have regional marketing people that are also focused exclusively on the Fortune Why should MIS directors buy Tandy equipment? What are your goals for selling to MIS in large corporations? Our market share is small — in the few- percent range. We would be very pleased to double that in the next year. I think every new piece of hardware that comes into the market, regardless of the manufacturer, has features that the whole industry reviews and has to determine the importance of for the long term.
Of course, customers themselves have an important vote as well. In fact, VGA is an option on our based machines today. The real significance of that is that all manufacturers now have the ability to bring some real innovations to hardware design as long as the operating environment is compatible with it and the software is compatible with it.
Does it matter? The rumor is that it needs an exceptionally large amount of memory to handle all these extended functions. So, if you believe their literature, it would appear to run on all other machines as well.
Anyone who focuses on it is the ultimate victim of fear, uncertainty and doubt. How badly were you harmed by that decision? We were anything but a hardware clone. But our sales have been very robust. What do you hope to accomplish during the next 10? In the microcomputer area, our No. One of the more interesting things that we did next was our barnstorming campaign in and We also made significant inroads in the education market. We gave free computer-literacy training to , school teachers.
The next 10 years will probably be more interesting than the last With all the advances being made in hardware and software, the end user is going to be the big beneficiary. BASIS is designed to keep pace with your world of information, and, without the constraint of hardware dependence. Fast, efficient information retrieval is possible in even the largest databases. Novice and casual users may retrieve information and generate reports using menus and simplified command statements.
In , the firm shipped 3. Once an IBM-only shop. Saavedra said Wells Fargo was drawn to Tandy because of its ability to provide on-site service. GE makes the switch General Electric Co. And, that makes sense. New files and record fields may be added or changed without reloading data.
BASIS is accurate, efficient, and secure. DM is the first relational DBMS with full-text handling capabilities integrated with complete database management facilities.
If you need to know who, what, where, when, or why.. Let DPS be your Guide. Digital is and will continue to be the dominant factor! Or call your local sales office.
The Powermate includes a processing unit with IM byte of random-access memory, a 1. It can accommodate five 5V4-in. Based on the Intel Corp. CPT, P. Box , Mitchell Road, Minneapolis, Minn. The Acer bit system runs at 16 MHz. No host changes required. Aspen Research NE. Does the vendor offer a true distributed matrix switch versus an electronic patch panel? Are there any documented problems with the control software, resulting in inability to control the switch?
Can references be contacted, with sites visited? Is performance monitoring integrated in the distributed matrix switch? I Does the switch provide V. And, we know that no competitor within our markets can match the service and support we offer.
Prove it to yourself. The Ivy portables are said to run the Unix operating system. The Model 40 features a 1. The Model 80 features an 80M-byte hard drive, and the Model features a M-byte hard drive instead of the 40M-byte drive. Ivy Microcomputer, 15 Ararat St. Software applications packages An entry-level computer-aided drafting and design program called Cub has been announced by Innovative Computer Aided Technology, Inc.
Macintosh has been introduced. Users can select record sizes of 1,, 2, or 4, char. Vectras and compatibles. Box , Cumberland Ave. Lafayette, Ind. Response, an integrated contingency planning system for data processing and corporate disaster recovery planning, has been announced by Mosaic Computer Security, Inc.
Mosaic, Massachusetts Ave. You can correct or bypass the error right away —without wading through transaction dumps—and then resume testing without losing valuable time. Best of all, InterTest's programmer-friendly menu screens and comprehensive Help Facility enable you to become more productive right away. It lets you catch the bugs that plague your programs. For more information, or to find out about our no obligation 30 day trial program, please write or call On-Line Software today.
On-Line Software International, Inc. Fully sealed. Runs ceel. Fits under an airplane seat. And cemes 4 te a box. It s one of our direct access storage devices DASD disk enclosures, and it delivers improved reliability, improved availability and greater compactness.
This is why these disks can be sealed inside their enclosures And it s why we re able to service our DASDs fast.. It all adds up to greater productivity. For specs on our full line, call your local Amdahl representative. The Hobbs Group, P. Box , S. Techpro, P.
Box , Springfield, Va. Bridgeware operates as a stand-alone application. MS-DOS 2. Other features include a rewritten source-entry utility and an 8-million-record limit. California Software, N. A code-generating graphics editor called Drawbridge has been introduced by Courseware Applications, Inc. Drawbridge automatically generates the source code required to create graphics displays.
Graphics objects available include arcs, boxes, circles, lines and polygons. They may be in color and can be either outlined or painted.
A built-in text editor allows the addition of text to graphics displays. It automates new or modified application testing, from simple program tests to the most complicated stress testing. The automated logging function permanently stores the screen dialogues on a file. You can then browse and customize your test stream dialogues with a variety of powerful on-line edit and utility functions.
VERIFY is then ready to retest any portion of your system, giving you the flexibility to control the application mix, input values and arrival rate of the transactions to be re-executed on CICS. Through an on-line menu display, you can see the exact differences VERIFY discovers during its interactive comparison.
And respond immediately with two full menus of mismatch processing options. It helps you get it right the first time. The V 2 -in. Emerald Systems, Mo- rena Blvd. Nth Group, P. Box , West Hills, Calif.
Information Storage, Inc. Features include self-loading and self-threading. M4 Data, Building 14, N. A series of internal hard disk drives for Apple Computer, Inc. Macintosh computers has been announced by the Rodime, Inc. Peripheral System Division. Both offer average seek times of 28 msec, and both have embedded SCSI controllers. Rodime, Suite , Chagrin Blvd. For the past 20 years, he has devoted his efforts to developing the field of Medical Geology. Finkelman is the author of more than publications and has been invited to speak in more than 50 countries.
Wood Jr. Finkelman was also awarded a U. X Olle Selinus is a Ph. During the s and s, he worked in mineral exploration, and, since the beginning of the s, his research work has been focused on environmental geochemistry, including research on medical geology.
He has served as the organizer of several international conferences in this field, was vice president for the International Geological Congress in Oslo in , and has published well over papers. Selinus was also in charge of external research and development at SGU. In he started the concept of Medical Geology as the "father of medical geology" and was, in , the cofounder and, after that, president of the International Medical Geology Association, IMGA. He has received several international awards and has been appointed Geologist of the Year in Sweden because of Medical Geology.
He has also been chief editor for other books on medical geology. Finkelman and Olle Selinus Reprinted from Geosciences. Cite as: Centeno, J. Geosciences , 4, All living organisms are composed of major, minor, and trace elements, given by nature and supplied by geology. Medical geology is a rapidly growing discipline dealing with the influence of natural geological and environmental risk factors on the distribution of health problems in humans and animals [1—3].
As a multi-disciplinary scientific field, medical geology has the potential of helping medical and public health communities all over the world in the pursuit of solutions to a wide range of environmental and naturally induced health issues. The natural environment can impact health in a variety of ways. The composition of rocks and minerals are imprinted on the air that we breathe, the water that we drink, and the food that we eat. For many people this transference of minerals and the trace elements they contain is beneficial as it is the primary source of nutrients such as calcium, iron, magnesium, potassium, and about a dozen other elements that are essential for a healthy life.
In excess, these elements can cause significant health problems because there is an insufficient amount of an essential element, or an excess of such elements such as arsenic, mercury, lead, fluorine, etc. The latter includes findings reported by the U. Geological Survey that even groundwater passing through some lignite beds can dissolve PAHs in sufficient concentrations to cause serious health issues [4]. Current and future medical geology concerns include: elevated levels of arsenic in drinking water in dozens of countries including the USA; mercury emissions from coal combustion and its bioaccumulation in the environment; the impacts of mercury, arsenic, and lead mobilizations in surface and ground water in regions were artisanal gold mining is conducted; the residual health impacts of geologic processes such as volcanic emissions, earthquakes, tsunamis, hurricanes, and geogenic dust; exposure to fibrous minerals such as asbestos and erionite; and the health impacts of global climate change.
