LOS ANGELES (CBS) — Most pregnant women know to keep their diets high in folic acid, to avoid raw foods and to stay away from alcohol and cigarettes to help keep their growing baby healthy. But there may be a new rule for pregnant women to follow.

A controversial Consumer Reports study recommends that pregnant women stay away from tuna all together because of high levels of the neurotoxin mercury.

READ MORE: Police Say 12 Arrested In Huntington Beach As Demonstrators Clash

There have been limitations on how much tuna pregnant women should eat for years. Both the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) recommend that women of childbearing age and children eat no more than 12 ounces per week of light tuna, including 6 ounces of white tuna.

But the Consumer Reports study concludes that there may be no safe levels of tuna for pregnant women.
The magazine tested 42 samples of tuna from cans bought in and around New York. Ever single sample tested had measurable levels of mercury, ranging from 0.018 to 0.774 parts per million (ppm). The researchers found that white tuna contains much higher levels of mercury than light tuna.

The study found the measured amount of mercury in white tuna to be so high that by eating just 2.5 ounces, a pregnant woman would exceed the daily mercury intake considered safe by the EPA. Comparably, eating a can of the light tuna tested by Consumer Reports would put a pregnant woman at risk.

The publication’s experts recommend that pregnant women should not consume tuna and that children over 45 pounds should have no more than 12.5 ounces of light tuna or 4 ounces of white tuna a week.

READ MORE: LAUSD Begins Phased-In Reopening Starting This Week

But Consumer Reports’ warning does not just go out to women of childbearing age, as mercury is dangerous for all humans. It is a lipid-soluble heavy metal, which means that once ingested it can be stored in the body indefinitely. It causes damage to all tissues and organs, especially the brain and kidneys. For pregnant women, exposure to mercury in-utero can damage an infant’s mental development and cognitive skills.

So why the issue with tuna? Mercury, and specifically a form called methylmercury, is present in most seafood. This is because of a phenomenon called bioaccumulation. Mercury released into the environment by natural sources like volcanoes or from humans accumulates in the tissues of animals in the food chain, until it reaches the largest predators. A tuna fish is one type of large predator that carries high levels of mercury in its body.

Actor Jeremy Piven of Entourage fame was rumored to have been diagnosed with mercury poisoning earlier this year because of his sushi habit. Piven, who plays the snarky character Ari Gold, ate sushi twice a day for twenty years.

But limiting seafood intake has its own risks, as it provides nutrients like Omega-3 fatty acids, which have been shown to help fetal development and reduce the risk of heart attack and stroke.
Groups like the National Fisheries Institute, who support the fishing industry, are quick to point out that none of the tested Consumer Reports samples are in excess of the FDA’s limit of 1 ppm.

The FDA has long been criticized for having mercury protection standards that are much too lax. The FDA does have the most liberal mercury level recommendation of anywhere in the rest of world. But in light of new research, including this latest study from Consumer Reports, the debate on mercury safety is set to continue.

MORE NEWS: LAPD Searching For 3 Men Suspected Of Posing As Construction Workers, Burglarizing Homes

To download a copy of the report click here.