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Arsenic Toxicity
Who is at Risk of Overexposure to Arsenic?

Course: WB 1576
CE Original Date: October 1, 2009
CE Renewal Date: October 1, 2011
CE Expiration Date: October 1, 2013
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Learning Objective

Upon completion of this section, you will be able to
  • identify the populations most heavily exposed to arsenic.


Today in the United States, the quantity of arsenic released by human activities exceeds amounts released from natural sources at least threefold.

The major sources of arsenic release to the environment are

  • arsenic-treated lumber discarded in landfills, and
  • coal fired power plants.

In addition, water and soil concentrations are far higher in areas where arsenic mineral deposits have been mined. The areas in the United States with the highest natural groundwater concentrations of arsenic are the Southwest, Northwest, Northeast, Alaska, and other areas near geothermal activity [ATSDR 2007].

Groundwater may also contain elevated concentrations of arsenic due to contamination from arsenical pesticide runoff. Groundwater is far more likely to contain high levels of arsenic than surface water. The concentration of arsenic in natural surface and groundwater is generally about 1 part per billion (ppb), but both may exceed 1,000 ppb in mining areas or where arsenic levels in soil are high [ATSDR 2007].

The U. S. Environmental Protection Agency (EPA) maximum contaminant level for arsenic in drinking water is 10 ppb. Surveys of U.S. drinking water indicate that about 80% of water supplies have less than 2 ppb of arsenic, but 2% of supplies exceed 20 ppb of arsenic [ATSDR 2007]. Both the trivalent and pentavalent forms of inorganic arsenic can be found in drinking water.

Low levels of naturally occurring mineral arsenic are present in soil.

Past Occupational Exposure

In the past, many occupations entailed exposures to arsenic (see Table 3). Studies have documented the scale of the problem.

Table 3. Past occupational exposure to arsenic.
Trades Occupations
  • Construction/contracting
  • Ore smelting
  • Semiconductor manufacture
  • Alloy manufacturing
  • Carpenters
  • Chicken and swine farming
  • Electronic manufacturing technicians
  • Pesticide, insecticide, and/or herbicide applicators
  • Smelter operator or engineer

Children's Exposures

Children may be exposed to arsenic in different ways.
  • Burning plywood treated with an arsenate wood preservative in a poorly ventilated cabin has been blamed for poisoning a family in rural Wisconsin [ATSDR 2007].
  • Wood treated with copper chromated arsenate (CCA) to prevent rotting due to growth of microorganisms is commonly used in marine applications, patio decks, and recreational structures for children's playgrounds. Cutting this wood or leaching of the preservative may lead to arsenic exposure. However it is not known whether, or to what extent, CCA-treated wood products may contribute to the exposure of people to arsenic [ATSDR 2007].
  • Children who play on wood structures treated with CCA have increased likelihood of dermal contact or ingestion of the arsenical through normal mouthing and play activities [ATSDR 2007].
  • Soil with high levels of arsenic is also an exposure risk for children due to pica or mouthing and play activities.
  • Drinking water contaminated with arsenic is another exposure risk for children.

Current Occupational Exposures

Currently, the most heavily exposed people in the United States are in those industries that use arsenic-containing compounds, including [Rossman 2007]

  • carpentry involving CCA pressure-treated lumber, and
  • copper or lead smelting,
  • electronics manufacturing industry,
  • pesticide application.

Non-Occupational Exposures

Situations in which non-occupational exposure to arsenic can occur.

  • Arsenic can cross the placenta, increasing the likelihood of exposure to the fetus [Lugo et al. 1969].
  • Living near sources of high ambient air levels of arsenic.
  • Water supply containing high levels of arsenic.

Exposure at School

Situations where students may be at risk of exposure to arsenic while attending school.
  • Schools whose water supply comes from wells contaminated with high levels of arsenic
  • Schools that have CCA-preserved wood playground equipment/structures.
  • Children who play on wood structures treated with CCA have increased likelihood of dermal contact or ingestion of the arsenical through normal mouthing and play activities [USEPA 2005].
  • Schools that are located near an industrial source that may emit arsenic into the air (such as a smelter).

Background Exposures

As a naturally occurring mineral, arsenic may be found in soil and/or groundwater. The National Health and Nutrition Examination Survey (2003-2004) measured levels of total arsenic and speciated arsenic in urine of a representative sample of the US population. The data reflect relative background contributions of inorganic and seafood-related arsenic exposures in the U.S. population [Caldwell et al. 2008].

Exposure to Arsenicals in Unexploded Ordnance

Exposure of the general public to unexploded ordnance containing chlorovinyl dichloroarsine (also known as lewisite) has been reported at U.S. locations where former munitions ranges were transferred from the military to be used for other purposes. These properties are formerly used defense sites or property transferred by the past five rounds of Base Realignment and Closure (i.e., 1988, 1991, 1993, 1995, 2005). The Department of Defense is currently working to further define the inventory of sites and acreage that are potentially contaminated with military munitions and to prioritize these sites for cleanup [EPA 2008].

Key Points

  • Groups at risk for overexposure to arsenic may include
    • Industrial workers.
    • People who work with CCA treated lumber.
    • Those who drink water from private wells with high levels of arsenic in certain geographic areas.
    • The fetus of a mother exposed to arsenic.

Progress Check

5. Currently, occupations that may entail exposure to arsenic include which of the following?

A. Sheet metal workers and pipe fitters.
B. Workers in computer chip fabrication facilities.
C. Shipyard workers and automobile mechanics.
D. Carpenters cutting lumber treated with arsenic-containing preservatives.
E. B and D.
F. A and C.


To review relevant content, see "Current Occupational Exposure" in this section.

6. Of the following, who is LEAST LIKELY to be at risk of arsenic exposure and toxicity?

A. A child attending a school with arsenic-containing wooden playground.
B. An adult who works as a smelter.
C. A person whose primary source of drinking water is from an artesian well.
D. A suburban family receiving municipal utility services.


To review relevant content, see "Exposure at School," "Past Occupational Exposure," and "Non Occupational Exposures" in this section.

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