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.

Metals and metallothionein in the liver of raccoons: utility for environmental assessment and monitoring.

The relationship between metallothionein levels and concentrations of several metals and radionuclides was examined in liver tissues of raccoons (Procyon lotor, n = 47) from the Department of Energy's Savannah River Site in South Carolina to determine the applicability of metallothioneins as an initial screening device for exposure assessment in free-living mammals and environmental monitoring. Using a fluorescent marker and a cell sorter to measure metallothionein, a significant positive correlation was found across animals between levels of metallothioneins and concentrations of selenium (Pearson's r = .30), mercury (Pearson's r = .3 1), and copper (Pearson's r = .30) in liver tissue. Arsenic, cobalt, silver, thallium, and tin were below detection limits in most or all liver samples. Other metals, including cadmium, chromium, radiocesium (137-Cs), copper, lead, manganese, strontium, and vanadium, showed only weak and nonsignificant correlations with metallothionein. Concentrations of mercury were correlated with concentrations of selenium (Pearson's r = .73), manganese (Pearson's r = .56), and strontium (Pearson's r = .57). In an a posteriori test, there was a still unexplained positive correlation between mercury (Pearson r = .56), selenium (Pearson r = .54), and radiocesium (Pearson's r = .38) concentrations and background cellular autofluorescence, and a negative correlation of strontium with the latter (Kendall tau = -.38). Background cellular autofluorescence may represent a generalized cellular stress response, or a yet unidentified biomarker. To better understand which metals contribute to the induction of metallothionein, principle component analysis (PCA) was performed. The first three principle components explained 78% of the variance, with highest loadings being from mercury and radiocesium. Metallothionein levels did not correlate well with the principal components from the metals and radiocesium, while autofluorescent background levels tended to correlate better.

Metals and metalloids in tissues of American alligators in three Florida lakes.

Concentrations of metals and selenium were examined in tissues of American alligators (Alligator mississippiensis) from three lakes in central Florida, in one of which alligators have exhibited reproductive or developmental defects. Our overall objective was to determine whether the levels of metals were sufficiently high to confound the association between chlorinated hydrocarbons, which are elevated in eggs and juvenile plasma, and reproductive impairment. The concentrations of all metals were relatively low compared to those reported for alligators from elsewhere in Florida and the southeastern United States, suggesting that reproductive impairment is not due to metals and that metals pose no health risk to the alligators. We also wanted to determine whether skin, biopsied tail muscle, or tail tip tissue, all easily collected from live alligators, could be used as surrogate measures of internal tissue loads. Concentrations of arsenic, cadmium, chromium, lead, manganese, mercury, and selenium in liver were highly correlated with at least one of the three biopsied tissues. Only tin showed no significant positive correlation. No single tissue gave a high prediction of liver levels for all metals, although skin gave the highest correlation for mercury, and tail muscle gave the best overall correlation for lead and cadmium.

A risk assessment for consumers of mourning doves.

Recreational and subsistence hunters and anglers consume a wide range of species, including birds, mammals, fish and shellfish, some of which represent significant exposure pathways for environmental toxic agents. This study focuses on the Department of Energy's (DOE's) Savannah River Site (SRS), a former nuclear weapons production facility in South Carolina. The potential risk of contaminant intake from consuming mourning doves (Zenaida macroura), the most popular United States game bird, was examined under various risk scenarios. For all of these scenarios we used the mean tissue concentration of six metals (lead, mercury, cadmium, selenium, chromium, manganese) and radiocesium, in doves collected on and near SRS. We also estimated risk to a child consuming doves that had the maximum contaminant level. We used the cancer slope factor for radiocesium, the Environmental Protection Agencies Uptake/Biokinetic model for lead, and published reference doses for the other metals. As a result of our risk assessments we recommend management of water levels in contaminated reservoirs so that lake bed sediments are not exposed to use by gamebirds and other terrestrial wildlife. Particularly, measures should be taken to insure that the hunting public does not have access to such a site. Our data also indicate that doves on popular hunting areas are exposed to excess lead, suggesting that banning lead shot for doves, as has been done for waterfowl, is desirable.

