The federal agency gave particular attention to pregnant and breastfeeding women, and in less than 24 hours the Center for Science in the Public Interest said the FDA’s advice is bad medicine.

After reviewing more than 220 public comments on the topic, the FDA reaffirmed its 2014 advice with this week’s final advice and recommends adults, including pregnant and breastfeeding women, should eat 4-ounce servings of “low-mercury” fish and/or shellfish at least two or three times per week.

“However, all fish contain at least traces of mercury, which can be harmful to the brain and nervous system if a person is exposed to too much of it over time,” according to the FDA’s final advice.

“The maximum level of consumption recommended in the final advice is consistent with the previous recommended level of 12 ounces per week. The new advice is consistent with the 2015-2020 Dietary Guidelines for Americans.”

The FDA advice says choices lower in mercury include some of the most commonly eaten fish, such as “shrimp, pollock, salmon, canned light tuna, tilapia, catfish and cod.”

Lisa Lefferts, senior scientist for the Center for Science in the Public Interest (CSPI), said the advice could literally be life threatening when it comes to one of the staples in many U.S. kitchens — tuna.

“If pregnant women or small kids followed the new advice from the government on mercury and tuna they could easily consume more mercury than is safe for developing brains,” Lefferts said in a written statement issued by CSPI on Thursday.

“The best advice for pregnant or nursing women and parents of small children is to choose fish that are low in mercury and high in omega-3 fatty acids, like salmon and sardines. They should avoid albacore tuna altogether, and consume tuna labeled as ‘light tuna’ very sparingly — no more than two ounces per week for women and one ounce per week for kids.”

The CSPI is a non-profit advocacy group based in Washington D.C. It was founded in 1971 by scientists from Ralph Nader’s Center for the Study of Responsive Law and focuses on nutrition and food safety policies.

Regardless of the actual danger, some FDA data suggests more than half of pregnant women don’t have anything to worry about because they simply don’t eat enough fish.

“An FDA analysis of fish consumption data found that 50 percent of pregnant women surveyed ate fewer than two ounces a week, far less than the amount recommended,” according to the agency’s advice.

“Because the nutritional benefits of eating fish are important for growth and development during pregnancy and early childhood, the agencies are advising and promoting a minimum level of fish consumption for these groups.”

One fish, two fish — advice covers 62 fish
While the FDA’s basic recommendations for amounts of fish that should be included for a healthy diet have not changed since it issued its draft advice in 2014, the final advice this week includes details designed to make it easier for consumers to follow the advice.

“In June 2014, the agency issued draft advice which encouraged pregnant women and others to eat between 8 and 12 ounces of fish a week of fish ‘lower in mercury’ but did not provide a list showing consumers which fish are lower in mercury,” FDA officials wrote in the final advice issued Wednesday.

“The advice issued today also takes into account more than 220 comments received from academia, industry, nongovernmental organizations and consumers as well as an external peer review of the information and method used to categorize the fish.”

An at-a-glance chart that FDA is hoping retailers and restaurants make available to consumers in point-of-sale materials breaks down 62 kinds fish and shellfish into three easy-to-understand categories:

• Best choices — adults should eat two to three servings a week;
• Good choices — adults should eat one serving a week; and
• Fish to avoid — pregnant and nursing women and children should not eat tilefish from the Gulf of Mexico; shark; swordfish; orange roughy; bigeye tuna; marlin; and king mackerel.

Fish in the “best choices” category make up nearly 90 percent of fish eaten in the United States, according to the FDA.

“For adults, a typical serving is 4 ounces of fish, measured before cooking,” according to FDA’s final advice.

“Serving sizes for children should be smaller and adjusted for their age and total calorie needs. It is recommended that children eat fish once or twice a week, seleced from a variety of fish types.”

Does location really matter?
All catfish and cod are not equal, according to the final advice from the FDA, especially when considering the question of mercury content. Staff from FDA worked with the Environmental Protection Agency to help determine the best advice regarding locally caught fish and shellfish.

“For fish caught recreationally, consumers are urged to check for local advisories wher they are fishing and gauge their fish consumption based on any local and state advisories for those waters. If no information on fishing advisories is available, eat just one fish meal a week from local waters and also, avoid other fish that week,” FDA advises.

Elizabeth Southerland, director of water science and technology at EPA, said in a news release that “it’s all about eating and enjoying fish of the right kind and in the right amounts.

“This joint advice not only provides information for fish consumers who buy from local markets, but it also contains good information for people who catch their own fish or are provided fish caught by friends or relatives.”