ABSTRACT
The first known As limit for drinking water was established in 1943. The United States of America set a value of 50 μg L−1 through their Environmental Protection Agency (EPA). Chile defined a value of 120 μg L−1 for drinking water through the Instituto Nacional de Normalización (INN) in 1970. The EPA ratified the value of 50 μg L−1 in 1975. Studies of that time, published in the international literature, indicated that this was a safe limit (Valencia 1999). To establish a safe limit, EPA in 1983 recommended considering the As valence states that strongly influence As toxicity and its health effects (c 2). The agency recommended including nutritional needs, because some scientific publications showed that arsenic is an essential nutrient for some vegetables and animal species, and that this metalloid might also be an essential nutrient for humans (Valencia 1999). In 1983, Chile assumed the limit of 50 μg L−1, established by EPA. In 1985, EPA again confirmed the enforced limit of 50 μg L−1 (Valencia 1999).
