Fish and Wildlife Advisory News - August 2003

Recent Advisory News

Current Events, News and Journal Articles

• Does mercury matter? Experts debate the big fish question: What to eat? - A recent article in the New York Times discussed the benefits and risks of eating fish. While experts agree that fish is good for you, many studies- though not all- have concluded that low levels of mercury found in fish can have subtle negative effects if certain fish are a major part of the diet. The article mentions that both the FDA and EPA have advised that the most sensitive populations (women of childbearing age and young children) restrict their consumption of certain fish. The FDA oversees fish sold in supermarkets, fish markets, and restaurants, and advises that 12 ounces a week of various kinds of fish is safe for women and children. The EPA, which is concerned with freshwater fish that anglers catch and eat, advises this same group to eat no more than six ounces week for adults, or two ounces a week for children. According to the article, the FDA has come under criticism from activist groups like the Mercury Policy Project for using a reference dose of 0.4 micrograms per kilogram of body weight, while the EPA uses a level of 0.1 micrograms per kilogram of body weight. Dr. David Acheson, the FDA's chief medical officer concerned with the mercury issue, feels the number is misleading because it is based on data from Iraq, and is out of date for groups at particular risk. FDA is also looking into another matter of concern, canned tuna. Canned tuna is by far the most consumed fish in the U.S. The Mercury Policy Project tested 48 cans of white and albacore tuna and found mercury levels averaged 0.5 parts per million, significantly higher than FDA data. According to the article, The Mercury Policy Project feels consumers, particularly women and children, should be warned separately about tuna, since it is so popular. At 0.5 ppm, a woman weighing 132 pounds who ate only 6 ounces of tuna in a week would be getting 1.4 micrograms of mercury per kilogram of body weight in that week- higher than the EPA standard. FDA is initiating more intense testing of tuna and will reconsider whether to say anything specifically about canned tuna based on those results.

  Source: Gorman, J. 2003. Does mercury matter? Experts debate the big fish question: What to eat? New York Times; July 29, 2003; pF5 col 01.




• Panel seeks to shield kids from dioxins - The Associated Press reported in early July that a scientific panel recommended the government should help women and girls reduce the amount of fats they consume in meat, poultry, fatty fish, and whole milk years before they become pregnant in order to protect infants from harmful exposure to dioxins. The Institute of Medicine of the National Academies made recommendations in a report that the government should target women and girls in particular because they can pass dioxins to their offspring through the placenta and breast milk. Urging women and others to follow national dietary guidelines, which recommend a diet low in saturated fats, could help prevent the problem because dietary fats from animal sources are known to contain higher levels of dioxins. Indigenous peoples in Canada and the US are especially vulnerable because they frequently eat fish and wild game, exposing them to higher than average levels of dioxins. Because current methods for analyzing dioxins in food are so expensive (>$1,000 per sample), scientists on the panel did not determine what levels are considered unsafe.

  Source: Gersema, E. 2003. Panel seeks to shield kids from dioxins. Associated Press; Tuesday, July 1, 2003.




• Farmed salmon is said to contain high PCB levels - Salmon is currently the third most popular fish consumed by Americans, after canned tuna and shrimp. Farmed salmon accounts for 60 percent of the salmon consumed in the US. A report released by the Environmental Working Group (EWG), a nonprofit environmental research and advocacy organization, says that 10 samples of farmed salmon bought at markets on the East and West Coasts were contaminated with PCBs at average concentrations far higher than for any other protein source, including all other seafood. The high concentrations do not exceed those set in 1984 by the FDA for commercially sold fish, but concentrations are in excess of the guidelines set by the EPA in 1999 for recreationally-caught fish. The article notes that the EWG study has not been published in a peer-reviewed Journal.

