Risk to consumers from mercury in bluefish (Pomatomus saltatrix) from New Jersey: Size, season and geographical effects

Relatively little attention has been devoted to the risks from mercury in saltwater fish, that were caught by recreational fisherfolk. Although the US Food and Drug Administration has issued advisories based on mercury for four saltwater species or groups of fish, there are few data on how mercury levels vary by size, season, or location. This paper examines total mercury levels in muscle of bluefish (Pomatomus saltatrix) collected from coastal New Jersey, mainly by recreational fishermen. Of primary interest was whether there were differences in mercury levels as a function of location, weight and length of the fish, and season, and in what risk mercury posed to the food chain, including people. Selenium was also measured because of its reported protective effects against mercury. Mercury levels averaged 0.35±0.02 (mean and standard error) ppm, and selenium levels averaged 0.37±0.01 ppm (N=206). In this study, 41% of the fish had mercury levels above 0.3 ppm, 20% had levels above 0.5 ppm, and 4% had levels above 1 ppm. Size was highly correlated with mercury levels, but not with selenium. While selenium levels did not vary at all with season, mercury levels decreased significantly. This relationship was not due to differences in the size of fish, since the fish collected in the summer were the smallest, but had intermediate mercury levels. Mercury levels declined from early June until November, particularly for the smaller-sized fish. While there were significant locational differences in mercury levels (but not selenium), these differences could be a result of size. The levels of mercury in bluefish are not sufficiently high to cause problems for the bluefish themselves, based on known adverse health effects levels, but are high enough to cause potential adverse health effects in sensitive birds and mammals that eat them, and to provide a potential health risk to humans who consume them. Fish larger than 50 cm fork length averaged levels above 0.3 ppm, suggesting that eating them should be avoided by pregnant women, children, and others who are at risk.     

Mercury and selenium in fish from the Savannah river: species, trophic level, and locational differences.

Levels of contaminants in fish are of considerable interest because of potential effects on the fish themselves, as well as on other organisms that consume them. In this article we compare the mercury levels in muscle tissue of 11 fish species from the Savannah River, as well as selenium levels because of its known protective effect against mercury toxicity. We sampled fish from three stretches of the river: upstream, along, and downstream the Department of Energy's Savannah River Site, a former nuclear material production facility. We test the null hypothesis that there were no differences in mercury and selenium levels in fish tissue as a function of species, trophic level, and location along the river. There were significant interspecific differences in mercury levels, with bowfin (Amia calva) having the highest levels, followed by largemouth bass (Micropterus salmoides) and pickerel (Esox niger). Sunfish (Lepomis spp.) had the lowest levels of mercury. As expected, these differences generally reflected trophic levels. There were few significant locational differences in mercury levels, and existing differences were not great, presumably reflecting local movements of fish between the sites examined. Selenium and mercury concentrations were positively correlated only for bass, perch (Perca flavescens), and red-breasted sunfish (Lepomis auritus). Mercury levels were positively correlated with body mass of the fish for all species except American eel (Anguilla rostrata) and bluegill sunfish (L. macrochirus). The mercury and selenium levels in fish tissue from the Savannah River are similar to or lower than those reported in many other studies, and in most cases pose little risk to the fish themselves or to other aquatic consumers, although levels in bowfin and bass are sufficiently high to pose a potential threat to high-level consumers.     

Mercury concentrations in three species of fish from North Atlantic offshore waters

Mercury concentrations were determined in tissues and organs of spiny dogfish (Squalus acanthias), cusk (Brosme brosme), and blackbellied redfish (Helicolenus dactylopterus) collected from Atlantic Ocean waters off the northeastern coast of the United States. Information was obtained on the spatial and temporal distribution of mercury in the organs and tissues of these fish.Cusk were obtained from 2 locations and blackbellied redfish from 4 locations. The mercury levels in both muscle and liver of cusk averaged about 0.30 ppm for one and 0.16 ppm for the second location. Gills and kidneys of cusk had mercury levels that averaged 0.08 ppm for both collections. In blackbellied redfish mercury levels in muscle and liver averaged about 0.08 ppm for all locations; gill and kidney tissues of this fish were less than 0.2 ppm.Spiny dogfish were obtained from 5 areas. No significant difference in mercury levels was found in muscle tissue as related to geographic area. Mercury levels ranged from 0.21 to 0.62 ppm. The kidneys of dogfish contained about 54% of the mercury level of muscle. The mercury level in gills of dogfish ranged from 0.06 to 0.21 ppm.Spiny dogfish pups were obtained from 6 adult females. Samples of muscle, liver, gill, kidney, and yolk of pups were analyzed for mercury. These same samples, except for the yolk, were obtained from the adult females. Mercury levels in all pup samples were less than 0.03 ppm, while mercury levels in adult females ranged from 0.03 to 1.1 ppm in all tissues and organs.     