Temporal trends in metal levels in eggs of the endangered roseate tern (Sterna dougallii) in New York.

Female birds sequester certain organic and inorganic compounds in their eggs which have been widely used as a bioindicator for examining the body burdens of contaminants and therefore the temporal and spatial trends of the contaminants in the environment. The same analyses can also reflect the status or vulnerability of the indicator species. Extensive bridge de-leading activities in the New York Bight (Cape May to Montauk) in the early 1990s coincided with a long-term study of the endangered roseate tern (Sterna dougallii) on Long Island, New York, affording the opportunity to test the utility of such fish-eating species as bioindicators of lead contamination, as well as the potential impact on the bird population itself. In this paper we test the null hypothesis that there were no temporal trends between 1989 and 1994 in metal levels in eggs of roseate terns nesting at Cedar Beach, Long Island, where the birds have been declining since the late 1980s. We report levels and trends for cadmium, chromium, manganese, mercury, and selenium as well as lead in abandoned eggs collected each year. There were significant interyear differences for all metals, with 1990 to 1992 generally having higher levels than 1989 and 1994. The yearly differences were particularly prominent for lead, where the 10-fold increase may have been partially due to the increased removal of leaded paint from bridges in the early 1990s, leading to increased lead in the aquatic environment. Cadmium and chromium are also released during de-leading. The causes for the higher levels in the other metals in the early 1990s are unclear. Metal levels in roseate tern eggs are several times higher than the median reported for most birds, and the possible impact on the population requires study.

Spatial patterns in a bioindicator: heavy metal and selenium concentration in eggs of herring gulls (Larus argentatus) in the New York Bight.

Concentrations of selenium and five heavy metals (lead, cadmium, mercury, chromium, and manganese) in the eggs of herring gulls (Larus argentatus) were studied at six breeding colonies in the New York Bight to detect locational differences and to explore their use as a bioindicator of point source or nonpoint source pollution. The herring gull is widespread in North America, Europe, and Asia, and has urban-adapted counterparts in the southern hemisphere as well. We anticipated that the chromium contamination at Jersey City and high levels of manganese in industrial releases to the Passaic River would be reflected in the nearest colony (Shooter's Island), and that lead contamination from bridge remediation would be apparent in the Jamaica Bay colonies. There were significant locational differences in all metal levels, although the patterns were not the same for all metals. Shooter's Island in Newark Bay ranked first or second for five of the elements, but inexplicably had the lowest mercury level. Cadmium levels were highest at Canarsie Pol in Jamaica Bay, but mercury levels were highest at the relatively isolated Lavallette colony in northern Barnegat Bay. Chromium and manganese levels were indeed highest at Shooter's Island, but the lead levels in Jamaica Bay were only intermediate. We predicted that the essential trace elements, manganese, chromium, and selenium, which are known to be present at relatively high concentrations in various animal species, would have relatively low coefficients of variation, reflecting homeostatic mechanisms. This was confirmed. In conclusion, herring gull egg contents can be used to monitor metal concentrations at nearby colonies to indicate areas of concern for particular metals. They may confirm suspected associations or identify hitherto unsuspected problems.

Heavy metal and selenium concentrations in feathers of egrets from Bali and Sulawesi, Indonesia.

Herons and egrets are ideal organisms to use asindicators of heavy metal exposure in an ecosystem because different speciesfeed at different levels of the food chain and live in both coastal andinland habitats. This paper reports on the concentration of heavy metals andselenium in the feathers of cattle egrets Bubulcus ibis that wereexamined from nesting and roosting sites in Bali and Sulawesi, Indonesia, andin feathers of little egrets Egretta garzetta and intermediate egretsE. intermedia from the same colony in Bali. Mercury and manganeseconcentrations were significantly higher in cattle egrets from Bali comparedto Sulawesi, but otherwise there were no significant differences. There weresignificant differences in lead, cadmium and mercury among the three egretspecies nesting on Bali: 1) the cadmium and mercury concentrations related tosize and trophic level (insectivorous cattle egrets had the lowestconcentrations, fish-eating intermediate egrets had the highestconcentrations), and 2) cattle egrets had significantly lower concentrationsof lead than the other two species. For cattle egrets, secondary flightfeathers had significantly higher levels of cadmium and mercury, and lowerlevels of manganese, than mixed breast and tertiary feathers, reflectingtemporal differences in exposure.

