SERUM IMMUNOGLOBULINS AND LYMPHOCYTE SUBSET DISTRIBUTIONS IN CHILDREN AND ADULTS LIVING IN COMMUNITIES ASSESSED FOR LEAD AND CADMIUM EXPOSURE

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Abstract
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 µg/dl for participants aged 6?35 mo; 6 µg/dl for participants aged 36?71 mo, 4 µg/dl for participants aged 6?15 yr; and 4.3 µg/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 µg/dl, were associated with increases in IgA, IgG, IgM, and circulating B lymphocytes. Among adults, urine cadmium levels over 1.5 µg/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 µg/dl in young children and at urine cadmium levels >1.5 µg/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.

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