Recent Advisory News

Current Events, News and Journal Articles

• Contaminant Loadings in Farmed Salmon vs. Wild Salmon - This study chemically analyzed five commercial salmon chows, four farmed salmon (one Atlantic, three chinooks) and four wild salmon (one chinook, one chum, two sockeyes) from the Pacific Coast. The fish and fish chow were analyzed for PCBs (112 congeners), polybrominated diphenylethers (PBDEs 41 congeners), 25 organochlorine pesticides (OPs), 20 polycyclic aromatic hydrocarbons (PAHs), and inorganic and methyl mercury. The authors found that farmed salmon showed consistently higher levels of PCBs, PBDEs, OPs (except toxaphene) than the wild salmon. Mean concentrations were 51.2 vs 5.3 ppb for total PCBs; 2.7 vs 0.18 ppb for total PBDEs; 41.8 vs 12.2 ppb for total OPs (except toxaphene). Concentrations of contaminants in farmed salmon are likely to have resulted from elevated levels of contamination in the commercial salmon chow (mean concentrations in 65.5 ppb for total PCBs; 1.9 ppb for total BPDEs; 48.1 ppb for total OPs except toxaphene). In general, PAHs were highest in the fish chow samples followed by the farmed fish and the three other wild fish. The hatchery produced feed, Bio-Oregon-1996, showed levels of PAHs 10 times higher than any other fish chow tested. Methylmercury and toxaphene concentrations were not significantly different between the wild and farmed salmon. Of the 5 commercial salmon chows tested, there was no clear low contaminant brand. The authors consider the human health implications of consuming farmed salmon from the perspective of the current WHO and Health Canada (2000) tolerable daily intake (TDI) values for PCBs. Based on a TDI of 1 pg TEQ/kg bw/day, their analysis indicated a safety concern for fish consuming individuals who consume farmed salmon raised on contaminated fish chow on a regular weekly basis.

  Source: Easton, M.D.L., D. Luszniak and E. Von der Geest. 2002. Preliminary examination of contaminant loadings in farmed salmon, wild salmon and commercial salmon feed. Chemosphere Volume 46, Issue 7 Pages 1053-1074.

• Changing Waters - News from Native California - The author describes an idyllic fishing experience she had on California’s Clear Lake in her youth and then proceeds to explain how the fish you eat today may have some extra things in them that you really don’t want - chemical contaminants. For Californians, PCBs and methylmercury are the two most important chemical contaminants of concern with regard to fish consumption advisories. The author provides background on sources of contamination for these two chemicals as well as a discussion of waterbodies affected by the California advisories. Also, a Native American conservation biologist comments about contaminants in waterfowl to illustrate how some entire ecosystems are affected. The variety of wildlife that can be contaminated is also provided. The author includes ways that Tribal groups might check on water quality and fish contamination in their local areas. The point is made that for reasons of dietary concern some Native peoples are trying to return to more traditional foods that include fish and game. Fish especially are recommended as a protein replacement for high cholesterol and high fat meat diets. Yet in some areas, traditional foods now pose contaminant problems. The author concludes that Native Americans need to be aware of specific contaminant problems in their local areas.

  Source: Ross, Jacquelyn. 2001. Changing Waters. News from Native California. Vol. 15 (1):32-34.

• New Study on Mercury Levels in Lake Natoma, California - Researchers in California suspect chronic sewage spills and polluted runoff are responsible for elevating levels of toxic mercury in bass and catfish in Lake Natoma, but they were surprised by evidence of a potential link between the amount of mercury in the fish and development in nearby Folsom.

  Source: Experts Probe Source of Mercury in Lake's Fish. Los Angeles Times, Jan 23, 2002 pB-7.

• EU Bans Imports of Chinese Shrimp Due to Contamination with Antibiotic - A veterinary committee voted on January 25 to block Chinese imports of honey, meats, and crustaceans into the European Union after tests detected residues of banned substances, including a potent antibiotic. EU inspectors found serious deficiencies in residue control in live animals and animal products being produced during a visit to China last November. One of the primary problems found was associated with chloramphenicol residues in samples from shrimps and prawns. This broad-spectrum antibiotic has been prohibited from use in food-producing animals in the EU since 1994. It is used in humans only in serious disease situations. Other seafood products collected from open sea fishing, are not affected by the EU ban.

