The government last revised its mercury guidance in 2004 when it said young children, pregnant women, nursing mothers and women who might become pregnant should eat seafood but avoid shark, swordfish, king mackerel and tilefish, which contain relatively high levels of mercury.
It recommended that this population eat up to 12 ounces a week of fish and shellfish that are lower in mercury, such as shrimp, salmon, pollock and catfish. These recommendations were by and large incorporated into dietary guidelines adopted by the health and agriculture departments in 2010.
Yet the 2004 advisory was based on studies conducted 20 years ago or more, and some say the results of those studies are out of date.
"Research carried out in the past decade has both clarified the beneficial nutritional effects of fish consumption during pregnancy and found adverse effects of prenatal methylmercury exposure at very low doses, at least an order of magnitude below exposures known to be harmful when the current Advisory was written," a group of 40 or so scientists and environmental advocacy groups wrote in a letter to Health and Human Services Secretary Kathleen Sebelius last month.
The scientists said they understood, from discussions with government officials, that the Food and Drug Administration and Environmental Protection Agency have jointly crafted an updated advisory but that the draft has stalled within the health department.
Both the FDA and the Department of Health and Human Services, of which the FDA is part, said the advisory is still under review but declined to indicate how far along it is in the process or when it might be released for public comment. The EPA referred questions to HHS.
"FDA and EPA are actively engaged in updating our advice, taking into account new science and data that has emerged since the 2004 advice published," an FDA spokeswoman, Theresa Eisenman, said in a statement.
The recent letter follows a similar request last July to President Barack Obama from a group of 22 U.S. senators who urged the FDA to release the updated advisory.
In September, Sebelius responded to the senators, saying that completing the updated advisory remained a priority, but she gave no details as to when the advisory might be released.
The FDA's 2004 advisory said that for most people, there is little danger from eating fish but that "some fish and shellfish contain higher levels of mercury that may harm an unborn baby or young child's developing nervous system."
As a U.S. senator, Obama worked to prevent the release of surplus U.S. mercury into global commerce.
He introduced a bill with Alaska Republican Lisa Murkowski to prohibit the transfer of elemental mercury by federal agencies and to ban U.S. exports of mercury by 2013. The Mercury Export Ban Act of 2008 was signed into law by President George W. Bush.
The National Fisheries Institute, which represents seafood producers, wholesalers, retailers and trade groups, did not immediately respond to telephone and emailed requests for comment, but on May 6 it announced it had created a new website "to correct dangerous misinformation about seafood and mercury."
"A space dedicated to debunking mercury myths is desperately needed because for years, activists have willfully fed an often lazy, unsuspecting and sympathetic media groundless warnings about eating fish," the organization's vice president, Mary Anne Hansan, said in the announcement.
The scientists who signed the letter to Sebelius want the government to give more detailed, and more nuanced, advice as to the risks and benefits associated with eating fish.
According to food safety consultant Edward Groth III, who was a signatory to the letter and published a 2012 report suggesting that the 2004 advisory is no longer adequate for protecting public health, said he expects the FDA's draft, based on discussions with its authors, to give consumers a much broader range of fish to choose from and more data to inform their decisions.
"All in all, the updated advisory seems like a significant improvement in both the quantity and quality of information for consumers on this topic, and it is really important that it move forward."
While a list of mercury concentrations in individual fish is listed in tables on the FDA's website, health advocates want to see the information presented in a way that the public can easily understand. In her letter to the senators last year, Sebelius said the health department is working on that too.
The FDA and EPA, she said, are working to craft supplemental materials "that will provide additional, plain language insights to consumers about fish consumption during pregnancy."
