Vaccine effectiveness threatened by everyday chemical
HSPH’s Philippe Grandjean answers questions about PFCs
In January 2012, a study in the Journal of the American Medical Association (JAMA) showed that perfluorinated compounds (PFCs)—which are widely used in manufactured products such as nonstick cookware, waterproof clothing, and fast-food packaging—dramatically lowered children’s immune response to tetanus and diphtheria vaccinations. The report suggested that these chemicals may be undermining one of the keystones of public health: childhood immunization. Lead author Philippe Grandjean, adjunct professor of environmental health at HSPH, talked about the study’s wide-ranging implications with Harvard Public Health editor Madeline Drexler.
Q: You found that 7-year-olds with twice the blood concentration of PFCs had about half the levels of antibodies in the blood to tetanus and diphtheria, compared with children with average PFC levels. Were you jolted by this finding?
A: Very much. I’ve talked to pediatric immunologists about this, and they have never seen anything like it. HIV infection, rare inborn diseases, or treatment with chemotherapy can do the same thing. But apart from those situations, these colleagues had never seen these kinds of effects.
Q: How exactly do PFCs dampen immunity?
A: Apparently, these compounds hinder communication between white blood cells—the cells that tell the body, ‘There is a foreign microorganism or foreign protein that is causing a possible danger, and the body needs to deal with it.’ We were misled to believe that the PFCs wouldn’t be active biologically, as they are very stable. But it turns out that they fit into certain proteins or receptors in the body.
Q: Are the effects limited to tetanus or diphtheria vaccines? Or are these signs of broader problems in immunity?
A: We looked at tetanus and diphtheria because both of those vaccines are proteins. But we don’t think that what we have seen is specific to tetanus or diphtheria. We think there is something going on there that reflects a more general immunotoxicity. I call it a sluggish immune system. Whatever is going on here, it’s the same system that kicks in when we are infected by disease-causing microorganisms.
Q: Would this fundamental damage to the immune system trigger such things as allergies or other conditions?
A: Possibly. The immune system is responsible for allergy development—and we know that there’s an allergy epidemic. Could these immunotoxicants be kicking the immune system out of balance?
You may even speculate further, because the immune system is also involved in conditions like autoimmunity and protection against cancer. We are not just talking about direct organ-related toxicity—to the brain or the reproductive system or the liver or the kidneys. We are talking about something that affects our whole body. It opens up a new perspective for studying how environmental chemicals affect public health.
Q: Why are these damaging substances so prevalent in our lives?
A: When the federal Toxic Substances Control Act was enacted in 1976, it only covered safety-testing requirements for new chemicals—all of the existing chemicals, such as PFCs, were grandfathered in. In the U.S., the production of PFOS [perfluorooctane sulfonate], one of the most common PFCs, ceased in 2002. But now PFOS is produced in increasing amounts in China, so we may be importing products that contain or have been treated with these chemicals from other countries. Though concentrations of PFOS in blood have come down over the last six or eight years in the U.S., we are being increasingly exposed to other PFCs which are, as a class, exempt from the strict rules that apply to new chemicals. Industry is introducing these chemicals as alternatives—but only now are we beginning to identify the toxic risks.
Q: What advice would you give consumers?
A: Minimize exposure to those substances as much as possible. PFCs serve some extremely useful purposes. They make your raincoat water repellent. They act as stain repellents on rugs. Food-wrapping materials like paper plates, microwave popcorn bags, and pizza boxes often contain these compounds.
The trick is to find alternatives that are just as useful but do not cause toxic effects. You can now get rain gear, wall-to-wall carpeting, and other products that are labeled “PFC-free” or “eco-friendly.” If consumers vote with their wallets and scientists push, then industry will realize there is a new market niche.