Metal levels in mourning doves from South Carolina: potential hazards to doves and hunters.

Most game birds are found in lower trophic levels, but since such birds are harvested and consumed by humans, there is a particular need to assess their contaminant levels. In this paper, we report concentrations of mercury, lead, cadmium, selenium, manganese, and chromium in the breast feathers, liver, and muscle of mourning doves (Zenaida macroura) collected at a partially drawn-down, contaminated reactor-cooling reservoir (Par Pond) on the Department of Energy's Savannah River Site in South Carolina and at nearby agricultural fields managed as dove hunting areas. We test the hypothesis that the levels in doves are not harmful to either dove populations or humans. We also tested the simultaneous effects of collection location, year (1992, 1993), and dove age-class (hatch-year vs after hatch-year) on heavy metal and selenium levels. For all three tissues, mercury levels were nondetectable at all locations. Lead was highest in tissues from agricultural fields with prior histories of dove hunting activities. Doves at those fields were likely ingesting lead shot to a greater degree than at the recently drawn-down reservoir which was closed to public access and hunting. For other metals, Par Pond doves had equally high or higher tissue levels. For all metals, levels in doves from South Carolina were generally within the lower range of those reported in the literature, suggesting that these metals were likely to pose no health problems to these doves. Except for lead and selenium, metal levels in dove muscle that we observed were well below reference metal doses established for human intake. Lead and selenium, at the levels described here, would only be a problem if a child (not an adult) ate 120 g of dove meat every day of the year. Thus, we conclude that meat from these doves, if consumed by hunters, would not pose a risk.

Heavy metal and selenium levels in Franklin's Gull (Larus pipixcan) parents and their eggs.

Lead, cadmium, mercury, chromium, selenium, and manganese concentrations were measured in the breast feathers of 25 pairs of Franklin's Gull (Larus Pipixcan) and in their eggs from a breeding colony at Agassiz National Wildlife Refuge in Northwestern Minnesota. Metal concentrations in eggs represent metals sequestered in the egg by females at the time of egg formation; while metal concentrations in parents represent concentrations of metals in blood supply at the time of feather formation. There were no significant sexual differences in metal concentrations in feathers, assuming the male to be larger of each pair, but there were significant differences between the concentrations of metals in parents and their eggs. Eggs had significantly higher concentrations of selenium and chromium, but significantly lower concentrations of all other metals than the feathers of their parents. There were few significant correlations among metal concentrations within the egg or within the feather of females, but there were correlations for the feathers of males. Lead and cadmium in feathers were positively correlated for both males and females. Chromium concentrations in eggs were generally higher than reported in the literature. The concentrations in eggs and the feathers of females were positively correlated for mercury, and negatively correlated for chromium and manganese.

Heavy metal and selenium concentrations in eggs of herring gulls (Larus argentatus): temporal differences from 1989 to 1994.

Concentrations of five metals and selenium in the eggs of herring gulls (Larus argentatus) were examined at a breeding colony on western Long Island, New York from 1989 to 1994. There were significant yearly differences in lead, cadmium, mercury, selenium, chromium, and manganese. Chromium and cadmium were significantly higher in 1993 compared to the other years. Lead levels were highest in 1989, and were uniformly lower in the succeeding four years. Manganese showed no clear pattern. Selenium concentrations decreased from 1991 through 1994, whereas mercury increased from 1992 through 1994. Generally, concentrations of cadmium were similar to those reported for avian eggs from elsewhere; mercury and lead were within the range, but were at the high end; and chromium concentrations were higher than elsewhere. For all years combined, there was a positive correlation between lead and cadmium concentrations and between chromium and manganese, and a negative correlation between lead and mercury concentrations. In conclusion, egg contents can be used to monitor heavy metal concentrations, but consecutive years must be examined because concentrations can vary significantly among years. Ideally, data are needed for more than three years before trends, or lack thereof, can be determined.

