Will FDA relax its warnings on seafood?

A quick reaction from the Environmental Protection Agency expressed "serious concerns" about the "scientifically flawed" report and, invoking the holy grail of scientific rigor, reiterated the agency's stance that mercury contamination cannot be taken lightly.

FDA officials say they're not preparing to change the guidelines but simply soliciting comments from other government scientists, according to an e-mail from FDA spokeswoman Stephanie Kwisnek.

The EPA and environmental activists appear skeptical. "It's important to note these comments -- from EPA -- have been very negative," says Sonya Lunder, a senior analyst at the nonprofit Environmental Working Group. The advocacy organization, which has seen both the draft report and the EPA response, is adamantly opposed to any attempt to ease the warnings about mercury in fish.

The apparent clash between the two agencies is a turnaround from four years ago when they issued a joint advisory with specific fish-consumption recommendations for groups at the highest risk for mercury-related health problems: women who are pregnant or nursing, women who might become pregnant and children. That advice included avoiding shark, swordfish, king mackerel and tilefish -- four fish species with the highest levels of mercury. The advisory also set an upper limit for eating seafood of any kind at two 6-ounce servings per week for those groups.

The science behind the policy is tricky. It's hard enough for epidemiologists to correlate one dietary factor to a health outcome. In this case, policymakers must assess what's known about two components of fish -- mercury and omega-3 fatty acids -- which have opposing effects on normal child development. Studies often look at either the risk of mercury intake or the benefit of fish eating, but rarely both.