If you’re like most health-conscious people, you’re probably eating more fish these days. But along with heart-healthy omega-3 fats, you may be getting something in your seafood that’s not so welcome: contaminants. A cautionary note regarding drug residues in imported fish comes from a study from the Johns Hopkins Center for a Livable Future in Baltimore. Published online in Environmental Science & Technology last November, it analyzed government-collected seafood inspection data from the U.S., Europe, Japan and Canada between 2000 and 2009.
Importing bad news
Some 85 percent of the seafood Americans consume is imported. And much of that is farm-raised (a practice called aquaculture) in Asia and elsewhere in the developing world. The problem is that other countries may have different standards for aquaculture, sometimes employing drugs banned here. In addition, most overseas fish farms are not inspected by U.S. officials. Moreover, though the government can detain suspect food imports without examining them (based on a history of prior recalls, for instance), only a fraction of imported seafood is actually tested for drug residues when it enters the country.
In fact, the Food and Drug Administration (FDA) checks just two percent of imports for contaminants (including drug residues, microbes and heavy metals), the study reported, compared to 20 to 50 percent in Europe, 18 percent in Japan and up to 15 percent in Canada. And when the FDA does inspect seafood imports, it looks for residues from only 13 drugs. In contrast, Europe tests for 34 drugs. That means overseas fish farms can be using a range of drugs for which the U.S. doesn’t even screen.
Last spring, the U.S. Government Accountability Office reported that only 0.1 percent of imported seafood was inspected specifically for drug residues in 2009 and concluded that the FDA’s oversight of the safety of imported seafood is limited—an understatement, indeed.
Shrimp top the list
Though seafood violations varied depending on the different inspection systems used across countries, the Hopkins researchers found that shrimp and prawns, overall, exceeded drug residue limits most frequently. Other problematic imported seafood included crab, basa (a type of catfish), eel and tilapia, most or all likely farmed. Of all countries, Vietnam had the most drug violations, followed by China and then other countries in Asia, including Thailand, Indonesia, Taiwan, India and Malaysia.
Antibiotics, antifungals and antiparasitics, as well as pesticides and disinfectants, are often used in fish farming to control diseases that can spread rampantly in crowded conditions. While routine exposure to such substances can pose a risk to aquaculture workers, the health effects of chronic low-level exposure in fish eaters are not fully known. At the very least, widespread use of antibiotics in aquaculture can contribute to the development of antibiotic-resistant bacteria and cause important antibiotic drugs to become ineffective in people.
Are other fish off the hook?
Contaminants in seafood are not limited to just farmed fish from developing countries. For example, as reported in a well-publicized study in Science in 2004, farmed salmon from Europe had the most PCBs (a man-made chemical whose manufacture was banned in 1979) and other potentially harmful industrial pollutants, while Chilean farmed salmon had less, which shows that problems in aquaculture occur in the developed world, too. (Changes in feeding practices in recent years may be reducing that problem.) And larger wild-caught fish, such as swordfish, have high levels of mercury, which can impair the nervous systems of developing fetuses, infants, and young children.
Despite these concerns over contaminants, the health benefits of fish outweigh potential risks. The U.S. Dietary Guidelines, the American Heart Association, the World Health Organization and other health authorities around the world recommend eating fish at least twice a week (at least 8 ounces total), preferably types rich in omega-3 fats such as salmon and sardines (though with certain caveats for pregnant and nursing women and young children).
A COOL idea
The 2011 Food Safety Modernization Act includes several provisions to help the FDA better monitor imported seafood. But given budgetary constraints, don’t expect a quick fix. Ideally the agency would not only test more imports, it would also check more overseas fish farms to make sure they meet U.S. standards in the first place.
That means it’s up to you to choose fish wisely—and your best recourse for limiting exposure to potential drug residues is to look primarily for domestic farmed seafood, suggests David Love, Ph.D., lead author of the Hopkins study, because it’s subject to more government oversight, including farm visits and inspection of safety plans. Certain wild-caught fish are also good options (see "Super seafood choices," below, for some farmed and wild seafood recommendations.) Seafood from Canada should be fine too, since no import violations were noted from there.
“Country of origin labeling” (COOL) regulations, which went into effect in 2005, can help you identify the source of seafood. They require supermarkets—but not restaurants, processed fish products, or, oddly enough, fish markets—to indicate where their fish come from and whether they were farmed or wild-caught.
In particular, you may want to limit or avoid imported Asian shrimp and prawns and all seafood from Vietnam (a big exporter of basa or “Asian catfish”). This is advice we don’t give lightly, since such exports help the economies of developing countries. Farmed imports, especially from Asia, are cheaper (think affordable shrimp), so forgoing or limiting them may mean a higher fish bill.
Three more fish tips
- Select fish lower on the food chain—anchovies, mackerel and sardines, for example. As larger predatory fish eat smaller fish, contaminants are concentrated and accumulated. Another benefit is that these smaller fish tend to have higher levels of omega-3 fats.
- Vary your seafood choices to minimize overexposing yourself to any particular contaminants they may contain. It’s okay to eat some farmed salmon, but perhaps not every week. Wild salmon is always a good option—and most canned salmon is wild (and cheap).
- Buy from a local fishmonger who has been in business for a while, buys direct from distributors, and can answer specific questions about the fish. Despite the good intentions of the COOL regulations, there is little oversight, so going to a trusted source is a better bet for getting high-quality fish.