Distribution of Hg and Se in Muscle and Liver of the Thornback Guitarfish Platyrhinoidis triseriata from the Eastern Pacific Ocean

Human consumption of the thornback guitarfish (Platyrhinoidis triseriata) is concentrated in coastal populations of the Pacific coast of Mexico as its meat is prized for its high quality. This study analyzes the distribution of mercury and selenium in the muscle and liver of Platyrhinoidis triseriata and the risk to human health associated with its consumption. In order to conduct these estimates, specimens were collected from the Eastern Pacific Ocean in 2015 and 2016 and found mean concentrations (µg g^?1 wet weight) of mercury ranging from 0.02 to 0.58 in muscle and 0.10 to 0.31 in liver. Selenium ranged from 0.14 to 1.31 in muscle and from 0.93 to 4.52 in liver. Mercury levels in the muscle of P. triseriata were significantly correlated (positive correlation) with the total length of the specimens. The predominant prey of P. triseriata was the shrimp Pleuroncodes planipes and according to the biomagnification factor, only mercury was biomagnified. The risk to consumers associated with the simultaneous presence of mercury and selenium in the muscle and liver of rays under the selenium health benefit value approach indicated that consumption of P. triseriata from this area is beneficial to human health.

     

Metal levels in flathead sole (Hippoglossoides elassodon) and great sculpin (Myoxocephalus polyacanthocephalus) from Adak Island, Alaska: potential risk to predators and fishermen

Increasingly there is a need to assess the contaminant levels in fish as indicators of the health and well-being of both the fish and their consumers, including humans. This paper examines the levels of arsenic, cadmium, chromium, lead, manganese, mercury, and selenium in the kidney, liver, and muscle of great sculpin and flathead sole from Adak Island in the Aleutian Islands, Alaska. Both species are consumed by the local Aleuts and others. There were significant differences in the levels of heavy metals as a function of tissue for both fish species; the liver of sculpin and sole generally had the highest levels of most metals, except for arsenic, lead, and selenium. Sole had significantly higher mean levels of arsenic in kidney (32,384 vs. 531 ppb, wet weight), liver (18,954 vs. 2532 ppb), and muscle (19,452 vs. 1343 ppb) than did sculpin. Sole also had higher mean levels of cadmium (230 vs. 63 ppb), lead (1236 vs. 48 ppb), mercury (150 vs. 107 ppb), and selenium (5215 vs. 1861 ppb) in kidney than did sculpin. There were significant correlations among weight and length measurements for both species. However, except for mercury, there were few significant correlations among tissue types for most metals. Only mercury and manganese levels were significantly correlated with size for sculpin (but not for sole). Levels of arsenic, lead, and mercury may pose a risk to predators that consume them, and arsenic and mercury may pose a risk to human consumers.     

Mercury Concentrations in Commercial Fish from Freshwater and Saltwater

Research was performed to investigate the concentration of mercury in muscle and liver of fish species from freshwater (Barbus xanthopterus, Barbus grypus, Liza abu) and saltwater (Cynoglossus arel, Periophthalmus waltoni, Otolithes ruber) in Khouzestan, Iran. In freshwater fish, muscle was polluted in comparison with liver except for Barbus xanthopterus which high levels of mercury were measured in liver. In saltwater fish liver was contaminated than muscle except for Cynoglossus arel which high level of mercury was found in muscle. Significant variations in metal values were evaluated using student’s t test at P < 0.05. Mercury concentrations were well above the permissible limits suggested by WHO and FDA guidelines.     

