New research supported in part by NIEHS indicates that exposure to common environmental pollutants that persist in the environment, such as DDT and polychlorinated biphenyls (PCBs), may diminish infants’ immune response to the tuberculosis (TB) vaccine known as bacillus Calmette–Guerin (BCG). The findings, published online Dec. 9 in the journal Environmental Health Perspectives, add to a growing body of research that indicates that chemicals in the environment may interfere with immune system function.
Scientists at the University of Rochester Medical Center in New York analyzed blood samples from 561 mother-infant pairs in eastern Slovakia. The infants received the TB vaccine within 4 days of birth. At 6 months of age, researchers found that infants with higher concentrations of PCBs and DDE, which is the main breakdown product of DDT, had lower levels of antibodies to BCG. A lower level of antibodies indicates a weaker response to the vaccine. Infants with high levels of both chemicals had the lowest antibody levels.
“This research contributes to our understanding of how early life environmental exposures may damage the developing immune system, and specifically, the response to a vaccination used worldwide,” said Bonnie Joubert, Ph.D., the NIEHS program administrator overseeing this research area.
Exposure to persistent pollutants is widespread
The study participants were from an area in Slovakia heavily contaminated with PCBs and DDT, and these chemicals were detected in more than 99 percent of the maternal and infant blood samples. The researchers pointed out that because these chemicals do not break down easily and therefore persist in the environment, people continue to be exposed even after the chemicals are no longer used.
For example, PCBs used in manufacturing and industrial applications were banned in the U.S. in 1979. The pesticide DDT is also banned in the U.S., but continues to be used for mosquito control in some parts of the world. Research has indicated that PCBs and DDT can still be detected and measured in U.S. populations and others worldwide.
Implications for immune response
According to the U.S. Centers for Disease Control and Prevention, TB is one of the world’s deadliest diseases, and one-third of the world’s population is infected with the bacterium that causes TB. The study indicates that exposure to certain environmental toxins may decrease the effectiveness of vaccines like BCG, which may help to explain why the immune response to these vaccines can vary.
The significance of the study extends beyond BCG vaccine responses and exposures to these two chemicals, said Todd Jusko, Ph.D., in a press release from the University of Rochester. “There are thousands of pollutants similar to PCBs and DDT with unknown health implications,” he said. “Our work provides a foundation for how these types of chemicals affect the developing immune system in infants around the world.”
Jusko, who led the research, is an assistant professor in the University of Rochester Departments of Environmental Medicine and Public Health Sciences. Other NIEHS grantees collaborating with Jusko included B. Paige Lawrence, Ph.D., also from the University of Rochester, Anneclaire De Roos, Ph.D., from Drexel University, and Irva Hertz-Picciotto, Ph.D., from the University of California, Davis.
Citation: Jusko TA, De Roos AJ, Lee SY, Thevenet-Morrison K, Schwartz SM, Verner MA, Palkovicova Murinova L, Drobna B, Kocan A, Fabisikova A, Conka K, Trnovec T, Hertz-Picciotto I, Lawrence BP. 2015. A birth cohort study of maternal and infant serum PCB-153 and DDE concentrations and responses to infant tuberculosis vaccination. Environ Health Perspect. doi:10.1289/ehp.1510101 [Online 9 December 2015].
(Virginia Guidry, Ph.D., is a technical writer and public information specialist in the NIEHS Office of Communications and Public Liaison.)