Isotopic (δ15 N) relationship of pregnant females and their embryos: Comparing placental and yolk-sac viviparous elasmobranchs.

Nitrogen stable isotopes ratios (δ15 N) were determined for selected tissues (muscle, liver, blood and yolk) of pregnant females and their embryos of a placental viviparous species, the Pacific sharpnose shark (Rhizoprionodon longurio), and a yolk-sac viviparous species, the speckled guitarfish (Pseudobatos glaucostigmus). The R. longurio embryo tissues were 15 N enriched compared to the same tissues in the pregnant female, using the difference in δ15 N (Δδ15 N) between embryo and adult. Mean Δδ15 N was 2.17‰ in muscle, 4.39‰ in liver and 0.80‰ in blood. For P. glaucostigmus, embryo liver tissue was significantly 15 N enriched in comparison with liver of the pregnant female (Δδ15 N mean = 1.22‰), whereas embryo muscle was 15 N depleted relative to the muscle of the pregnant female (Δδ15 N mean = -1.22‰). Both species presented a significant positive linear relationship between Δδ15 N and embryo total length (LT ). The results indicated that embryos have different Δδ15 N depending on their reproductive strategy, tissue type analysed and embryo LT .

Trophic Structure and Biomagnification of Total Mercury in Ray Species Within a Benthic Food Web.

Stable isotopes of C (δ13C) and N (δ15N) were used to explore the trophic structure and evaluate mercury (Hg) biomagnification in the food web of muscle of three commercially important ray species from the Pacific coast of Baja California Sur (PCBCS): the shovelnose guitarfish (Pseudobatos productus), banded guitarfish (Zapteryx exasperata), and bat ray (Myliobatis californica). The food web of these ray species predominately consisted of zooplankton, three species of fish, and five species of invertebrates. Mean δ15N values in all species ranged from 10.54 ± 0.18‰ in zooplankton to 17.84 ± 0.81‰ in the shovelnose guitarfish. Mean δ13C values ranged from - 22.05 ± 0.75‰ in the red crab to - 15.93 ± 0.78‰ in the bat ray. Mean total Hg concentration ([THg]) in all species ranged from 0.0009 ± 0.0002 mg kg-1 ww in zooplankton to 0.24 ± 0.19 mg kg-1 ww in the banded guitarfish. The food web magnification factor was 6.38 and significantly greater than 1.0. The present study describes [THg] biomagnification in the benthic food web of three ray species of the PCBCS. This provides an important baseline knowledge of the biomagnification dynamics and pathways of Hg in this environment for these multiple interacting species.

Nanospray liquid chromatography/tandem mass spectrometry analysis of steroids from gray whale blubber.

RATIONALE: Analysis of steroids from precious blubber biopsies obtained from marine mammals, especially endangered species, can provide valuable information on their endocrine status. Challenges with currently used ELISA methodology include lack of absolute quantitation and incompatibility with multiple steroids analysis due to limited biopsy mass. Development of a sensitive, accurate analytical method for this purpose is critical. METHODS: A nanospray liquid chromatography/tandem mass spectrometry (nanoLC/MS/MS) method was validated for sensitive, specific and quantitative analysis of three steroid hormones, without derivatization, extracted from 50 mg blubber samples. Data was acquired with an LTQ XL ion trap mass spectrometer in positive ion mode, using single reaction monitoring. All three steroids were analyzed in a single run. Cholic acid was used as a surrogate internal standard for quantitation due to its steroidal structure and lack of measurable endogenous levels in blubber. RESULTS: The lowest limits of quantitation for progesterone, testosterone, and hydrocortisone were significantly improved compared to previous studies using conventional LC/MS/MS. The lowest limit of detection was 7 fg/µL using a 1 µL injection volume. Calibration curves for steroid quantification showed good linearity (r2 >0.99) between 14 and 3620 fg/µL, and accuracy was <20% for interday and <10% for intraday. After validation, the method was successfully applied to quantification of steroids in gray whale blubber samples. CONCLUSIONS: The nanoLC/MS/MS method is more sensitive than traditional LC/MS/MS for steroid analysis. It is also compatible with other important biopsy analyses due to its small blubber mass requirement. This will benefit the reproductive and stress assessments for all marine mammals, particularly endangered populations. Copyright © 2017 John Wiley & Sons, Ltd.

