Times Gets Slippery on Sushi
More on the mercury beat: The National Fisheries Institute is angry about a front-page New York Times, and a related piece yesterday, claiming that restaurant sushi contains dangerous amounts of mercury. No surprise there. The Institute represents fisherpersons, who make a living off the large fish that are sliced into tiny bits and sold to raw fish lovers at a huge markup. But I think they have a point. In her Jan. 23, above-the-fold lede, food columnist Marian Burros wrote that people eating six pieces of sushi a week on a regular basis “would exceed the levels considered acceptable by the Environmental Protection Agency.” Further down, Burros wrote that six pieces of sushi from most of the restaurants and stores the Times investigated would contain more than 49 micrograms of mercury, which she described as the amount the EPA “deems acceptable for weekly consumption over a period of several months.” But this isn’t really true.
The limits Burros referred to come from the EPA’s “reference dose,” which the EPA defines as exposures that are “likely to be without an appreciable risk of deleterious effects during a lifetime.” [italics mine] There is no weekly reference dose. Nor is it “dangerous” to exceed the daily “reference dose” on a weekly or even a monthly basis. For one thing, there has never been a clinical case of mercury poisoning from eating fish in the United States. To be sure, scientists know that methyl mercury is a neurotoxin, if the dose is large enough. They know that large fish and sea mammals contain disproportionately large amounts of methyl mercury. These animals are high on the seafood chain–which mercury enters through industrial pollution and volcanic eruptions. To determine what amount of mercury-containing seafood was safe to eat, the EPA had access to two major, decades-long studies of seafood consumption. One came from the Seychelles–islands in the Indian Ocean. The mothers in that study who ate lots and lots of mercury-containing fish had kids who were smart and healthy. But in another study, in the Faeroes Islands, children whose mothers ate seafood including lots of pilot whale meat had more subtle neurological problems, on average, than those that didn’t. Some have theorized that the healthy ingredients in the Seychelles fish counteracted the mercury, while the pilot whale flesh may have contained other substances, like PCBs, that made it more dangerous. To be on the safe side, the EPA used the Faeroes Islands data to establish its “reference dose.” To be even safer, it set the dose at ten times lower than the lowest amount of mercury consumption that had caused harm to children in the Faeroes. Oh yeah–Did I mention that these reference doses come from studies of harm to fetuses of pregnant women, a particularly vulnerable group? And that recent studies have shown that the kids of fish-eating moms are healthier than those whose mothers avoid fish during pregnancy?
To be sure, there are some scientists who feel that mercury is not well-studied enough to be sure that even the “reference dose” is safe. But if you gathered together a room of people who are knowledgeable about mercury toxicity, most of them would conclude that the *Times *piece was alarmist.