By Janet Raloff
Tiny concentrations of two common pollutants — chemicals known as PFOA and PFOS — in the blood may be linked to impaired immunity in children, a new study finds. In kids with the highest exposure to the chemicals, vaccinations can fail to trigger sufficient quantities of protective antibodies.
“We were shocked, to be frank, in the magnitude of the effect,” says study leader Philippe Grandjean, a physician at the Harvard School of Public Health in Boston. He and his European colleagues describe their findings in the Jan. 25 Journal of the American Medical Association.
The long-lived pollutants — part of a class of chemicals called perfluorinated compounds, or PFCs — have been generated over the years by the production of chemicals that impart nonstick properties and water- and stain-repellency to fabrics, cookware and more, including older formulations of treatments marketed under such trade names as Teflon and Scotchgard. Pervasive environmental contaminants, PFCs taint air, water and food.
For the new study, Grandjean’s group followed 587 children in Denmark’s Faroe Islands (about midway between Norway and Iceland) from before birth through age 7. The researchers measured PFCs in the blood of the kids’ moms during pregnancy and in the children at ages 5 and 7. Blood concentrations of the chemicals, Grandjean points out, were in the same ballpark, if a bit lower, than those typically seen in Americans.
The Faroese youngsters received standard childhood immunizations, and their antibody responses to tetanus and diphtheria were measured as babies and before and after booster vaccinations at age 5.
Children with the highest perfluorinated pollutant exposures tended to exhibit a less robust response to the vaccines, both before and after their booster shots.
Among children in the top third of exposure to the chemicals PFOA, PFOS and a third related compound that goes by the nickname PFHxS, “inadequate response to the vaccinations was particularly common,” Grandjean observes. When subpar responses occur — antibody levels below 0.1 international units per milliliter — “we can’t rely on a vaccine as being effective,” he explains.
The findings mean the immune system is somehow deficient, Grandjean says, and they raise questions about whether such deficiencies might also point to a heightened vulnerability to allergy, asthma and even, potentially, autoimmune disease.
Toxicologist Margie Peden-Adams of the University of Nevada, Las Vegas finds the new study impressive. “Those of us in the field will be excited to see it.”
The immune system is one of the most sensitive systems for toxicity, Peden-Adams says. In rodent tests, her team showed fetal and adult exposure to PFOS diminishes antibody production to foreign substances.
In cell-based studies, Emanuela Corsini of the University of Milan in Italy and her colleagues saw related problems and identified two different mechanisms for the apparent immunotoxicity of PFOA versus PFOS. Although primary PFC manufacturers have stopped using or are voluntarily phasing out both compounds, Corsini notes, she says these chemicals remain “of toxicological concern due to their environmental persistence and potential to bioaccumulate through the food chain.”