Billions of people, most in developing countries, are afflicted by these and other environmental health issues that can be avoided, prevented, mitigated or minimized only after detailed and comprehensive research and educational outreach have been conducted and solutions identified, if possible. XII This Special Issue of Geosciences marks an important milestone in the global growth and maturation of medical geology. The current Special Issue discusses recent advances in medical geology, providing examples from research conducted all over the world.
Among the topics to be discussed are: x Geochemistry of soils and the occurrence of anthrax spores Griffin et al. Finally, this Special Issue follows months of collaboration between the International Medical Geology Association IMGA and Geosciences journal, and it is result of the commitment of these two organizations of promoting the interest of medical geology worldwide. We believe that with these types of high quality publications, the medical geology community at large will now have an authoritative and influential journal in the geoscience community that would continue to report on significant advances of global impact to the development of medical geology.
Department of Health and Human Services, the U. Food and Drug Administration or the U. Federal Government. XIII References 1. Selinus, O.
Principles of Medical Geology. Griffin, D. Geosciences , 4, — Martin, R. Luffman, I. Risk Factors for E. Stearman, W. Candeias, C. Pinto, M. Moore-Nall, A. Geosciences , 5, 15— Voutchkova, D. Geosciences , 5, 45— Eggers, M. Geosciences , 5, 67— XIV Arifin, Y. Geosciences , 5, — These data identified the elements, calcium Ca , manganese Mn , phosphorus P and strontium Sr , as having statistically significant differences in concentrations between county type anthrax occurrence versus no occurrence.
Reprinted from Geosciences. Cite as: Griffin, D. Introduction B. There are over strains of Bacillus anthracis, and all pathogenic strains carry both pX01 and pX02 virulence plasmids [6].
Two separate groups of B. Animal outbreaks of anthrax are a common occurrence in the contiguous United States, and they are typically constrained to a few geographical regions e. Genetic analyses of WNA clade isolates show evidence of a north to south distribution pattern that is rooted in northern Canada [7]. Costs associated with outbreaks can be significant.
Even small outbreaks can significantly impact the economic well-being of the livestock industry, where profit margins are based on low expected annual herd losses [13].
Given the geographic restriction of most annually-occurring cases and outbreaks of anthrax in the contiguous United States, geochemical data obtained by the U. These data may help decision makers better prepare for and mitigate potential or actual outbreak events and provide an accurate graphical representation of areas within the contiguous United States that favor the natural propagation of this species.
Experimental Section 2. In a major geochemical mapping project such as this, the quality of chemical analyses is of utmost importance. Reimann et al. In this project, field duplicates were not collected. This approach was evaluated during the pilot studies Smith et al. Based on the results of the pilot studies, it was felt that the additional collection of field duplicates during the national-scale study would not add significantly to the QC analysis and, therefore, was not worth the added expense.
The remaining four QC procedures were carried out fully. In this project, trueness estimation was done on three separate levels. Smith initiated the final QC tier, which included the insertion of two blind RMs within each batch of 20—30 samples. Precision was assessed both by repeated analyses of RMs and by replicate analyses of real project samples.
A complete discussion of the QC protocols used in this project, including detailed tables of bias and precision, is given in Smith et al. State county outbreak and case data were compiled from state animal health organizations and the National Animal Health Reporting System [18]. In summary, there were sample sites located within these 46 counties. Table 1. State, county and U.
In summary, there were 89 sample sites located within these 27 counties. Statistics The non-parametric Mann—Whitney U test was utilized to evaluate differences in geochemistry between counties where anthrax outbreaks or cases had been reported since the year and counties within the same states where no cases were noted for the same time period using SPSS IBM, Tampa, FL, USA [19].
For statistical analyses, those values were set at the MDL for the respective elements e. Results and Discussion Comparing sample sites from 46 counties seven states, MN, MT, NV, ND, OR, TX and SD that had reported anthrax outbreaks or cases to 89 sites from 27 counties same states that did not report outbreaks or cases resulted in the identification of seven elements with statistically significant differences in their respective concentrations Table 2, all counties, Column 2.
With the exception of Nb and Sr, the total state average of elemental concentrations was higher in anthrax-positive counties. When the elements were looked at individually, several trends emerged. Strontium data were significantly different in three of the seven states. Calcium These concentrations were similar in both types of counties, with only one instance where average concentrations in negative counties exceeded positive counties, and that was in NV at 5.
This anomaly can be explained in that the average concentrations in both the negative and positive counties were the second and third overall highest average concentrations in comparison to the data obtained from each of the other evaluated states. Overall, calcium data were significantly different between county types in three of the seven states.
Table 2. All Counties Texas N. Dakota S. Elements Cd, Ce, Hg, Mg and Sc did not show significance in any of the states and were not included to simplify the table.
Overall, P data were significantly different in three of the seven states. Nickel Average Ni concentrations by state, with the exception of MT, were higher in anthrax-positive counties. The only significant difference in Ni concentrations by state occurred in SD.
Niobium Significant differences in total Nb concentrations occurred with only two states showing contrasting data, TX and OR, with average concentrations higher in anthrax-positive counties and in anthrax-negative counties, respectively.
Elevated concentrations such as this may mask a relationship. Sulfur The total S significant difference high concentrations in negative counties occurred over a small concentration range 0.
Other Elements Similar to the observation with sulfur, the total Sn significant difference high concentrations in positive counties was opposite that observed with the two state-level data sets. Several other elements, such as Al, Ba, Mo, Na, Pb, Rb and Tl, exhibited significant differences in multiple or individual states, but in many cases, one state produced a significant difference in anthrax-positive counties and, in another, in anthrax-negative counties.
Cesium data produced a significant p-value below 0. Of the 40 elements screened, seven Ca, Nb, Ni, P, S, Sn and Sr gave significant differences when samples from all seven states were evaluated as a whole. Of these, eight were positive meaning the concentration was higher in anthrax counties significant differences and one Nb was negative the concentration was lower in anthrax counties.
The overall differences in concentrations of other elements, such as Ni and S, also resulted in both significant negative and positive results, and thus, the overall observation is either weak or not valid. This observation was also noted with the S data. It may be that one of these or other elements do contribute to virulence, but further research is needed to determine the potential role and threshold concentrations.
The remaining three overall positive differences Ca, P and Sr had significant p-values in at least three of the seven states for each element. Manganese was selected for inclusion in the group of selected relevant elements Ca, Mn, P and Sr given the predominance of significantly positive state data and the skew produced by the lone negative. The regional distribution and concentration ranges for these four elements Ca, Mn, P and Sr and Zn an element required for the lethal factor are illustrated in Figure 2.
Other elements that have been reported to influence this pathogen include Na and S [2,4], and both of these elements resulted in at least one significantly positive state data set Table 2.
Also of note are elements, such as Ba and Rb both close neighbors to calcium and strontium in the periodic table , which produced multi-state negative significance data, that may inhibit virulence by mechanisms, such as mimicking a critical virulence element [22]. In this case, the probability of conversion is suppressed in geographic regions where the mimicking element exceeds a given threshold concentration. It is interesting as can be observed in Figure 3 that the concentrations of both of these elements are relatively low in many of the anthrax-positive counties of ND, SD, MN and TX.
Using concentrations observed at sample sites in the states listed in Table 2 for Ca, Mn, P and Sr, several tentative threshold concentrations can be selected for each element in regard to the likelihood of an outbreak occurring at a given location. As an example, the minimum concentration observed in any of these state counties for Ca is 0. Calcium, phosphorus, manganese, strontium and zinc soil concentration gradient maps for the contiguous United States.
