Reducing lead exposure in children.

The near elimination of lead-related childhood fatalities and encephalopathy by the 1970s and the sharp decline in mean blood lead levels nationwide documented between 1976 and 1980 are two milestones in the fight against lead poisoning. In the case of the latter, we know the antecedents, such as controls on the sale, use, and lead content of lead paint, improved chelation therapy, and increased awareness and case finding; however, the antecedents' relative contributions are not known due to a lack of evaluation. Similarly, the effect of a variety of social-welfare programs has not been evaluated. Since the 1970s, our perception of the problem of lead toxicity and consequently its control has changed. First steps have been made toward attaining one primary preventive objective, controlling the multiple sources of new inputs of lead to the biosphere that contribute to asymptomatic lead toxicity. The lead content of widely used commodities has been reduced (canned foods and gasoline) or virtually eliminated (paint). The benefits of passive measures used to attain reductions in lead exposure have been documented to a greater extent than those of active programs. The best example of a successful primary and passive preventive measure is the availability of lead-free gasoline since 1974, which largely accounts for decreases in ambient air lead concentrations nationwide and the recent shift to lower values in the distribution curve of children's blood lead levels. The latter provides a margin of safety for children before known toxic levels are reached. The contribution of reductions in dietary lead to changes in blood lead levels has not been well documented. Studies also show the benefits of the use of lead-free paint in new housing. Compared to children living in older homes with deteriorating lead paint, those living in lead-free homes are at low risk for lead toxicity. Likewise, affected children who move to lead-free homes are at low risk for further toxicity. Despite reductions of new inputs, reservoirs of concentrated lead remain in urban areas in soil, dust, and existing housepaint that will continue to be hazardous to children for decades to come. The second National Health and Nutrition Examination Survey (1976-1980) described a population at continued risk of toxicity. Although lead poisoning is a problem in all socioeconomic and racial groups, poor black urban children remain at highest risk of chronic lead exposure. Compared to controlling new inputs, the control of existing sources of lead in and around housing is a more intractable problem.(ABSTRACT TRUNCATED AT 400 WORDS)