Levels of environmental pollutants in flounder (Platichthys flesus L.) and cod (Gadus morhua L.) caught in the waterway of Glomma,Norway. II. Mercury and arsenic

The present study is a survey on mercury and arsenic pollution in two sedentary fish species stationed in or close to the Glomma estuary in the Hvaler archipelago, Norway. Mercury and arsenic were determined individually in 80 flounder (Platichthys flesus L.) and 100 cod (Gadus morhua L.). The fish were caught at five different localities near or in the relatively polluted Glomma estuary. There were significantly higher mercury and arsenic concentrations in fillets of flounder than in fillets of cod (wet weight), 0.15 vs. 0.08 mg/kg and 5.2 vs. 4.1 mg/kg, respectively. Seasonal variation in mercury concentration was only found in flounder, with a significantly higher level in spring than in autumn. A significant increase in mercury content with increasing age was found for both species. For cod, a significantly higher arsenic level was found on the outer stations as compared to the inner stations, while arsenic levels in flounder was less dependent on sampling site.     

Health effect of long-term diet mercury contaminated tuna. Part II. Accumulation and retention of mercury and selenium in organs and clinical symptoms (author's transl)]

Health effects of long-term tuna diet in cats were examined. The cats were fed daily with three kinds of tuna, containing different concentrations of mercury and selenium. The following results were obtained. 1) A high correlation was noted between the amount of fish intake and the mercury level in hair and blood samples of cats. 2) Mercury levels in organs were elevated corresponding with the amount of tuna consumption, but the distribution of mercury in organs of cats exposed to mercury in tuna flake differed from that in tuna fresh meat. In the liver, the ratio of methyl mercury to the total mercury was very low with an average of 11.5% of the ratio. 3) With regard to selenium, there was no correlation between intake of selenium and selenium levels in the cerebrum, celebellum, and kidneys, exept in the liver (r=0.766). 4) None of the cats had definite methyl mercury poisoning, but some slight disturbances were noted in several cats.     

Mercury and selenium concentrations in fish samples from Cachoeira do PiriáMunicipality, ParáState, Brazil

Mercury is a major public health concern because of its widespread occurrence in the environment and its toxic effects on humans, mainly through fish ingestion. On the other hand, selenium is known by its antioxidant effect. For this reason, the knowledge of the correlation between mercury and selenium concentrations in fish samples can bring important information allowing a better understanding of mercury equilibrium in the inhabitants of the Amazon region. In this paper, total mercury and selenium levels were measured in carnivorous (47), omnivorous (44), and herbivorous (4) fish species caught in rivers and in an artificial lake in Cachoeira do PiriáMunicipality, situated in ParáState, Amazon region. The mercury concentration ranged from 1.15 to 13.44 nmol g(-1) and selenium from 2.44 to 14.56 nmol g(-1) for carnivorous species. For noncarnivorous species, mercury concentration ranged from 0.08 to 2.03 nmol g(-1) and selenium from 1.27 to 15.32 nmol g(-1). The molar ratios between mercury and selenium contents obtained for carnivorous and noncarnivorous species were 0.65 and 0.14, respectively. Mercury and selenium levels were positively correlated with fish body mass (weight) only for Hoplias malabaricus (n=35, R2=0.565, P<0.005 and R2=0.608, P<0.005, respectively). Selenium and mercury concentrations were statistically positively correlated only for H. malabaricus (n=35, R2=0.787, P=0.005) and Leporinus sp. (n=38, R2=0.485, P<0.005) known locally as Traíra (carnivorous) and Aracu (omnivorous), respectively.     

Exposure analysis of five fish-consuming populations for overexposure to methylmercury

Mercury, in the form of methylmercury, is found in a myriad of fish species consumed by recreational and subsistence fishers around the world. Many agencies have attempted to address the issue of mercury consumption, resulting at times in the placement of advisories on waterways used for fishing. In this study, consumption rates of three Native American populations and two recreational fishing populations consuming freshwater or saltwater fish species were examined. These consumption rates were combined with fish contamination data to assess the level of exposure to methylmercury and to determine if any of these populations exceed a derived tolerable daily intake (TDI) for methylmercury (0.035 to 0.08 microg/kg/day). The TDI is unlikely to result in adverse health effects and is based on scientific studies investigating sensitive endpoints in children of mothers who consume fish over prolonged periods of time. Results from the exposure analysis indicate that many within the Native American populations exceed the TDI. This occurs even though the mercury concentrations in certain fish species are comparable to concentrations found in fish from open waters where "background" levels are assumed. Recreational anglers consuming freshwater species have exposure levels below the TDI as do nearly all anglers consuming saltwater species. Similar populations or populations having comparable consumption patterns of fish with equal or higher mercury levels in other areas will also exceed the TDI level for mercury. The public health implications of this exposure analysis are discussed.     

