When the online journal Public Library of Science Medicine (PLoS Medicine) accepted a paper that provided new evidence that environmental pollutants reduce the effectiveness of childhood vaccinations, the editors turned to a Cornell professor to put the findings in context.

"The study provides a stark example of the heightened immune vulnerabilities that exist during early life and that must be adequately protected from environmental insult if we are to minimize health risks to children," wrote Rodney Dietert, professor of immunotoxicology in the College of Veterinary Medicine at Cornell, in the Aug. 22 online edition of PLoS Medicine.

The study on which he was commenting was led by Carsten Heilmann of Denmark's National University Hospital. It shows that children exposed to PCBs have reduced antibody responses to childhood vaccinations. The researchers studied children whose diet of whale blubber in the North Atlantic Ocean's Faroe Islands exposed them to 10 times more PCBs than children in Northern Europe and used what Dietert calls "a very valuable measure [a T cell-dependent functional immune response] of immunosuppression."

Dietert points out that the new study adds great weight to the growing evidence that PCBs have deleterious effects on children's immune function. He stressed that the findings are a warning call that young children are far more sensitive to immunotoxicants than adults, and that toxicity testing in adults does not predict effects in young children.

The study, he said, has just the right kind of measures to detect links between environmental toxin exposure and immune dysfunction and to "reconsider the wisdom of exposing pregnant women, infants and children to drugs and chemicals with unknown developmental immunotoxic risks," he said, noting that that includes most approved drugs and chemicals.