Dr. Philippe Grandjean from the University of Southern Denmark tells Reuters Health, "Pollutants, such as PCBs (polychlorinated biphenyls), may be partially responsible that vaccinations don't 'take' in some children."
"I believe that this is yet another reason to protect children -- and pregnant women -- against chemical pollutants."
Grandjean and colleagues studied vaccination responses in two birth cohorts from the Faroe Islands.
Exposure to PCBs, chemicals commonly used in industry, are 10 times higher in the Faroe Islands than in Northern Europe.
Grandjean says this is "because traditional diets may include whale blubber contaminated with PCBs."
The scientists determined PCB exposure by analyzing a pregnant woman's blood, and her early or "transition" milk, as well as children's blood samples.
The 119 children who got diphtheria and tetanus vaccines were examined at 18 months.
Among 119 children who got diphtheria and tetanus vaccines, there was a strong correlation between prenatal PCB exposure and antibody concentrations.
The scientists found the greater the PCB exposure, the lower the antibody protection.