  The article notes three previous studies of farmed salmon which support the EWG findings and found comparable high PCB concentrations. These include: a study conducted at the University of Surrey (England) of salmon purchased in Scotland and Belgium and reported in 2002 in Environmental Science and Technology; a government study for the Food Safety Authority of Ireland, reported in March 2002; and a study by Dr. Michael Easton of International EcoGenInc in British Columbia, Canada reported in 2002 in Chemosphere. The Easton (2002) study, and the EWG study, found the PCB concentrations in farmed salmon in the US and Canada were 5 to 10 times higher than those in wild salmon. The average PCB concentration in wild salmon is about 5 ppb; while farmed salmon averaged 27 ppb, far below the FDA standard of 2,000 ppb. EPA guidelines say that if a person eats fish twice a week, it should contain no more than 4 to 6 ppb. EWG, based in Washington and financed by private foundations, used the seafood industry's own fish consumption data to report how many Americans regularly eat salmon. About 25% of Americans eat salmon; 23.1 million consumers eat it more than once a month, while 1.3 million consumers eat it once a week, and 180,000 eat salmon more than twice a week. From these figures EWG conducted a cancer risk assessment of exposure to PCBs from farmed salmon. The assessment estimates that 800,000 consumers face an increased lifetime cancer risk of more than one in 10,000 from eating farmed salmon, and 10.4 million consumers face an increased cancer risk exceeding one in 100,000.

  Source: Burros, M. 2003. Farmed salmon is said to contain high PCB levels, The New York Times; July 30, 2003.




• Human mercury toxicity and ice angler fish consumption: are people eating enough to cause health problems? - Mercury contamination of aquatic ecosystems is a worldwide environmental concern, primarily because bioaccumulation of mercury in fish exposes consumers to health risks. During 2001-2002, the authors interviewed ice fishers on Monona Bay, Wisconsin to determine health risk associated with fish consumption and methylmercury (MeHg) intake. The majority of fishers (95%) were not at risk of mercury toxicity because they did not consume enough fish to cause health problems. The remaining 5% of ice fishers barely exceeded the mercury toxicity threshold, with the exception of one fisher who exceeded the threshold by 0.926 ppm. Fishers in the study were all male and predominantly Caucasian. In the study population, fish consumption was independent of awareness of consumption advisories, as well as the educational level, income, and age of the fisher. Findings suggest that future communication efforts should (1) identify groups of fishers most at risk and (2) create policies to effectively communicate with these groups.

  Source: Flaherty, C., Sass, G., and K. Stiles. 2003. Human mercury toxicity and ice angler fish consumption: are people eating enough to cause health problems? Risk Anal 23 (3): 497-504.




• Methyl mercury and inorganic mercury in Swedish pregnant women and in cord blood: influence of fish consumption - The authors studied exposure to methylmercury (MeHg) in pregnant women (total mercury [T-Hg] in hair) and their fetuses (MeHg in cord blood) in Sweden in relation to fish consumption. Women were recruited at prenatal clinics in late pregnancy to participate in an exposure study of environmental pollutants. Fish consumption was evaluated using food frequency questionnaires including questions on fish consumption habits. In addition, levels of inorganic mercury (I-Hg) and selenium (Se) were determined in cord blood. On average, women consumed fish (all types) 6.7 times/month (range 0-25 times/month) during the year in which they became pregnant. Women reported that they ate less freshwater fish--species that might contain high concentrations of MeHg--during than before pregnancy. Total Hg in maternal hair (median 0.35 ppm; range 0.07-1.5 ppm) was significantly associated (p < 0.001) with MeHg in cord blood (median 1.3 ppb; range 0.10-5.7 ppb). Total mercury hair and MeHg cord blood levels increased with increasing seafood consumption. Segmental hair sample analysis revealed that T-Hg close to the scalp was lower and more closely correlated with MeHg in cord blood than T-Hg levels in segments further from the scalp corresponding to earlier periods in pregnancy.

  Source: Bjornberg, K., Vahter, M., Petersson-Grawe, K., Glynn, A., Cnattingius, S., Darnerud, P., Atuma, S., Aune, M., Becker, W., and M. Berglund. 2003. Methyl mercury and inorganic mercury in Swedish pregnant women and in cord blood: influence of fish consumption. Environ Health Perspectives 111 (4): 637-41.




