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USGS1990

Selenium in wetlands and waterfowl foods at Kesterson Reservoir, California, 1984

Kesterson Reservoir (Kesterson) received subsurface agricultural drainwater containing high levels of salts and selenium from farmland in the San Joaquin Valley of California. The accumulation of selenium in wetlands and waterfowl foods at Kesterson was investigated during May, August, and December of 1984. High concentrations of selenium were found in water, sediments, terrestrial and aquatic vegetation, and aquatic insects. Mean selenium concentrations in aquatic plants and insects ranged from 1.5 to 170 (μg/g dry weight and were about 11 to 290 times those found at a nearby reference site. Concentrations in some waterfowl food plants and insects at Kesterson were up to 64 times those reported to be a health hazard to birds. Selenium concentrations were more seasonally variable in aquatic plants than in aquatic insects. Few differences in selenium accumulation were found among ponds. Deposition of selenium in plant parts was not uniform; rhizomes contained higher concentrations than seeds and leaves were intermediate. Most biota bioaccumulated maximum selenium concentrations that were 1,000 to nearly 5,000 times the concentration in the water.

California↗

USGS2024

Nitrate exposure from drinking water and dietary sources among Iowa farmers using private wells

Nitrate levels are increasing in water resources across the United States and nitrate ingestion from drinking water has been associated with adverse health risks in epidemiologic studies at levels below the maximum contaminant level (MCL). In contrast, dietary nitrate ingestion has generally been associated with beneficial health effects. Few studies have characterized the contribution of both drinking water and dietary sources to nitrate exposure. The Agricultural Health Study is a prospective cohort of farmers and their spouses in Iowa and North Carolina. In 2018–2019, we assessed nitrate exposure for 47 farmers who used private wells for their drinking water and lived in 8 eastern Iowa counties where groundwater is vulnerable to nitrate contamination. Drinking water and dietary intakes were estimated using the National Cancer Institute Automated Self-Administered 24-Hour Dietary Assessment tool. We measured nitrate in tap water and estimated dietary nitrate from a database of food concentrations. Urinary nitrate was measured in first morning void samples in 2018–19 and in archived samples from 2010 to 2017 (minimum time between samples: 2 years; median: 7 years). We used linear regression to evaluate urinary nitrate concentrations in relation to total nitrate, and drinking water and dietary intakes separately. Overall, dietary nitrate contributed the most to total intake (median: 97 %; interquartile range [IQR]: 57–99 %). Among 15 participants (32 %) whose drinking water nitrate concentrations were at/above the U.S. Environmental Protection Agency MCL (10 mg/L NO 3 -N), median intake from water was 44 % (IQR: 26–72 %). Total nitrate intake was the strongest predictor of urinary nitrate concentrations (R 2 = 0.53). Drinking water explained a similar proportion of the variation in nitrate excretion (R 2 = 0.52) as diet (R 2 = 0.47). Our findings demonstrate the importance of both dietary and drinking water intakes as determinants of nitrate excretion.

