Recent Advisory News

• Aroostook Band of Micmacs Tribal Fish Advisory - The Aroostook Band of Micmacs, located in Maine, has developed a fish advisory brochure which is now included with every fishing license that is issued to members of the Tribe. This represents a great majority of Tribal members who consume fish. The advisory largely corresponds with the state of Maine advisory regarding all freshwater and marine species, with more restrictive advice for striped bass and bluefish, and Do Not Eat advice for lobster tomalley. The advisory also concerns commercial species including shark, swordfish, mackerel, tilefish, and canned tuna. Pregnant women and children under 8 are given more restrictive consumption advice than the general population.

  Source: For more information, go to the Contacts page of the NLFWA and contact the Tribe's Environmental Department. You can also Download the Advisory (PDF, 208 KB).

• Health Canada Issues Information on Mercury Levels in Fish - Health Canada recently advised Canadians to limit consumption of the following fish: shark, swordfish, and fresh and frozen tuna. Pregnant women, women of child-bearing age and young children were advised not to eat more than one meal per month of these fish. Health Canada noted that the advisory did not cover canned tuna which typically contains smaller, younger tuna that have not accumulated substantial concentrations of mercury in their tissues. Health Canada also reiterated its previously issued advice that the potential exposure to mercury can occur through eating these species over a lifetime and also reviewed the issues surrounding the presence of mercury, a naturally-occurring contaminant in fish. Health Canada has established a guideline of 0.5 ppm for mercury in commercial fish and this guideline value is enforced by the Canadian Food Inspection Agency. The guideline was first set in the 1970s, and based on a recent review is still considered appropriate to ensure that the health of Canadians is protected from the toxic effects of methylmercury.

  Source: Health Canada website.

• British Mercury Alert Over Swordfish, Shark and Marlin - United Kingdom consumers - specifically young women and children under 16 years of age- were recently alerted not to eat shark, swordfish or marlin because the fish might contain potentially dangerous concentrations of mercury. The British Food Standards Agency advised all other adults not to eat more than one portion of fish a week. The BFSA has also asked for a further review of tuna consumption although the agency believes consumers can continue to eat it safely. The agency issued the alert particularly to women who intend to become pregnant as well as those who are currently pregnant over concerns that mercury may lead to developmental problems in the fetuses of pregnant mothers, in infants, and in young children. A BFSA spokeperson said that eating one portion of shark, swordfish, or marlin a week could put a person very close to the limit of safety established by the World Health Organization. Children eating this portion of fish every week would exceed the margin of safety for consumption. The BFSA planned to meet in June to determine whether further actions are needed. Further actions might include ensuring importers, supermarkets and restaurants tested mercury levels in their fish.

  Source: James Meikle, The Guardian, May 11, 20002.

Current Events, News and Journal Articles

• Fish Tissue Quality in Coastal Waters Receiving Point Source Discharges - The authors’ objective for this study was to determine contaminant concentrations in edible fish tissue collected at eight coastal sites receiving wastewater discharges and from two reference sites. The mean total PAH concentrations were 1.79 ng/g (reference sites) and 2.17 ng/g (wastewater impacted sites). Of the PAHs, pyrene was detected most frequently (63% of all samples) at a mean of 2.17 ng/g wet weight. The mean total PCB concentrations were 4.8 ng/g (reference sites) and 31.6 ng/g (wastewater-impacted sites). Tissue concentrations of dieldrin and cis-chlordane were about 8 times higher in fish collected from waterwater receiving waters, although total DDT and total pesticide concentrations were not elevated at the same sites. All concentrations of total PCBs and chlorinated pesticides were below US health-based standards. Trace metal concentrations in fish tissues were statistically similar at all collection sites. The detection rate for the metals in fish tissue was zinc and mercury (100%), total arsenic and copper (92%), and selenium (88%). Mercury tissue levels exceeded the Florida health-based standard of 0.5 ppm for limited fish consumption in a third of the samples and averaged 0.4 ppm wet weight (range 0.08 to 0.85 ppm)

  Source: M.A. Lewis, G.I. Scott, D.W. Bearden, R.L. Quarles, J. Moore, E.D. Strozier, S.K. Sivertsen, A.R. Dias, and M. Sanders. 2002. Fish Tissue quality in near-coastal areas of the Gulf or Mexico receiving point source discharges. The Science of the Total Environment 284:249-261.

