Blood lead secular trend in a cohort of children in Mexico City. II. 1990-1995

The authors determined the secular trend in blood lead levels in a cohort o f 91 children born in Mexico City between 1987 and the beginning of 1993. T he 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 m o during a 66-mo period. The overall geometric mean blood lead level was 8. 6 mu g/dl (range = 1.0-61.0 mu g/dl). A repeated measures analysis of varia nce revealed a significant downward linear trend in blood lead levels by ye ar (p < .001)-from an estimated marginal geometric mean of 14.2 mu g/dl in 1990 to 6.3 mu g/dl in 1995. There was also a significant linear age effect (p < .001); blood lead levels generally fell during the 36th-66th mo. Fami ly use of lead-glazed pottery significantly elevated blood lead levels (p = .006), and the effect magnified as age increased (Age x Pottery Interactio n [p = .014]). Although the overall downward trend in blood lead levels dur ing the time period described corresponded to a reduction in various source s of lead exposure, there was no alteration in production, distribution, or use of leaded pottery. Currently use of lead-glazed ceramic pottery is one of the most profound sources of lead exposure in the Mexican population.