Using Domestic and Free-Ranging Arctic Canid Models for Environmental Molecular Toxicology Research.

The use of sentinel species for population and ecosystem health assessments has been advocated as part of a One Health perspective. The Arctic is experiencing rapid change, including climate and environmental shifts, as well as increased resource development, which will alter exposure of biota to environmental agents of disease. Arctic canid species have wide geographic ranges and feeding ecologies and are often exposed to high concentrations of both terrestrial and marine-based contaminants. The domestic dog (Canis lupus familiaris) has been used in biomedical research for a number of years and has been advocated as a sentinel for human health due to its proximity to humans and, in some instances, similar diet. Exploiting the potential of molecular tools for describing the toxicogenomics of Arctic canids is critical for their development as biomedical models as well as environmental sentinels. Here, we present three approaches analyzing toxicogenomics of Arctic contaminants in both domestic and free-ranging canids (Arctic fox, Vulpes lagopus). We describe a number of confounding variables that must be addressed when conducting toxicogenomics studies in canid and other mammalian models. The ability for canids to act as models for Arctic molecular toxicology research is unique and significant for advancing our understanding and expanding the tool box for assessing the changing landscape of environmental agents of disease in the Arctic.

Evaluating Hair as a Predictor of Blood Mercury: The Influence of Ontogenetic Phase and Life History in Pinnipeds.

Mercury (Hg) biomonitoring of pinnipeds increasingly utilizes nonlethally collected tissues such as hair and blood. The relationship between total Hg concentrations ([THg]) in these tissues is not well understood for marine mammals, but it can be important for interpretation of tissue concentrations with respect to ecotoxicology and biomonitoring. We examined [THg] in blood and hair in multiple age classes of four pinniped species. For each species, we used paired blood and hair samples to quantify the ability of [THg] in hair to predict [THg] in blood at the time of sampling and examined the influence of varying ontogenetic phases and life history of the sampled animals. Overall, we found that the relationship between [THg] in hair and blood was affected by factors including age class, weaning status, growth, and the time difference between hair growth and sample collection. Hair [THg] was moderately to strongly predictive of current blood [THg] for adult female Steller sea lions (Eumetopias jubatus), adult female California sea lions (Zalophus californianus), and adult harbor seals (Phoca vitulina), whereas hair [THg] was poorly predictive or not predictive (different times of year) of blood [THg] for adult northern elephant seals (Mirounga angustirostris). Within species, except for very young pups, hair [THg] was a weaker predictor of blood [THg] for prereproductive animals than for adults likely due to growth, variability in foraging behavior, and transitions between ontogenetic phases. Our results indicate that the relationship between hair [THg] and blood [THg] in pinnipeds is variable and that ontogenetic phase and life history should be considered when interpreting [THg] in these tissues.

Developmental timing of sodium perchlorate exposure alters angiogenesis, thyroid follicle proliferation and sexual maturation in stickleback.

Perchlorate, a common aquatic contaminant, is well known to disrupt homeostasis of the hypothalamus-pituitary-thyroid axis. This study utilizes the threespine stickleback (Gasterosteus aculeatus) fish to determine if perchlorate exposure during certain windows of development has morphological effects on thyroid and gonads. Fish were moved from untreated water to perchlorate-contaminated water (30 and 100mg/L) starting at 0, 3, 7, 14, 21, 42, 154 and 305 days post fertilization until approximately one year old. A reciprocal treatment (fish in contaminated water switched to untreated water) was conducted on the same schedule. Perchlorate exposure increased angiogenesis and follicle proliferation in thyroid tissue, delayed gonadal maturity, and skewed sex ratios toward males; effects depended on concentration and timing of exposure. This study demonstrates that perchlorate exposure beginning during the first 42 days of development has profound effects on stickleback reproductive and thyroid tissues, and by implication can impact population dynamics. Long-term exposure studies that assess contaminant effects at various stages of development provide novel information to characterize risk to aquatic organisms, to facilitate management of resources, and to determine sensitive developmental windows for further study of underlying mechanisms.