• Mercury levels in high-end consumers of fish - Consumption of food containing mercury has been identified as a potential human health risk. The EPA and the National Academy of Sciences (NAS) recommend keeping the whole blood mercury level < 5.0 ppb or the hair level < 1.0 ppm. This corresponds to a reference dose (RfD) of 0.1 micrograms / kg body weight per day. In this study, all patients in a 1-year period (n = 720) who were seen in a private internal medicine practice in San Francisco, CA, were evaluated for mercury using the current RfD. Data were statistically analyzed for 89 subjects. Mercury concentrations ranged from 2.0 to 89.5 ppb for the 89 subjects. The mean for 66 women was 15 ppb [standard deviation (SD) = 15 ppb], and for 23 men was 13 ppb (SD = 5 ppb); 89% had concentrations exceeding the RfD. The study subjects consumed 30 different types of fish. Swordfish had the highest correlation with mercury level in the blood. Significant reduction (p < 0.0001) in serial mercury blood levels over time was observed in 67 patients after they stopped eating fish. A substantial percentage of patients had diets high in fish; of these, a high proportion had blood mercury levels exceeding the maximum level recommended by the EPA and NAS. The mean mercury level for women in this survey was 10 times that of levels found in a recent population survey by the U.S. Centers for Disease Control and Prevention. Some children had mercury levels > 40 times the national average.

  Source: Hightower, J. and D. Moore. 2003. Mercury levels in high-end consumers of fish. Environmental Health Perspectives 111(4):604-8.




• PCB congener distributions in muscle, liver, and gonad of Fundulus heteroclitus from the lower Hudson River Estuary and Newark Bay - Gradients in sediment polychlorinated biphenyl (PCB) concentrations and PCB congener profiles exist along the length of the Hudson River, NY. The authors evaluated differences in site and tissue gradients in PCB concentration and congener profiles in resident mummichog (Fundulus heteroclitus) collected from PCB-contaminated sites in the lower Hudson River and the New York/New Jersey Harbor Estuary. Fish were sampled from three PCB-contaminated sites; Piermont Marsh (P), Iona Marsh (I), and Newark Bay (NB), and from two control sites (Flax Pond, NY; Succotash Salt Marsh, RI). Congener profiles were statistically analyzed using principal component analysis (PCA) and general linear model (GLM) profile analysis. Chemical analysis results showed that PCB contaminated fish had tissue concentrations almost 10-times higher than controls. The study also showed that there were no site differences in PCB body burden (all tissues combined) among fish from the contaminated sites. However, relative PCB levels differed between organs: NB fish (gonad=liver>muscle); I and P fish (gonad>liver>muscle). In contrast to PCB content, PCB congener profiles did show site differences; NB mummichog being depleted in the less chlorinated congeners relative to I and P fish, probably resulting from different PCB sources to these fishes. PCB congener patterns were however similar between liver, gonad, and muscle within a site. PCA and GLM analyses provided complementary results, both analyses indicated differences in site, but not in tissue, distributions of PCB congeners. The authors demonstrated that unlike congener profiles, total PCB levels differ dramatically among tissues and that PCB differences among tissues can vary with site.

  Source: Monosson, E., Ashley, J., McElroy, A., Woltering, D., and A. Elskus. 2003. PCB congener distributions in muscle, liver, and gonad of Fundulus heteroclitus from the lower Hudson River Estuary and Newark Bay. Chemosphere 52 (4): 777-87.




• Renal toxicity in rats after oral administration of mercury-contaminated boiled whale livers marketed for human consumption - Some Japanese have traditionally eaten the internal organs of small cetaceans (toothed whales and dolphins), and a mixed package of boiled liver, kidney, lung, and other organs is still marketed for human consumption. Recently, the authors reported that these organs contain very high mercury concentrations. In this study, the authors investigated the absorption, distribution, and excretion, via analysis of biochemical parameters in serum and urine after a single oral dose of boiled whale liver containing 1,980 ppm of total mercury and 23.5 ppm of methyl mercury to rats (0.2 g boiled liver/100 g rat). A single dose of the boiled liver resulted in significant increases in mercury concentrations in rat kidney tissue, urinary volume, and the urinary excretion of N-acetyl-beta-D-glucosanidase, albumin, and sodium suggesting renal toxicity caused by inorganic mercury. Approximately 95% of the total mercury dose was excreted in feces and less than 0.05% was excreted in the urine. The mercury absorption rate from the boiled whale liver was approximately 5%. Results suggest that human consumption of boiled whale liver may cause acute intoxication by inorganic mercury.