Figure 3. Barium and rubidium soil concentration gradient maps for the contiguous United States. Individual maps and one combined showing the sites where each of these concentrations occurred. Conclusions The evaluation of geochemical data from a series of selected sample sites in seven states identified four elements that had significant differences in concentrations between anthrax-positive and anthrax-negative counties.
The elements were Ca, Mn, P and Sr, which in part match historical observations. The USGS data set is a valuable tool that can be used to determine the background distribution of pathogens in soils of the contiguous United States. Being able to predict the natural occurrence of this agent may help guide animal and public health planning and response efforts.
The use of trade names is for descriptive purposes only and does not imply endorsement by the U. Author Contributions All authors contributed equally to this manuscript. Conflicts of Interest The authors declare no conflict of interest. References 1. Weinberg, E. The Influence of soil on infectious-disease. Experientia , 43, 81— A survey of the occurrence of Bacillus anthracis in North American soils over two long-range transects and within post-Katrina New Orleans.
Kochi, S. Zinc content of the Bacillus anthracis lethal factor. Fems Microbiol. Hugh-Jones, M. The ecology of Bacillus anthracis. Aspects Med. Wright, G. Studies on immunity in anthax. Requirement for phosphate for elaboration of protective antigen and its partial replacement by charcoal. Qi, Y. Utilization of the rpoB gene as a specific chromosomal marker for real-time PCR detection of Bacillus anthracis.
Kenefic, L. Pre-Columbian origins for North American anthrax. PLoS One , 4, e, doi Van Ert, M. Global Genetic Population Structure of Bacillus anthracis. PLoS One , 2, e, doi Elias, S. Life and times of the Bering land bridge. Nature , , 60— Williams, R. Mongoh, M.
Salb, A. Descriptive epidemiology of detected anthrax outbreaks in wild wood bison bison bison athabascae in northern Canada, — Ramsey, R. Factors affecting beef cow-herd costs, production, and profits. Smith, D. Geological Survey Data Series ; U. Reimann, C.
Pilot studies for the North American Soil Geochemical Landscapes Project—Site selection, sampling protocols, analytical methods, and quality control protocols.
Garrett, R. Relative spatial soil geochemical variability along two transects across the United States and Canada. Dytham, C. Pasteur, L. On the etiology of anthrax. Comptes Rendus Seances Acad. Van Ness, G. Soils of the United States favorable for anthrax. Heldman, E. Barium ions enter chromaffin cells via voltage-dependent calcium channels and induce secretion by a mechanism independent of calcium. Major sources of contamination include smelting operations, coal combustion, hard rock mining, as well as their associated waste products, including fly ash, mine wastes and tailings.
The number of uncontained arsenic-rich mine waste sites throughout the world is of growing concern, as is the number of people at risk of exposure. Inhalation exposures to arsenic-bearing dusts and aerosol, in both occupational and environmental settings, have been definitively linked to increased systemic uptake, as well as carcinogenic and non-carcinogenic health outcomes.
It is therefore becoming increasingly important to identify human populations and sensitive sub-populations at risk of exposure, and to better understand the modes of action for pulmonary arsenic toxicity and carcinogenesis.
In this paper we explore the contribution of smelting, coal combustion, hard rock mining and their associated waste products to atmospheric arsenic.
We also report on the current understanding of the health effects of inhaled arsenic, citing results from various toxicological, biomedical and epidemiological studies.
This review is particularly aimed at those researchers engaged in the distinct, but complementary areas of arsenic research within the multidisciplinary field of medical geology.
Cite as: Martin, R. Environmental arsenic is released via chemical and physical weathering processes, biological activity and volcanic emissions, while anthropogenic sources include mining, metal smelting and burning of coal.
Emissions of arsenic-bearing particulate matter PM are of particular concern for human populations living in proximity to an emission source.
Arsenic and inorganic arsenic compounds are classified as Group 1 carcinogens and are associated with cancers of the lung, bladder, kidney, skin, liver and prostate [2]. It should be noted that within the general population, inhalation is only considered a minor exposure pathway for inorganic arsenic compounds, and ingestion is considered the primary exposure pathway [2].
Despite their substantial contribution to global atmospheric arsenic species, mining operations play an understudied role in the generation of contaminated dust and aerosols [10]. To identify some of the emerging issues associated with arsenic in particulate matter this review presents key findings from a range of distinct but complimentary areas of research within the multidisciplinary field of medical geology, including geochemistry, toxicology, biomedicine and epidemiology.
We will discuss two key themes: i the origin, occurrence and current monitoring of mining-related arsenic in the atmosphere; and ii the current understanding of the health effects of inhaled arsenic, citing results from various toxicological, biomedical and epidemiological studies. To compare or describe the impacts of different types of mining operations, specific mining terms are used. Generation of Dust and Aerosol: An Overview Mining operations release arsenic into the atmosphere via wind-borne dispersal of arsenic-laden particulates [11], with dust being the dominant transport medium for these emissions [3].
Mining operations associated with an opencut coal mining operation in India, for example, generate 9. Active and abandoned mine tailings, mine sites and processing facilities also represent important sources of dust [17—22]. Future analysis may reveal the relationship between total arsenic concentration and particle size in these mine tailings samples. While most mining operations generate coarse dust, high temperature processes, such as smelting and coal combustion, are typically associated with fine particulates, accumulation-mode particulates, and vapors [10].
Total arsenic TAs concentration ppm of each mine waste sample is also shown. Our results obtained using a modified sieving method protocol described by Kim et al. Coarse and fine particulates have widely varying atmospheric residence times, and as a result, widely varying distributions. Arsenic associated with the fine fraction may remain in the atmosphere between seven [24] and up to 10 days reviewed in Matschullat [3] , and can travel long distances [25].
Coarse particulates have a much shorter atmospheric residence time, typically minutes to hours due to a larger settling velocity [10]. Particle segregation of mine waste can occur during airborne transport, thereby reducing the size of the individual particles deposited [17]. In addition to mining operation type, atmospheric contaminant concentrations are also influenced by the distance and position of a sampling site in relation to the source, the height of the source e.
Origin, Production and Release of Particulate Arsenic It is widely accepted that global atmospheric arsenic fluxes are dominated by mining-related industries involving high temperature processing [3]. While it is well-documented that mine tailings represent major sources of arsenic-contaminated dust throughout the world [10,19,28,29], the contribution by these sources to total global atmospheric arsenic fluxes is yet to be assessed [3].
The occurrence of arsenic-bearing phases in unprocessed ore and the generation of particulate arsenic by different types of mining processes will be reviewed in the following sub-sections. Fugitive emissions of particulate arsenic may occur at various stages of high temperature processing, as well as during the transport and storage of ores, concentrates and waste heaps [37].
Although high efficiency control devices are often employed in smelters to reduce emissions, the quantity of total arsenic emitted from a single smelting operation can be substantially high. For example, around t of arsenic are emitted annually from the Copper Smelter Complex Bor, in eastern Serbia [38]. Furthermore, uncontained smelter flue dusts represent an important potential source of airborne arsenic, compared with other secondary smelter by-products [39]. Over a period of 20 years, a copper smelter in Japan produced an estimated t of arsenic-rich flue dust Stockpiled by-products of the smelting process with high arsenic content present ongoing sources for redistribution.
Coal Combustion Coal is a complex mixture of organic and inorganic compounds formed over millions of years from successive layers of fallen vegetation.
