By Ruth Kava, Ph.D., R.D., Aubrey Noelle Stimola, Rivka Weiser, Lynnea Mills
Posted: Monday, December 13, 2004

REPORT
Publication Date: December 13, 2004

Introduction
Pediatric Vaccines and Autism    
PCBs in Salmon and Cancer   
Cell Phones Cause Brain Tumors    
Nightlights and Leukemia     
Chemicals in Cosmetics     
Mercury in Seafood Causes Neurological Problems in Humans  
Cheeseburgers and Cardiovascular Disease (CVD)  
Antibiotics Cause Breast Cancer    
Teflon Causes Health Problems in Humans   
Soda Causes Esophageal Cancer    
Dishonorable Mention     
Deodorants, Antiperspirants Cause Breast Cancer 
Plastics Cause Cancer

The Scare:
Over the past decade, virtually every mainstream nutrition organization has advised Americans to eat fish regularly—two or more times, or up to 8 ounces, per week.(21) This advice emphasizes oily fish—such as salmon—because the oils in these fish contain omega-3 polyunsaturated fatty acids, which are thought to be particularly healthful. Consumption of these fatty acids is associated with a decreased risk of repeated heart attacks. But in the past year, salmon, particularly salmon raised by aquaculture, i.e. “fish farming,” have been under attack for being contaminated by polychlorinated biphenyls, commonly called PCBs. Some groups have repeatedly warned consumers that farmed salmon is too heavily contaminated with PCBs for regular consumption and that they should eat only wild-caught salmon, which have been reported to contain lower levels of such compounds. The result has been confusion and the avoidance of a perfectly good source of protein, healthful fatty acids, and other nutrients.

Where Did the Scare Come From?
In 2003 the Environmental Working Group (EWG) released a study of 7 salmon that found that those fish raised by aquaculture contained more PCBs than wild-caught fish did. The study was not peer-reviewed or published in a scientific journal. The EWG report fanned fears of PCBs acting as human carcinogens as well as possible estrogenic compounds (so-called “endocrine disruptors”). Estrogenic compounds, it was feared, could mimic human estrogens and lead to infertility, some cancers, or other hormone-related disorders. In January 2004, the journal Science published a more substantial paper that assessed the PCB content of salmon raised by aquaculture and compared it to the PCB content of wild salmon.(22) In addition to finding that farmed salmon contained more PCBs than wild salmon, the results also indicated that salmon raised by European fish farms had more PCBs than those raised on farms in North and South America. Further, the authors concluded “consumption of farmed Atlantic salmon may pose health risks that detract from the beneficial effects of fish consumption.” Later in the year, several other scientists expressed disagreement with this conclusion in letters to the journal’s editor, but many (although not all) of the popular media ignored those disagreements, rather than adding to later coverage of this topic.

The Media Coverage:
ABC News covered the salmon story, both in its television news broadcasts and on its Internet site. The Internet version of the story, headlined “Study finds farmed salmon contain pollutants,” was picked up by other Internet news sites.(23-25) In a relatively responsible review, the ABC story interviewed the authors of the Science report as well as experts from the fields of toxicology and nutrition who tended to moderate the more extreme language that labeled farmed salmon as “toxic” or carcinogenic.

Some other media also provided balanced coverage. In particular, a site called Healthcastle(26)  presented a less alarmist review of studies that had been published on this issue and clearly summarized the guidelines of various government agencies on the levels of PCBs considered safe to consume. Their key message was to not give up salmon and other fish completely. Another balanced report was presented by the Miami Herald, which quoted Dr. George Blackburn of the Harvard Medical School: “I recognize why people hesitate,” he says. “You have to do a risk/benefit analysis. But people don’t get enough omega-3, and salmon is one of the cheapest ways to get it. Even if there are tiny doses of toxins, we don't want that to guide people away from the benefits.”(27)

Other media outlets provided a less even-handed view. For example, Science Daily, from Indiana University, simply described the Science study without presenting any interpretation or criticism of its conclusions.(28) Earlier, the Washington Post reported in a news piece that “farmed salmon consumption may be posing a health threat to millions of Americans,” and the New York Times called PCBs “probable human carcinogens.”(29,30) More recently, the New York Times published an article describing the efforts by some restaurants, supermarkets, and salmon fisheries to avoid farmed salmon.(31) The article did not question the advisability of these actions. The least balanced presentation was that of the Environmental Working Group, which had published its own small study in 2003 (see above). A press release(32)  by this group proclaimed “First-Ever U.S. Tests of Farmed Salmon Show High Levels of Cancer-Causing PCBs” (and this was based on their study of only seven fish!).

The Bottom Line:
The dire warnings about PCBs in farmed salmon are based on exaggerated fears and ignorance of the true nature of the compounds or what hazard if any they pose to humans. First, the evidence for the estrogenic effects of PCBs is highly conjectural. They are only weakly estrogenic, and the evidence that they have disruptive effects on either animal or human health has been labeled implausible by expert researchers.(33) 

Second, PCBs have not been shown to be human carcinogens. Epidemiologic studies that examined industrial workers exposed to high levels of PCBs in the workplace did not lead to elevated concerns. In fact, chloracne (an acne-like skin condition) and eye irritation were the only consistent results of high level, long-term exposures.(34)

It is true that when high levels of PCBs are fed to laboratory animals over their lifetimes, the animals may develop tumors. Such experimental results led the Environmental Protection Agency (EPA) to consider PCBs animal carcinogens and possible human carcinogens—and this designation allows groups like EWG to greatly exaggerate their risk to humans. But the EPA made no allowance for the fact that no human could eat enough PCBs (present in only very small amounts in our foods) to mimic the level of exposure experienced by experimental animals. They thus ignored the most basic dictum of toxicology—“The Dose Makes The Poison.”(35)  Many chemicals that occur naturally in our food supply also cause cancer when fed to laboratory animals at very high doses: this does not mean we must eliminate them from all our foods.(36)  Rather, it should reassure us that trace amounts of most synthetic chemicals are likewise harmless as they are normally consumed. It is unfortunate that such unwarranted and exaggerated claims of risks to health are broadcast; avoiding particular foods based on such claims will be detrimental rather than beneficial to consumers’ health.

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