Interactions between environmental lead exposure and sociodemographic factors on cognitive development

A total of 375 children who lived in Port Pirie, South Australia, and surro unding towns were followed from birth to ages 11-13 y. Possible interaction s between lifetime average blood lead concentration and sociodemographic fa ctors (including gender, parents' occupational prestige [as a surrogate of socioeconomic status], quality of home environment, and maternal intelligen ce quotient) on children's intelligence quotients were examined. Although n o statistically significant interaction between blood lead concentration an d any of these covariates was found, the results suggested that-after adjus tment for a wide range of covariates-children from socially disadvantaged b ackgrounds (adjusted regression coefficient = -9.6 intelligence quotient po ints per log unit of blood lead concentration; 95% confidence interval = -2 .5, -17.7) were more sensitive to the effects of lead than those of a highe r socioeconomic status (adjusted regression coefficient = -2.9; 95% confide nce interval = 3.8, -9.6). In addition, girls (adjusted regression coeffici ent = -7.4; 95% confidence interval = -1.7, -13.1) were more sensitive to t he effects of lead than boys (adjusted regression coefficient = -2.6; 95% c onfidence interval = 2.9, -8.0). These results were basically consistent wi th our findings observed at ages 2 y, 4 y, and 7 y.