We appreciate the comments from Dr Brenna in response to our article about the potential health effects of prenatal and preconception environmental exposures that cause some women, on learning about the risks of mercury in fish, to avoid eating fish altogether.

Dr Brenna is correct that the US Environmental Protection Agency/Food and Drug Administration official fish advisory currently does not include large tuna in its list of fish to avoid during pregnancy. We have submitted a proof correction to the journal to clarify this point. However, it is important to recognize that several state-level fish advisories recognize the higher mercury content in albacore and tuna steaks. Minnesota, Michigan, and Washington all specifically recommend less frequent consumption of white canned tuna and tuna steaks compared with the federal guidelines; Washington lists tuna steaks on its “Don’t Eat” list. In addition, California includes tuna, fresh/frozen bluefin, and bigeye tuna on its list of the 7 fish with high mercury. According to the US FDA’s table of Mercury Levels in Commercial Fish and Shellfish (1990-2010), mercury concentrations in the larger species of tuna range from 0.354 ppm in yellowfin tuna to 0.689 ppm in bigeye tuna compared to concentrations in healthier alternatives, such as salmon (0.022 ppm), tilapia (0.013 ppm), and chunk light tuna (0.128 ppm). In fact, bigeye tuna is the species with the fifth highest concentration of mercury on the list, which falls immediately below the fish to avoid. In addition, Consumer Reports magazine in January 2011 published the results of mercury testing on 42 samples of canned tuna and showed that samples of white tuna had 0.217-0.774 ppm of mercury, with an average of 0.427 ppm, which confirms that white tuna should not be considered a low-mercury fish.

The fish consumption message is indeed complex, as Dr Brenna points out. Our aim is to simplify the message as much as possible for patients while still considering important health benefits. We want to encourage women to eat healthy fish but to choose wisely when doing so. This counseling will help keep women healthy during pregnancy while lowering mercury exposures that can affect the developing fetus adversely.