Coal contains detectable levels of the vast majority of elements in the periodic table, including arsenic and other potentially toxic and environmentally sensitive elements [40,41]. Although much of the arsenic in coal is associated with the inorganic or mineral fraction such as pyrite and other sulphide minerals , a significant portion is associated with organic matter [42,43]. Arsenic in coal occurs in three non-exclusive distinct forms: arsenical pyrite, arsenopyrite and arsenate species [44,45].
The inverse correlation between arsenic concentration and particle size which has been observed demonstrates that volatilized arsenic preferentially adsorbs or condenses on the finer particles [31]. Furthermore, higher combustion temperatures result in higher concentrations of particulate arsenic. Solid by-products of the combustion process, including fly ash and bottom ash, are major sinks for arsenic. An early study by Ondov et al.
Despite the widespread use of ESPs in Europe, a reported t of arsenic were emitted from the combustion of coal during [35]. Similarly, in China around t of arsenic were emitted from coal-fired power plants during [51]. Arsenic emissions arising from coal burning industries are an ongoing issue of global significance.
Mine Tailings Fugitive dust emissions from mine wastes and mechanical processes associated with the hard rock mining industry such as crushing of sulphide ore and concentrates, and mechanical disturbance and wind erosion of uncontained mine tailings [10,53] are also associated with elevated levels of arsenic [17—19,54].
This is not surprising given that mine wastes and tailings are often characterized by extremely high arsenic concentrations. The preferential enrichment of arsenic in the finer size fraction in mine tailings [21,57] suggests that re-suspended dusts are characterized by higher arsenic content than the material from which it is suspended.
A Global Issue The magnitude of the problems associated with arsenic contamination from mining operations is a serious ongoing issue in many localities throughout the world, and there are no indications of abatement.
If the projected increase in global copper production over the next 20 years is correct [58], it could be reasonably expected that smelter emissions, and the generation of flue dust and other associated waste products, will also increase [39]. Furthermore, despite an overall increase in the number of coal plant retirements in some localities [59], the global demand for coal is predicted to rise at a rate of 1. Expansion of coal consumption reflects substantial increases in China and India [60].
In India, arsenic-contaminated fly ash from coal combustion processes occupies more than 65, acres, rendering the surrounding land unsuitable for agriculture [61]. Although not increasing substantially, the number of abandoned mines worldwide runs into millions [62], and their impact is likely to increase due to population growth and urban expansion. In Australia, there are more than 50, registered abandoned mines ranging from isolated minor surface works to more extensive and complex sites [64,65] In Mexico, the area affected by mining activities is estimated to be over Each year in China the mining industry produces wastes that occupy an additional ha [67], and around Mt of tailings are stockpiled on land that is urgently needed for other purposes [68].
Given the widespread geographical distribution of arsenic-rich mine wastes and the global reliance on smelting and coal combustion for various products and services, the systematic characterization and ongoing monitoring of particulate arsenic generated by mining operations are becoming increasingly important for reliably determining the impacts on human health and the environment [45].
Monitoring and Assessment A number of monitoring and assessment studies have been undertaken for different purposes: i to identify the dominant emissions sources of arsenic; ii to predict the potential contribution of an identified arsenic emission source to the atmosphere; and iii to identify the airborne arsenic species Table 1.
According to the World Health Organization WHO [70], the excess lifetime risk of contracting lung cancer if continuously exposed to 6. The different methodologies used to collect PM from mining operations are reflected in the contrasting size fractions and reporting units listed in Table 1. Measurement of total suspended particulates TSP was the United States of America standard for atmospheric aerosol until the discovery of the relationship between particle size and lung deposition of inhaled particles [71].
To meet the new PM10 health-based standard adopted by the USA, Europe and elsewhere during the mid to late s , collection devices such as the cascade impactor and multiple orifice uniform deposit impactor MOUDI have been used in various atmospheric monitoring studies [10,18,54]. The relationship between particle size and human exposure will be reviewed in detail in Section 4. Particulate arsenic may also be measured in size-fractionated mine waste samples generated through dry sieving bulk samples [21,57].
While this technique cannot provide a quantitative assessment of atmospheric arsenic at a particular location, the data may be useful for predicting potential particulate arsenic emissions from the source.
Atmospheric arsenic concentrations vary between localities and the type of emission source Table 1. The following sub-sections examine the contribution of each emission source to atmospheric arsenic levels in various localities throughout the world.
Smelting Much of the atmospheric arsenic research and monitoring published to date has focused on emissions from smelting operations. This reflects the dominant contribution by smelter emissions to global anthropogenic atmospheric arsenic inputs.
As reviewed in Matschulatt [3], copper and zinc smelting activities contribute of 12, and t of arsenic respectively into the atmosphere per year, whereas steel production contributes a comparatively lower annual quantity of 60 t per annum.
It should also be noted that in some industrial localities, smelting and other processes associated with the manufacturing of ceramic materials represent important sources of arsenic in the atmosphere [27].
Smelting operations produce the greatest localized air and soil arsenic concentrations while coal combustion distributes arsenic to the air in substantially lower concentrations over a wider area [73]. In the vast majority of case studies summarized in Table 1, concentrations exceeded, and in some cases, greatly exceeded, the annual WHO-prescribed target value [70].
Similarly, a maximum arsenic concentration of Interestingly, a declining trend in atmospheric arsenic levels was reported at all of the UK monitoring locations, except the Walsall smelter site [26]. The authors postulated that widespread industrial switching from coal combustion to oil and gas as a domestic energy source for space heating was the probable cause for the overall decline in atmospheric arsenic in the UK [26].
Similar results were recorded in an industrial area in Spain, whereby reductions in atmospheric arsenic concentrations were significantly associated with decreases in industrial activities, specifically the production of ceramic materials [27].
Although the quantification of arsenic in TSP provides one measurement of arsenic contamination in the atmosphere, this measurement may underestimate the respiratory health risks to nearby communities due to the inverse relationship between particle size and arsenic content.
After the introduction of particle size-selective criteria, various studies have measured and compared arsenic content in the PM10 and PM2. For example, an air monitoring study conducted approximately 3. Similar studies conducted in the same locality yielded comparable results [74,75]. In contrast to these findings, one study reported that PM2. These results highlight the importance of site-specific investigations during health-based risk assessments.
The greatest atmospheric arsenic levels generated by smelting operations occur in close proximity to the smelter, and decrease with increasing distance from the source [4,76,77]. Multiple reports suggest that the maximum concentrations are typically found within 1 km of the smelter site [4,78—81]. Furthermore, declines in concentrations have been observed over a relatively short distances. For example, atmospheric arsenic levels at a distance of 1 and 2.
These results were supported by a complementary soil-based study that documented an exponential decline in soil arsenic and heavy metal concentrations within 1 km of a lead smelter in the Czech Republic, followed by a less-steep decrease between 1 and 6 km [37].
Meteorological variables, particularly surface wind circulation, play a critical role in determining the transport and spatial distribution of the pollution plume from smelting operations [82].
Contrary to the general trend between concentration and distance from the emission source, Serbula et al. Compared with the mid-distance sampling location institute , the farthest sampling location Jugopetrol, which is downwind from the pollution source experienced high-frequency exposure to the emissions as a result of dominant WNW and NW winds.
To further highlight the impact of prevailing wind direction, the maximum concentration reported at Jugopetrol was equal to the maximum recorded at the sampling location closest to the smelter Table 1.
Similar relationships between atmospheric arsenic and other metals , and surface wind characteristics in the vicinity of copper smelters have been documented [74,83].
In addition to wind direction, wind speed plays an important role in determining particulate arsenic distribution from smelting operations. The greatest concentrations of arsenic and other metallic elements emitted from the copper smelter in Bor occurred during calm conditions wind speed less than 0.