• Contaminant residues in seabird eggs from the Canadian Arctic - The authors examined contaminant residues in eggs of four species of seabirds: glaucous gulls (Larus hyperboreus), thick-billed murres (Uria lomvia), black-legged kittiwakes (Rissa tridactyla), and black guillemots (Cepphus grylle) from several sites in the Canadian Artic. Eggs of glaucous gulls collected at sites in the High Arctic contained higher organochlorine concentrations than those in the western Low Arctic. The authors concluded that this was likely due to dietary differences among colonies as suggested by stable isotope results, although they could not rule out differences in overwintering areas. Total PCBs, total DDT, total Chlordane, total chlorobenzenes, and dieldrin concentrations were significantly lower in thick-billed murres from Prince Leopold Island (High Arctic) as compared to colonies in the eastern Low Arctic. The authors concluded that this difference was probably due to the effects of diffent atmospheric deposition patterns in the High and Low Arctic coupled with use of different overwintering areas since murres from Prince Leopold Island appeared to winter farther north than murres from the other sampled colonies. Higher mercury concentrations were observed in eggs at higher latitudes for most species sampled. Trophic and dietary differences and similarities suggested by stable nitrogen and carbon isotope data in this study provided explanations for the spatial patterns of contaminant concentrations observed among seabird colonies.

  Source: B.M. Braune, G.M. Donaldson, and K.A. Hobson. 2002. Contaminant residues in seabird eggs from the Canadian Arctic II. Spatial trends and evidence from stable isotopes for intercolony differences. Environmental Pollution 117:133-145.

• Mercury in Zooplankton Diet - In lakes, methylmercury bioaccumulates up the food chain, from algae to minute zooplankton to fish. Paul Pickhardt and his colleagues studied the effects of elemental mercury and methylmercury in a laboratory lake ecosystem using Daphnia. After 2 and 3 weeks, the researchers sampled water, algae, and Daphnia and found that methylmercury concentrations in zooplankton were lower after an algal bloom. This suggested that the algal bloom diluted mercury concentrations in individual cells by spreading the mercury out among a larger number of individual algae cells thus offering the Daphnia less contaminated food. Fish could ultimately be exposed to higher levels of methylmercury per algal cell when an algal bloom was not present. Methylmercury concentration in zooplankton decreases dramatically after an algal bloom. The study also found that algal cells in simulated lake ecosystems with larger algae populations not only contained less mercury but also less methylmercury. In addition, Daphnia in systems with more algae contained much less methylmercury than Daphnia in systems with less algae. Irrespective of the amount of algae present, Daphnia always accumulated higher concentrations of methylmercury than elemental mercury. The study results indicate that fish can be exposed to 2-3 times more methylmercury when a lake is not experiencing an algal bloom episode than when it is.

  Source: Zooplankton diet of mercury varies. Science News, 3/30/2002, Vol. 161 Issue 13, p205, 1/3p, 1c

• Which Fish Are Safe for Kids? - Concern about elevated levels of mercury in some types of fish has prompted the American Academy of Pediatrics (AAP) to recommend that parents limit the amount of fish children are eating. This article in the popular magazine Prevention explains that the benefits of eating certain types of fish have to be weighed against the health risks. Eating seafood - particularly large, long-lived predator species at the apex of the food chain, such as king mackerel, shark or swordfish is the primary way children are exposed to methylmercury. It can damage the developing brain and nervous system, kidneys, and immune system. Unfortunately, preparation and cooking techniques do not reduce the mercury content of fish because mercury binds tightly to protein in the muscle tissue. The article's recommendations include:
  • Avoiding shark, swordfish, king mackerel, and tilefish that contain the highest mercury concentrations often exceeding the FDA's advisory limit of one part per million. These species should not be eaten, especially by pregnant women, nursing women, and children under 5.
  • Restricting to 2 oz, (1 meal per week): Walleye, pike, bass, muskie, and other freshwater fish may also contain high mercury levels.
  • Restricting to 12 oz, (2 or 3 meals per week): The top commercial fish-canned tuna, shrimp, pollock, salmon, cod, catfish, clams, flounder, halibut, sole, crabs, and scallops-which account for about 85% of the fish we eat and have mercury levels low enough that a few meals per week are safe.

  Source: Kozak, D. and S. Harrar. 2002. Which Fish Are Safe for Kids? Prevention, 2002, Vol. 54 Issue 1, p44, 1p, 1c

• Bioaccumulation of PCBs in Fish - Potomac River Study - Researches studied water, sediments, and aquatic biota in a tidal river-marsh on the Potomac River near Washington, DC to assess baseline concentrations of PCBs and bioaccumulation in fish. The mean sediment total-PCB concentration in biota ranged from 150 ng/g to 450 ng/g wet weight, with the highest PCB concentrations being observed in channel catfish. Apparent bioaccumulation factors (biota/water PCB concentration ratios) for PCB congeners showed a parabolic relation with n-octanol/water partition coefficients, which confirms some previous investigations. There was no clear trend between apparent bioaccumulation factors and trophic level.

