Which Seafood Is Lowest in Contaminants?
How often do you eat seafood? Fish can be a great source of nutrients and omega-3 fatty acids, but varying levels of contaminants can cause the risks to outweigh the benefits of eating them so maybe it's best to restrict your diet to types of fish that are least likely to accumulate dangerous contaminants. We can help you determine the safest choices for your plate. Let's look deeper at which fish are safe and which are not.
How Fish Become Contaminated
We have polluted our oceans and rivers with the byproducts of industrialization. In the process, numerous waste products, have found their way into bodies of water directly or via runoff. Through the food chain, some of these contaminants accumulate, sometimes to dangerous levels, in the tissues of fish and other aquatic life. When we considered the types and concentrations of accumulations that are most present, it came to attention that generally speaking, the larger the fish, the more likely it’s had time to accrue high levels of toxins due to length of exposure. So let's keep that in mind when choosing fish at the market — smaller may mean younger, and younger fish have had less time to accumulate toxins.
Mercury
Mercury is a by-product of fossil fuel combustion and some manufacturing, and it winds up in landfills as the result of irresponsible trash disposal. Once it finds its way into a water source, bacteria convert it into a form called methylmercury, which is highly toxic to humans and animals. Fish then eat plankton that has ingested the methylmercury-contaminated bacteria, and the dangerous process of bioaccumulation begins.
Other Chemicals
Industrial Chemicals and pesticides can also accumulate to dangerous levels — and some of them can persist in the environment for a long time. Polychlorinated biphenyls (PCBs), once used as mechanical lubricants and coolants, haven’t been legal to use in US manufacturing since 1977, but they continue to find their way into our fish supply. Consumption of PCBs can cause anemia, acne-like conditions and stomach problems. PCBs may also damage the liver and thyroid gland and are a probable human carcinogen.
Another type of chemical that often ends up in fish is a flame retardant called Polybrominated Diphenyl Ethers (PBDEs). You can find it in upholstery, foam carpet pads, mattresses, electronics, and tons of other items, where it can leach out into the environment. In humans, it can impair learning and disrupt hormones. PCBs, PBDEs and other chemicals can build up in the sediment beneath river and lake water, so bottom feeders are most likely to absorb them.
Antibiotics in Fish
Did you know that many farmed fish test positive for antibiotic residues? One study, which took fish samples from numerous locations across Shanghai City, China, found antibiotic residues in up to 91% of finfish and 17% of shrimp. Antibiotic resistance has also become a problem in Chilean fisheries, where the majority of the world’s farmed salmon comes from. Researchers in Africa found multiple antibiotic resistances in their fisheries as well. Given that farmed fish must do something to control problems in their tanks, it’s probably best to skip the farmed fish and eat wild-caught varieties (in moderation).
Safest Fish to Eat
So how do we at least cut back or control our exposure? Limit fish consumption to types that are less likely to accumulate toxins, such as anchovies, salmon, sardines, pollock, herring and trout. Crab, clams, oysters and scallops are also great choices. Check labels every time, avoiding farmed imports. If you catch your own fish, check for state or national advisories in your local area, and clean your fish well. Be sure to remove the skin if possible as well as internal organs, before cooking.
Fish can be a yummy and nutritious addition to some diets, but we do need to be careful about our sources and consider how much we're willing to ingest when chemicals may come as a side order to the meal. If in doubt, it may be best to pass it up and choose something with fewer risks.