Selenium and Mercury Concentrations in Brood-Stock Walleye Collected from Three Sites on Lake Oahe

A decline in the walleye Stizostedion vitreum sport fishery in lower Lake Oahe, South Dakota, was documented in the early 1980s and has been attributed to poor natural reproduction and/or recruitment. Contaminants were suspected of causing low natural reproduction/recruitment in lower Lake Oahe as well as low hatchability of eggs produced from broodstock walleyes taken from lower Lake Oahe. Concentrations of dissolved selenium in the Cheyenne River, which enters lower Lake Oahe, have increased considerably over the last 15 years. To determine whether selenium concentrations contributed to the reproduction problems in the lower Lake Oahe walleye population, adult walleye were collected during spawning operations in April 1994, 1995, and 1996 to obtain tissue samples. Muscle, liver, reproductive tissue, and unfertilized eggs were analyzed with a modified fluorometric method for determining selenium concentrations in plants. These tissues were also analyzed for mercury content using cold-vapor atomic absorption. No statistical differences (p < 0.05) in selenium or mercury concentrations among sites could be determined that would explain differential walleye egg hatchability. Correlation analysis determined significant inverse associations existed between the gonadal somatic index of male walleye and gonadal tissue selenium concentrations (r =−0.41, p = 0.0012). Both walleye sexes exhibited significant inverse associations between the hepatic somatic index (HSI) and liver selenium concentrations (males r =−0.33, p = 0.0095; and females r =−0.38, p = 0.0034). Positive relationships existed for female walleye selenium concentrations in the liver and the ovaries (r = 0.37, p = 0.003) and the liver and muscle tissue (r = 0.28, p = 0.027). Mercury concentrations in walleye ovaries were positively correlated with HSI (r = 0.30, p = 0.0012), length (r = 0.36, p = 0.0046), relative weight (r = 0.36, p = 0.0054), and muscle concentrations (r = 0.49, p = 0.0001). Mercury concentrations in male walleye muscle were correlated with age (r = 0.57, p = 0.0001), length (r = 0.79, p = 0.0001), and mercury concentrations in the testes (r = 0.43, p = 0.0006). Received: 26 February 2000/Accepted: 18 August 2000     

Trace metals in some fish species of South Carolina

Summary Samples of fish from freshwater and saltwater sources of ocean, rivers, and lakes over the state of South Carolina were collected. The fish collected were Shrimp, Silver Snapper, White Bass, Catfish, Mudfish and Trout. The sample flasks were incubated in a constant temperature stirring water bath at 58°C until clear solution in reagent-grade nitric acid. Triplicate samples of fish muscle tissue were analyzed by wet digestion and dry digestion methods. Trace metal levels were determined by flame atomic absorption using a Perkin-Elmer Model 306 spectrophotometer. Mercury determination was made by Coleman MAS-50 mercury analyzer. A significant finding of this report is that salt-water fish have more trace metal levels than freshwater fish, and larger fish have higher trace metals than smaller fish. Iron and zinc levels were much higher in Shrimp than any other species analyzed.     

Species differences in contaminants in fish on and adjacent to the Oak Ridge Reservation, Tennessee

Risks to humans and other organisms from consuming fish have become a national concern in the USA. In this paper, we examine the concentrations of 137Cs, arsenic, beryllium, cadmium, lead, mercury, and selenium in three species of fish from two river reaches adjacent to the US Department of Energy's Oak Ridge Reservation in Tennessee. We were interested in whether there were species and locational differences in radiocesium and metal concentrations and whether concentrations were sufficiently high to pose a potential health risk to humans or other receptors. Striped bass (Morone saxatilis) were significantly larger than white bass (M. chrysops), and crappie (Pomoxis spp.) were the smallest fish. Lead was significantly lower in striped bass, mercury was significantly higher in striped bass, and selenium was significantly higher in white bass compared to the other species. There were no other species differences in contaminants. White bass, the only species that was sufficiently abundant for a comparison, had significantly higher concentrations of cadmium, lead, and selenium in fillets from the Clinch River and significantly higher concentrations of mercury in fillets from Poplar Creek. The low concentrations of most contaminants in fish from the Clinch River do not appear to present a risk to humans or other consumers, although mercury concentrations in striped bass ranged as high as 0.79 ppm, well above the 0.5-ppm action level for human consumption of some US states.     

