Longitudinal changes in blood lead level in children and their relationship to season, age, and exposure to paint or plaster.

Children screened for lead poisoning in the Brownsville district of New York City in either summer or winter were followed with blood lead tests for approximately six months to one year from screening to measure longitudinal changes in blood lead level and to identify some determinants of the changes. Only minimal evidence was found of the hypothesized summer rise in blood lead level, while the predominant trend seemed to be for blood lead levels to display statistical regression to the mean. In children found to have low to intermediate blood lead levels (less than 55 microgram/100ml) at screening, variables which were found to predict a rise in blood lead level of 10 microgram/100ml or greater from winter to summer were under age three and/or exposure to paint or plaster.