Iowa↗

USGS2011

Source-water susceptibility assessment in Texas—Approach and methodology

Public water systems provide potable water for the public's use. The Safe Drinking Water Act amendments of 1996 required States to prepare a source-water susceptibility assessment (SWSA) for each public water system (PWS). States were required to determine the source of water for each PWS, the origin of any contaminant of concern (COC) monitored or to be monitored, and the susceptibility of the public water system to COC exposure, to protect public water supplies from contamination. In Texas, the Texas Commission on Environmental Quality (TCEQ) was responsible for preparing SWSAs for the more than 6,000 public water systems, representing more than 18,000 surface-water intakes or groundwater wells. The U.S. Geological Survey (USGS) worked in cooperation with TCEQ to develop the Source Water Assessment Program (SWAP) approach and methodology. Texas' SWAP meets all requirements of the Safe Drinking Water Act and ultimately provides the TCEQ with a comprehensive tool for protection of public water systems from contamination by up to 247 individual COCs. TCEQ staff identified both the list of contaminants to be assessed and contaminant threshold values (THR) to be applied. COCs were chosen because they were regulated contaminants, were expected to become regulated contaminants in the near future, or were unregulated but thought to represent long-term health concerns. THRs were based on maximum contaminant levels from U.S. Environmental Protection Agency (EPA)'s National Primary Drinking Water Regulations. For reporting purposes, COCs were grouped into seven contaminant groups: inorganic compounds, volatile organic compounds, synthetic organic compounds, radiochemicals, disinfection byproducts, microbial organisms, and physical properties. Expanding on the TCEQ's definition of susceptibility, subject-matter expert working groups formulated the SWSA approach based on assumptions that natural processes and human activities contribute COCs in quantities that vary in space and time; that increased levels of COC-producing activities within a source area may increase susceptibility to COC exposure; and that natural and manmade conditions within the source area may increase, decrease, or have no observable effect on susceptibility to COC exposure. Incorporating these assumptions, eight SWSA components were defined: identification, delineation, intrinsic susceptibility, point- and nonpoint-source susceptibility, contaminant occurrence, area-of-primary influence, and summary components. Spatial datasets were prepared to represent approximately 170 attributes or indicators used in the assessment process. These primarily were static datasets (approximately 46 gigabytes (GB) in size). Selected datasets such as PWS surface-water-intake or groundwater-well locations and potential source of contamination (PSOC) locations were updated weekly. Completed assessments were archived, and that database is approximately 10 GB in size. SWSA components currently (2011) are implemented in the Source Water Assessment Program-Decision Support System (SWAP-DSS) computer software, specifically developed to produce SWSAs. On execution of the software, the components work to identify the source of water for the well or intake, assess intrinsic susceptibility of the water- supply source, assess susceptibility to contamination with COCs from point and nonpoint sources, identify any previous detections of COCs from existing water-quality databases, and summarize the results. Each water-supply source's susceptibility is assessed, source results are weighted by source capacity (when a PWS has multiple sources), and results are combined into a single SWSA for the PWS.'SWSA reports are generated using the software; during 2003, more than 6,000 reports were provided to PWS operators and the public. The ability to produce detailed or summary reports for individual sources, and detailed or summary reports for a PWS, by COC or COC group was a unique capability of SWAP-DSS. In 2004, the TCEQ began a rotating schedule for SWSA wherein one-third of PWSs statewide would be assessed annually, or sooner if protection-program activities deemed it necessary, and that schedule has continued to the present. Cooperative efforts by the TCEQ and the USGS for SWAP software maintenance and enhancements ended in 2011 with the TCEQ assuming responsibility for all tasks.

Texas↗

USGS1998

The environmental occurrence of herbicides: The importance of degradates in ground water

Numerous studies are being conducted to investigate the occurrence, fate, and effects on human health and the environment from the extensive worldwide use of herbicides to control weeds. Few studies, however, are considering the degradates of these herbicides in their investigations. Our study of herbicides in aquifers across Iowa found herbicide degradates to be prevalent in ground water, being detected in about 75% of the wells sampled. With the exception of atrazine, the frequencies of detection in ground water for a given herbicide increased multifold when its degradates were considered. Furthermore, a majority of the measured concentration for a given herbicide was in the form of its degradates—even for a relatively persistent compound such as atrazine. For this study, degradates comprised from 60 to over 99% of a herbicide's measured concentration. Because herbicide degradates can have similar acute and chronic toxicity as their parent compounds, these compounds have environmental significance as well as providing a more complete understanding of the fate and transport of a given herbicide. Thus, it is essential that degradates are included in any type of herbicide investigation.

Iowa↗

USGS2001

Lead poisoning of waterfowl by contaminated sediment in the Coeur D'Alene River

The Coeur d'Alene River basin in Idaho has been contaminated by mine tailings that have impaired the health of wildlife since the early 1900s. In other parts of the world, virtually all lead poisoning of waterfowl is caused by the ingestion of manmade lead artifacts, primarily spent lead shotshell pellets or, occasionally, fishing sinkers. However, in the Coeur d'Alene River basin in Idaho, nonartifactual lead poisoning was the ultimate cause of death of most of 219 (77%) of 285 waterfowl carcasses that had been found sick or dead from 1992 through 1997. The majority of these 219 waterfowl (172 tundra swans [Cygnus columbianus], 33 Canada geese [Branta canadensis], and 14 other species) were poisoned by ingesting river sediment that was contaminated with lead. The next most common cause of death (20 instances, 7%) was lead poisoning accompanied by ingested shotshell pellets. The remaining 46 waterfowl succumbed to trauma, infectious diseases (aspergillosis, avian cholera, tuberculosis), or miscellaneous problems, or the cause of death was not determined.

