Serum immunoglobulins and lymphocyte subset distributions in children and adults living in communities assessed for lead and cadmium exposure.

This study assessed the impact of environmental cadmium and lead exposure on the immune system of more than 2000 children and adults. Serum immunoglobulins [immunoglobulins (Ig) A, G, and M] and peripheral blood lymphocyte phenotypes (T cells, B cells, NK cells, and CD4/CD8 subsets) were measured in a total of 2041 children and adults who lived either in sites with elevated soil levels of cadmium and lead (n = 1561) or in comparison communities (n = 480). The blood lead and urine cadmium levels of participants were somewhat higher than national averages. Mean blood lead levels were 7 microg/dl for participants aged 6-35 mo; 6 microg/dl for participants aged 36-71 mo, 4 microg/dl for participants aged 6-15 yr; and 4.3 microg/dl for participants aged 16-75 yr. Multivariate analysis indicated no marked differences in any of the immune marker distributions attributed to lead for adults or children over 3 yr of age. However, in children under age 3, increased blood lead levels, principally those over 15 microg/dl, were associated with increases in IgA, IgG, IgM, and circulating B lymphocytes. Among adults, urine cadmium levels over 1.5 microg/g were associated with higher levels of IgA and circulating B lymphocytes. No evidence of immunosuppression was noted. The findings of potential immunologic effects at lead levels > 15 microg/dl in young children and at urine cadmium levels > 1.5 microg/g in adults are interesting, but too few participants had these high levels to delineate a threshold. Therefore, we find these results intriguing, but requiring confirmation in populations with higher exposure levels.