Developmental timing of perchlorate exposure alters threespine stickleback dermal bone.

Adequate levels of thyroid hormone are critical during development and metamorphosis, and for maintaining metabolic homeostasis. Perchlorate, a common contaminant of water sources, inhibits thyroid function in vertebrates. We utilized threespine stickleback (Gasterosteus aculeatus) to determine if timing of perchlorate exposure during development impacts adult dermal skeletal phenotypes. Fish were exposed to water contaminated with perchlorate (30mg/L or 100mg/L) beginning at 0, 3, 7, 14, 21, 42, 154 or 305days post fertilization until sexual maturity at 1year of age. A reciprocal treatment moved stickleback from contaminated to clean water on the same schedule providing for different stages of initial exposure and different treatment durations. Perchlorate exposure caused concentration-dependent significant differences in growth for some bony traits. Continuous exposure initiated within the first 21days post fertilization had the greatest effects on skeletal traits. Exposure to perchlorate at this early stage can result in small traits or abnormal skeletal morphology of adult fish which could affect predator avoidance and survival.

Perchlorate trophic transfer increases tissue concentrations above ambient water exposure alone in a predatory fish.

This study examined effects of varying concentrations of the environmental contaminant perchlorate in northern pike (Esox lucius) based on exposure in water and/or from prey (threespine stickleback, Gasterosteus aculeatus). Routes of exposure to pike were through contaminated water at 0, 10, or 100 mg/L perchlorate for 49 d and/or through feeding, 1 per day over 14 d, sticklebacks that were previously maintained in water at 0, 10, or 100 mg/L perchlorate. Both water and food significantly contributed to pike tissue concentrations of perchlorate as compared to controls, but, as expected for a water-soluble contaminant, perchlorate did not biomagnify from prey to predatory fish. Pike gastrointestinal tissue retained significantly more perchlorate than other tissues combined. Route of exposure and concentration of perchlorate in various media are important to consider in risk assessment when evaluating uptake and tissue concentration of perchlorate because significantly higher tissue concentrations may result from combined prey and water exposures than from prey or water exposures alone in a concentration-dependent manner.

Fasting durations of Steller sea lion pups vary among subpopulations-evidence from two plasma metabolites.

Geographic differences in population growth trends are well-documented in Steller sea lions (Eumetopias jubatus), a species of North Pacific pinniped listed under the U.S. Endangered Species Act in 1990 following a marked decline in population abundance that began during the 1970s. As population growth is intrinsically linked to pup production and survival, examining factors related to pup physiological condition provides useful information to management authorities regarding potential drivers of regional differences. During dam foraging trips, pups predictably transition among three fasting phases, distinguished by the changes in the predominant metabolic byproduct. We used standardized ranges of two plasma metabolites (blood urea nitrogen and ß-hydroxybutyrate) to assign pups to fasting categories (n = 1528, 1990-2016, 12 subpopulations): Recently Fed-Phase I (digestion/assimilation-expected hepatic/muscle glycogen usage), Phase II (expected lipid utilization), transitioning between Phases II-III (expected lipid utilization with increased protein reliance), or Phase III (expected protein catabolism). As anticipated, the majority of pups were classified as Recently Fed-Phase I (overall mean proportion = 0.72) and few pups as Phase III (overall mean proportion = 0.04). By further comparing pups in Short (Recently Fed-Phase II) and Long (all other pups) duration fasts, we identified three subpopulations with significantly (P < 0.03) greater proportions of pups dependent upon endogenous sources of energy for extended periods, during a life stage of somatic growth and development: the 1) central (0.27 ± 0.09) and 2) western (0.36 ± 0.13) Aleutian Island (declining population trend) and 3) southern Southeast Alaska (0.32 ± 0.06; increasing population trend) subpopulations had greater Long fast proportions than the eastern Aleutian Islands (0.10 ± 0.05; stabilized population). Due to contrasting population growth trends among these highlighted subpopulations over the past 50+ years, both density-independent and density-dependent factors likely influence the dam foraging trip duration, contributing to longer fasting durations for pups at some rookeries.