Idaho↗

USGS2004

Mercury hazards from gold mining to humans, plants, and animals

Mercury contamination of the environment from historical and ongoing mining practices that rely on mercury amalgamation for gold extraction is widespread. Contamination was particularly severe in the immediate vicinity of gold extraction and refining operations; however, mercury, especially in the form of water-soluble methylmercury, may be transported to pristine areas by rainwater, water currents, deforestation, volatilization, and other vectors. Examples of gold mining-associated mercury pollution are shown for Canada, the United States, Africa, China, the Philippines, Siberia, and South America. In parts of Brazil, for example, mercury concentrations in all abiotic materials, plants, and animals--including endangered species of mammals and reptiles, collected near ongoing mercury-amalgamation gold mining sites were far in excess of allowable mercury levels promulgated by regulatory agencies for the protection of human health and natural resources. Although health authorities in Brazil are unable to detect conclusive evidence of human mercury intoxication, the potential exists in the absence of mitigation for epidemic mercury poisoning of the mining population and environs. In the United States, environmental mercury contamination is mostly from historical gold mining practices, and portions of Nevada remain sufficiently mercury-contaminated to pose a hazard to reproduction of carnivorous fishes and fish-eating birds. Concentrations of total mercury lethal to sensitive representative natural resources range from 0.1 to 2.0 microg/L of medium for aquatic organisms; from 2,200 to 31,000 microg/kg BW (acute oral) and from 4,000 to 40,000 microg/kg (dietary) for birds; and from 100 to 500 microg/kg BW (daily dose) and from 1,000 to 5,000 microg/kg diet for mammals. Significant adverse sublethal effects were observed among selected aquatic species at water concentrations of 0.03-0.1 microg Hg/L. For some birds, adverse effects, mainly on reproduction, have been associated with total mercury concentrations (microg/kg FW) of 5,000 in feathers, 900 in eggs, and 50-100 in diet, and with daily intakes of 640 microg/kg BW. Sensitive nonhuman mammals showed significant adverse effects of mercury when daily intakes were 250 microg/kg BW, when dietary levels were 1,100 microg/kg, or when tissue concentrations exceeded 1,100 microg/kg. Proposed mercury criteria for protection of aquatic life range from 0.012 microg/L for freshwater life to 0.025 microg/L for marine life; for birds, less than 100 microg/kg diet FW; and for small mammals, less than 1,100 microg/kg FW diet. All these proposed criteria provide, at best, minimal protection.

Archives of Environmental Contamination and Toxico↗

USGS2007

Concentrations of metals in water, sediment, biofilm, benthic macroinvertebrates, and fish in the Boulder River watershed, Montana, and the role of colloids in metal uptake

To characterize the partitioning of metals in a stream ecosystem, concentrations of trace metals including As, Cd, Cu, Pb, and Zn were measured in water, colloids, sediment, biofilm (also referred to as aufwuchs ), macroinvertebrates, and fish collected from the Boulder River watershed, Montana. Median concentrations of Cd, Cu, and Zn in water throughout the watershed exceeded the U.S. EPA acute and chronic criteria for protection of aquatic life. Concentrations of As, Cd, Cu, Pb, and Zn in sediment were sufficient in the tributaries to cause invertebrate toxicity. The concentrations of As, Cu, Cd, Pb, and Zn in invertebrates from lower Cataract Creek (63, 339, 59, 34, and 2,410 μg/g dry wt, respectively) were greater than the concentrations in invertebrates from the Clark Fork River watershed, Montana (19, 174, 2.3, 15, and 648 μg/g, respectively), that were associated with reduced survival, growth, and health of cutthroat trout fed diets composed of those invertebrates. Colloids and biofilm seem to play a critical role in the pathway of metals into the food chain and concentrations of As, Cu, Pb, and Zn in these two components are significantly correlated. We suggest that transfer of metals associated with Fe colloids to biological components of biofilm is an important pathway where metals associated with abiotic components are first available to biotic components. The significant correlations suggest that Cd, Cu, and Zn may move independently to biota (biofilm, invertebrates, or fish tissues) from water and sediment. The possibility exists that Cd, Cu, and Zn concentrations increase in fish tissues as a result of direct contact with water and sediment and indirect exposure through the food chain. However, uptake through the food chain to fish may be more important for As. Although As concentrations in colloids and biofilm were significantly correlated with As water concentrations, As concentrations in fish tissues were not correlated with water. The pathway for Pb into biological components seems to begin with sediment because concentrations of Pb in water were not significantly correlated with any other component and because concentrations of Pb in the water were often below detection limits.