  Source: EU bans imports of Chinese food products due to contamination with banned substances. Associated Press, Friday, January 25, 2002.

• PBDEs in Fish - In Virginia, freshwater fish have been found to contain the highest reported concentrations of a common, but controversial flame retardant, penta bromo diphenyl ether (PBDE). Some of the compounds in PBDE, including its BDE molecules, are similar in chemical structure to PCBs. The chemical structure of BDEs also resembles thyroxin, a thyroid hormone. Preliminary studies indicate that BDEs could potentially interfere with the metabolism of thyroid hormones and their transport throughout the body. Virginia scientists examined more than 1,000 fish from 332 different sites in the Roanoke and Dan River basins. The researchers found that 89 percent of the fish analyzed were contaminated with BDE-47, one of the two main constituents of PBDE. One carp from the Hyco River contained more than 47 ppb BDE-47, the highest concentration to be reported in any fish to date.

  Robert Hale from the Virginia Institute of Marine Science (VIMS), is the main author of a report on the study published in the December 2001 issue of Environmental Science and Technology. More than 50% of the fish samples examined in that study were found to contain more BDE-47 than PCB-153, the most abundant of the PCB molecules.

  While current environmental levels of BDE may not be dangerous, studies show that these concentrations are increasing. But demand for PBDE continues to increase in the United States, which accounts for 98 percent of worldwide use. The Brominated Flame Retardants Industry Panel (BFRIP) reported that in residential home fires, PBDE can slow down a fire, allowing residents time to escape and reducing property damage.

  PBDE also has been detected in sewage sludge, renewing concerns about the long-term safety of the U.S. biosolids program because of the potential for these chemicals to enter the food supply. In the U.S., 60% of the sewage sludge or biosolids produced is now spread on land as a fertilizer. A National Academy of Sciences review, "Risks from Toxicants and Pathogens in Biosolid Fertilizers," is scheduled for release this spring.

  Additional information on bromine based flame retardants such as PBDE is available on the Bromine Science and Environmental Forum website at: http://www.bsef.com

  Source: Pat Hemminger. Flame Retardant Chemical Found in Fish, Humans. Environmental News Service, January 31, 2002.

• Oyster Toadfish as a Biomarker for PAH Contamination? - Results of a study of oyster toadfish (Opsanus tau) in Virginia indicate that fish from reference stations in the York and Elizabeth Rivers contained lower levels of polycyclic aromatic hydrocarbon (PAH) metabolites than fish from more polluted stations. PAH metabolite levels in bile of the fish from mildly polluted stations were 7 to 10 times higher than those from reference stations. Furthermore, PAH metabolite levels in fish from a moderately polluted station and a highly polluted station were 20 and 50 times greater, respectively, than those from reference stations. PAH metabolite levels in bile of oyster toadfish correlated well with the PAH contamination gradient in the Elizabeth River sediments. The authors did not find high levels of biliary PAH metabolites in muskrats (Ondatra zibethicus) collected along the polluted sections of the Elizabeth River, probably due to the herbivorous nature of the muskrat. Assuming that the hepatobiliary system and the gastrointestinal tract are the major pathways of biotransformation and excretion of PAHs in the muskrats, the contaminated diet appears to be a more important route of exposure for muskrats (and possibly oyster toadfish) to PAHs than transdermal transfer. The authors proposed oyster toadfish as a useful biological sentinel for early detection of estuarine PAH pollution.

  Source: Deshpande, AD, RJ Huggett and RA Halbrook. 2002. Polycyclic aromatic hydrocarbon metabolites in the bile of a territorial benthic fish, oyster toadfish (Opsanus tau) from the Elizabeth River, Virginia. Archives of Environmental Contamination and Toxicology. Vol. 42(1): 43-52.