  Source: Endo, T., Haraguchi, K., and M. Sakata. 2003. Renal toxicity in rats after oral administration of mercury-contaminated boiled whale livers marketed for human consumption. Archive of Environmental Contamination and Toxicology 44 (3): 412-416.




• Factors affecting enhanced mercury bioaccumulation in inland lakes of Isle Royale National Park, USA - The authors investigated factors causing mercury concentrations in northern pike to exceed the consumption advisory level (>0.5 ppb) in some inland lakes of Isle Royale National Park. Using ultraclean techniques, the authors sampled water, zooplankton, macroinvertebrates, and fishes in 1998 and 1999 from one advisory lake, Sargent Lake, for analysis of total mercury (THg) and methylmercury (MeHg). For comparison purposes, samples also were collected from a non-advisory lake, Lake Richie. THg concentrations in northern pike were significantly higher in Sargent Lake (p<0.01) than in Lake Richie. Unexpectedly, mean concentrations of both THg and MeHg in open water samples were slightly higher in Lake Richie, although zooplankton in Sargent Lake contained higher mean levels of THg and MeHg than in Lake Richie. Mercury levels in macroinvertebrates were similar between lakes, but were different between taxa. The THg levels in age-1 yellow perch and adult perch in the two lakes were similar, but concentrations in large adult perch (>160 mm) in Sargent Lake were twice the concentrations in Lake Richie. The authors found that stable isotopes (delta(13)C and delta(15)N) in biota showed that pike from the two lakes are positioned at the same trophic level (4.2 and 4.3), but the food web was more pelagic-based in Sargent Lakeand benthic-based in Richie Lake. The authors concluded that factors causing concentrations in large pike to be higher in Sargent Lake might include higher MeHg bioavailability and a food web that enhances bioaccumulation.

  Source: Gorski, P., Cleckner, L., Hurley, J., Sierszen, M., and D. Armstrong. 2003. Factors affecting enhanced mercury bioaccumulation in inland lakes of Isle Royale National Park, USA. Science of the Total Environment 304(1-3): 327-48.




• Spatial variation and correlations of mercury levels in the terrestrial and aquatic components of a wetland dominated ecosystem: Kejimkujik Park, Nova Scotia, Canada - In this study, the authors analyzed the ranges and spatial variation of mercury concentrations in various media in the wetland ecosystems of Kejimkujik Park, Nova Scotia. Mercury levels in 5-year-old yellow perch ranged from 0.12–0.72 ppm (wet weight) in 24 lakes. Mercury concentrations in red maple ranged from 5 to 41 ppb and in white pine ranged from 5 to 58 ppb (dry weight). Total mercury concentrations were found to be significantly higher in epiphytic lichens (maximum of 660 ppb) and in feather mosses (maximum of 395 ppb) as compared to vascular species. The soil Ah horizon contained the highest concentrations for both mercury and gold, with maximum values of 466 and 42.8 ppb respectively; the C-horizon appears to contain the most Zn (maximum 209.9 ppb). Lake water pH and dissolved organic carbon (DOC) were the variables most highly correlated with mercury concentrations in lake waters and yellow perch. No correlations were observed between mercury in terrestrial components and mercury in yellow perch. The study emphasizes the importance of understanding linkages between terrestrial and aquatic ecosystems.

  Source: Rencz, A., O'Driscoll, N., Hall, G., Peron, T., Telmer, K., and N. Burgess. 2003. Spatial variation and correlations of mercury levels in the terrestrial and aquatic components of a wetland dominated ecosystem: Kejimkujik Park, Nova Scotia, Canada. Water, Air, and Soil Pollution 143 (1/4): 271-288.