Montana↗

USGS2003

Ranking terrestrial vertebrate species for utility in biomonitoring and vulnerability to environmental contaminants

The measurement of contaminant tissue concentrations or exposure-related effects in biota has been used extensively to monitor pollution and environmental health. Terrestrial vertebrates have historically been an important group of species in such evaluations, not only because many are excellent sentinels of environmental contamination, but also because they are valued natural resources in their own right that may be adversely affected by toxicant exposure. Selection of appropriate vertebrates for biomonitoring studies frequently relies on expert opinion, although a few rigorous schemes are in use for predicting vulnerability of birds to the adverse effects of petroleum crude oil. A Utility Index that ranks terrestrial vertebrate species as potential sentinels of contaminants in a region, and a Vulnerability Index that assesses the threat of specific groups of contaminants to these species , have been developed to assist decision makers in risk assessments of persistent organic pollutants, cholinesterase-inhibiting pesticides, petroleum crude oil, mercury, and lead shot. Twenty-five terrestrial vertebrate species commonly found in Atlantic Coast estuarine habitat (Rattner et al. 2001a) were ranked for their utility as biomonitors of contamination and their vulnerability to pollutants in this region. No single species , taxa, or class of vertebrates was found to be an ideal sentinel for all groups of contaminants . Although birds have overwhelmingly been used to monitor contaminants compared to other terrestrial vertebrate classes, the nonmigratory nature and dietary habits of the snapping turtle and mink consistently resulted in ranking these species as excellent sentinels as well. Vulnerability of Atlantic Coast populations of these species varied considerably among groups of contaminants . Usually a particular species was found to be at high risk to only one or two groups of contaminants , although a noteworthy exception is the bald eagle, which is highly vulnerable to all five of the contaminant groups examined. This index could be further enhanced by generation of additional comparative toxicity data to facilitate interspecific extrapolations. The Utility and Vulnerability Indices have application to many types of habitats in addition to estuaries and are of value to natural resource and risk managers that routinely conduct local, regional, or national environmental quality assessments.

Archives of Environmental Contamination and Toxico↗

USGS2017

Assessment of the potential respiratory hazard of volcanic ash from future Icelandic eruptions: A study of archived basaltic to rhyolitic ash samples

Background The eruptions of Eyjafjallajökull (2010) and Grímsvötn (2011), Iceland, triggered immediate, international consideration of the respiratory health hazard of inhaling volcanic ash, and prompted the need to estimate the potential hazard posed by future eruptions of Iceland’s volcanoes to Icelandic and Northern European populations. Methods A physicochemical characterization and toxicological assessment was conducted on a suite of archived ash samples spanning the spectrum of past eruptions (basaltic to rhyolitic magmatic composition) of Icelandic volcanoes following a protocol specifically designed by the International Volcanic Health Hazard Network. Results Icelandic ash can be of a respirable size (up to 11.3 vol.% < 4 μm), but the samples did not display physicochemical characteristics of pathogenic particulate in terms of composition or morphology. Ash particles were generally angular, being composed of fragmented glass and crystals. Few fiber-like particles were observed, but those present comprised glass or sodium oxides, and are not related to pathogenic natural fibers, like asbestos or fibrous zeolites, thereby limiting concern of associated respiratory diseases. None of the samples contained cristobalite or tridymite, and only one sample contained quartz, minerals of interest due to the potential to cause silicosis. Sample surface areas are low, ranging from 0.4 to 1.6 m2 g−1, which aligns with analyses on ash from other eruptions worldwide. All samples generated a low level of hydroxyl radicals (HO•), a measure of surface reactivity, through the iron-catalyzed Fenton reaction compared to concurrently analyzed comparative samples. However, radical generation increased after ‘refreshing’ sample surfaces, indicating that newly erupted samples may display higher reactivity. A composition-dependent range of available surface iron was measured after a 7-day incubation, from 22.5 to 315.7 μmol m−2, with mafic samples releasing more iron than silicic samples. All samples were non-reactive in a test of red blood cell-membrane damage. Conclusions The primary particle-specific concern is the potential for future eruptions of Iceland’s volcanoes to generate fine, respirable material and, thus, to increase ambient PM concentrations. This particularly applies to highly explosive silicic eruptions, but can also hold true for explosive basaltic eruptions or discrete events associated with basaltic fissure eruptions.

