The Broad Scope of Health Effects From Chronic Arsenic Exposure

Update on a Worldwide Public Health Problem

Marisa F. Naujokas; Beth Anderson; Habibul Ahsan; H. Vasken Aposhian; Joseph H. Graziano; Claudia Thompson; William A. Suk

Disclosures

Environ Health Perspect. 2013;121(3):295-302. 

In This Article

Worldwide Concerns for Arsenic Exposure

Arsenic exposure is a major environmental public health concern worldwide and a primary concern for exposure is via drinking water ( Table 1 ). The WHO and Australia set or confirmed a guideline level of 10 μg/L for arsenic in drinking water in 2008 and 2011, respectively (National Health and Medical Research Council 2011; WHO 2008). The U.S. EPA promulgated that it lowered the maximum contaminant level (MCL) from 50 μg/L to 10 μg/L, effective in 2002 (U.S. EPA 2001). In many developing countries, including Bangladesh, 50 μg/L is still the commonly adopted guideline, primarily because of difficulties in remediating arsenic below that level (WHO 2008). The excess cancer risk associated with lifetime arsenic exposure at water concentrations of > 10 μg/L is approximately 1 in 300, which is 30–300 times higher than the cancer risks estimated for exposure to other known carcinogens in drinking water at concentrations equal to current U.S. drinking-water standards (Smith et al. 2002).

What is the extent of chronic exposure via drinking water? The answer varies greatly depending on regional and local sources of arsenic ( Table 1 ). For example, in Maine, the U.S. Geological Survey reported that 18.4% of wells tested had > 10 μg/L arsenic and estimated that 24,000–44,000 households might be affected (Nielsen et al. 2010). A recent study predicted that 42.7% of the area of aquifers in the southwestern United States has arsenic concentrations of ≥ 10 μg/L, although portions of these areas are in remote regions (Anning et al. 2012). Of 63,000 wells tested in North Carolina, 1,436 (2.3%) had arsenic concentrations of > 10 μg/L with a maximum of 806 μg/L (Sanders et al. 2012). In comparison, in Bangladesh in 1998, shortly after discovery of arsenic contamination, it was estimated that up to 94% of tube wells in certain regions and 35% of all wells in the country contained > 50 μg/L arsenic (Smith et al. 2000b). In Chile, San Pedro de Atacama drew most of its public drinking water from the Vilama River, which contained approximately 600–680 μg/L arsenic, and some homes with no public supply drew water from the San Pedro River, which contained 170 μg/L; in contrast, a town 40 km away had an average drinking-water arsenic concentration of 15 μg/L (Hopenhayn-Rich et al. 1996).

Testing is required to determine whether a given source of drinking water has high levels of arsenic. Even if the local municipality does not test private wells for arsenic, test kits are available worldwide through local municipalities, public health offices, and commercial sources accessible via the Internet (Water Quality Association 2012; Massachusetts Department of Environmental Protection 2011). Hot spots of arsenic contamination of drinking-water sources can occur because of proximity to naturally occurring arsenic found in certain types of bedrock and sediments as well as proximity to hazardous waste sites. Therefore, drinking-water sources with high arsenic concentrations can exist in very close proximity to sources with low arsenic concentrations, with differences noted even in neighboring individual wells.

Another source of growing concern for arsenic exposure is through diet. For persons with limited exposure to arsenic via drinking water, diet is the major source of exposure (EFSA 2009). Rice, organic rice syrup, fruits, juices, and other grains can contain significant amounts of arsenic (FDA 2012; Jackson et al. 2012; Norton et al. 2012). Furthermore, rice consumption has been shown to be associated with urinary arsenic levels in pregnant women and children (Davis et al. 2012; Gilbert-Diamond et al. 2011). Because of their level of consumption of rice products, children < 3 years of age are estimated to have the greatest exposures to arsenic via diet (EFSA 2009).

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