Total Mercury, Total Selenium, and Monomethylmercury Relationships in Multiple Age Cohorts and Tissues of Steller Sea Lions (Eumetopias jubatus).

Steller sea lion (Eumetopias jubatus) tissue mercury concentrations increasingly above thresholds of concern occur in regions of Alaska where lack of population recovery is noted. Selenium-monomethylmercury interactions may mitigate toxicosis but may also result in functional selenium deficiency, impacting essential selenium-dependent processes. Physiologically driven differences in tissue concentrations (organotropism) of total mercury ([THg]), total selenium ([TSe]), and monomethylmercury ([MeHg+ ]) confound interpretation for various age cohorts. Archived tissues from Alaska Steller sea lions (2002-2016) were used to compare [THg], [MeHg+ ], and [TSe] across age cohorts and tissue types. Liver [THg] ranged from 0.05 to 63.7 µg/g. Fetal and pup livers had significantly lower [THg] and [TSe], higher percentage MeHg+ , and greater range of molar TSe:THg than subadult and adult livers. Molar Se:MeHg+ ratios, including Se in excess of nonmethylmercury, were dependent on [MeHg+ ] in fetuses and pups. While [THg] varied significantly by muscle type (heart vs. skeletal) and anatomical location, concentrations were strongly correlated. Biomagnification and/or bioaccumulation of THg in liver of older animals confounded comparison with other tissues; however, in fetal and pup liver [THg] correlated with other tissues. In contrast, liver [MeHg+ ] correlated with other tissues across all age classes. Fetal and pup tissues, which reflect in utero exposure and are subject to limited bioaccumulation, are ideal for assessing mercury exposure related to dam diet, including intertissue comparison, and represent key cohorts of concern. Evaluating [MeHg+ ] and [TSe] in tissues from multiple age cohorts allows better intertissue comparison, providing insight into time courses, routes of exposure, and potential for adverse effects. Environ Toxicol Chem 2022;41:1477-1489. © 2022 SETAC.

Fetal mercury concentrations in central California Pacific harbor seals: Associated drivers and outcomes.

Mercury (Hg) is a well-known toxicant in wildlife and humans. High total Hg concentrations ([THg]) have been reported in central California harbor seals Phoca vitulina richardii. We evaluated the effects of presence/absence of early natal coat (lanugo), year (2012 to 2017), sex, stranding location, and trophic ecology (ẟ13C and ẟ15N values) on hair [THg] along coastal central California. Also examined were [THg] effects on growth rates of pups in rehabilitation and probability of release (e.g., successful rehabilitation). The [THg] ranged from 0.46-81.98 mg kg-1 dw, and ẟ15N and ẟ13C ranged from 13.6-21.5‰, and -17.2 to -13.0‰, respectively. Stranding location, year, and presence of lanugo coat were important factors explaining variation in [THg]. Seals from Sonoma and San Mateo County had higher [THg] than other locations. Seals with full or partial lanugo coat had lower [THg]. Seals from 2016 and 2017 had higher [THg] than those from 2015. Hair [THg] exceeded lower and upper toxicological thresholds (>20 mg kg-1 by year (5.88% to 23.53%); >30 mg kg-1 (0% to 12.31%)) with a pronounced increase from 2015 to 2016. Pups in 2017 had significantly higher odds ratio of [THg] above 20 mg kg-1 than pups of 2015, and pups in 2016 had significantly higher odds ratio than those from 2013 and 2015 (similar when using 30 mg kg-1). Pups in Sonoma County had the highest odds ratio for [THg] in lanugo above 20 mg kg-1. ẟ15N values were higher in 2015-2017, particularly relative to 2014, probably associated with the El Niño event. The [THg] was not a good predictor for probability of release and mass-specific growth rates in captivity. Further investigation of temporal trends of [THg] in harbor seals is warranted given the relatively high percentage of samples exceeding threshold values, particularly in the most recent sampling years.