Environmental Health↗

USGS1995

Contaminants in fishes from great lakes-influenced sections and above dams of three Michigan Rivers: III. Implications for health of bald eagles

Recently, there have been discussions of the relative merits of passage of fishes around hydroelectric dams on three rivers (Au Sable, Manistee, and Muskegon) in Michigan. A hazard assessment was conducted to determine the potential for adverse effects on bald eagles that could consume such fishes from above and below dams on the three primary rivers. The hazard assessments were verified by comparing the reproductive productivities of eagles nesting in areas where they ate primarily fish from either above or below dams on the three primary rivers, as well as on two additional rivers in Michigan, the Menominee and Thunder Bay. Concentrations of organochlorine insecticides (OCI), polychlorinated biphenyls (total PCBs), 2,3,7,8-tetrachlorodibenzo- p -dioxin equivalents (TCDD-EQ), and total mercury (Hg) were measured in composite samples of fishes from above and below hydroelectric dams on the Manistee and Muskegon Rivers, which flow into Lake Michigan, and the Au Sable River, which flows into Lake Huron. Mean concentrations of OCI, total PCBs, and TCDD-EQ were all greater in fishes from below the dams than in those from above. The hazard assessment indicated that current concentrations of Hg and OCI other than DDT (DDT + DDE + DDD) in fish from neither above nor below dams would present a significant hazard to bald eagles ( Haliaeetus leucocephalus ). Both total PCBs and TCDD-EQ in fishes from below the dams currently present a significant hazard to bald eagles, since their mean hazard quotients (HQ) were all greater than one.

Michigan↗

USGS2004

Avian mortality events in the United States caused by anticholinesterase pesticides: A retrospective summary of National Wildlife Health Center records from 1980 to 2000

We reviewed the U.S. Geological Survey National Wildlife Health Center (NWHC) mortality database from 1980 to 2000 to identify cases of poisoning caused by organophosphorus and carbamate pesticides. From the 35,022 cases from which one or more avian carcasses were submitted to the NWHC for necropsy, we identified 335 mortality events attributed to anticholinesterase poisoning, 119 of which have been included in earlier reports. Poisoning events were classified as confirmed (n = 205) when supported by findings of ≥50% inhibition of cholinesterase (ChE) activity in brain tissue and the detection of a specific pesticide in the gastrointestinal contents of one or more carcasses. Suspected poisonings (n = 130) were defined as cases where brain ChE activity was ≥50% inhibited or a specific pesticide was identified in gastrointestinal contents. The 335 avian mortality events occurred in 42 states. Washington, Virginia, and Ohio had the highest frequency of events, with 24 (7.2%), 21 (6.3%), and 20 (6.0%) events, respectively. A total of 8877 carcasses of 103 avian species in 12 orders was recovered. Because carcass counts underestimate total mortality, this represents the minimum actual mortality. Of 24 different pesticides identified, the most frequent were famphur (n = 59; 18%), carbofuran (n = 52; 15%), diazinon (n = 40; 12%), and fenthion (n = 17; 5.1%). Falconiformes were reported killed most frequently (49% of all die-offs) but Anseriformes were found dead in the greatest numbers (64% of 8877 found dead). The majority of birds reported killed by famphur were Passeriformes and Falconiformes, with the latter found dead in 90% of famphur-related poisoning events. Carbofuran and famphur were involved in mortality of the greatest variety of species (45 and 33, respectively). Most of the mortality events caused by diazinon involved waterfowl.

