h regard to its activity in biological systems (Levander et al., 1977, p. 117). Typical "background" exposure levels in humans range from 20 to 70 micrograms/day, with most of the exposure coming from food (ORNL, 1989, p. 77). In general, domestic animals and man contain less than 0.3 ppm on a wet weight basis; the total human body content varies between 3 and 4 mg and increases with age (Levander et al., 1977, p. 24). Arsenic tends to concentrate in the hair, nails, and teeth (Levander et al., 1977, p. 24). While a small amount of the chemical may not harm a living organism, larger quantities can. In recognition of this fact, the U.S. Environmental Protection Agency's present Interim Drinking Water Standard is set at 50 micrograms/liter (Smith et al., 1992, p. 47). Moreover, identical or very close water standards exist internationally (Stohrer, 1991, p. 526).
Still though, endemic contamination of freshwater supplies has been reported in various areas including Taiwan, Chile, India, and Mexico (Fan, 1990, p. 165). In addition, several population groups in these localities have suffered from high incidences of cancer.
Arguello et al., for example, reported on a large group of patients seen for arsenical skin cancers in the Cordoba region of Argentina (Smith et al., 1992, p. 184). The area was known to have a high concentration of arsenic in its drinking water (Smith et al., 1992, p. 184). The study found keratoderma in 100% of the patients examined (Levander et al., 1977, p. 184).
Additionally, in Taiwan, artesian wells with high concentrations of arsenic have been associated with a high mortality from a variety of cancers (Smith et al., 1992, p. 5470). The arsenic content of certain wells ranges from 0.05 ppm to over 1.0 ppm (Levander et al., 1977, p. 202). Tseng et al. surveyed a group of 40,421 Taiwanese who were, therefore, "at risk" for arsenic exposure (Levander et al., 1977, p. 182). Among such ot...