Mercury maternal transfer in two placental sharks and a yolk-sac ray from Baja California Sur, Mexico.

Total mercury (THg) concentrations were measured in muscle and liver of two placental viviparous sharks, the Pacific sharpnose shark (Rhizoprionodon longurio) and the brown smooth-hound (Mustelus henlei); as well as in the muscle, liver, and yolk of the yolk-sac viviparous speckled guitarfish (Pseudobatos glaucostigmus) in Baja California Sur. The aim was to determine which factors could be involved in maternal transfer and resultant maternal and embryonic THg concentration. Higher THg concentrations were found in pregnant females compared to embryos paired tissues. THg concentrations of embryo tissues decreased with total length (TL), except for the muscle of the Pacific sharpnose shark. THg concentrations of embryo muscle was positively related to THg concentration in the muscle of pregnant females. Embryos TL, muscle THg concentration of pregnant females, percentage of THg concentration in embryos, along with the reproductive strategy are relevant factors required to improve our understanding of THg concentration in embryo tissues.

Blood-based biomarkers of selenium and thyroid status indicate possible adverse biological effects of mercury and polychlorinated biphenyls in Southern Beaufort Sea polar bears.

We examined biomarkers of selenium status (whole blood Se; serum Se; glutathione peroxidase activity) and thyroid status (concentrations and ratios of thyroxine, T4; tri-iodothyronine, T3; albumin) in polar bears to assess variations among cohorts, and relationships to circulating concentrations of contaminants. Concentrations of total mercury (Hg) in whole blood were similar among cohorts (prime aged males and females, older animals, ages≥16 years, and young animals, ages 1-5 years; 48.44±35. 81; p=0.253). Concentrations of sum of seven polychlorinated biphenyls (∑PCB7) in whole blood were greater in females (with and without cubs, 26.44±25.82 ng/g ww) and young (26.81±10.67 ng/g ww) compared to males (8.88±5.76 ng/g ww, p<0.001), and significantly related to reduced body condition scores (p<0.001). Concentrations of Se and albumin were significantly greater in males than females (whole blood Se, males, 42.34 pmol/g ww, females, 36.25±6.27 pmol/g ww, p=0.019; albumin, males, 4.34±0.34 g/dl, females, 4.10±0.29 g/dL, p=0.018). Glutathione peroxidase activity ranged from 109.1 to 207.8 mU/mg hemoglobin, but did not differ significantly by sex or age (p>0.08). Thyroid hormones were greater in females (solitary females and females with cubs) compared to males (p<0.001). Biomarkers of Se status and concentrations of T3 were significantly positively related to Hg in all prime aged polar bears (p<0.03). Albumin concentrations were significantly positively related to total TT4, and significantly negatively related to concentrations of ∑PCB7 (p<0.003). Total thyroxine (TT4) was significantly negatively associated with blood concentrations of ∑PCB7 in solitary females (p=0.045). These data suggest that female polar bears were more susceptible to changes in blood-based biomarkers of selenium and thyroid status than males. Further classifications of the physiologic states of polar bears and repeated measures of individuals over time are needed to accurately assess the biological impact of combined toxicant exposures.

Streptococcus phocae isolated from a spotted seal (Phoca largha) with pyometra in Alaska.

A spotted seal harvested by subsistence hunters in Kotzebue Sound, Alaska (USA), showed a grossly enlarged uterus and associated lymph nodes. Streptococcus phocae was isolated from the purulent uterine discharge. Histopathologic examination revealed inflammation that was limited to the uterine mucosa. Lymph nodes draining the affected organ were reactive but no evidence of active infection was found in the lymph nodes. This report is the first Streptococcus phocae isolated from spotted seals as well as the first report of pyometra as the main pathologic finding associated with this pathogen. Isolation of this pathogen from Alaska expands the reported range to arctic pinnipeds. Zoonotic potential remains unknown.

