Measurement of Organochlorines in Commercial Over-the-Counter Fish Oil Preparations: Implications for Dietary and Therapeutic Recommendations for Omega-3 Fatty Acids and a Review of the Literature

Archives of Pathology & Laboratory Medicine, Jan 2005 by Melanson, Stacy Foran, Lewandrowski, Elizabeth Lee, Flood, James G, Lewandrowski, Kent B

RESULTS

The results of the analysis are shown in the Table. None of the 5 brands contained detectable amounts of PCBs or OCs. We previously tested the mercury levels in 5 overthe-counter preparations of fish oil. None of the 5 brands contained significant amounts of mercury. No mercury (less than 6 �g/L) was detected in the Nordic Ultimate, Sundown, and Kirkland brands. The Omega Brite brand had 12 �g/L of mercury, and the CVS brand contained 10 �g/L.16

COMMENT

Organochlorines are a group of toxic chemicals that can be divided into OC pesticides (chlordane, dieldrin, DDT, aldrin, endrin, heptachlor, hexachlorobenzene, mirex, toxaphene) and OC nonpesticides (PCBs, PBB, polychlorinated dibenzofurans and polychlorinated dibenzodioxins). DDT and PCBs will be discussed as representatives from each category.17

Polychlorinated biphenyls are a family of 209 congeners with 2 linked phenyl rings and variable chlorination. PCBs are colorless and odorless chemicals that were widely used in electrical equipment such as transformers and capacitors before 1977. Of the PCBs produced in the United States before 1976, 1.2 billion pounds ended up in rivers, lakes, and ultimately the oceans, where they accumulate in wildlife. Bottom-feeding fish ingest PCBs, and the PCBs become more concentrated higher up on the food chain (0.6-20 parts per million [ppm] in edible fish high in the food chain).18,31-33 A higher degree of chlorination correlates with an increased resistance to biodegradation. Some properties that made PCBs and other OCs so useful in industrial applications, such as stability and nonflammability, enable them to persist in the environment for long periods (environmental half-lives as long as 5 years). These toxins can still be found in older x-ray equipment, refrigerators, televisions, and fluorescent lighting fixtures.17

Polychlorinated biphenyls have been responsible for widespread environmental contamination affecting both animals and humans. In 1988, PCBs were linked to the death of 20000 European harbor and gray seals, which represented 60% of the local population. The seals died after a viral outbreak of Morbillivinis, presumably because the PCBs diminished the seals' immune response to viral infections. Humans have also been affected. Rice oil contaminated with PCBs was the culprit in both the Yusho incident in 1968 and the Yucheng incident in 1979.14 In 1968, approximately 1000 people were poisoned. Followup of a subset of children in this population showed growth retardation, movement disorders, generalized slowness, and a substantial IQ deficit (average 70). In the 1979 incident, approximately 2000 people in Taiwan were exposed to contaminated rice oil. Babies born to the exposed mothers showed a small but systematic lower IQ and higher scores for behavioral disorders.34

Acute high levels of PCB exposure occurred in industrial accidents before 1977, when PCBs were still manufactured. Exposed subjects experienced eye irritation, headache, fatigue, skin eruptions, nausea and vomiting, digestive disturbances, and liver dysfunction.17 More commonly, people are chronically exposed to PCBs from the consumption of tainted fish. PCBs are readily absorbed into the body but are only slowly metabolized and excreted. Half-lives range from 1 to 460 days, depending on the level of chlorination. The liver is the primary site of metabolism where hydroxylation and conjugation occur, but metabolism is slow, and most PCBs accumulate in adipose tissue. Chronic effects include dermatologie manifestations, developmental deficits with exposure in utero, disruption of thyroid or female sex hormones, elevation of liver enzymes (overt hepatotoxicity uncommon), decreased immunity, impaired memory and learning in adults and children, and carcinogenesis.19,27,35,36