Managing hazardous pollutants in Chile: arsenic.

Chile is one of the few countries that faces the environmental challenge posed by extensive arsenic pollution, which exists in the northern part of the country. Chile has worked through various options to appropriately address the environmental challenge of arsenic pollution of water and air. Because of cost and other reasons, copying standards used elsewhere in the world was not an option for Chile. Approximately 1.8 million people, representing about 12% of the total population of the country, live in arsenic-contaminated areas. In these regions, air, water, and soil are contaminated with arsenic from both natural and anthropogenic sources. For long periods, water consumed by the population contained arsenic levels that exceeded values recommended by the World Health Organization. Exposure to airborne arsenic also occurred near several large cities, as a consequence of both natural contamination and the intensive mining activity carried out in those areas. In rural areas, indigenous populations, who lack access to treated water, were also exposed to arsenic by consuming foods grown locally in arsenic-contaminated soils. Health effects in children and adults from arsenic exposure first appeared in the 1950s. Such effects included vascular, respiratory, and skin lesions from intake of high arsenic levels in drinking water. Methods to remove arsenic from water were evaluated, developed, and implemented that allowed significant reductions in exposure at a relatively low cost. Construction and operation of treatment plants to remove arsenic from water first began in the 1970s. Beginning in the 1990s, epidemiological studies showed that the rate of lung and bladder cancer in the arsenic-polluted area was considerably higher than mean cancer rates for the country. Cancer incidence was directly related to arsenic exposure. During the 1990s, international pressure and concern by Chile's Health Ministry prompted action to regulate arsenic emissions from copper smelters. A process began in which emission standards appropriate for Chile were set; this process included careful evaluation of risks versus mitigation costs for abatement options. Such options were developed and implemented. More recently, local communities have pressed for more significant reductions of arsenic in air and water. Considerable experience was gained with the arsenic experience on how to manage this type of hazardous pollutant, in a context of trade-offs among production, jobs, income, and health. In this review article, we cover arsenic levels in Chile's air, water, and soils and discuss health impacts and patterns of exposure. We also describe the process followed to set arsenic regulatory standards, as well as abatement options for air and water and the associated costs.