Exposure to chemicals like polychlorinated biphenyls (PCBs) and DDE, the main breakdown product of the insecticide DDT may reduce responses to certain vaccines, according to a study published in Environmental Health Perspectives. 

Researchers from the University of Rochester Environmental Health Sciences Center  analyzed blood samples and immune responses from 516 healthy mother-infant pairs living in an area of eastern Slovakia that is noted to have a high prevalence of environmental toxins. The tuberculosis vaccine was given to each baby within four days after birth.

The researchers then measured the babies’ antibody responses to the vaccine six months later.

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Data showed that harmful chemicals were detected in more than 99% of the blood samples. But infants who had the highest concentrations of PCBs and other chemicals in their blood tended to have the lowest antibodies for fighting TB. In fact, babies whose PCB concentrations ranked in the 75th percentile had 37% lower antibodies for the TB vaccine, compared to babies with PCB concentrations in the 25th percentile.

DDE was not as strongly associated as PCBs with a reduction in vaccine antibody levels, but its presence also substantially reduced the infant response to the TB vaccine; infants with exposures to both chemicals fared the worst, the study researchers said.

Like other persistent chemicals, PCBs and DDE cross the placenta and are readily passed from mother to child through breastfeeding. Development of a robust immune system is a complex and intricate process in early life, the researchers noted, and therefore even small changes can lead to long-term dysfunction.

Funding was provided by the National Cancer Institute and the National Institute of Environmental Health Sciences.


1. Jusko T,  De Roos AJ,  Lee SY, et al. A birth cohort study of maternal andiInfant serum PCB-153 and DDE concentrations and responses to infant tuberculosis vaccination. Environ Health Perspect; DOI:10.1289/ehp.1510101.