Mercury and Selenium in a Top-Predator Fish, <Emphasis Type="Italic">Trichiurus lepturus</Emphasis> (Linnaeus, 1758), from the Tropical Brazilian Coast,Rio de Janeiro

Muscular mercury and selenium were assessed in a voracious fish from three Brazilian coastal areas with different environmental conditions. Mercury was higher in specimens from Ilha Grande Bay (0.35 ± 0.17 μg g⁻¹) than in cutlassfish from Guanabara Bay (0.30 ± 0.15 μg g⁻¹) and Buzios coast (0.13 ± 0.08 μg g⁻¹), respectively. No difference was found regarding selenium among these areas. Mercury was positively correlated with fish length and size intervals (sub-adult, small and large adult), suggesting that larger and older fish bioaccumulated more mercury. A large excess of molar selenium in relation to mercury was observed.     

Mercury content of commercially important fish of the Seychelles,and hair mercury levels of a selected part of the population

Mercury and methyl mercury concentrations were determined in the muscle of 12 of the most important commercial fish species found in Seychelles waters. The concentration of mercury in a few of the larger specimens of Kingfish (Acanthocybium solandri), Becune (Sphyraena forsteri), Carangue balo (Caranx gymnostethus), and Bonito (Euthynnus affinis) exceeded the provisional maximum permissible level of 1.0 mg/kg of total mercury established by the Food and Drug Administration (1979) in the United States. More than half of the Dogtooth tuna (Gymnosarda unicolor) examined exceeded this level with two fish having levels of 3.3 and 4.4 ppm. The hair mercury levels of fishermen and mothers and their newborn babies have been examined since the Seychelles population has one of the highest fish consumption figures in the world (80–100 kg per person per annum), much of it being predatory species.     

Mercury in canned tuna: white versus light and temporal variation

There are abundant data and advisories for mercury levels in wild fish, but far fewer for commercial fish that compose a large majority of the fish most people eat. Until recently, relatively little attention has been devoted to examining mercury in canned tuna, despite its great importance in human diets. There is substantial media coverage of the benefits and risk from fish consumption, but few peer-reviewed data on canned tuna, the most commonly consumed fish in the United States. In this paper, we examine the levels of total mercury in canned tuna obtained from a New Jersey grocery store from 1998 to 2003, looking for temporal consistency within this data set and particularly for comparison with the Food and Drug Administration's 1991 study. We analyzed 168 cans individually for total mercury. All values are reported as parts per million (= microg/g) on a wet weight basis. In a subset of samples analyzed for total and inorganic mercury, the inorganic mercury was below detection levels; hence at least 89% of the mercury can be considered methylmercury. We found that white-style tuna had significantly more total mercury (mean 0.407 ppm) than light-style tuna (mean 0.118 ppm), presumably reflecting that "white" tuna is albacore, a species relatively larger than the skipjack tuna, which is commonly available as "light" or "chunk light." The maximum mercury in a can was 0.997 ppm, but 25% of white tuna samples exceeded 0.5 ppm. Data suggest a slight increase in levels since 1991, and mercury levels were significantly higher in 2001 than in other years. The mean level of mercury in white tuna (mean 0.407 ppm) was significantly higher than the mean value of 0.17 ppm currently used by the U.S. Food and Drug Administration (FDA) in its risk assessment and public information. There were no significant differences in mercury levels in tuna packed in oil compared to water. Draining contents had no effect on mercury levels, and the fluid, both oil and water, contained little mercury. These data indicate that people who eat canned tuna frequently can choose light tuna and reduce their mercury intake. Canned mackerel had much lower levels of mercury than tuna. Since cans of white tuna frequently exceed the FDA's original action level of 0.5 ppm, it would be prudent to continue some systematic monitoring of the nation's canned fish supply, particularly as the targets of commercial fisheries inevitably change as certain stocks become depleted.     

