THE DECLINE IN BLOOD LEAD LEVELS IN THE UNITED-STATES - THE NATIONAL-HEALTH AND NUTRITION EXAMINATION SURVEYS (NHANES)

Objective.-To describe trends in blood lead levels for the US populati on and selected population subgroups during the time period between 19 76 and 1991. Design.-Two nationally representative cross-sectional sur veys and one cross-sectional survey representing Mexican Americans in the southwestern United States. Setting/Participants.-Participants in two national surveys that included blood lead measurements: the second National Health and Nutrition Examination Survey, 1976 to 1980 (n=983 2), and phase 1 of the third National Health and Nutrition Examination Survey, 1988 to 1991 (n=12119). Also, Mexican Americans participating in the Hispanic Health and Nutrition Examination Survey, 1982 to 1984 (n=5682). Results.-The mean blood lead level of persons aged 1 to 74 years dropped 78%, from 0.62 to 0.14 mu mol/L (12.8 to 2.8 mu g/dL). M ean blood lead levels of children aged 1 to 5 years declined 77% (0.66 to 0.15 mu mol/L [13.7 to 3.2 mu g/dL]) for non-Hispanic white childr en and 72% (0.97 to 0.27 mu mol/L [20.2 to 5.6 mu g/dL]) for non-Hispa nic black children. The prevalence of blood lead levels 0.48 mu mol/L (10 mu g/dL) or greater for children aged 1 to 5 years declined from 8 5.0% to 5.5% for non-Hispanic white children and from 97.7% to 20.6% f or non-Hispanic black children. Similar declines were found in populat ion subgroups defined by age, sex, race/ethnicity, income level, and u rban status. Mexican Americans also showed similar declines in blood l ead levels of a slightly smaller magnitude over a shorter time. Conclu sions.-The results demonstrate a substantial decline in blood lead lev els of the entire US population and within selected subgroups of the p opulation. The major cause of the observed decline in blood lead level s is most likely the removal of 99.8% of lead from gasoline and the re moval of lead from soldered cans. Although these data indicate major p rogress in reducing lead exposure, they also show that the same sociod emographic factors continue to be associated with higher blood lead le vels, including younger age, male sex, non-Hispanic black race/ethnici ty, and low income level. Future efforts to remove other lead sources (eg, paint, dust, and soil) are needed but will be more difficult than removing lead from gasoline and soldered cans.