• Exposure Analysis of Native and Recreational Fishing Populations for Overexposure to Methylmercury - Methylmercury is found in a variety of fish species consumed by recreational and subsistence fishers around the world. Many governmental agencies have attempted to address the issue of mercury consumption which has resulted in the issuance of advisories on waterbodies used for fishing. This study examined fish consumption rates of three Native American populations and two recreational fishing populations consuming freshwater or saltwater fish. These consumption rates were evaluated with fish contamination data to assess levels of exposure to methylmercury and to determine if these fish-consuming populations exceeded the derived tolerable daily intake (TDI) for methylmercury (0.035 to 0.08 g/kg/day). The TDI value is based on studies investigating sensitive endpoints in children whose mothers consumed fish over prolonged periods of time and is unlikely to result in adverse health effects. Results from the exposure analysis indicated that many individuals within the Native American populations exceeded the TDI. Recreational fishers consuming freshwater fish had exposure levels below the TDI as did nearly all fish-eating populations consuming saltwater species. Fisher populations with comparable fish consumption patterns, consuming fish with equal or higher mercury concentrations, will also exceed the TDI level for mercury. The authors discuss the public health implications of this exposure analysis.

  Source: Marien, K. and GM Patrick. 2001. Exposure analysis of five fish-consuming populations for overexposure to methylmercury. Journal of Exposure Analysis and Environmental Epidemiology 11(3): 193-206.

• Methylmercury and the Health of Indigenous Peoples: a Risk Management Challenge - Methylmercury in aquatic ecosystems and bioaccumulated in aquatic species, especially fish, is a major public health concern worldwide. Currently, efforts are underway to reduce the anthropogenic release of mercury, which will over time, reduce human exposure. At the present time however, it is critical to address management of the risks of mercury exposure as they exist today. Of principal concern are the impacts of mercury on indigenous subsistence populations that depend on fish as a primary food source. This includes populations in remote Arctic areas of developed countries, such as Canada and the United States, as well as in developing countries such as Brazil. Over the last 30 years, research into these impacts has shown that, other than in very severe pollution situations such as occurred in Minamata, Japan, direct impacts on human health are difficult to prove. In contrast to this, the indirect negative effects of mercury on health, that have occurred through the disruption of lifestyle and consumption patterns combined with the socio-economic and socio-cultural consequences among the affected indigenous populations, have been significant in many cases. The authors believe these social factors have raised serious challenges for public health workers in determining practical health policies on this issue. Developing health policy relating to environmental contaminants is presented in conjunction with the problem of assessing the role of the various factors contributing to the impact on health as a result of socio-cultural disruption. These factors include changes in diet and lifestyle due to the real or perceived risk of mercury. Standard risk assessment processes, based on the lowest observed adverse effects level (LOAEL) or no observed adverse effects level (NOAEL) used in defining health policies may be an over-simplistic theoretical extrapolations when viewed in the context of social science concerns. Both approaches, however, have relevance to health policies that address the risks posed by environmental contaminants. The authors believe that the standard physical sciences approach of the last 30 years needs to be linked with the social sciences approach, with its focus on the indirect impacts of mercury exposure, to provide a more holistic approach to public health policy development. With this more holistic approach in mind, the authors review mercury data from the perspective of both physical and social sciences and they attempt to draw on the findings in both disciplines to provide suggestions for development of a more integrated approach in policy development relating to human health and human exposure to mercury, especially among indigenous peoples in remote areas and in developing countries. Development of a more holistic and integrated approach may help limit adverse health effects in the indigenous communities affected.

  Source: Wheatley, B. and M. A. Wheatley. 2000. Methylmercury and the health of indigenous peoples: a risk management challenge for physical and social sciences and for public health policy. The Science of the Total Environment 259(1-3): 23-29.

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For more information on EPA's Fish and Wildlife Contamination Program, contact: Jeffrey Bigler at US EPA, 1200 Pennsylvania Ave., NW (4305), Washington, DC 20460; email: bigler.jeff@epa.gov.

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Revised February, 2002