Concentrations of metals and trace elements in blood of spectacled and king eiders in northern Alaska, USA

In 1996, we measured concentrations of arsenic, barium, cadmium, lead, mercury, and selenium in blood of adult king (Somateria spectabilis) and spectacled (Somateria fischeri) eiders and duckling spectacled eiders from northern Alaska, USA. Concentrations of selenium exceeded background levels in all adults sampled and 9 of 12 ducklings. Mercury was detected in all adult spectacled eiders and 5 of 12 ducklings. Lead concentrations were above the clinical toxicity threshold in one duckling (0.64 ppm) and two adult female spectacled eiders (0.54 and 4.30 ppm). Concentrations of cadmium and mercury varied between species; barium, cadmium, mercury, and selenium varied between sexes. In female spectacled eiders, mercury concentrations increased during the breeding season and barium and selenium levels decreased through the breeding season. Selenium declined at 2.3 +/- 0.9% per day and levels were lower in spectacled eiders arriving to the breeding grounds in northern Alaska than in western Alaska. The variation in selenium levels between breeding areas may be explained by differences in timing and routes of spring migration. Most trace elements for which we tested were not at levels currently considered toxic to marine birds. However, the presence of mercury and elevated lead in ducklings and adult female spectacled eiders suggests these metals are available on the breeding grounds.     

Mercury residues in tissues of dead and surviving birds fed methylmercury.

Concentrations of mercury in passerine birds fed diets containing 40 ppm methylmercury were similar in tissues of birds that died from mercury poisoning and in those that were sacrificed after half the group had died. Residues were higher in tissues of birds that died, but the differences were not statistically significant. Residue levels were highest in livers, followed by kidneys and brains. Levels of mercury were similar in breast muscle, carcass, and whole body. Mercury levels were highest in redwinged blackbirds, lowest in grackles, and intermediate in starlings and cowbirds. Mercury concentrations exceeded 20 ppm in all tissues of all species and were similar to levels reported in wild birds known to have died of mercury poisoning.     

Mercury residues in tissues of dead and surviving birds fed methylmercury

Summary Concentrations of mercury in passerine birds fed diets containing 40 ppm methylmercury were similar in tissues of birds that died from mercury poisoning and in those that were sacrificed after half the group had died. Residues were higher in tissues of birds that died, but the differences were not statistically significant. Residue levels were highest in livers, followed by kidneys and brains. Levels of mercury were similar in breast muscle, carcass, and whole body. Mercury levels were highest in redwinged blackbirds, lowest in grackles, and intermediate in starlings and cowbirds. Mercury concentrations exceeded 20 ppm in all tissues of all species and were similar to levels reported in wild birds known to have died of mercury poisoning.     

Changes in mercury levels in harbor porpoises from the Bay of Fundy,Canada, and adjacent waters during 1969–1977

Mercury levels were studied in a sample of 146 harbor porpoises taken in the Bay of Fundy, Canada, and adjacent waters during 1969–77. Mean concentrations of total mercury recorded in 5-year old males (exemplifying sexually mature adults) were 1.12 ppm in axial muscle, 0.38 in cerebrum, 0.31 in cerebellum, 2.00 in kidney, and 15.7 in liver. Respective means in tissues of 5-year old females were 1.46, 0.42, 0.21 2.77 and 16.2 ppm. There was a clear correlation of increase in total Hg with age in the tissues examined. Except in the liver, mercury levels were less well correlated with weight and body length than with age. Hg levels were not significantly correlated (p > 0.05) with weight and lengthwithin age classes, except marginally in the case of liver (P 0.10). Hg in muscle was virtually all in the methylated form, but in liver only about 17% was methylated. The proportions in other tissues were intermediate (kidney about 41%, mam-mary gland about 46%, brain about 8 to 52%). Levels in liver were thought to be those giving the best indication of changes in background levels of mercury in the food chain. Significant changes in Hg tissue levels appear to have occurred during the 9-year study period. Liver Hg levels in both sexes decreased from 1970 to 1971, remained low for 3 years, increased again in 1974, and continued to do so in the years following. Data are presented suggesting that this also occurred in other tissues. Since there is no evidence of a change in diet in this period, we speculate that the decline in Hg levels could be correlated with a dominance of relatively mercury-poor Gulf Stream water in the Bay of Fundy approaches in 1971–73, as opposed to the usual dominance by waters of the Nova Scotia current.