Human Health Risks
In addition to risking both fish and environmental health, aquacultural practices endanger human health:
- Antibiotics: Fish farms frequently use antibiotics to control disease in their crowded pens. By eating fish that have been treated with antibiotics, consumers may be ingesting harmful levels of antibiotic residues. More importantly, the use of antibiotics in aquaculture increases the risk of harmful bacteria becoming resistant to specific antibiotics, undermining the effectiveness of those antibiotics in treating human illness. Finally, antibiotics used in aquaculture often enter the environment, where they contaminate wild seafood. In one study, drug residues in wild fish were found to exceed Food and Drug Administration (FDA) safety levels.
- Fungicides: The chemical malachite green is used as a fungicide to prevent the growth of fungus on fish eggs. Malachite green is believed to be toxic, mutagenic, and carcinogenic in animals. Although its use in aquaculture is banned in the U.S., it is still used in many countries that contribute to our seafood supply. The FDA does not test imported salmon for this chemical, despite evidence that our imported salmon may be contaminated.
- Dyes: It is estimated that 95% of Atlantic salmon is farmed, and almost all of it is dyed pink to make it more palatable to consumers. Although the effects of these dyes on health are not well known, recent studies have indicated possible links between artificial food colorings and hyperactivity in children as well as retinal damage.
- Persistent Organic Pollutants: Persistent organic pollutants (POPs) such as PCBs and dioxins are chemical compounds that resist biodegradation and therefore “persist” in the environment. As such, they tend to bioaccumulate up the food chain and can cause significant health concerns for both humans and the environment, associated with increasing the risk of cancer, disrupting the endocrine system, and contributing to developmental and reproductive problems. A 2004 study in the journal Science found that farmed Atlantic salmon have such high levels of PCBs that the authors advised against eating more than one meal per month of farmed salmon from certain areas based on the EPA’s recommended exposure levels. Although all fish accumulate POPs from the environment into their fats, farmed fish do so at a higher rate than wild fish. This is because farmed fish are fed on a diet high in contaminated fish oils and fishmeal. Fewer chemicals accumulate in wild fish because their diet contains less of the contaminated fats and because they get more exercise, reducing their fat levels.
- Nutrition: Farmed fish contain lower levels of protein, a lower ratio of omega-3 to omega-6 fatty acids, and higher levels of total fat. Unless you know where your seafood comes from, it might not be offering the health benefit you think it does.
 Hites, Ronald A. et al. “Global Assessment of Organic Contaminants inFarmed Salmon.” Science, vol. 303, January 2004