Low wind speeds inhibit the dispersal of local pollution away from the emission source and can therefore lead to very high localized concentrations of atmospheric pollutants [38].
Coal Combustion Global coal combustion contributes an estimated t of arsenic to the atmosphere each year, equating to approximately half the contribution from copper smelting [3]. Atmospheric arsenic concentrations in coal combustion emissions are generally lower and typically distributed over a wider area. However, in heavily industrialized areas such as around Beijing, concentrations may be substantially greater [9].
Given that high temperature processes are typically associated with fine and accumulation-mode particles, arsenic levels in PM10 and PM2. Comparable average PM10 arsenic concentrations were recorded in Beijing Wind conditions appear to play an important role in the dispersal of atmospheric arsenic emitted by coal combustion sources [9]. Figure 2. Relationship between total atmospheric arsenic concentration and wind speed in Beijing, China, for the period February to March Reprinted from Yang et al.
Mine Tailings Research into mine tailings as a source of atmospheric arsenic has gained momentum in the last decade. Mine tailings have the potential to generate high levels of dust with extremely high atmospheric arsenic concentrations, particularly in arid and semi-arid environments [10]. Comparable with the trend observed around smelting operations, the impact of mine tailings on atmospheric arsenic levels are typically greatest at the source [11,17,18,54].
Arsenic enrichment in the finer fractions of size-fractionated mine tailings has been reported [19,21,57]. Although these findings are not reflective of actual atmospheric arsenic emissions from a particular source, the finer size fractions are more susceptible to wind-borne transport and are most likely to be re-suspended by wind or mechanical disturbance. Kim et al.
Although there were distinct differences in the arsenic distributions amongst the wastes, there were obvious inverse relationships between grain size and arsenic concentration. The high arsenic content recorded in the dust size fraction of each sample range, — ppm illustrates the potential of their corresponding sources to generate potentially hazardous emissions [21].
The effects of seasonality on particulate arsenic emissions from mine tailings have also been investigated. Meteorological factors associated with different seasons, especially rainfall and temperature, have been shown to have a dramatic impact on arsenic mobility through the air [54,90]. During the dry summer months in the City of Lavrion, Greece, concentrations of arsenic in PM10 increased dramatically more than 6 times compared with concentrations during late winter [54,90].
Similarly, a study in Aznalcazar, southwest Spain, found that sporadic rainfall and low convective atmospheric dynamics during the late winter were associated with relatively low re-suspension of PM from heavy metal mining wastes [54]. During summer, the combination of intensive convective circulation and low rainfall facilitates surface drying leading to enhanced re-suspension of PM.
Low rainfall and decreased humidity lead to increased atmospheric particulates, and therefore, increased atmospheric arsenic concentration [90]. The most common forms of arsenic in the environment include the trivalent arsenite and pentavalent arsenate species [93], and they are often found occurring together [94,95]. It is widely recognized that arsenite species have greater mobility in the environment [97] and are reported to be 25 to 60 times more toxic than the corresponding pentavalent forms [98].
Since the oxidation state of arsenic in soil, water, and other environmental matrices is one of the key factors governing toxicity, speciation analysis is of interest in human exposure studies.
Speciation analysis has been used widely for the identification and quantification of arsenic species in bulk samples of surface soils and mine wastes [94,95,99,].
However, comparatively less work has been conducted in relation to arsenic speciation in atmospheric PM generated by mining operations [9,18,44,74—76,83].
Research conducted to date indicates that both arsenate and arsenite may co-exist in smelter, coal combustion and gold roaster emissions [9,44,45,74—76,83,94] although reported levels for the trivalent species are generally much lower than those for the arsenates Table 1.
For example, arsenate and arsenite concentrations in coal combustion emissions in China were 67 and 4. Similarly, Oliveira et al. The presence of arsenite in smelter emissions may result from the reduction of arsenate by aerosol sulphur dioxide S IV complexes during transport of the emission plume []. Airborne monitoring programs combined with speciation analysis demonstrate clearly that airborne arsenic is a serious and ongoing issue in mining communities and heavily industrialized areas throughout the world.
Summary of the average, minimum and maximum total arsenic TAs concentrations recorded in particulate matter PM from various mining operations, including smelting, coal combustion and mine waste. Where applicable, all units of distance measurement have been converted to metric system. Human Exposure Communities living in the vicinity of mining operations may be exposed to airborne arsenic-contaminated particulates and be at risk of health deterioration though absorption after dermal and eye contact, or by ingestion after inhalation [28].
However, arsenic absorption through the skin following dermal and eye contact is a minor contributor compared with ingestion and inhalation exposures [25] and will not be further discussed here. Furthermore, incidental ingestion of arsenic-contaminated particulates, usually as a result of contaminated food or water supplies, has been the most thoroughly investigated pathway, and its significant range of adverse effects have been well documented following acute, intermediate and chronic exposures [25], negating the need for further detailed review here.
For the general population, ingestion is typically considered the primary exposure pathway to arsenic, and inhalation of arsenic bearing PM has been considered to be a minor exposure route [2]. The relatively neglected topic of inhalation exposure with consequent issues linked to airborne PM containing arsenic species from proximate mining industries needs to be addressed.
For example, exposure assessments of communities living in the vicinity of smelting and coal combustion operations suggest that inhalation may play a similar, if not more important role than ingestion, in the overall exposure to airborne particulate arsenic [4,—].
In addition, it has been shown that children are particularly susceptible to inhalation exposure due to: i their increased likelihood of coming into contact with dust [78]; and ii children inhale a greater volume of air than adults relative to their size []. Therefore, in the following sections we will consider some of the ways in which inhaled arsenic-contaminated particulates generated by mining operations may lead to systemic absorption, toxicity, and arsenic-related disease endpoints.
In order to understand how arsenic becomes mobile or bioavailable and exerts its toxic effects in the human body, we will begin with a discussion on the fate of inhaled particles in the RT with particular emphasis on the role that particle size plays in determining the ultimate absorption or defense mechanisms. Deposition Location and Particle Clearance from the Respiratory Tract RT The location and manner in which PM is deposited in the RT are critical for understanding how the arsenic-bearing particles might react with different lung constituents.
When PM is inhaled, a proportion of the particles are retained while the remainder are expelled via exhalation. Retained particles are deposited in different regions of the RT according to their size [—] and as a general rule, the smaller the particle the deeper it will penetrate into the RT and the longer it will be retained Table 2; [72,]. To protect the body against foreign materials, the human respiratory system has developed a range of physiological lines of defense [,].
We will review the deposition location of inhaled particles as a function of particle size, the methods of clearance from each location, and pathways for absorption. Deposition of PM10 in different regions of the human respiratory tract [,] as a function of particle size data from Newman [72] , including the estimated retention time of the particle size in each deposition location data from Bailey [].
The vast majority of particles deposited in the extra-thoracic region are removed via a combination of nose-blowing, sneezing and mucociliary transport to the gastrointestinal GI tract [].
Nose-blowing clears from 0. Particles in the pharynx may reach the GI tract within one hour following deposition [], and a very small proportion around 0. Ingestion is therefore the dominant exposure pathway to particles deposited in the extra-thoracic region.
This region consists of the trachea, bronchi and terminal bronchioles []. Particles deposited here are of particular importance because lung carcinomas occur preferentially in the bronchial airways []. Particles trapped in the mucous produced by the bronchial epithelial cells are typically cleared by mucociliary transport into the throat, and then expectorated or swallowed [28,,]. While it is generally accepted that mucociliary transport is the principal clearance mechanism in the first 24 h [], the rate of clearance depends upon on the clearance velocity of the mucous, particle shape, charge and surface geochemistry [].
