Children exposed to elevated levels of long-chain perfluorocarbon (PFC) compounds might have compromised immune systems, suggests an immunotoxicity study (J. Am. Med. Assoc., DOI: 10.1001/jama.2011.2034). Scientists have known that PFCs—found in food wrappers, nonstick cookware, and other consumer products—accumulate in people and animals, and they have long suspected the compounds of having adverse effects on human health. In a first-of-its-kind assessment, an international research team led by Philippe Grandjean of Harvard School of Public Health examined children vaccinated for diphtheria and tetanus who were born and raised on the Faroe Islands. On that archipelago, located north of Scotland, residents consume large amounts of seafood, which accumulates particularly high levels of PFCs. On the basis of data the researchers collected from the children over an eight-year period, they concluded that a twofold increase in a child’s PFC level correlates with an almost 50% decrease in overall antibody production. “These findings suggest a decreased effect of childhood vaccines and may reflect a more general immune system deficit,” Grandjean and coworkers write. But first, more work is needed to determine whether other vaccines have the same result, they add.