Ohio, Virginia, Washington↗

USGS2001

Review and analysis of available streamflow and water-quality data for Park County, Colorado, 1962-98

Information on streamflow and surface-water and ground-water quality in Park County, Colorado, was compiled from several Federal, State, and local agencies. The data were reviewed and analyzed to provide a perspective of recent (1962-98) water-resource conditions and to help identify current and future water-quantity and water-quality concerns. Streamflow has been monitored at more than 40 sites in the county, and data for some sites date back to the early 1900's. Existing data indicate a need for increased archival of streamflow data for future use and analysis. In 1998, streamflow was continuously monitored at about 30 sites, but data were stored in a data base for only 10 sites. Water-quality data were compiled for 125 surface-water sites, 398 wells, and 30 springs. The amount of data varied considerably among sites; however, the available information provided a general indication of where water-quality constituent concentrations met or exceeded water-quality standards. Park County is primarily drained by streams in the South Platte River Basin and to a lesser extent by streams in the Arkansas River Basin. In the South Platte River Basin in Park County, more than one-half the annual streamflow occurs in May, June, and July in response to snowmelt in the mountainous headwaters. The annual snowpack is comparatively less in the Arkansas River Basin in Park County, and mean monthly streamflow is more consistent throughout the year. In some streams, the timing and magnitude of streamflow have been altered by main-stem reservoirs or by interbasin water transfers. Most values of surface-water temperature, dissolved oxygen, and pH were within recommended limits set by the Colorado Department of Public Health and Environment. Specific conductance (an indirect measure of the dissolved-solids concentration) generally was lowest in streams of the upper South Platte River Basin and higher in the southern one-half of the county in the Arkansas River Basin and in the South Platte River downstream from Antero Reservoir. Historical nitrogen concentrations in surface water were small. Nitrite was not detected, most un-ionized ammonia concentrations were less than 0.02 milligram per liter, and all nitrate concentrations were less than 1.2 milligrams per liter. Nitrate concentrations were higher in urban and built-up areas than in rangeland and forest areas. Most median concentrations of total phosphorus at individual sites were less than 0.05 milligram per liter, and concentrations were not significantly different among urban and built-up, rangeland, and forest areas. An upward trend in total phosphorus concentration was determined for flow from the East Portal of the Harold D. Roberts Tunnel, but the slope of the trend line was small and the concentrations were equal or nearly equal to the detection limit of 0.01 milligram per liter. Using median phosphorus loads for two South Platte River sites, the annual phosphorus load transported out of Park County in the South Platte River was calculated to be about 10,000 pounds. Median iron and manganese concentrations for most areas of Park County were less than in-stream water-quality standards, even though several individual concentrations were one to two orders of magnitude larger than the standards. The largest concentrations of aluminum, cadmium, chromium, copper, iron, manganese, nickel, and zinc were from the upper North Fork South Platte River Basin or the Mosquito Creek Basin. All ground-water concentrations of chloride and most ground-water concentrations of sulfate were less than the U.S. Environmental Protection Agency (USEPA) drinking-water standard of 250 milligrams per liter. Median dissolved-solids concentrations in ground water ranged from 160 milligrams per liter in the crystalline-rock aquifers to 257 milligrams per liter in the sedimentary-rock aquifers. Dissolved-solids concentrations greater than the USEPA drinking-water standard of 500 milligrams per liter were detected in abo

Water-Resources Investigations Report↗

USGS1998

Retrospective study of the diagnostic criteria in a lead-poisoning survey of waterfowl

Between 1983 and 1986 the National Wildlife Health Center (NWHC) conducted a nationwide study of lead poisoning of waterfowl from federal and state refuges. This survey was done to assist in identifying zones with lead-poisoning problems. One thousand forty one moribund or dead waterfowl were collected and examined. The presence or absence of 13 gross lesions selected as indicators of lead poisoning and 3 lesions indicating body condition was recorded. Lead-poisoning diagnoses were based on the finding of at least 6 8 ppm (wet weight) lead in the liver and either lead shot in the gizzard content or at least one convincing gross lesion indicative of lead poisoning. Four hundred and twenty-one of these waterfowl were diagnosed as lead-poisoned. The NWHC survey provided a comprehensive basis for estimating the sensitivities, specificities, and likelihood ratios of the gross lesions of lead poisoning and the associated hepatic lead concentrations for several species of waterfowl. Some of the 13 defined gross lesions were more common than others; frequencies ranged from 3% to 80% in the 421 lead-poisoned waterfowl. The most reliable indicators of lead poisoning were impactions of the upper alimentary tract, submandibular edema, myocardial necrosis, and biliary discoloration of the liver. Each of the 13 lesions occurred more frequently in the lead-poisoned birds, but each of the lesions also occurred in waterfowl that died of other causes. The number of lead shot present in a bird?s gizzard was only weakly correlated with its hepatic lead concentration; however, this weak correlation may have been adequate to account for differences in hepatic lead concentrations among species, once the weights of the species were taken into account. Although lead-poisoned ducks tended to have higher hepatic mean lead concentrations than did lead-poisoned geese or swans, the differences were probably a result of a greater dose of shot per body weight than to kinetic differences between species. Hepatic lead concentrations were independent of age and sex. Ninety-five percent of waterfowl diagnosed as lead-poisoned had hepatic lead concentrations of at least 38 ppm, dry weight (10 ppm, wet weight). Fewer than 1% of the waterfowl that died of other causes had a concentration that high. This 5th percentile, of 38 ppm dry weight (10 ppm wet weight), is a defensible criterion for identifying lead-poisoned waterfowl when interpreting hepatic lead concentrations in the absence of pathological observations.

