Relation of lead and social factors to IQ of low-SES children: a partial replication.

An independent replication of a previous study (Schroeder et al., 1985) of the effects of interactive social environmental factors on the relationship of lead and Stanford-Binet IQ was performed on 75 of 80 low-SES black children screened by county health departments in North Carolina. Children's mean blood lead (PbB) level was 20.8 micrograms/dl (range, 6.3 to 47.4). Multivariate regression analyses showed no significant interactions between PbB and age, sex, maternal IQ, Caldwell home environment score, or SES (Hollingshead Two-Factor Index). There was a highly significant negative relationship between both mean and maximum PbB levels with IQ, p less than .002; that is, IQ decreased linearly as PbB increased. The most accurate and precise regression model included lead, maternal IQ, home environment, and gender.