Fish and Wildlife Advisory News - November 2002

Recent Advisory News

• Mercury Big in Recent News - A number of recent news articles have discussed the potential health risks of eating fish contaminated with high levels of mercury. Most of these articles have cited recent research by Dr. Jane Hightower, who presented her findings at the EPA’s Fish Forum in Burlington, Vermont in late October. Dr. Hightower screened 720 patients from March 2000 to March 2001, and then tested the mercury blood levels of patients who reported eating more than two servings of fish a week (the maximum the EPA recommends for pregnant women and small children). The tests showed that of 116 patients who had their blood tested, 89 percent showed mercury levels greater than the 5 ppm, the level recognized as safe by the National Academy of Sciences. Hightower’s paper is due to be published in the November issue of Environmental Health Perspectives. Most recent news articles on this topic also reviewed the causes of mercury contamination in fish, the health benefits and risks of eating contaminated fish, and the current recommendations by the EPA and the FDA.

  Sources: Manning, Anita. Nov 5, 2002. If you eat a lot of fish, you may run health risk. USA TODAY.

  Sharon L. Crenson. Oct 19, 2002. Study Records Elevated Mercury Levels in Fish Consumers. The Associated Press.

  Mendoza, Martha and Sharon L. Crenson. Oct 12, 2002. Eating too much fish? Research of mercury contamination leaves huge gaps in knowledge. The Associated Press.

• High mercury exposure in 10 percent of Hong Kong students - Reuters reports that a government study in Hong Kong found that as many as 10 percent of high school students there may be at risk of mercury poisoning because of their high consumption of fish such as tuna and swordfish. The 2001-2002 study found 10 percent of 903 students surveyed had dietary habits which gave them a mercury exposure of 6.41 micrograms per kilogram of body weight a week, which exceeds the 5 microgram safety limit set by the World Health Organization. The Hong Kong government said it might conduct a population-wide food consumption survey to study the dietary exposure of the territory's 6.8 million residents. The government is advising consumers not to eat excessive amounts of predatory fish such as shark, tuna, and swordfish, according to the report.

  Source: Reuters, Oct 25 2002. High mercury exposure in 10 percent of Hong Kong students. Environmental News Network (ENN).

Current Events, News and Journal Articles

• Level and extent of mercury contamination in Oregon fish - The authors conducted a probability survey of 154 Oregon stream and river sites to assess the extent of mercury contamination in fish tissue. Whole-fish sample of small (<120 mm) and large (>120 mm) fish were sampled at each site. Overall, mean mercury levels in small fish (0.031 ppm), large piscivores (0.284 ppm), and large invertivores (0.055 ppm) were found within fairly narrow ranges. Mercury values were always above detection limits (0.0025 ppm) and almost always below 0.4 ppm. Because of the great ecoregion diversity across the state, the authors concluded that the narrow range in fish tissue mercury levels suggests that atmospheric transport is an important source of mercury. In small fish, mercury levels were typically low and showed little difference among fish taxa. In larger fish, mercury concentrations were significantly related to fish size. Piscivores (pike,minnow and bass) had higher mercury concentrations, and the slope of their mercury concentration/length relationship was much steeper than for invertivores. Salmonids represented the most commonly occurring fish taxon in Oregon, exceeded 0.1 ppb mercury (deemed protective for fish-eating mammals) in an inferred 15% of stream lengths where they occurred. Although they were found at fewer sites, pike minnows and bass exceeded 0.1 ppm mercury in an inferred 96 and 70%, respectively, of stream lengths where they occurred.

  Source: Peterson SA, AT Herlihy , RM Hughes, KL Motter, and JM Robbins. Level and extent of mercury contamination in Oregon lotic fish. Environmental Toxicolology and Chemistry 2002 Volume 21(10): 2157-64.

• California DDT Program Shows Success - The Associated Press reported on a recent study showing that a sand cap installed two years ago at a Superfund site off the Palos Verdes Peninsula is working well and has contained the DDT contamination sediment. From 1947 to 1971, the DDT manufacturer Montrose Chemical Corp. routinely discharged the pesticide into sewers that flowed into the ocean. An estimated 1,800 tons of DDT settled on the sea floor over a 17 square mile area. Based on this successful 2-year test, EPA officials expect to make a proposal next year to cover about 3 square miles of sea floor with clean sediment dredged from the nearby harbor.

  Source: The Associated Press, October 1 2002. Study: Calif. DDT Program Working.

• Organotin pollution in deep-sea fish from the northwestern Mediterranean - This study attempted to determine the concentrations of organotin (butyltin and phenyltin) compounds in deep-sea fish collected in the Mediterranean. The concentrations of tributyltin (TBT) and its degradation products, triphenyltin (TPT), and mono- and diphenyltin (MPT, DPT), were determined in different tissues (liver, gills, digestive tube, and muscle) of several fish species. Total butyltin residues were up to 175 ppb (wet weight), and they were comparable to levels found in coastal fish collected along the Catalan coast. In contrast, deep-sea fish contained much higher levels of phenyltins (up to 1700 ppb wet weight), and particularly TPT (up to 1430 ppb wet weight), than previously reported concentrations in shallow-water organisms. The authors concluded that these results confirm the long-range transport of organotin compounds to the deep-sea environment, and the subsequent exposure of fish inhabiting these areas. The use of TPT in agriculture and as an antifouling agent, coupled with its transport to the deep-sea environment associated to particulate matter, and its nonbiodegradable nature in the food chain may account for the high residue levels detected in deep-sea organisms.