Regional variations and relationships among cytokine profiles, white blood cell counts, and blood mercury concentrations in Steller sea lion (Eumetopias jubatus) pups.

The Steller sea lion (SSL) population west of 144°W longitude experienced a significant population decline. While there appears to be a stable or increasing population trend in rookeries in the Gulf of Alaska (GOA) and Southeast Alaska (SEA), some rookeries within the Aleutian Islands (AI) have failed to recover. Previous studies found regional differences in whole blood total mercury concentrations ([THg]) showing more than 20% of AI pups had [THg] above critical thresholds for increased risk of immunological effects and other adverse outcomes. Measurements of immune cell-signaling proteins can be used to evaluate the immune status of marine mammals in relation to [THg]. We compared serum cytokine and chemokine concentrations in pups among regions (AI, eastern GOA, SEA), and examined associations among cytokines, chemokines, white blood cell (WBC) counts, and [THg]. Considering liver is an important target organ for mercury and immune protein synthesis we additionally examined the relationship of [THg] with liver-related enzymes serum aspartate (AST) and alanine aminotransferase (ALT). We observed regional differences in cytokine and chemokine measurements and immune protein associations. There was a positive association between total WBC counts and [THg] in AI pups, whereas a negative association between lymphocytes and [THg] in SEA pups. These findings may indicate regional variation in proliferation and differentiation of hematopoietic cells, differences in immune system development, and/or a difference in antigenic stimuli. No associations between [THg] and cytokines, chemokines, AST or ALT were found. Observed regional differences in cytokine and chemokine milieu during gestational and early development in SSL pups could lead to an imbalance in cell differentiation that could impact immunological resiliency in juvenile and adult life stages. We report concentration ranges of a suite of cytokines and chemokines which may prove to be a useful metric for ecotoxicology and risk assessment studies in SSLs and other wildlife.

Mercury concentrations in Baja California Sur fish: Dietary exposure assessment.

Total mercury concentrations ([THg]) in muscle were determined in commercial finfish and elasmobranchs from Baja California Sur (BCS), Mexico to evaluate dietary Hg exposure for BCS communities, including the relationship of trophic ecology, length and mass with [THg] that might drive future consumption advice (e.g., recommend limited consumption of large fish for some species). The [THg] ranged from 0.06 to 528.02 µg kg-1 ww in finfish and 17.68-848.26 µg kg-1 ww in elasmobranchs. Relative to the consumption threshold set for predatory fish in Mexico, all species had a concentration below 1000 µg kg-1 ww. As expected, 16 (4.02%) and 75 (18.84%) individual fish were above advisory thresholds of 500 and 200 µg kg-1 ww, respectively. The hazard quotients (HQs) in most species were significantly <1.0, only banded guitarfish showed a significant median HQ > 1.0. Thus, the relative level of risk of high Hg exposure is low for most species.

Assessment of clinical outcomes associated with mercury concentrations in harbor seal pups (Phoca vitulina richardii) in central California.

Monomethyl mercury (MeHg+) from the diet can cause mild to severe neurotoxicosis in fish-eating mammals. Chronic and low-level in utero exposure also can be neurotoxic, as documented in laboratory animal studies and epidemiologic investigations. In free-ranging animals, it is challenging to study low-level exposure related neurotoxicosis, and few studies have investigated the relationship between mercury (Hg) and adverse outcomes in wild populations. Relative to Hg concentrations on admission we evaluated different types of behaviors for 267 Pacific harbor seal (HS; Phoca vitulina richardii) pups at The Marine Mammal Center from 2015 to 2019 during rehabilitation after stranding and maternal separation. Admitted HS pups underwent a clinical exam; including sex and weight determination, and hair (partly lanugo grown in utero) and blood samples were collected for total Hg concentration ([THg]) determination. All pups were monitored weekly (behavior assessments included response to tactile stimulation, movement, swimming, interactions with other seals, hand feeding, and feeding independently), and days in rehabilitation and survival were recorded. There was a significant negative correlation between [THg] and responses to tactile stimulation and movements, measured in both hair and whole blood (p < 0.05). This relationship was found both during the intensive care unit (ICU) stage, and during the pool stage of rehabilitation. Additionally, there was a significant association between greater [THg] and number of days spent in rehabilitation, although there was no relationship between [THg] and survival. There was a significant sex difference, with greater [THg] in female pups, which contrasts with previously published findings in juvenile and adult harbor seals. Our findings support small, but significant associations between gestational THg exposure and clinical effects for tactile sensory response and movement, and longer rehabilitation durations for HS pups, although there was considerable variability among animals.

