Chemicals cut vaccine effectiveness

Certain chemicals in the environment may reduce the effectiveness of childhood vaccines according to research in a new study in the Journal of the American Medical Association.

Scientists looked specifically at PFCs, perfluorinated compounds , widely used in products that repel water, grease and stains. Children with higher levels of PFCs in their bodies did not get optimal protection from their vaccines, according to the study.

"Routine childhood immunizations are a mainstay of modern disease prevention. The negative impact on childhood vaccinations from PFCs should be viewed as a potential threat to public health," says study author Dr. Philippe Grandjean, adjunct professor of environmental health at Harvard School of Public Health in Boston.

PFCs are used to make non-stick cookware, rain gear, fast-food packaging, strain-resistant carpets and fabrics, and many other products. The chemicals can get into the food chain and drinking water and stay in our bodies and the environment for years.

The EPA is working with companies to eliminate the use of certain PFCs in products by 2015, but many goods imported from other countries contain PFCs.

Grandjean and his fellow researchers wanted to find out how PFCs affected the immune system of children. They looked at the immunization records of 587 children from a Danish fishing community where the exposure to the compounds from eating fish, is common. The children received routine tetanus and diphtheria vaccines and at ages 5 and 7 were tested for antibody levels, an indication of how well the immune system would fight the disease if infected.

They found that children who had twice as much PFCs in their blood had half the antibody response to the two vaccines.

"You can only lose a certain amount [of antibody response] and then you won't have enough antibody left to fend off the disease if you were infected later on," explains Grandjean.

Because of their high fish consumption, scientists assumed that the Danish children would have higher levels of PFCs in their blood than children elsewhere. But the levels were the same or slightly lower than what is found in children in the United States.  Young people in America are more likely to be exposed to PFCs from house dust that gathers near carpet or furniture treated with the chemicals.

"It was very surprising to us that children are vulnerable to these kinds of effects and now we worry that these effects may also influence other aspects of the immune system and other vaccinations," explains Grandjean.

According to the CDC there is widespread exposure to PFCs in the U.S. population , though the levels are now declining. Scientists don't yet now how these chemicals affect humans, but studies in laboratory animals and wildlife have been troubling.

According to the EPA, "Animal studies have shown that some PFCs are associated with a variety of effects including cancer, liver toxicity, immune function, and effects on development. It is unknown whether these same effects would occur in humans, though we know that many of the PFCs remain in the human body for long periods of time."

Parents can find more information about childhood exposures to PFCs from the website for the Agency for Toxic Substances and Disease Registry.