  Source: Borghi V. and C Porte. 2002. Organotin pollution in deep-sea fish from the northwestern Mediterranean. Environmental Science and Technology Volume 36 (20): 4224-8.

• Effects of de-acidification and decreased atmospheric mercury deposition in a Wisconsin lake - Mercury emissions in Wisconsin have declined substantially over the past 10 years. Parallel declines have been observed in the surface waters of Little Rock Lake. The authors reported that the mercury declines also extend to the fish community and they present evidence of a contemporaneous decline in mercury concentrations in fish tissue. Two separated basins of the lake were studied in an effort to isolate and quantify the relative importance of de-acidification and reduced mercury deposition on mercury levels in fish tissues. Statistical modeling indicated that mercury levels in fish in both basins decreased by roughly 30% between 1994 and 2000 due to decreased atmospheric mercury loading. De-acidification accounted for an additional 5% decrease in one basin and an additional 30% decrease in the other basin since the basins were de-acidified at different rates. Results of this study are consistent with the hypothesis that depositional inputs of SO4 and Hg (II) co-mediate the biosynthesis of methyl mercury and thereby co-limit bioaccumulation. The authors suggest that modest changes in acid rain or mercury deposition can significantly affect mercury bioaccumulation in fish over relatively short time periods.

  Source: Hrabik, T R and C J Watras. 2002. Recent declines in mercury concentration in a freshwater fishery: isolating the effects of de-acidification and decreased atmospheric mercury deposition in Little Rock Lake. Science in the Total Environment Volume 297 (1-3): 229-37.

• Infertility, blood mercury concentrations, and dietary seafood consumption - The purpose of this study was to compare blood mercury concentrations of infertile couples with those of fertile couples in Hong Kong, and to examine the relationship between blood mercury levels and seafood consumption. The study population included 157 infertile couples and 26 fertile couples with no known occupational exposure to mercury. Mercury levels in whole blood samples were monitored and information on the quantity of seafood consumption among infertile couples was collected using a food-frequency questionnaire. Resulting blood mercury levels and seafood consumption levels were compared for infertile and fertile couples. Results showed that infertile couples had higher blood mercury levels than fertile couples. Furthermore, infertile males with abnormal semen and infertile females with unexplained infertility also had higher blood mercury levels than their fertile counterparts. Blood mercury levels were positively correlated with amount of seafood consumption. Infertile subjects with elevated blood mercury consumed larger quantities of seafood. The authors concluded that higher blood mercury levels are associated with male and female infertility and higher seafood consumption is responsible for the elevated blood mercury levels in infertile individuals.

  Source: Choy, C M, C W Lam, LT Cheung, CM Briton-Jones, LP Cheung and C J Haines. Infertility, blood mercury concentrations, and dietary seafood consumption: a case-control study. British Journal of Obstetrics and Gynocology 2002 Volume 109 (10):1121-5.

• Use of historical biochemical endpoints in fish to predict sediment contamination - Studies conducted in Bayou Bartholomew, Arkansas in 1994 revealed a significant relationships between individual fish health from 13 sites and specific biochemical responses. Evaluation of several biochemical endpoints indicated the bioavailable occurrence of either PCBs or metals. To evaluate this relationship, sediments were collected at 4 sites in Bayou Bartholomew during 2000, where fish, collected in 1994, had previously shown the highest hepatic cytochrome P4501A (CYP1A) and heme oxygenase (HO) expression. Sediment samples were analyzed for 89 PCB congeners, 18 organochlorine pesticides, and 25 metals. Total PCB concentrations ranged from 6.5 to 704 ppb (dry weight). Several PCB congeners were detected; however, congeners 81, 87, 99, 114, and 153 represented up to 33, 22, 29, 92, and 55% of the sum of PCBs from the 4 sites, respectively. Total organochlorine pesticide concentrations ranged from undetectable to 53.2 ppb (dry weight). Dachtal, DDT, DDE, DDD, heptachlordieldrin, hexachlorobenzene, and Lindane isomers were detected in the majority of samples. The organophosphate pesticides, malathion, chlorpyrifos, and dimethoate were also detected. Both p,p'-DDE and p,p'-DDD were the most predominant of the pesticides measured (0.5-14.1 and 0.7-58.5 ppb dry wt), respectively. Concentrations of all metals were below sediment quality guideline values. The authors concluded that the results were consistent with PCBs being the causative agents for the adverse biochemical responses observed in fish sampled from this waterway.

  Source: Schlenk D, Y Sapozhnikova , JP Baquirian and A Mason. Predicting chemical contaminants in freshwater sediments through the use of historical biochemical endpoints in resident fish species. Environmental Toxicology and Chemistry 2002 Volume 21(10):2138-45.

