Immunologic effects of background exposure to polychlorinated biphenyls and dioxins in Dutch preschool children

Prenatal exposure to polychlorinated biphenyls (PCBs) and dioxins is associ ated with changes in the T-cell lymphocyte population in healthy Dutch infa nts. We investigated whether these changes persist into later childhood and whether background exposure to PCBs and dioxins is associated with the pre valence of infectious or allergic diseases and humoral immunity at preschoo l age. The total study group consisted of 207 healthy mother-infant pairs. We estimated prenatal exposure to PCBs and dioxins by the sum of PCBs 118, 138, 153, and 180 (Sigma PCB) in maternal and cord plasma and in breast-fed infants by the dioxin, planar, and mono-ortho PCB toxic equivalent (TEQ) l evels in human milk At 42 months of age, current body burden was estimated by the Sigma PCB in plasma. We assessed the prevalence of infectious and al lergic diseases by parent questionnaire, and measured humoral immunity by a ntibody levels for mumps, measles, and rubella after primary vaccination. W e performed immunologic marker analyses of lymphocytes in a subgroup of 85 children. Prenatal PCB exposure was associated with an increased number of lymphocytes, T-cells, and CD3CD8(+) (cytotoxic), CD4(+)CD45RO(+) (memory), T-cell receptor (TcR) alpha beta (+), and CD3(+)HLA-DR+ (activated) T cells and lower antibody levels to mumps and measles at preschool age. Adjusted for confounders, prenatal PCB exposure was associated with less shortness o f breath with wheeze, and current PCB body burden was associated with a hig her prevalence of recurrent middle-ear infections and of chicken pox and a lower prevalence of allergic reactions. A higher dioxin TEQ was associated with a higher prevalence of coughing, chest congestion, and phlegm. We conc lude that in Dutch preschool children the effects of perinatal background e xposure to PCBs and dioxins persist into childhood and might be associated with a greater susceptibility to infectious diseases. Common infections acq uired early in life may prevent the development of allergy, so PCB exposure might be associated with a lower prevalence of allergic diseases.