  Source: Crimmins B S; Brown P Doelling; Kelso D P; Foster G D. 2002. Bioaccumulation of PCBs in aquatic biota from a tidal freshwater marsh ecosystem. Archives of Environmental Contamination and Toxicology, Vol. 42(4) pp. 396-404, May 2002

• Organochlorine Chemical Residues in Fish from the Mississippi River Basin - In 1995, fish were collected from 34 National Contaminant Biomonitoring Program (NCBP) stations and 13 National Water Quality Assessment Program (NAWQA) stations in the Mississippi River basin (MRB). Additionally in 1996, fish were collected at a reference site in West Virginia. The samples collected at each site included 4 composite samples, each comprising 10 adult common carp (Cyprinus carpio) or black bass (Micropterus spp.) of the same sex. All samples were analyzed for organochlorine chemical (OC) residues by gas chromatography with electron capture detection. At the NCBP stations, representing large rivers, OC concentrations were generally lower than those sampled in the mid-1980s. DDT residues (primarily p,p'-DDE) were detected at all sites including the WV reference site. However, only traces (£0.02 mg/g) of the parent insecticide (p,p'-DDT) were present, indicating continued weathering of past DDT residues. Fish DDT concentration (as p,p'-DDE) from cotton-farming regions of the lower MRB were high enough to constitute a hazard to fish-eating wildlife. Concentrations were especially high at the NAWQA sites on lower-order rivers and streams of the Mississippi embayment. Of the OC detected, mirex was found at only two sites in Louisiana, while toxaphene was found exclusively in the lower MRB. More widespread in their distribution were most of the cyclodiene pesticides (dieldrin, chlordane, and heptachlor epoxide), but concentrations were generally lower than in the 1980s except at one Mississippi River site near Memphis, TN and concentrations were also somewhat elevated at sites in the Corn Belt. Endrin was detected only at the Memphis, TN site. In general, PCB concentrations declined since the 1980s, but residues were detected (³0.05 mg/g) at approximately 35% of stations sampled and primarily at station in the more industrialized portions of the Mississiippi River Basin.

  Source: Schmitt CJ. 2002. Organochlorine chemical residues in fish from the Mississippi River basin, 1995. Arch Environ Contam Toxicol 43(1):81-97.

• Toxic Equivalency Factors for PAHs Applied to Shellfish Monitoring - Fish and shellfish are exposed to a broad spectrum of polycyclic aromatic hydrocarbons (PAH) following oil spills at sea, and can become contaminated via this exposure. Because finfish have a more effective mixed-function oxidase enzyme system than shellfish, they are able to metabolize and excrete PAH more effectively than shellfish. Contamination by high-molecular weight PAH is therefore usually observed in shellfish, and particularly in bivalve molluscs. These same PAH have carcinogenic potential and are therefore of concern for human consumers. In addition to oil spills, PAH compounds are generated by a wide range of combustion processes. In this study, the authors compare monitoring data gathered following recent oil spills (both of crude oil and diesel fuel), with data from other studies including those conducted around a former gasworks site and downstream of an aluminium smelter in the UK, and from nationwide mussel monitoring studies undertaken in the UK and the USA (National Status and Trends program), as well as in other countries in Europe. PAH concentrations are summed and expressed as benzo[a]pyrene equivalents, their relative concentrations being weighted in relation to the carcinogenic potential of individual PAH compounds using toxic equivalency factors (TEF). The authors’ aim was to assess the usefulness of this approach in fishery resource monitoring and management following oil spills. This approach appears to be useful and the relative ranking of the various studies seems to reflect the relative degree of human health concern due to the differing contamination sources. This tool appears to be applicable to studying PAHs derived from oil spills, as well as industrial and combustion sources.

  Source: Law RJ, C. Kelly, K. Baker, J. Jones, A. D. McIntosh, and C.F. Moffat. 2002. Toxic equivalency factors for PAH and their applicability in shellfish pollution monitoring studies. J Environmental Monitoring 4(3):383-388.

• Determination of Mercury in Seafood Method - An interlaboratory method performance (collaborative) study involving ten laboratories was conducted of a method for the determination of mercury in foods of marine origin. The method evaluated was using flow injection-cold vapor atomic absorption spectrometry after wet digestion using a microwave oven technique. The study was preceded by an initial training round using samples of known identity. The method was applied to a total of 7 seafood products: blue mussel, cod muscle, crab, scampi, black scabbard fish, longnose velvet dogfish, and Portuguese dogfish with mercury residues of 0.14, 0.24, 0.35, 0.59,11.42, 4.2, and 13.2 mg/g, respectively. The participating laboratories received the materials as blind duplicates, and participants were asked to perform single determinations on each sample. Repeatability relative standard deviations for mercury ranged from 2.4 to 14.0% while reproducibility relative standard deviations ranged from 7.7 to 16.6%.

  Source: Julshamn K., and J Brenna. 2002. Determination of mercury in seafood by flow injection-cold vapor atomic absorption spectrometry after microwave digestion: NMKL interlaboratory study - Nordic Committee on Food Analysis. J AOAC Int 85(3):626-31.

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 July, 2002