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Tacoma Smelter Plume.Arsenic and lead levels are considered to be of concern, not an emergency.

The chemical elements lead and arsenic are potentially toxic to people. Although lead and arsenic occur naturally in the environment, their concentrations have increased. and they have become more widely distributed because of human activities. Societal concerns about excessive human exposure to lead and arsenic prompted development of new products and practices to reduce or eliminate the many industrial and residential uses of the two elements. The principal historical sources of lead (leaded gasoline, lead-based paint) and arsenic (arsenical pesticides) are now outlawed in the United States. As a result, overall human exposure to lead and arsenic is much lower than in the past: however. the legacy of environmental contamination because of past lead and arsenic use is taking on renewed importance. Recent scientific research suggests that human health, especially for infants and small children. may be adversely affected by exposure to lower levels of lead and arsenic than previously believed. Hence. taking additional steps to reduce human exposure to the remaining sources of lead and arsenic may be warranted. Soil is a major repository for lead and arsenic released by human activities. Some soils are naturally high in lead or arsenic, but many have been artificially enriched through a variety of means. Contaminated soils contain total concentrations of elements exceeding the natural back- ground level for local soils. Contamination is an intrinsic property of soil. and contaminated soils are easy to identify by chemical testing. They may or may not pose a health hazard. depending on the amount and…