Pregnant women need to be more selective when it comes to eating fish, according to a health group examining the draft of a federal guideline regarding fish consumption advised.

The Environmental Working Group (EWG) says that if pregnant women follow the recommendations jointly drafted by the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA), they will be at risk of exposing their unborn babies to high levels of mercury because the recommendations are not specific enough. Mercury is a chemical that can harm the brain development in fetuses and young children when consumed in large amounts.

The EWG wrote in its report that the agencies' lists of high mercury and low mercury fish that pregnant women, breastfeeding women, women looking to get pregnant and young children should avoid are not complete. For example, the FDA and the EPA classified canned albacore tuna as a low mercury fish, even though some studies have found that this type of fish can have high levels of mercury. The EWG added that canned tuna is also on the National Resources Defense Council's high-mercury seafood list.

In order to better understand the risks involved if women were to follow the FDA and EPA's guidelines, the EWG conducted a study on 254 women from 40 states who were of childbearing age. All of the women reported either eating around or slightly more than the amount that the FDA and EPA decided on in their draft recommendations, which was eight to 12 ounces of low-mercury fish and shellfish per week for women who are pregnant, nursing or planning on getting pregnant to eat. The researchers also measured the women's mercury levels.

The researchers found that 30 percent of the women had mercury levels that were higher than what the EPA would say was safe. Nearly 60 percent of the women had levels that would be considered dangerous by Phillipe Grandjean, an adjunct professor at the Harvard School of Public Health who conducted the mercury analysis for the study.

When the researchers looked at the type of fish that the women were eating, they found that the majority of the mercury that was ingested came from fish species that the government did not advise against. This finding suggests that the FDA and EPA guidelines are not providing clear recommendations for women, which are then putting unborn babies at risk.

"When you eat seafood during pregnancy, you get the benefits from omega-3s but from mercury you have the risk of toxicity," Grandjean said. "If you get a little bit of mercury it can be offset by the omega-3s. But that means you don't get the full benefit of the omega-3s and other nutrients in seafood. So women should minimize mercury exposure because only then will they get the maximum benefit of seafood."

The EWG is urging the FDA and the EPA to update its draft guidelines.