Archives of Environmental Contamination and Toxico↗

USGS1994

Contaminants in fishes from Great Lakes-influenced sections and above dams of three Michigan rivers. II: Implications for health of mink

Populations of mink ( Mustela vison ) have declined in many areas of the world. Such declines have been linked to exposures to synthetic, halogenated hydrocarbons. In the Great Lakes region, mink are fewer in areas along the shore of the Great Lakes and their tributaries where mink have access to fish from the Great Lakes. Recently, there has been discussion of the relative merits of passage of fishes around hydroelectric dams on rivers in Michigan. A hazard assessment was conducted to determine the potential for adverse effects on mink, which could consume such fishes from above or below dams on the rivers. Concentrations of organochlorine insecticides, polychlorinated biphenyls (PCBs), 2,3,7,8-tetrachloridibenzo- p -dioxin equivalents (TCDD-EQ), and total mercury were measured in composite samples of fishes from above or below hydroelectric dams on the Manistee and Muskegon Rivers, which flow into Lake Michigan, and the Au Sable River, which flows into Lake Huron. Concentrations of organochlorine insecticides, PCBs, and TCDD-EQ were all greater in fishes from below the dams than those from above. Concentrations of neither organochlorine insecticides nor mercury in fishes are currently a risk to mink above or below the dams. All of the species of fishes collected from downstream of the dams contained concentrations of PCBs and TCDD-EQ, which represent a hazard to mink. The hazard index for PCBs was less than one for the average of all species from the upstream reaches of the Manistee and Au Sable Rivers, but not the Muskegon. The hazard index (concentration in fish/NOAEC) was greater than 1 for all of the species collected from below the dams, in all three rivers. The greatest hazard index was observed for carp ( Cyprinus carpio ) downstream on the Muskegon River. Because the concentrations of PCBs used in the hazard assessment were corrected for relative toxic potencies, the hazard ratios based on PCBs should be similar to those based on TCDD-EQ. This was found to be true. Thus, either total PCBs or TCDD-EQ could be used as the critical toxicant in the hazard assessment. However, if uncorrected concentrations of PCBs, expressed as Aroclors ® , were used in the hazard assessment, the toxicity of the weathered mixture would have been underestimated by approximately five-fold, and, in that instance, TCDD-EQ would be the critical contaminant for the hazard assessment. The average maximum allowable percentage of fish from above the dams, which would result in no observable adverse effects of TCDD-EQ, was 70%. Based on the average TCDD-EQ concentrations in the fishes, an average of 8.6% of the diet could be made up of fishes from below dams on the rivers. The most restrictive daily allowable intakes were for carp on the Muskegon and steelhead trout ( Onchorhyncus mykiss ) on the Manistee Rivers. Only 2.7% of the diet could be made up of these two species from influenced portion of the Au Sable River, they would be exposed to 390 μg PCBs and 8.55 ng of TCDD-EQ per day, respectively (Giesy et al. 1994b). Thus, it would take 15.1 or 77 days for mink to receive their total annual dose of PCBs or TCDD-EQ, respectively. At least for chinook salmon, the critical contaminant for the purposes of hazard assessment would be total concentrations of PCBs. Consuming chinook salmon for as little as 2 weeks would deliver the annual allowable dose of PCBs to mink.

Michigan↗