Heavy metal and selenium levels in feathers of known-aged common terns (Sterna hirundo).

Concentrations of five metals and selenium in the breast feathers of known-aged common terns (Sterna hirundo) were examined at a breeding colony in Massachusetts, USA. Concentrations of selenium, chromium, and manganese increased significantly with age among adults (2-21 years old), whereas concentrations of mercury, cadmium, and lead did not. Concentrations of cadmium, selenium and manganese were lower in fledglings (20-23 days old) than in adults. Concentrations of mercury, however, were higher in fledglings than in adults, and concentrations of chromium were higher in fledglings than in young adults, probably reflecting higher exposure to these metals in the breeding area than in the winter quarters where the adults' feathers were grown. At least for mercury, excretion of metals into the feathers at each molt was an efficient protective mechanism, preventing continued accumulation in the body with increasing age.

Heavy metal and selenium levels in feathers of young egrets and herons from Hong Kong and Szechuan, China.

Several species of herons and egrets frequently nest in colonies in areas where humans also concentrate. Since the birds feed on intermediate-sized fish that themselves concentrate pollutants, they can be used not only to assess the levels of contaminants in avian tissues but as indicators of contaminants in the environment. The concentration of heavy metals and selenium in the breast feathers of fledgling black-crowned night herons Nycticorax nycticorax and Chinese pond herons Ardeola bacchus from the Tu Jing Yan heronry outside Chengdu, Szechuan Province in China; and from fledgling black-crowned night heron, little egret Egretta garzetta, great egret Egretta alba and cattle egret Bubulcus ibis from the Mai Po heronry in Hong Kong, were determined. Breast feathers were also collected from adult great egrets in Hong Kong. Adult great egrets had significantly higher levels of all heavy metals than did young great egrets. There were no significant interspecific differences in metal levels among the young at Szechuan China, except for chromium (pond herons had higher levels). There were significant differences among the young nesting at Hong Kong for all metals examined. Great egrets had lower, and night herons had higher, levels of lead than the other young. Night herons also had the highest levels of cadmium, manganese, and selenium compared to the other young. Great egret chicks had the lowest mercury levels, while little egret had the highest levels. Lead levels for all the birds in both Hong Kong and Szechuan were among the highest in the world, and this was attributed to the continued use of leaded gasoline.

Heavy metal and selenium levels in endangered wood storks Mycteria americana from nesting colonies in Florida and Costa Rica.

Colonially-nesting birds often nest in coastal areas, along rivers, or near other bodies of water that also are potentially polluted from industrial, agricultural or urban development. The levels of heavy metals and selenium were examined in the feathers of young wood storks Mycteria americana nesting in Northeastern Florida and from adult and young storks nesting on the Tempisque River on the west coast of Costa Rica. There were no significant yearly differences among the chicks from Costa Rica. Concentration of mercury, cadmium, and lead were significantly higher in the chicks from Florida compared to those from Costa Rica. Adult wood storks at Costa Rica had significantly higher levels of lead, cadmium, selenium, and manganese than young from the same colony.

Heavy metal and selenium concentrations in black skimmers (Rynchops niger): gender differences.

Most studies of heavy metals and selenium have not examined or have failed to find differences in concentrations in the tissues of birds as a function of size or sex. Heavy metal and selenium concentrations were analyzed in breast feathers of adult black skimmers Rynchops niger, a species with marked sexual size dimorphism in which males average 35% heavier than females. Females had significantly higher concentrations of lead and cadmium than males, but there were no gender differences in mercury, selenium, chromium, manganese, and copper despite the marked sexual dimorphism in body size. There were no significant correlations of bird weight or wing length and metal and selenium concentrations, and few correlations among metal and selenium concentrations in the feathers.

Heavy metal and selenium levels in young cattle egrets from nesting colonies in the northeastern United States, Puerto Rico, and Egypt.

