Recent Advisory News

• Maryland Issues Statewide Advisory - Maryland has just issued updated advice for the consumption of recreationally caught fish in all of the state's rivers and streams and most lakes and impoundments. Smallmouth and largemouth bass and bluegill are covered under the statewide advisory for mercury, with different meal frequencies suggested for different segments of the population. Waterbody-specific advisories for other contaminants were also updated as part of the new advisory release. The state emphasizes that the contaminant levels observed in Maryland fish have not changed, but that the updated EPA guidance was used to re-evaluate risks to residents, especially pregnant or nursing women and children. The advisory does not include the Chesapeake Bay - a contaminant study is still underway for the bay and results will be known next year. Find out more at Maryland's website or the Washington Post Metro section. The Baltimore Sun also published an article about the new advisory.

Current Events, News and Journal Articles

• Results of Mercury Study on Alaskan Salmon - Total mercury and methylmercury concentrations in four Alaskan salmon species (Chum, Coho, Chinook, and Sockeye salmon) were determined in muscle and liver tissues from fish collected in four rivers (Yukon, Kuskokwim, Nushagak, and Kvichak) draining into the Eastern Bering Sea. The authors reported that the arithmetic mean concentrations of total mercury in salmon muscle for the species sampled ranged from 0.034 to 0.096 ppm wet weight and in liver tissue ranged from 0.054 to 0.112 ppm. Difference in the total mercury and methylmercury concentrations between species were statistically significant, however the differences between species in the same river system were not significant except for chinook salmon. The authors also reported that in salmon muscle samples, total mercury and methylmercury concentrations were correlated, and the mean methylmercury concentrations were lower than the total mercury concentrations (p=0.001). This contrasts with the evidence for some freshwater species where there was little difference between the total mercury and methylmercury concentrations. For salmon, methylmercury levels were 78% and 63% of total mercury levels for muscle and liver tissue, respectively. The authors also reported that total mercury levels in slamon increased with fish lengths. Based on their data, the authors estimated a bioconcentration factor ranged from 2.5 x 104 and varied 2-fold between the species tested. Despite the estimated BCF factor, the authors point out that Alaskan salmon did not exceed critical human health values (0.200 ppm) and therefore do not pose a risk for salmon food consumers. In conclusion, the authors point out that most of the body burden of mercury accumulated in the ocean is returned to the spawning areas in the form of methylmercury which is a readily bioavailable form. This mercury can then become a much more concentrated source of methylmercury to surface waters than atmospheric deposition. The authors estimate using numbers of fish returning to spawn and the levels of mercury in the fish that for the Kvichak River, 0.1 kg of methylmercury was added to the surface waters in one year. This amount is equivalent to approximately 0.02% of mercury released in the United States. The authors further estimated a 20-year total mass loading for methylmercury of 21 kg to the Bristol Bay drainage area (consisting of 8 river systems) could be transported from the ocean via migrating salmon.

  Source: Zhang, X., A.S. Naidu, J.J. Kelley, S.C. Jewett, D.Dasher, and L.K. Duffy. Baseline Concentrations of Total Mercury and Methylmercury in Salmon Returning Via the Bering Sea (1999-2000). Marine Pollution Bulletin 42 (10):993-997.

• Mercury in Swordfish from the South Atlantic - From January 1997 to December 1999, swordfish of 10-412 kg caught in the southwestern Atlantic Ocean were analyzed for total mercury concentration, and the relationship of mercury concentration to fish weight was also examined. Fish tissue was digested in concentrated sulfuric and nitric acid, followed by analysis using cold vapor atomic absorption spectrophotometry. Total mercury was correlated to total body weight using least squares regression analysis. A total of 192 specimens were analyzed. Mercury concentrations ranged from 0.04-2.21 ppm, with a mean value of 0.62 ppm. About 14% of the samples analyzed were above the tolerance limit for mercury of 1 ppm, confirming that swordfish bioaccumulate mercury, at least in fish of commercial weight. For a sample subset of fish weighing less than 100 kg., the total mercury content averaged 0.53 ppm, vs. 0.94 ppm for fish weighing greater than 100 kg.

  Source: Mendez, E., H. Giudice, A. Pereira, G. Inocente, and D. Medina. Total mercury content - fish weight relationship in swordfish (Xiphias gladius) caught in the Southwest Atlantic Ocean. Journal of Food Composition and Analysis 2001 Vol 14(5):453-460.

• Shark-fin soup and methylmercury: To eat or not to eat? - The author examined the potential contamination of shark with mercury and methylmercury. The paper also discusses other aspects of this issue including: bioaccumulation of methylmercury in marine fish and shellfish; US guidelines relating to dietary intake of mercury from fish; the impact of other nutrients on mercury and methylmercury toxicity; and further action which should be taken by regulatory authorities to minimize the risk to human health and the environment.

  Source: Omaye, S. T.. 2001. Shark-fin soup and methylmercury: To eat or not to eat?. Food Technology 2001 Vol.55(10):26.

• Feeding Behavior as a Biomarker for Contaminant Levels - This study examined the feasibility of using prey capture behavior as a biomarker of water contamination. Feeding behavior of adult mummichogs from 13 different sites was studied. Site contaminant concentrations were highly correlated with each other, and prey capture ability was related to sediment, tissue contaminant concentrations, and genetic analyses. The number of prey captured was highest at the cleanest site. Sites with the lowest capture rates typically were the most contaminated. Also, the presence of the Mdh-A(a) allele was significantly correlated with number of captures. Gut content analyses of fish from sites with the largest number of captures were dominated by grass shrimp. The authors concluded that prey capture is an ecologically relevant behavioral biomarker, but is not particularly sensitive because of within-site variation. In addition, behavioral differences seemed to be related to overall pollution levels rather than to specific contaminants.

