Blood Lead Secular Trend in a Cohort of Children in Mexico City. II. 1990–1995

Abstract The authors determined the secular trend in blood lead levels in a cohort of 91 children born in Mexico City between 1987 and the beginning of 1993. The authors grouped children by calendar year in which they reached 36 mo of age (i.e., 1990–1995), and their blood lead levels were measured every 6 mo during a 66-mo period. The overall geometric mean blood lead level was 8.6 μmlg/dl (range = 1.0–61.0 μmlg/dl). A repeated measures analysis of variance revealed a significant downward linear trend in blood lead levels by year (p < .001)—from an estimated marginal geometric mean of 14.2 μmlg/dl in 1990 to 6.3 μmlg/dl in 1995. There was also a significant linear age effect (p < .001); blood lead levels generally fell during the 36th-66th mo. Family use of lead-glazed pottery significantly elevated blood lead levels (p = .006), and the effect magnified as age increased (Age x Pottery Interaction [p = .014]). Although the overall downward trend in blood lead levels during the time period described corres...