Chemical compounds widely used in fast-food packaging, waterproof clothing were associated with lower vaccine immune response in young children, says study.
The study, in Tuesday's Journal of the American Medical Association (JAMA), is the first to show how perfluorinated compounds can negatively affect the response to vaccines.
PFCs can be transferred to children before birth via the mother, or after birth from exposure in the environment, according to the report.
Grandjean appeared alarmed because routine childhood immunizations "are a mainstay of modern disease prevention."
Researchers "were surprised by the steep negative associations, which suggest that PFCs may be more toxic to the immune system than current dioxin exposures," said Grandjean.
PFCs have thousands of industrial and manufacturing uses, and most Americans have traces of the chemical compounds in their bodies.
Earlier studies have shown that PFC concentrations in mice similar to those found in people suppressed immune response. The negative effects of the compounds on people however have not been well studied.
The experts studied data on infants at the National Hospital in Torshavn, on Denmark's Faroe Islands, during 1999-2001. Of those studied, 587 children participated in follow-up examinations at ages five and seven, when they were tested for immune response to tetanus and diphtheria vaccinations.
The level of PFCs were measured in maternal pregnancy blood serum, and in the blood serum of children at age five, to determine prenatal and postnatal exposure.
The results show a link between exposure to PFCs and a lower antibody response to tetanus and diphtheria vaccines than normal.
A lower level of antibodies increases the risk that the children will not have an adequate immune response for long-term protection against tetanus and diphtheria, according to the study authors.
"A two-fold greater concentration of three major PFCs was associated with a 49 percent lower level of serum antibodies in children at age 7 years," the report read.
The PFC concentrations "are similar to or slightly below those reported in US women," while most serum PFC levels in the children at age five "were lower than those measured in US children aged 3 to 5 years in 2001-2002," the report said.
Bisphenol A (BPA), another chemical compound widely used in cans, beverage bottles and in some dental fillings, is a suspected "endocrine disruptor," which can result in breast and prostate cancer and affect the developing brains of infants and children.