Colonially-nesting species of herons and egrets breed mainly in coastal areas, along rivers or near other large bodies of water. Such areas are also preferred for human development, exposing nesting birds to various pollutants. From 1989-1991, the concentrations of heavy metals and selenium were studied in the feathers of fledgling cattle egrets Bubulcus ibis, a terrestrially-feeding insectivore, from New York and Delaware in the northeastern United States, from Puerto Rico, and from Egypt. There were geographic differences in the concentrations of lead, mercury, cadmium, manganese, selenium, and chromium in the feathers of these egrets. Lead levels were 41 times higher in the feathers of cattle egrets from Cairo compared to the other sites. This difference was attributed to the continuing use of leaded gasoline and the dense automobile traffic in Cairo. However, other differences remain unexplained. Similarly, levels of chromium and manganese were also higher in Cairo than at any other sites. Cadmium levels were similar at all places except for higher levels in eastern Puerto Rico. Mercury concentrations were twelve times higher in the feathers of cattle egrets at Aswan compared to Cairo. In Puerto Rico, we also compared levels in adult cattle egrets with young and found higher concentrations of mercury and manganese, but lower concentrations of selenium in the adults. Using feathers from young cattle egrets is a potentially sensitive tool for biomonitoring for metals, especially lead, since they reflect the local area surrounding the breeding colony.

Metal levels in regrown feathers: assessment of contamination on the wintering and breeding grounds in the same individuals.

Birds are useful indicators of environmental contamination because they are relatively large, conspicuous, top predators in food chains. However, concentrations of contaminants in a bird's tissues reflect the bird's exposure over wide temporal and spatial scales. Birds are most useful as monitors of exposure when these scales are known. In this paper we report concentrations of lead, cadmium, mercury, and selenium in breast feathers of common terns (Sterna hirundo) and roseate terns (S. dougallii) trapped during incubation at breeding colonies in New York and Massachusetts. Terns arrived on the breeding grounds with breast feathers grown on their wintering grounds, and regrew certain feathers that were plucked for analysis. The regrown feathers were themselves plucked, and both sets of feathers were analyzed. For roseate terns at Cedar Beach and common terns at both sites there was a significant increase in mercury levels in the feathers grown on the breeding grounds compared to those grown on the wintering ground. The differences in mercury were far greater at Bird Island than at Cedar Beach. Selenium levels at Cedar Beach were higher for the regrown feathers than the initial feathers for roseate terns, but not for common terns. Lead and cadmium levels were not significantly different at either site for either species. These results suggest that terns are exposed to significantly higher levels of mercury in the northeastern United States than they are in the wintering grounds in South America.

Exposure assessment for heavy metal ingestion from a sport fish in Puerto Rico: estimating risk for local fishermen.

Sport or subsistence fishermen sometimes underestimate the risks from eating local fish and distrust authorities regarding potential hazards from fish. We report on lead, cadmium, selenium, and mercury levels in snook, locally called robalo (Centropomus spp.), consumed by local fishermen in Puerto Rico, who ate up to 23 fish/wk. Median levels (in ppb, dry weight) for muscle, adipose, and liver ranged from 683 to 780 for lead, 37 to 600 for cadmium, 50 to 146 for mercury, and 361 to 3986 for selenium. Lead levels were similar in all tissues, and selenium and cadmium levels were highest in the liver. Mercury was higher in muscle than in liver. Computing exposure via ingestion for the average fisherman indicated that if one were to consume robalo throughout the year one would be exposed in excess of the EPA Reference Dose (RfD) for mercury. Using a widely accepted maximum consumption of 200 g/d for fishermen yielded hazard indices (daily consumption/RfD) below 1 for all four metals, with a value approaching 1 for mercury in adults, and over 1 for 16-kg children. The possibility that in certain localities and cultures sport or subsistence fishermen may consume fish at levels substantially above 200 g/d should be investigated in performing risk assessments, particularly outside the continental United States.

Role of the physician in environmental medicine.

This article describes the role of the medical history and of laboratory findings in diagnosing diseases caused by environmental chemicals. An understanding of routes of exposure is crucial in appropriate diagnosis and in preventing further harm. A listing of potential sources of information is also included.