This is Jon Hamilton‘s excellent explanation of this disturbing risk possibility, reported yesterday in JAMA. From Common Chemicals Could Make Kids’ Vaccines Less Effective

The more exposure children have to chemicals called perfluorinated compounds, the less likely they are to have a good immune response to vaccinations, a study just published in JAMA, the Journal of the American Medical Association shows.

The finding suggests, but doesn’t prove, that these chemicals can affect the immune system enough to make some children more vulnerable to infectious diseases.

For decades now, PFCs have been used in nonstick coatings, stain-resistant fabrics and some food packaging. And because they persist in the environment for years, they have become common around the globe.

“You can find them in polar bears,” says Dr. Philippe Grandjean, the study’s lead author who works at both Harvard and the University of Southern Denmark.

Studies in animals have shown that PFCs can weaken the immune system.

Grandjean wanted to know whether this was happening in children. So he led a team that studied nearly 600 kids in the Faroe Islands, which lie about halfway between Scotland and Iceland.

The Faroese have levels of PFCs similar to those of U.S. residents. Grandjean figured if the chemicals were having an effect, it would show up in the way kids’ bodies responded to vaccinations.

Normally, a vaccine causes the production of lots of antibodies to a specific germ. But Grandjean says the response to tetanus and diphtheria vaccines was much weaker in 5-year-olds whose blood contained relatively high levels of PFCs.

“We found that the higher the exposure, the less capable the kids were in terms of responding appropriately to the vaccine,” Grandjean says. The results raise the possibility that “the immune system is not really developing optimally.”

The health effects of PFCs are still poorly understood. But in the past decade, government scientists have become increasingly concerned about possible links to developmental problems in children.

If this turns out to be coincidental, without causal connection, all well and good. But if there’s something here that, on the precautionary principle, would lead us to ban or limit PFCs – it’s likely we’ll do it first in more affluent countries. This may protect some children – but if the children of entire continents are left unprotected, not only are those children at direct risk, their communities may constitute international disease paths. In a world with routine international travel and shipping, diseases don’t need green cards.