Furthermore, the ciliary movement is ineffective if the mucous is not of the correct viscosity due to illness or pharmacological action []. As described in sub-Section 4. Alternatively, these particles may be phagocytosed and cleared by alveolar macrophages, and then either absorbed into regional lymph nodes via lymphatic vessels [] or transported into the ciliated airways and cleared via mucociliary transport []. This latter process may take weeks to months to complete [].
Alveolar macrophages are important cells of the immune system, exhibiting major phagocytic abilities and in response to inflammatory reactions, release reactive oxygen species ROS.
Under normal exposure conditions, the components of the inflammatory reaction interact synergistically with ROS to eliminate foreign material from the respiratory system []. Effects of Exposure Duration and Solubility Variation in the solubility of different arsenic compounds is important for exposure and risk assessment studies [57]. Deposited particles containing soluble arsenic compounds may expose nearby cells to a high concentration of arsenic [], which rapidly declines as the dissolved arsenic is removed from the lungs [] via absorptive mechanisms through the airway epithelium [].
Lantz et al. Less soluble particles on the other hand that are retained in the lung expose the target tissue to arsenic for a longer period of time up to weeks , as observed in rodents after intratracheal instillation of inorganic arsenic compounds of varying solubility [,,,].
In the case of long-term exposure days to years , a steady state between deposition and clearance will be reached and the retained fraction will remain in the lungs for most of the exposure period [].
Consequently, retention of particles containing soluble and slightly soluble arsenic compounds, especially those particles deposited in the alveolar region and sequestered in the lymph nodes, may expose cells to low doses of arsenic for a prolonged period of time.
It is frequently reported that long-term, low-level exposures to arsenic may be predictive of toxic effects [,,] and the pathogenesis of lung diseases, such as lung carcinoma []. Figure 3 illustrates that following inhalation, arsenic can follow different pathways leading to systemic absorption, and each pathway is highly dependent upon particle solubility and method of clearance. Systemic exposure to arsenic may occur as a result of ingestion following mucociliary clearance, by dissolution in the lung fluid, direct entry into lymph nodes, or by phagocytosis.
Systemic exposure to arsenic following inhalation of arsenic-bearing particulates could therefore be considered as a multi-pathway process with differing durations and intensities of exposure. Potential pathways leading to systemic absorption of inhaled arsenic, including clearance mechanisms and their associated durations and intensities of exposure. Adapted from Wang []. Pulmonary Bioavailability of Inhaled Arsenic The bioavailable fraction of arsenic is considered to be an important determinant of toxicity and the associated disease response [].
The term bioavailability may be interpreted in a number of different ways [], however and for the purposes of this review paper, the terms bioavailability and bioaccessibility will be used in accordance with the definitions prescribed by Ng et al. Briefly, the portion of a contaminant that is absorbed into the body following exposure is referred to as the bioavailable fraction and is typically measured in vivo [].
Bioaccessibility on the other hand refers to the soluble fraction of a compound following in vitro gastrointestinal or pulmonary extraction, and may be used as a surrogate for estimating the bioavailability of a contaminant [].
ALF is analogous to the fluid produced by macrophages during phagocytosis [] and has a pH of around 4. Biological fluid pH is an important parameter governing the solubility of arsenic and other metals. For example, arsenic solubility measured as a percentage of the total arsenic concentration of mine waste, was reported as When determining pulmonary arsenic bioaccessibility, it may therefore be prudent to also investigate the behavior of arsenic in the more acidic ALF solution.
A limited number of studies aimed at comparing the bioaccessibility of other metallic compounds in SLF and ALF solutions reported significantly higher dissolution rates of potentially toxic metals in ALF [,]. Conversely, Plumlee et al. Furthermore, the differences may also be attributed to the contrasting dissolution times used in each study: the mine waste and the dry lake dust samples underwent dissolution times of around 2 h [57] and 24 h [], respectively.
Given that fine particles may be retained in the RT for prolonged periods of time Table 2 , incubation duration is a particularly important parameter in bioaccessibility studies.
Pulmonary bioaccessibility tests may be more reliable predictors of bioavailability than the widely-used aqueous solubility tests, since Rhoads and Sanders [] reported that arsenic, and other metals with low aqueous solubility, were highly soluble in the lungs of rats. Summary A summary of some of the key factors governing bioavailability of inhaled arsenic-bearing particles is proposed Figure 4.
Particle size governs the deposition location of inhaled particulates in the RT. Knowledge of the location and solubility of deposited particles is important for predicting the methods of clearance from and retention time in the RT, and therefore the types of lung fluids with which the particles may interact. Contact with pulmonary fluids can then release arsenic from inhalable arsenic-bearing particulates.
Since the retention of arsenic in the body is predictive of toxicity and the pathogenesis of disease [,,], the long-term pulmonary bioavailability of arsenic represents important consideration in the health risk assessment of populations living in mining-affected regions. Figure 4. Diagrammatic representation of the interactions between key factors governing the pulmonary bioavailability of arsenic.
Importance of Metabolic Transformation in Arsenic Toxicity 5. Arsenic Biomethylation The role of metabolism in arsenic toxicity has been the subject of several detailed reviews [—] therefore the following discussion will provide an overview of the key concepts only. Methylation is the major metabolic pathway for ingested inorganic arsenic in most mammals, and occurs via alternating reduction of pentavalent arsenic to the trivalent state, followed by oxidative addition of a methyl group [,—].
The remaining portion deposits differentially in other target organs and tissues including the kidneys and the lungs, as well as keratinized tissues such as skin, nails, and hair [—]. Various studies have demonstrated that the unstable trivalent intermediary products, MMAIII and DMAIII, are highly reactive and substantially more toxic than the inorganic and pentavalent compounds [,,,,].
Arsenic methylation is therefore widely considered to be a bioactivation pathway rather than a detoxification process [], with the resulting toxicity closely linked to the methylation status and valence state of the metabolites [].
Therefore, understanding the arsenic biomethylation pathway is critical to elucidating its subsequent action as a toxin and carcinogen []. Figure 5. Metabolic pathway of inorganic arsenic. Reprinted from Chilakpati [] with permission from Elsevier.
Oxidative Stress as a Mode of Action for Arsenic Carcinogenesis Although several modes of action for arsenic carcinogenesis have been presented in the literature including oxidative stress, suppressed DNA repair, altered methylation patterns, genotoxicity and cell proliferation [], the oxidative stress theory has been intensively investigated and is supported by a substantial mass evidence [—].
Oxidative stress refers to an imbalance between the production of reactive oxygen species ROS , or free radicals, and antioxidant defense mechanisms [].
Free radicals are characterized by the presence of unpaired electrons and the associated reactivity can lead to tissue injury []. The first oxidative stress theory for arsenic proposed that a minor metabolite of DMAV, dimethylarsine a trivalent arsenic compound , is produced via a process of reduction in vivo [], possibly following a reaction between DMAIII and specific coenzymes important for cellular respiration [].
Dimethylarsine is estimated to be around times more toxic than DMAIII which is a potent genotoxin in its own right []. Through the addition of another molecule of oxygen, the dimethylarsenic radical forms the dimethylarsenic peroxyl CH3 2AsOO radical.
The generation of oxidative stress as a potential mode of action of arsenic for its disease endpoints is an ongoing area of research and the associated complexities have been comprehensively reviewed [,,,]. The Human Lung as a Target Organ for Arsenic Toxicity Remarkably, arsenic is the only reported human lung carcinogen for which there is sufficient evidence of pulmonary carcinogenicity as a result of both inhalation and ingestion exposures [25,].
Smith et al. Distinguishing between the different routes of exposure is complicated not only by the arsenic transformations that take place in the body, but also the common target organs following the different exposure pathways []. The high variability in pulmonary solubility observed for different arsenic compounds [,,] also represents a confounding factor.
