Day: October 12, 2009

Is There Arsenic in My Environment?

Patient Presentation
A pediatrician was at a professional conference and was discussing lead toxicity with some colleagues. One person made the comment that lead was a huge problem but he also had to deal with arsenic in his area. The pediatrician registered surprise and inquired why. The other pediatrician noted that in his area there were many military installations and therefore there was contaminated soil. He said that building ordinances only allowed building down to a certain depth to minimize potential exposure and ground water was monitored closely. The pediatrician was interested in finding out if there was arsenic in her local environment and found a map of arsenic in ground water for the United States from the National Geological Survey. Unfortunately there was no data for her area.

Discussion
Arsenic (As) is a semimetal found in Group 15 of the Periodic Table of Elements which is shared by Nitrogen, Phosphorus, Antimony and Bismuth. It is not considered by chemists as a heavy metal, but is often lumped in with Mercury and Lead because all have similar toxic affects. Elemental arsenic is not toxic itself, but inorganic and organic compounds are toxic. Trivalent inorganic compounds are particularly toxic because they are highly lipid soluble. Arsenic is bound by plasma proteins, hemoglobin and leukocytes and then is concentrated in the gastrointestinal tract, liver, kidneys, spleen, and lungs. Acute toxicity can cause an acute paralytic syndrome with cardiovascular collapse, central nervous depression and death within hours. It can also cause an acute gastrointestinal syndrome including acute vomiting and hematemesis, profuse diarrhea and hematochezia. Acute multiorgan system failure can then occur. Chronic toxicity usually has skin changes (i.e. melanosis, keratosis) and peripheral neuropathy as common presentations. Arsenic is also a carcinogen.

Exposures to arsenic include:

  • Environment – water, air, marine animals, and fossil fuels. Fruits, vegetables, milk and rice can also be contaminated, as can glues and pigments.
  • Industrial exposures through manufacturing glass and electronics, wood preservatives, metal alloy hardening, and pesticides and herbicides.
  • Arsenic is also used as a poison for suicide or homicide. Arsenic can be used as a vesicant or inhalation chemical warfare agent.

Children are most likely to encounter arsenic through contaminated food and water and through pesticides and herbicides. Adults are most likely to encounter arsenic through occupational exposure.

Arsenic levels are best determined from a 24 hour urine sample, as blood is unreliable. Treatment includes decontamination and chelation therapy using 2,3-dimercaptopropanol (aka BAL) and Dimercaptosuccinic Acid (DMSA).

Learning Point
The United States National Geological Survey made several maps of arsenic in ground water in 2001, with data collected from public and private water supplies. In many areas of the country no data is available. This is particularly true in rural areas where many people rely on ground wells which are generally unregulated.

Like any scientific data, the maps can be interpreted in many different ways and the American Geological Institute published an article describing some of these nuances:

“If the question is, “Where are the most people exposed to arsenic?” the resulting map might point to areas of dense population relying on large public water supply systems. To answer, “Where are people exposed to the highest levels of arsenic?” a map might finger rural areas where private wells containing high arsenic concentrations commonly go untreated. A map answering, “Where will reducing arsenic be most costly?” could identify areas with the greatest number of wells high in arsenic; or where high arsenic occurs with high sulfate; or where drilling new wells may be required. These different “treatment cost” maps may not point to the same areas that other maps highlight to show the “most population” and “highest arsenic.””

For much of the country there is no available data. However, the maps can give health care providers some idea if their patients and themselves are potentially living in an environment where arsenic is a problem.

One paper using a statistical model estimated that 8.2% of the area of the United States is potentially contaminated. This is contrasted with other global areas particularly South East Asia in Bangladesh (35.4%) and Cambodia (45.8%) and Vietnam (15.8%). If the arsenic problem is measured in other terms (such as the number of people estimated to be drinking contaminated water) Bangladesh is by far the country with the worst arsenic problem.

Questions for Further Discussion
1. Is your local environment contaminated with arsenic?
2. What are the clinical signs of mercury toxicity?
3. What are the clinical signs of lead toxicity?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Arsenic

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

Cullen NM, Wolf LR, St Clair D. Pediatric arsenic ingestion. Am J Emerg Med. 1995 Jul;13(4):432-5.

U.S. Geological Survey, 200212, Arsenic in Ground Water of the United States: National Atlas of the United States, Reston, VA.
Available from the Internet at http://water.usgs.gov/nawqa/trace/arsenic/ (cited 9/10/09).

Ryker S. Mapping arsenic in groundwater. Geotimes. Available from the Internet at http://www.agiweb.org/geotimes/nov01/feature_Asmap.html (rev. 11/2001, cited 9/10/09).

Amini M, Abbaspour KC, Berg M, Winkel L, Hug SJ, Hoehn E, Yang H, Johnson CA. Statistical modeling of global geogenic arsenic contamination in groundwater. Environ Sci Technol. 2008 May 15;42(10):3669-75.

Rahman MM, Ng JC, Naidu R. Chronic exposure of arsenic via drinking water and its adverse health impacts on humans. Environ Geochem Health. 2009 Apr;31 Suppl 1:189-200.

ACGME Competencies Highlighted by Case

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

  • Practice Based Learning and Improvement
    12. Evidence from scientific studies related to the patients’ health problems is located, appraised and assimilated.
    13. Information about other populations of patients, especially the larger population from which this patient is drawn, is obtained and used.
    14. Knowledge of study designs and statistical methods to appraisal clinical studies and other information on diagnostic and therapeutic effectiveness is applied.
    15. Information technology to manage information, access on-line medical information and support the healthcare professional’s own education is used.

    Author
    Donna M. D’Alessandro, MD
    Professor of Pediatrics, University of Iowa Children’s Hospital