Vaccine effectiveness reduced by common environmental toxin, Harvard study finds

By Deborah Kotz, Globe Staff

Vaccines, we’re told, aren’t 100 percent effective. That’s why some of us come down with the flu after getting a flu shot. Sometimes, our immune system doesn’t mount a strong enough response to an immunization, so defenses are down when a pathogen invades.

Now a new Harvard School of Public Health study suggests this may sometimes be due to exposure to certain environmental toxins. The researchers measured levels of perfluorinated compounds (PFCs) -- found in food packaging, stain-resistant carpets, and nonstick pans -- in nearly 600 children who lived in the Faroe Islands in the Norwegian Sea and found that those who had the highest levels of PFCs had a 50 percent lower reaction to tetanus and diphtheria vaccines, according to the study published in yesterday’s Journal of the American Medical Association.

“Previous studies have suggested that vaccine effectiveness may be reduced by other chemicals, like PCBs, but with PFCs we saw a much steeper effect, and this was surprising to us,” said study author Dr. Philippe Grandjean, an environmental health physician at Harvard.

Levels of PFCs found in the Faroe children (who consume high levels of seafood associated with increased PFC exposure), he added, are similar to those found in American children, but it’s not known whether the same effect occurs with other vaccinations. “We’re not worried about kids coming down with diphtheria or tetanus, which are rare,” Grandjean said, “but the chemical might very well be interfering with other immunizations.”

There’s certainly no reason for parents to panic over the finding, said Dr. Rick Malley, an infectious disease expert at Children’s Hospital Boston who wasn’t involved with the research. “I would say it’s an elegant study and it’s provocative, but it’s just showing an association, not a cause and effect.” The study design, he added, doesn’t tell us whether PFCs actually lower the effectiveness of vaccines or whether kids with high PFC levels have something else that’s interfering with their immune response.

What’s more, other things interfere with immunizations. A 2009 clinical trial published in Lancet found that administering acetaminophen to infants before vaccinations led to fewer fevers and febrile seizures but also reduced the immune response to common vaccines, which has led many pediatricians to stop recommending that parents give a dose of Tylenol to babies before vaccinations.

That said, PFCs could become the next bisphenol A -- a chemical once ubiquitous in baby bottles until studies linked high levels to increased risks of cancer, sexual dysfunction, and heart disease. Now it’s hard to find a baby bottle that isn’t labeled BPA-free.

At the moment, those who want to take precautions to lower their exposure to PFCs may have a tough time, said Olga Naidenko, a senior scientist with Environmental Working Group. The chemical is used widely in takeout pizza boxes, microwave popcorn bags, Teflon pans, and stain-proof materials.

And the Environmental Protection Agency doesn’t require testing for it in public drinking water, though it is considering a new regulation that would implement testing.

For now, consumers can make an effort to steer clear of takeout containers that have shiny coatings -- which often contain PFCs -- and cooking with nonstick pans only at medium heat to avoid a breakdown of the coating. If you’re shopping for a new carpet, you may want to ask the manufacturer to install materials that are untreated with artificial chemicals.