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Is the PCB Content of Fish Oil High Enough to be Dangerous?

By Nicholas Bronson

September 25, 1010











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            The dietary supplement fish oil has become very popular in recent years due to the variety of health benefits that it is associated with, however, fish oil has come under fire recently for its polychlorinated biphenyl (PCB) content. Two environmentalists, Chiles, B., & Manthey, C (2010), are leading a proposition 65 lawsuit against several fish oil manufacturing companies. On their website they claim that the 10 fish oil products that they tested have “high levels of toxic contaminants such as PCBs” (


The lawsuit appears to be valid, as the manufacturers of the supplement have no warning about the PCBs that are present in their fish oil products. While it is concerning that the fish oil manufacturers may be breaking the law, the lawsuit does not address the important question of whether the level of PCBs in fish oil could actually be dangerous or if levels are too low to be harmful.  


Fish Oil and its Effects


Fish oil is a supplement that can be derived from a variety of different fish. It contains omega-3 fatty acids, which are correlated with numerous health benefits.  These benefits include: “improving cognitive functioning, suppressing inflammation, and promoting the health of blood vessels in the brain and body” (Fish oil may ward off schizophrenia, 2010). Newer studies even indicate “that omega-3s may also have anti-cancer properties” (Omega-3s may reduce the risk of colon cancer, 2010). Fish oil has even been called the “one essential nutrient most missing in our modern day diet” (

Omega-3 fatty acids had a much larger presence in diets of the past, but the way that many foods are produced in the modern day deprives these foods of much of their omega-3 content. Taking fish oil is an easy way for one to get omega-3s without having to eat very much fish, which can contain high levels of mercury as well as other toxins. Fish oil is commonly treated for mercury and PCBs, but many fish oil products still contain noticeable PCB levels.

PCBs and their Negative Effects

PCBs are “a broad family of man-made organic chemicals” which were produced “from 1929 until their manufacture was banned in 1979” (‌epawaste/‌hazard/‌tsd/‌pcbs/‌pubs/‌laws.htm). PCBs are correlated with numerous adverse health effects including cancer, endocrine problems, and reproductive issues such as birth defects. These chemicals do not break down easily, and therefore once they are introduced into the environment, it is very difficult to remove them from the environmental cycle. Fish are particularly susceptible to absorbing PCBs due to bio-magnification. Because fish live in contaminated waters, they absorb harmful chemicals from simply inhabiting tainted waters. The reason fish have a higher PCB content than the smaller aquatic organisms is because they eat many of these smaller organisms, accumulating significant levels of PCBs over time. A portion of this PCB content remains in fish oil, even after the product is treated.










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Review of the Studies:

            The meta-analysis conducted by Bourdon et al. investigated the possible implications of ingesting low dosages of PCBs daily via fish oil, as well as other similar substances such as seal derived oil. In this study the PCB content of these supplements was measured against the tolerable daily limit for PCBs. None of the supplements tested exceeded the tolerable daily limit if only one gram was taken per day, however the recommended dosage was often two to three grams per day. Only one supplement that contained oil from seals exceeded the “20 ng kg-BW−1 day−1 TDI” limit even at the dosage of three grams per day (Bourdon, 2010). The analysis suggested that fish oil does not exceed the tolerable daily limits for PCBs, however, the analysis did offer a disclaimer stating that PCB content may accumulate over time, and could potentially result in negative health effects after extended fish oil use. The analysis concluded by suggesting that fish oil has numerous benefits, and if fish oil which is “derived from small, cold-water, fatty fish” is ingested, the PCB content will be less substantial than taking products that do not fit these criteria (Bourdon, 2010).

            A study done by Miriam et al. (2004) examined the possibility of vegetable oils as an alternative to fish oil. Vegetable oils “are sources of the shorter chain precursor forms of n-3 fatty acids” (Miriam, 2004). This study suggested that the levels of contaminants in fish oil has been lowering due to improved methods of treatment, and improved methods of manufacturing fish oil. The research study also stated that vegetable oils do not have enough of the omega-3 fatty acids EPA and DHA to replace fish oil as a source of omega-3 fatty acids. While vegetable oils have significantly lower levels of contaminants than fish oil, vegetable oil could never have the potent effect that fish oil is correlated with. Finally, the study concludes by stating that contaminant levels in fish oil have to be analyzed and monitored closely going into the future (Miriam, 2004).