• Catchment area composition and water chemistry heavily affects mercury levels in perch (Perca fluviatilis L.) in circumneutral lakes - The authors examine the environmental impact of mercury levels in perch (Perca fluviatilis) using Partial Least Square regression (PLS) on 48 environmental descriptors assessing land use, various catchment area and lake characteristics, lake water chemistry, and fish stock. Lake specific intercepts of Hg level vs. fish length regressions are used to describe the Hg concentration in the fish. Hg levels in perch from 78 circumneutral lakes were primarily influenced by land use surrounding the lakes. Boreal forest lakes had fish with the highest Hg burden, while fish from lakes heavily influenced by arable land possessed lower contents. In addition, Hg levels were negatively correlated to the concentrations of dissolved ions and total nutrients in lake water, and to the perch growth rate, whereas the relationship was positive to the concentration of TOC/humic matter. The pH of the lake did not have any significant influence on the Hg content in perch in these circumneutral lakes. Hg levels in perch from lakes surrounded by large wetlands were less satisfactorily explained by the environmental descriptors. This suggests that the Hg levels in fish from these lakes are also influenced by other factors.

  Source: Sonesten, L. 2003. Catchment area composition and water chemistry heavily affects mercury levels in perch (Perca fluviatilis L.) in circumneutral lakes. Water, Air, and Soil Pollution 144 (1): 117-139.




• Methodology for the assessment of human health risks associated with the consumption of chemical contaminated freshwater fish in South Africa - Industrialized countries like the US have developed strategies and associated guidance to conduct chemical contaminant surveys using fish and use these data to reduce the heath risk to fish consumers. The authors provide a generic method that will give guidance in conducting fish contaminant surveys to provide information regarding the possible health risk if the fish are consumed by recreational and subsistence fishermen in South Africa. The fundamentals of the method are based on water catchment information, socio-demographic information of consumers of fish in the catchment, bioaccumulation potential and health risks of the analytes, sound sampling design, risk assessment procedures and performing monitoring at different scales and depths. These aspects of the methodology are presented as 10 major steps that focus on the surveys and optimizing the application of resources. Although the method detailed by the authors focuses on assessing the potential health risk to the consumers, many of the aspects would apply equally well to any investigation aimed at assessing chemical contaminant levels in fish. As these surveys identify areas where fish have unacceptably high chemical contaminant concentrations, this information can be used in catchment management programs to implement remedial actions that would ensure that the fish populations are fit for present and future human consumption.

  Source: Du Preez, H., Heath, R., Sandham, L., and B. Genthe. 2003. Methodology for the assessment of human health risks associated with the consumption of chemical contaminated freshwater fish in South Africa. Water-South Africa 29 (1): 69-90.




• Fish biliary PAH metabolites estimated by fixed-wavelength fluorescence as an indicator of environmental exposure and effects - Biliary PAH metabolites have been studied since the 1980s as an indicator of exposure of fish to PAHs. Measurements of PAH metabolites, however, are often costly and time-consuming. The authors describe a simple and rapid method, fixed-wavelength fluorescence (FF), used to measure the concentrations of benzo(a)pyrene (B[a]P)-type and naphthalene (NAPH)-type PAH metabolites in the bile of brown bullheads (Ameiurus nebulosus) collected from Old Woman Creek, the Ottawa River, Cuyahoga River-harbor and Cuyahoga River-upstream. Biliary PAH metabolites in fish from the less contaminated Old Woman Creek were significantly lower than those from the industrially contaminated Ottawa and Cuyahoga rivers. Biliary PAH metabolite levels also were found to be related to the PAH sediment contamination for four sites except Cuyahoga River-upstream, and to the prevalence of fish barbel abnormalities and external raised lesions observed in all rivers except those sampled from the Ottawa River. The authors report that statistical analysis revealed a significant association between the occurrence of barbel abnormalities and biliary NAPH-type metabolite concentrations and between the occurrence of raised lesions and concentrations of B[a]P-type metabolites. This study provides additional support that FF is an effective bile analysis method for determining the PAH exposure of fish. The authors believe the measurement of PAH metabolites could help establish causal relationship between chemical exposures and effects (barbel abnormalities and raised lesions).

  Source: Xang, X., Peterson, D., Baumann, P., and E. Lin. 2003. Fish biliary PAH metabolites estimated by fixed-wavelength fluorescence as an indicator of environmental exposure and effects. Journal of Great Lakes Research 29 (1): 116-123.

Meetings and Conferences

For More Information

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.