EFFECTS OF POLYCHLORINATED-BIPHENYLS (PCBS) AND DIOXINS ON GROWTH ANDDEVELOPMENT

Polychlorinated biphenyls (PCBs) and dioxins are potentially toxic com pounds which occur widely in the environment. Their effects on the gro wth and development of infants at the levels currently found in highly industrialised western countries is not well known. This Dutch multic enter study, combining animal and human studies, tries to answer this question. Animal studies showed that PCB 169, given once during pregna ncy at a dose of 1.8 g kg(-1) bodyweight, has an effect on development al parameters, dopamine regulation and fertility, Effects on thyroid h ormones were also found in animals, probably due to both a competitive binding of PCB metabolites to the thyroxine binding protein and incre ased glucuronidation. Perhaps to compensate for this, an increased dio dase activity in the brain was found, Human studies involved 400 mothe r-infant pairs, half of them being breast-fed, the other half were fed a formula devoid of PCBs and dioxins, PCB levels were measured in ser um and dioxin and PCB levels in breastmilk. Levels were found to be as high as previously found in highly industrialised countries. Growth a nd development were carefully documented, but no data are as yet avail able, In pregnant women, a significant negative correlation was found between some dioxin and PCB congeners in milk and plasma thyroid hormo nes, while newborn infants showed higher thyroid stimulating hormone ( TSH) at higher levels of dioxin exposure. In summary, data from this c ombined multicenter study involving animals and humans increases our i nsight into the potentially negative effects of PCBs and dioxins on gr owth and development.