For systemically absorbed arsenic, via inhalation or ingestion, research suggests that the pulmonary system may function as a target tissue for toxicity based on the observation that dimethylarsine is excreted as a gas from the circulation via the lungs [,]. High partial pressures of molecular oxygen in the lungs may promote dimethylarsenic and dimethylarsenic peroxyl radical formation as dimethylarsine is excreted and passed through to the respiratory system [,,].
According to Styblo et al. A reduced capacity to methylate arsenicals could be associated with an increased risk of toxicity due to prolonged retention of inorganic arsenic in the lung []. In support of these observations, various in vivo studies have reported that arsenic toxicity is closely linked with a prolonged retention of inorganic arsenic in the lungs of rodents [,].
Further studies to examine the direct effects of inorganic arsenic compounds on pulmonary cells in order to elucidate the carcinogenic mode of action of retained arsenic-bearing particulates are suggested. Direct Effects of Arsenic on Pulmonary Cells Some of the key effects of arsenic exposure on a range of different pulmonary cell lines are summarized in Table 3.
Since the dose response of arsenic can be substantially different in animal models compared with in vivo human exposure [], this section will primarily focus on studies involving pulmonary cell lines, specifically human bronchial epithelial HBE cells derived from human lung epithelium [], alveolar macrophage AM cells, which are typically harvested from animals [], and human pulmonary fibroblast HPF cells.
HBE and AM cells represent the first lines of defense against foreign particles [], while HPF cells are important for regeneration and repair of chemically or mechanically damaged tissues []. As discussed by Dodmane et al. Pulmonary Cytotoxicity of Arsenic Cytotoxicity assays, and the measurement of representative parameters associated with cell pathology, are widely used to quantitatively assess the in vitro potency of a toxicant in the whole animal.
Clear dose-response relationships between arsenic concentration and cytoxicity have been established in HBE cells [,,—], HPF cells [—] and AM cells []. Figure 6 shows a notable decrease in HPF and HBE cell survival, in a time- and concentration-dependent manner, following 24 and h treatments with sodium arsenite []. A similar study found that arsenic trioxide was also toxic to HPF cells, however greater concentrations were required to produce similar effects [].
The differential cytotoxicities observed between these two trivalent arsenic compounds can be attributed to the fact that arsenic trioxide has a lower solubility in the lung than sodium arsenite []. Consistent with other lines of evidence presented in previous sections, recent studies confirm that methylated arsenicals are more cytotoxic to pulmonary cells than the inorganic trivalent forms [,,].
Cytotoxicity was quantified by measuring reductions in cell number, cell volume and colony formation following a 24 h exposure period [,]. Differences in arsenic-induced cytotoxicity endpoints reported in the literature may be attributed to variability in a number of experimental parameters: i the arsenic species or compound; ii the cell exposure duration; ii the cell systems used in each study; and iii the methods for assessing cytotoxicity endpoints.
Moreover, chronically exposed arsenic-transformed HBE cells constitutively generate cellular ROS probably hydrogen peroxide in the absence of further arsenic exposure []. Constitutive generation of ROS was found to be necessary for activating certain signaling pathways that regulate cell survival and cell proliferation []. Enhanced arsenic-induced ROS generation and accumulation have been associated with dose-dependent responses in rates of cell proliferation and colony formation in HBE cells [—] as well as anti-apoptotic signaling [].
Increased cell proliferation is a distinguishing characteristic of cancer cells and is crucial for tumor formation, while apoptosis plays an important role in killing abnormal cells so that they cannot form tumors []. One study reported that increased cell proliferation of arsenic-exposed cells was mediated by anti-apoptotic-signaling induced by cyclooxygenase, COX-2 [], an enzyme associated with inflammation and other pathogenesis [].
Cytotoxicity of sodium arsenite in: A human lung fibroblast cells, and B human lung epithelial cells, following 24 and 12 h treatments. Reprinted from Xie et al. ROS production has also been linked with gene expression changes in HBE cells consistent with several of the proposed mechanisms for arsenic carcinogenesis [] including oxidative stress, DNA damage and a weakened tumor-suppression response [,,].
Suckle et al. The in vivo study identified phenotypic characteristics consistent with malignant lung epithelial cells [], and whole genome expression profiling identified potential mitochondrial oxidative stress and increased metabolic energy output, which is indicative of increased mitochondrial energy production [].
Importantly, chronic arsenic exposure may therefore target mitochondrial function leading to enhanced ROS generation and cancer-related gene signaling []. Antioxidants that target mitochondrial function could play a role in ameliorating some of the effects of arsenic in chronically-exposed populations []. The Warburg effect is a metabolically supportive phenotype for the increased energy demands associated with the growth, proliferation and invasion of cancer cells see the review by Vander Heiden et al.
Unlike normal cells which produce lactate under anaerobic conditions only, the Warburg effect states that cancer cells generate large quantities of lactate regardless of oxygen availability [].
This study was potentially the first to link an environmental toxicant with the induction of the Warburg effect, and thus this discovery may assist in identifying the role of arsenic toxicity in other diseases associated with disrupted energy metabolism, such as diabetes and atherosclerosis [].
Arsenic-Induced Suppression of Alveolar Macrophage AM Function Alveolar macrophages AM serve as the front line of cellular defence against foreign material by clearing the air spaces of any infectious, toxic or allergenic particles that have penetrated mechanical defences, such as the nasal passages and mucociliary transport system [].
Under normal conditions, ROS are secreted by alveolar macrophages in response to phagocytosis or stimulation with specific agents, and play a key role in efficiently killing invading pathogens []. Various detrimental effects of arsenic on these important cell functions have been observed Table 3.
For example, Palmieri et al. Soluble trivalent arsenic was notably more potent at inhibiting ROS production than the corresponding pentavalent form, with superoxide inhibition occurring at respective concentrations of 0. Gercken et al. Both the studies by Lantz et al. Suboptimal phagocytosis by AM cells has been associated with a decreased ability to clear dead or dying cells from the respiratory system thereby leading to pathological inflammation [] as well as an increased susceptibility to pulmonary infection such as pneumonia, in respiratory health-compromised individuals [].
Arsenic-Induced Inhibition of the Wound Healing Response in Human Bronchial Epithelial HBE Cells As the respiratory epithelium is frequently injured by inhaled pollutants or micro-organisms, the epithelial wound repair response plays a critical role in the maintenance of epithelial barrier integrity [].
Concentration-dependent arsenic-induced inhibition of wound healing in mechanically-wounded HBE cells has been demonstrated Table 3. The highest concentration ppb resulted in the expansion of the wound area in the first hour, followed by Further analyses indicated that overexpression of matrix metalloproteinase MMP-9 , an enzyme important for human respiratory healing and wound closure [], leads to dysregulated wound repair in the presence of arsenic and reductions in cellular migration [].
Furthermore, general interference with airway ATP signalling has been linked with chronic lung diseases, such as chronic obstructive pulmonary disease COPD []. Arsenic-induced suppression of the wound healing response as a result of both acute and chronic exposures well below levels typically associated with inhalation where arsenic has been linked with disease presentation may ultimately result in a reduced ability of the lung epithelium to effectively and sufficiently close a barrier breach [,,].
Wound healing assay of 16HBE14o- cells exposed chronically 4—5 weeks to 0, , or nM sodium-arsenite: A Representative images of initial wounding left column , 30 min post-wounding middle column , and 1 h post-wounding right column. Reprinted with permission from Sherwood et al. Direct effects of arsenic exposure on human bronchial epithelial HBE cells, human pulmonary fibroblast HPF cells, and pulmonary alveolar macrophage AM cells. All experiments were conducted in vitro, unless otherwise specified.