            In a third study conducted by Fernandes et al. (2006), it is suggested that too much attention is paid to PCBs and not enough towards other chemicals such as polychlorinated dibenzo-p-dioxins and dibenzofurans. Unfortunately there is very limited knowledge about the effects of these chemicals on humans (Fernandes, 2006).


            While we do know some information about PCBs, there is still much to be learned PCBs. For starters, measuring PCB levels is an imperfect science, as there are several different ways to measure PCB levels. One of them looks “at all 209 separate compounds in the PCB chemical family,” while  “the second way looks at toxicity based on the 12 most toxic compounds in the PCB family” ( Researchers are not sure which method is a more accurate predictor of the dangers associated with PCBs, and it is very difficult to determine which chemicals are associated with the most serious health risks. Another problem with measuring PCBs is that there is not enough research on the possible synergistic effects of different PCB chemicals. It is even possible that the negative effects of PCBs are magnified when certain chemicals are together in high levels.

Because PCBs are not well understood, it is hard to determine whether the small PCB concentration in fish oil could be damaging over time. A long-term study of people taking fish oil would have to be conducted in order to determine weather fish oil has long term health effects or not. Research on the other potentially harmful chemicals in fish oil must also be conducted. There has been more focus on the PCB content of fish oil than the other chemicals because PCBs are better understood, but there are numerous other chemicals that could be present in fish oil that may very well be just as harmful, or more harmful than PCBs.

The proposition 65 lawsuit against the fish oil companies will most likely result in stricter filtering and distillation of fish oil, especially in the companies producing fish oil with higher levels of PCBs. This will further reduce the already low chance of suffering adverse effects from ingesting the small amounts of PCBs in fish oil (




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Summary and Conclusion:

While the potential negative effects of fish oil are not well understood, the potential positive effects of fish oil are very clear.  Fish oil can greatly improve one’s health depending on the health ailment that he or she suffers from, and can protect a healthy person from numerous health problems. Omega 3’s fatty acids seem to be some of the most major components missing from the modern diet.

It is most likely safe to take fish oil despite the PCB content of the supplement. If one suffers from the effects of mental problems, cardiovascular problems, or even cancer, taking fish oil would most likely be very beneficial. It is prudent to take fish oil that is derived from small, cold water fish until the effects of PCBs are better understood, however, there is no evidence that correlates taking fish oil with adverse health effects due to PCBs. 




Bay Area News Group. (2010, March 2). Lawsuit claims PCBs found in 10 fish oil     

supplements; Product labeling sought. Retrieved from

Bourdon, J. A., Bazinet, T. M., Arnason, T. T., Blais, J. M., White, P. A., & Kimpe, L. E. (2010, August 6). Polychlorinated biphenyls (PCBs) contamination and aryl hydrocarbon receptor (AhR) agonist activity of Omega-3 polyunsaturated fatty acid supplements: Implications for daily intake of dioxins and PCBs. Food and Chemical Toxicology. doi:10.1016/‌j.fct.2010.07.051

Chiles, B., & Manthey, C. (2010). Our Prop. 65 Lawsuit. In Retrieved from

Fernandes, A. R., Rose, M., Gem, M., Mortimer, D. N., & White, S. (2006, September). Dioxins and polychlorinated biphenyls (PCBs) in fish oil dietary supplements: occurrence and human exposure in the UK. Food Additives and Contaminants, 23(9), 939-947.

Fish oil may ward off schizophrenia: omega-3 fatty acids in the oil may prevent brain changes associated with the chronic mental disorder . (2010, July 1). Mind, Mood, & Memory.

Laws and regulations. (2010, May 22). Polychlorinated Biphenyls. Retrieved from Environmental Protection Agency website:‌epawaste/‌hazard/‌tsd/‌pcbs/‌pubs/‌laws.htm

Miriam, J. N., Covaci, A., Gheorghe, A., & Schepens, P. (2004, February 26). Time trend investigation of PCBs, PBDEs, and organochlorine pesticides in selected polyunsaturated fatty acid rich dietary fish oil and vegetable oil supplements. Journal of Agricultural and Food Chemistry, 52(6), 1780-1788. doi:10.1021/‌jf035310q

Omega-3s may reduce the risk of colon cancer: The anti-inflammatory fatty acids appear to have many other health benefits, too. (2010, July). Healthy Years, 7.

Why you need omega 3 fish oil. (2010). Healthy omega 3 fish oil. Retrieved from





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