FDA Mischief: Mercury in Fish


When I give talks on health and the environment, I almost always get asked about mercury. People want to know whether it’s safe to eat fish, whether the mercury in fish is dangerous, and how they can protect themselves. These questions are relatively straightforward to answer (see below for my three tips), but people are confused by all the conflicting advice emerging from the Federal government these days.

Back in 2004, the FDA and the EPA got together and issued a joint warning about fish and mercury. I complained a bit back then because I didn’t think the warning was specific enough, but at least the two agencies were on the same page.

Now, in the waning days of the Bush Administration, the FDA has produced a bizarre draft document that ignores the science showing the harmful effects of prenatal exposures to mercury, and concludes that eating fish with relatively high levels of mercury can be beneficial.  This conclusion stands in stark contrast to previous work by the National Academy of Sciences and EPA. EPA scientists were given only a few weeks to comment on the 433 page FDA report and their comments are scathing.

EPA’s most important criticisms include:

1.  The FDA analysis of the benefits of eating fish is based on the total amount of “average fish” consumed rather than distinguishing among types of fish.  This ignores the science that shows some fish have low mercury levels and higher amounts of omega-3 fatty acids and some fish have high mercury with little benefit from omega-3s.

2.  The FDA analysis of the harm of eating fish focuses on age at talking, rather than the more sensitive endpoints of cognitive and sensory function as the key endpoint in children. This allows them to overlook adverse impacts that occur at lower levels. This problem is compounded by modeling that has not been peer-reviewed or undergone sensitivity testing, meaning that it may be seriously flawed.

3.  FDA downplays neurodevelopmental effects of mercury by omitting and mischaracterizing the scientific data.  For example, FDA presents the fish benefit findings from a paper but does not mention the same paper’s finding that the mercury in the fish has an adverse effect on brain development.  In other cases, FDA inaccurately characterizes  the studies – reporting findings and conclusions that cannot be found in the cited paper.

Even with these flawed assumptions, FDA admits that up to 10 percent of the population may experience adverse effects from eating diets that include significant amounts of high mercury fish.  FDA dismisses this concern as unimportant alleging that such high mercury fish diets are “unusual”, which is incorrect; albacore tuna, which is high in mercury, is a very common fish in the U.S. diet.

So here’s my advice to women of reproductive age:

  • Steer clear of the high mercury fish, such as swordfish, shark, ahi tuna, and orange roughy;
  • Take it easy (once a week or less) for fish with intermediate mercury levels such as bluefish, grouper, bass, albacore tuna, and halibut;
  • Choose these low-mercury fish for plenty of Omega-3s: herring, salmon, sardines, flounder, sole, and tilapia.

You can get more information about which fish are high and which are low at our website, and you can even calculate your mercury intake or download a handy wallet card.

Meanwhile the FDA needs to get it’s act together and give people advice that is grounded in science and reflects the facts.