Specific cell lines are listed in accordance with the abbreviations used in each study. Human bronchial or alveolar epithelial cells Dose-dependent reduction in cell survival; chromosomal aberrations Na-arsenite 0.
Epidemiological and Exposure Monitoring Epidemiological studies provide an important link between health effects and air pollution exposure, because they provide an accurate representation of the health records and environmental conditions pertaining to a well-defined population []. In this regard epidemiological studies of industrially-exposed cohorts conducted during the mids have provided strong evidence of a causative role for airborne arsenic in respiratory cancer mortality.
This has resulted in a diverse but important body of historical epidemiological evidence accrued on the health risks and disease outcomes associated with known, high level occupational inhalation exposures [—]. However, with increasing concerns regarding the effects of peripheral exposure to potential carcinogens, there is increasing attention directed at the health of communities living in the vicinity of smelting and mining operations and uncontained mine wastes and tailings.
Notwithstanding the common source of the concerns, it has been observed that there are important differences between the situations of occupationally- and environmentally-exposed cohorts.
Occupational studies usually differ methodologically from the environmental investigations in that there is a contained area of contamination and a restricted population who are exposed to high levels of airborne material. Whereas studies of environmental exposure in communities living in arsenic-affected areas usually start at birth, and the exposure itself may not be recognized for many years and may be intermittent, thereby rendering epidemiological studies more difficult to design and interpret, particularly since they are observational only.
For these reasons, we report separately on the findings for each exposure type, since they will address different aspects of the effects of airborne particulate matter on health. Similar conditions were reported at the Ronnskar smelter in Sweden []. Lower values for airborne arsenic were typically found in areas such as the administration departments, electrical and machine workshops, outdoor environment, building department and general office area [,]. Symptoms of severe arsenic exposure among smelter workers observed during the s included a notable rise in the rate of sick days due to various acute and chronic respiratory disorders [].
Arsenic trioxide-laden dust generated as a by-product of the copper smelting process deposited in the nose and respiratory airways forms arsenous acid on contact with moisture, resulting in necrosis of the mucous membranes []. Emphysema and ischemic heart disease were also noted []. Despite the prevalence of these non-malignant respiratory disorders, meta-analysis of the available epidemiological data did not detect any statistically significant excesses in mortality among smelter workers compared to the control cases [,].
The first cases of lung cancer that were traced to the work environment occurred at a Swedish smelter in the s whereby a five-fold increase in lung cancer mortality compared with controls was observed []. Occupational health investigations at other smelting operations, as well as comprehensive reassessments and meta-analyses of previously reported data, demonstrated strong links between airborne arsenic exposure and respiratory cancer [—,,].
Lubin et al. Over a 50 year period, deaths due to respiratory cancers were observed, comprising lung cancers and 14 cancers of the larynx. No other cause of death was found to be associated with arsenic exposure, with the possible exception of COPD []. In addition to smelting, other studies have demonstrated a link between lung cancer and arsenic exposure at hard rock mining operations []. One of the most comprehensively investigated cases relates to four tin mines and three associated smelting operations in southern China, where underground miners were exposed to respirable concentrations of arsenic ranging between 0.
Chen and Chen [] reported that the rates of lung cancer were strongly associated with cumulative dust exposure, arsenic exposure and duration of exposure. While the magnitude of risk from mining odds ratio OR , 8. The potential additive carcinogenic effects of inhaled crystalline silica, cigarette smoking and exposure to radon could not be ruled out []. To examine the distribution of arsenic in the body following long-term exposure, researchers collected and analysed tissues from deceased workers from the Ronnskar smelter in Sweden, and from various controls, and correlated these with the cause of death [].
Post-mortem investigations discovered elevated levels of arsenic and seven other metals of concern in the lung, liver and kidneys of the deceased workers [,]. Although the arsenic content diminished in liver tissue, a longer biological half-life of arsenic was observed in the lung [].
Similar findings have been reported in animal studies []. An extended biological half-life and retention of arsenic in lung tissue may have implications for the development of respiratory disease. Lung cancer risk in a cohort of Chinese tin miners was more dependent on the duration of arsenic exposure than then intensity [].
Conversely, exposure intensity was more important in determining the lung cancer risk than duration in smelter workers [,], indicating a need for comparative studies with consistent exposure and outcome criteria. However, occupational inhalation exposure to airborne arsenic remains a serious health issue in some localities.
Urinary arsenic speciation analysis revealed that higher occupational exposures and skin damage cases were associated with a decreased capacity for arsenic methylation []. Similar results have been reported elsewhere []. These findings support the premise that suppressed methylation capacity results in an increased risk of arsenic toxicity due to the retention of arsenic in the body [].
Inadvertent Environmental Exposures It has been found that a number of populations around the world live in the vicinity of active or abandoned mining operations [28], and there exists overwhelming epidemiological evidence suggesting that there is an increased risk of arsenic exposure for these communities [4—9,78,,].
These studies show that children are particularly susceptible to inhalation exposure since they respire a greater relative volume of air with respect to their size, and may therefore be exposed to correspondingly higher levels of airborne contaminants than adults.
Children also have an increased likelihood of coming into contact with soil and dust through playing in dirt contaminated with arsenic residues [78,,]. As a consequence, many human exposure monitoring studies have focussed on measuring arsenic exposure in child populations [4,7,,,,]. Measurement of arsenic in human nails, hair, urine and blood concentrations are commonly used for determining arsenic uptake in humans [78,,,,].
Blood and urine arsenic levels provide a reliable short-term measure of arsenic exposure because arsenic is readily excreted from the bloodstream via the kidneys [25]. Analysis of arsenic deposited in the toenails and hair provides useful indicators when the measurement of long-term, low-level arsenic exposure is required [—]. It has also been shown that analysis of the arsenic content of particles that have adhered to the hands of children can also be used as an indicator of potential exposure [4].
It is important to note that although such biological markers of arsenic exposure as those reported above are useful for predicting the degree of risk, elucidating the exact pathway to environmental uptake of arsenic in localities where multiple exposure pathways exist is not straightforward [].
However, particles that have been deposited on the ground or other surfaces may be either ingested due to physical contact, or resuspended as dust, and then inhaled [19,]. From the work reported in the above investigations, it is clear that human arsenic exposure is governed by a number of variables.
There are important inverse relationships which have been frequently reported between the concentration of airborne arsenic levels and the distance from the source, and between biological arsenic levels and the distance of the home, playground or school environment from metal smelters and other mining operations [4,7,,]. Buchet et al. Correspondingly, the average arsenic concentration on the hands of children living within the 1 km zone was ten times greater than those children living further away [4].
Similarly, Hwang et al. As cautioned by Frost et al. Milham and Strong [] demonstrated that fluctuations in urine arsenic levels among children living near a copper smelter were closely associated with changes in prevailing wind direction.
In this study, the urine arsenic concentrations of children living downwind of the smelter decreased simultaneously with shifts in wind direction [].
Another study of children living near a former copper smelter site reported elevated biological arsenic levels during the summer, a time when seasonal factors enhance the mobilisation of dust from uncontained mine wastes, such as tailings and flue dust [].
Carcinogenic and non-carcinogenic risks associated with inhalation exposure to atmospheric arsenic emitted by coal combustion have recently been estimated in exposed Chinese populations [9,]. Consequently, it has been estimated that more than two million residents in Beijing have an increased risk of developing cancer as a result of probable exposure to atmospheric arsenic, generated principally from coal combustion [9].
Recent measures of daily total inorganic arsenic inhalation exposure values for Beijing residents 0. These studies indicated that daily intakes of arsenite and arsenate in Beijing were 0.
The House Committee on Transportation and Infrastructure
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