• Reference values for total mercury levels in hair and fish in Amazonia - The authors conducted a study of mercury concentrations in hair and fish tissue, together with an assessment of the prevalence of mercury poisoning symptoms, in four communities in the Amazon Basin not impacted by gold mining in order to establish reference values. These communities were located by a river course (Santana do Ituqui and Caxiuana) or by a lake (Aldeia do Lago Grande and Vila do Tabatinga). The mean total mercury concentrations in hair was 4.33 ppm (0.40-11.60 ppm) in 321 individuals from Santana do Ituqui, 3.98 ppm (0.40-11.76 ppm) for 316 persons in Aldeia do Lago Grande, 5.46 ppm (0.37-49.85 ppm ) for 504 individuals from Vila do Tabatinga and 8.58 ppm (0.61-45.59 ppm) for 203 inhabitants from Caxiuana. Although fish consumption was very high in all 4 communities, no symptoms associated with mercury poisoning were found. Mean mercury levels in fish ranged from 0.006 to 2.529 ppm for carnivores and from 0.008 to 0.871 ppm for noncarnivores. These mercury levels suggest that further studies including examination of a larger number of communities would lead to values of "normal" mercury concentration in the Amazonian Region significantly above the limits suggested by the World Health Organization.

  Source: Santos EC, VM Camara , IM Jesus ,ES Brabo, EC Loureiro, AF Mascarenhas, KF Fayal, GC Sa Filho, FE Sagica , MO Lima , H Higuchi, and IM Silveira. A contribution to the establishment of reference values for total mercury levels in hair and fish in Amazonia. Environ Res 2002 Volume 90 (1):6-11.

• Potential risk to wood storks from mercury in Carolina Bay fish - Carolina bays are freshwater wetlands that serve as important feeding habitats for the endangered wood stork (Mycteria americana). In these bays, water levels fluctuate widely and tend to be acidic and rich in dissolved organic carbon. These factors favor mercury methylation and bioaccumulation in fish. To assess potential risks to wood storks consuming mercury contaminated fish, the authors sampled fish from 10 bays on the Savannah River Site, SC, used by storks. Whole body mercury levels were analyzed in 258 fishes of three species including lake chubsucker, mud sunfish. and redfin pickerel commonly consumed by the storks. Risk factors for nestlings and free-ranging adults were calculated using published no and lowest observable adverse effect concentration (NOAEC and LOAEC) values for birds. Higher trophic level fish and those from wetlands with shallow maximum depths and fluctuating water levels were more likely to exceed NOAEC and LOAEC values. Calculation of exposure rates of nestling wood storks showed that the birds were at highest risk during the first 10 days of the nestling period. The authors concluded that there is potential for concern for wood storks foraging in relatively shallow bays with fluctuating water levels, even though there is no obvious local source of mercury to these wetland areas.

  Source: Brant HA, CH Jagoe, JW Snodgras, AL Bryan Jr, and JC Gariboldi. Potential risk to wood storks (Mycteria americana) from mercury in Carolina Bay fish. Environ Pollution 2002 Volume 120 (2): 405-13.

• Raccoon as a bioindicator of mercury contamination at Savannah River - For this study, 95 raccoons were collected from the U.S. Department of Energy's Savannah River Site (SRS) and from public hunting areas. Animals were collected near the Steel Creek delta stream drainage system and at a former reactor-cooling reservoir (pond B) that received inputs of mercury-contaminated Savannah River water. Mercury levels were analyzed in raccoon hair, liver, kidney, muscle, and spleen tissues. In addition, animals were also collected from a natural stream floodplain system (Upper Three Runs/Tinker Creek) located upstream of mercury use and storage areas and near coal ash basins. These samples were compared to samples collected from off-site hunting areas near the SRS. Mercury concentrations among internal tissues were significantly correlated. Hair concentrations did not correlate well with internal tissue and was a poor indicator of raccoon mercury exposure. Despite this, the authors consider raccoons as potentially good indicators of mercury contamination because internal tissue levels were higher in animals from areas with known mercury inputs than in those from reference areas. The authors found that muscle biopsies could be used as biomarkers for contaminant exposure. Muscle mercury levels ranged from 0-0.14 ppm from nearby hunting grounds, indicating that people hunting in designated areas near the SRS are at negligible risk for mercury via consumption of raccoon meat. Several raccoons collected from the SRS had muscle Hg concentrations at or near the FDA action level (1 ppm) for seizing commercial fish due to mercury contamination. The authors suggest that some SRS raccoons contain mercury levels that warrant concern if these currently restricted areas are open to public hunting. The authors also point out that 64 raccoons from this study had mercury tissue levels that were considered elevated by the U.S. FWS standard (>1.1 ppm) of ecosystem health for one or two tissues (hair, liver, or kidney), and 17 had high mercury levels in most or all tissues.

  Source: Lord C G; KF Gaines, CS Boring, IL Brisbin Jr, M Gochfeld, and J Burger. 2002. Raccoon (Procyon lotor) as a bioindicator of mercury contamination at the U.S. Department of Energy's Savannah River Site. Volume 43 (3): 356-363

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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.