POSTNATAL EXPOSURE TO CHLORINATED DIOXINS AND RELATED CHEMICALS ON LYMPHOCYTE SUBSETS IN JAPANESE BREAST-FED INFANTS

Effects of postnatal exposure to polychlorinated dibenzo-p-dioxins (PC DDs), polychlorinated dibenzofurans (PCDFs) and coplanar polychlorinat ed biphenyls (Co-PCBs) on lymphocyte subpopulations were investigated in the peripheral blood of 36 breast-fed Japanese babies. As a result, estimated total intakes of these chemicals in toxic equivalent quanti ty (TEQ) converted into 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3, 7,8- TCDD) equivalents from the breast milk positively and negatively corre lated with the respective percentages of CD4+ and CD8+ lymphocytes in the blood of breast-fed babies. Consequently, the ratios of CD4+ to CD 8+ T cells showed significant increasing tendency with the estimated t otal TEQ intakes. Therefore, our study suggests that exposure to backg round levels of the highly toxic organochlorine compounds through the breast milk influences the human neonatal immune system. (C) 1998 Else vier Science Ltd. All rights reserved.