Postnatal exposure to PCBs found to depress immune responses New research in Denmark links the ingestion by mothers of polychlorinated biphenyls (PCBs) to reduced immune responses in their children. PCBs have been used a great deal since the 1930s in a variety of industrial applications, from flame retardants to lubricants to pesticide... New research in Denmark links the ingestion by mothers of polychlorinated biphenyls (PCBs) to reduced immune responses in their children. PCBs have been used a great deal since the 1930s in a variety of industrial applications, from flame retardants to lubricants to pesticides. The compounds are extremely stable, and therefore difficult to break-down. PCBs are also highly toxic, with a particular impact on the reproductive system, and likely carcinogens. Because of environmental and health concerns, the use of PCBs has declined sharply since the 1970s. The compounds still persist though, generally leaving high concentrations in animals higher up the food chain, including whales. The research was conducted on the remote Faroe Islands, a Danish territory half-way between Norway and Iceland. 'The Faroe Islands represents a unique setting for studies of PCB immunotoxicology. While dioxin exposure is not increased, average PCB exposures are up to 10-fold higher than average levels in northern Europe due to the traditional habit of eating pilot whale blubber,' reads the report. Two groups were compared - the first group of mothers had a 'traditional' diet, which includes whale blubber, while the other would have a more 'western' diet, without whale blubber. PCBs could be passed through either prenatal contact or postnatal contact from breast milk. The methodology was simple - to compare the levels of vaccination antibodies in the two groups at different ages. 'This study provides epidemiological evidence for an association between exposure to environmental pollutants and a reduction of antibody production after routine childhood immunisations,' reads the report. Once born, the children were studied at 18 months to test for antibodies from routine vaccinations of diphtheria and tetanus. The group was subsequently tested at age seven. The levels of PCB in the Faroese diet is thought to be higher than average. However, 'the results of the present study suggest possible adverse influences on the immune function may well occur also at lower exposure ranges prevalent worldwide,' reads the report. Because PCBs can be passed from mother to child through breastfeeding, the researchers believe that much of the PCB transfer could be through breastfeeding. The research points to the development of the thymus, essential in immune system development, which is not complete at birth. However, there was no control, meaning that evidence on the effects of PCBs was not conclusive. 'Had the study included a comparison group with much lower PCB exposure, the high percentage of Faroese children with low diphtheria antibody concentrations could perhaps have been convincingly linked to increased PCB exposure,' reads the report. The data obtained suggest that the greatest impact of PCBs is in very early life. 'Although PCB exposure levels have tended to decrease in many parts of the world, the present results suggest that further efforts are needed to minimise this hazard,' reads the report. Countries Denmark