  Source: Weis, J.S., J. Samson, T. Zhou, J. Skurnick, and P. Weis. 2001. Prey Capture Ability of Mummichogs (Fundulus heteroclitus) as a Behavioral Biomarker for Contaminants in Estuarine Systems. Canadian Journal of Fish and Aquatic Science July 2001. Vol.58 (7):1442-1453.

• Prenatal Exposure to PCBs and Associated Neurobehavioral Deficits in the Faroe Islands - Prenatal exposure to PCBs was investigated in more than 400 children born in the Faroe Islands from 1986 to 1996. Cord blood and cord tissue concentrations showed excellent correlation. The highest PCB concentrations found were more than 1,000 times higher than the lowest concentrations detected. At age seven, more than 90% of the sample population was reexamined and deficits in performance on several neurobehavioral tests were found. High concentrations of PCBs in cord blood were associated with deficits in performance on several neurobehavioral tests. Prenatal exposure to mercury, however, could be a confounding factor in the results, since high concentrations of mercury were also detected in cord blood.

  Source: Grandjean, P., P. Weihe, V. W. Burse, L. L. Needham, E. Storr-Hansen, B. Heinzow, and F. Debes. Neurobehavioral Deficits Associated with PCB in 7-Year-Old Children Prenatally Exposed to Seafood Neurotoxicants. Neurotoxicolology and Teratology Jul-Aug 2001. Vol23 (4):305-318.

• Are Fish Fact Sheets Reaching the Target Audience? - The researchers interviewed anglers on the Savannah River to determine the effectiveness and perception of a supplemental fish fact sheet jointly developed by South Carolina, Georgia, federal agencies, and the Consortium for Risk Evaluation with Stakeholder Participation. The objectives of the study were to determine: (1) whether anglers had previously read the Fish Fact Sheet or had knowledge of the consumption advisories; (2) what message they gleaned from the fact sheet; (3) who they thought the fact sheet was intended to reach, and who should receive the Fact Sheet; (4) who should be most concerned about health risks from chemically contaminated fish; and (5) what was the best method of communicating and distributing the advisory and health risk information. In 1991, the authors interviewed 92 fishermen (37% black, 62% white) during the fishing season. One half of the fishers interviewed had some knowledge about consumption advisories, mainly from the media (64%). There were no ethnic differences in whether the anglers knew about the advisories or understood the major message of the fact sheet, but there were significant ethnic differences in the ways people thought the health risk from eating contaminated fish could be reduced.

  Source: Burger, J., and L. Waishwell. Are we reaching the target audience? Evaluation of a fish fact sheet. Science of the Total Environment September, 2001. Vol.277(1-3):77-86.

• Fish Oil Supplements Tested for Omega-3 Concentrations and Mercury Levels - An independent evaluator of dietary supplements and nutrition products, ConsumerLab.com, released results of its Product Review of Omega-3 Fatty Acids from Marine Fish Oils. EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are fatty acids that have been shown to help reduce cardiovascular disease and pain associated with rheumatoid arthritis, as well as showing promise in the treatment of several other conditions. A current concern associated with fish oil products is their potential contamination with mercury. Of the 20 products tested, 6 were found to have inadequate amounts of the fatty acids, ranging from 33% to 82% of the concentrations claimed on the labels. None of the samples were found to contain detectable levels of mercury (less than 1.5 parts per billion (ppb)). The study raises the issue of whether people who are taking omega-3 supplements to prevent or treat heart disease are actually receiving an effective dose of DHA and EPA from their supplement.

  Source: Consumerlab.com. Fish oil supplements free of mercury, but 30% lacking in key ingredient: Test Results of Omega-3 Fatty Acid Products Tuesday November 20, 2001

• DDT/DDE Levels in Breat Milk Among Hispanic Immigrants - The goals of this study were to (1) determine the concentration of DDT/DDE in the breast milk of mothers residing in the Yakima River Basin in Washington, (2) assess the impact of fish consumption on the total DDT/DDE body burden, and (3) to determine if the amount of DDT/DDE received by the breastfed infants exceeds levels that could produce harmful health effects. In general the authors found that fish consumption did not significantly increase the concentration of DDT/DDE breast milk concentrations. Women born in Mexico had elevated levels of DDT/DDE breast milk concentrations as compared to US born subjects regardless of fish consumption. Infant daily intake levels for the various subject groups were determined and compared to acceptable daily intake levels. Infant daily intake levels for the various groups were determined and compared to acceptable daily intake levels. The authors concluded by recommending breastfeeding benefits for these mothers of infant daily levels for the various groups were compared to acceptable daily breastfeeding.

  Source: Marien, K., A Conseur, and M Sanderson. The effect of fish consumption on DDT and DDE levels in breast milk among Hispanic immigrants. Journal of Human Lactation September 1998 Vol. 14(3):237-242.

• Scientific American Article on Effects of Eating PCB-contaminated Fish - A recent article in Scientific American reports on the cognitive damage caused by polychlorinated biphenyls (PCBs). Historically, research has associated exposure to PCBs with memory problems in infants and children. In a new study, led by Susan Schantz of the University of Illinois, results suggest that PCBs can also affect adults. Fish eaters older than 49 years that ate at least 24 pounds of fish from Lake Michigan annually were less able to recall a story after hearing it than people who consumed less than 6 pounds of fish. The reserachers further point out that some manufacturing plant workers may be exposed to 10 to 100 times as much PCB as fish eaters in the study and therefore may be at greater risk for PCB-related cognitive impairment.

  Source: McCook. When Fish is Not Brain Food. Scientific American August 2001 Vol. 285 (2):23-27

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.

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Revised December, 2001