Polychlorinated biphenyl exposure after vaccination negatively affects antibody concentrations

Exposure to polychlorinated biphenyls (PBCs) is associated with immunotoxic effects on serum concentrations of specific antibodies against diphtheria and tetanus vaccinations, according to research published online June 20 in Environmental Health Perspectives.

Researchers assessed a total of 587 children at age 5 years (before and after a booster vaccination against diphtheria and tetanus) and at age 7 years. At these time points, the investigators measured total serum PCB concentrations and antibody concentrations. Data were also obtained on the child's serum PCB concentration at age 18 months and the PCB concentration in maternal milk. Before the booster vaccination, antidiphtheria antibody concentration was inversely associated with PCB concentrations at age 18 months. At age 7 years, there was an inverse association between antibody concentrations and PCB concentration at 18 months. At 5 years of age, patients with a doubling of PCB concentration in maternal milk and 18-month serum had 30% increased odds of demonstrating antidiphtheria antibody concentrations below the clinically protective level of 0.1 IU/L.

The authors stated, "The clinical importance of our findings is therefore that the PCB exposure may increase the risk of a child not being protected against diphtheria and, possibly, tetanus, despite a full schedule of vaccinations."