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AN UPDATE ON SOME ARSENIC PROGRAMS AT THE US EPA
Citation:
Abernathy, C. O., M. Beringer, R L. Calderon, T. F. McMahon, AND E. Winchester. AN UPDATE ON SOME ARSENIC PROGRAMS AT THE US EPA. International Conf on Arsenic Exposure and Health Effects V, July 19 - 21, 2002.
Description:
An Update on Some Arsenic Projects at the United States
Environmental Protection Agency*
Charles O. Abernathy1, Michael Beringer2, Rebecca L Calderon3,
Timothy McMahon4 and Erik Winchester3
Offices of Science and Technology1, Solid Waste and Emergency
Response2, Research and Development3 and Pesticides Program4,
Washington, DC and Research Triangle Park, NC
Please address all Correspondence to: Dr. Charles O. Abernathy, Office of Science and Technology (4304T), US EPA, 1200 Pennsylvania Avenue NW, Washington, DC 20460-0001,
p: 202-566-1084; f: 202-566-1140; Email: abernathy.charles@epa.gov
* The opinions expressed in this manuscript are those of the authors and do not necessarily reflect the opinions or policies of the US Environmental Protection Agency.
RUNNING TITLE: Some Arsenic Programs at the US EPA INTRODUCTION Although arsenic (As) can exist in four valence states (-3, 0, +3, and +5; Welch et al., 1988), the primary toxic environmental forms are arsenate (+5) and arsenite (+3). Both natural and anthropogenic sources contribute to the environmental As load. Natural sources include the geologic formations (e.g., rocks, soil, and sedimentary deposits), geothermal and volcanic activity. The concentrations of As in the earth's crust vary, but are generally reported to range from 1.5 to 5 mg/kg (NAS, 1977, Abernathy et al., 1997; ATSDR, 2000).
Anthropogenic sources include wood preservatives, pesticides, industrial, mining and smelting wastes. Their relative impact depends on factors such as the level of human activity, distance from the pollution sources, and dispersion and fate of the released As. In recent years, about 90% of the US annual industrial As use is for chromated copper arsenate (CCA; ATSDR, 2000). CCA is used in wood treatment for construction of decks, fences or other outdoor residential applications, but under a voluntary agreement reached with the wood treatment industry, these uses are being phased out (FR, 2002). Agricultural uses of As included pesticides, herbicides, insecticides, defoliants, and soil sterilants. Inorganic As pesticides are no longer used; the last agricultural application was canceled in 1993 and are presently only used in sealed ant bait and wood preservatives. Organic arsenicals are still a constituent of some pesticides. The most widely used is monosodium methanearsonate (MSMA), applied to cotton to control broadleaf weeds (Jordan et al., 1997), Small amounts of disodium methanearsonate (DSMA) are also applied to cotton fields as herbicides. Other organic arsenicals (e.g., roxarsone and arsanilic acid) have been approved by the Food and Drug Administration for use as feed additives for poultry and swine and these additives undergo little or no degradation before excretion (NAS, 1977).
Since arsenicals vary greatly in their toxicity, it is important to consider the form and valence state in assessing toxicity. [When As is reported as total As, the data are often of little use in understanding As toxicity and exposure.] However, we do have some data on the various forms of As. In fish and seafood, the organic forms, arsenobetaine (AsB) and arsenocholine (AsC), appear to have little or no toxicity (Sabbioni et al., 1991; Donohue and Abernathy, 1999). Accordingly, the early focus was on the inorganic forms of As [arsenite (+3) and arsenate (+5); NRC, 1999). Recently, however, it has been reported that the trivalent (+3) monomethylated and dimethylated metabolites of inorganic As are the most toxic forms and are the most likely candidates for the putative active forms (Thomas et al., 2001).
Inorganic As can exert many adverse health efforts after acute or chronic exposures. At nonlethal, but high doses, As can cause gastroenterological effects, shock, neuritis and vascular effects in humans (Buchanan, 1962; Abernathy et al., 1997). Although acute exposures to high doses of As can cause adverse effects, the EPA is mainly concerned with the chronic effects of exposure to low concentrations of As (North et al., 1997).
HEALTH EFFECTS
NON-CANCER Many non-carcinogenic effects have been reported in humans after exposure to As-contaminated drinking water. The most commonly observed signs are dermal, including alterations in pigmentation and palmar-planter keratoses on the hands, the soles of the feet and the torso. Their presence on parts of the body not exposed to the sun is characteristic of As exposure (Yeh, 1973). These same alterations have been reported in patients treated with Fowler's solution (1% potassium arsenite; Cusick et al., 1982). Chronic As exposure is often associated with gastroenterological changes, spleen and liver enlargement and periportal fibrosis (Morris et al., 1974; Nevens et al., 1990; Mazumder et al., 1997). There have also been a few reports of cirrhosis after As exposure, but alcohol consumption is a confounding factor (NRC, 1999). Peripheral vascular changes after As exposure have also been reported. In Taiwan, blackfoot disease (BFD) has been the most severe manifestation of this effect. BFD is a peripheral vascular insufficiency which may result in gangrene of the feet and other extremities. Other vascular effects, e.g., Reynaud's Disease, have been described in Chile (Zaldivar et al., 1974) and Mexico (Cebrian, 1987). In the US, increased SMRs for hypertensive heart disease were noted in both males and females from Utah after As exposure from drinking water (Lewis et al., 1999) and indicate that As affects the cardiovascular system.