Synanthropic primates in Asia: potential sentinels for environmental toxins.

Macaques are similar to humans both physiologically and behaviorally. In South and Southeast Asia they are also synanthropic, ecologically associated with humans. Synanthropy with humans raises the possibility that macaques come into contact with anthropogenic toxicants, such as lead and mercury, and might be appropriate sentinels for human exposures to certain toxic materials. We measured lead (Pb) and mercury (Hg) levels and characterized the stable isotopic compositions of delta(15)N and delta(13)C in hair from three groups of free-ranging macaques at the Swoyambhu temple in Kathmandhu, Nepal, an urban population that has abundant contact with humans. Hair lead levels were significantly higher among young macaques and differed among the three groups of macaques that were sampled. Hair Hg levels were low. No statistical association was found between stable isotopic compositions (delta(15)N and delta(13)C) and Pb and Hg levels. Our data did not find evidence that lead levels were associated with diet. We conclude that, in this population of macaques, behavioral and/or physiologic factors may play a significant role in determining exposure to lead. Chemical analysis of hair is a promising, noninvasive technique for determining exposure to toxic elements in free-ranging nonhuman primates.

Mercury concentrations in Southern Beaufort Sea polar bears: variation based on stable isotopes of carbon and nitrogen.

Total Hg concentration was measured in hair and whole blood of 52 adult Southern Beaufort Sea polar bears (Ursus maritimus) captured in the spring of 2005. Stable isotopic signatures (i.e., 13C/12C, delta13C; 15N/14N, delta15N) in hair and two blood compartments (packed blood cells/clot and serum) were determined to assess the variation of Hg concentrations among polar bears in relation to their feeding ecology and other biological factors. Concentrations of Hg in hair and blood (2.2-23.9 microg/g dry wt and 0.007-0.213 microg/g wet wt, respectively) were within the range of values previously reported for polar bears in Canada and East Greenland. Mercury concentration in hair from females was higher than that in hair from males, and concentration was related to interactions between delta13C, delta15N, and longitude of capture location. Mercury concentrations in hair were inversely correlated to delta13C in hair and blood, suggesting that polar bears with greater total Hg concentrations fed more on pelagic prey, such as ringed seals or beluga whale, than on benthic prey. Variability in Hg concentrations in polar bear hair and blood may be the result of intraspecific or regional variation in prey selection rather than strictly trophic level interactions.

Inorganic nutrients and contaminants in subsistence species of Alaska: linking wildlife and human health.

OBJECTIVES: To determine inorganic nutrient and contaminant concentrations in subsistence foods consumed by Alaska Natives, concentration changes related to common preparation methods and provide a basic risk-benefit analysis for these foods. STUDY DESIGN: Eleven essential and six non-essential elements were measured in foods derived from spotted seals and sheefish. METHODS: Essential nutrients in foodstuffs were compared to Daily Recommended Intake (DRI) criteria. Non-essential elements were compared to Tolerable Daily Intake Limits (TDIL). These comparisons serve as a risk-benefit analysis, not as consumption advice. RESULTS: Cooking altered nutrient and contaminant concentrations. Spotted seal muscle and kidney are rich in Fe and Se; liver in Cu, Fe, Mo and Se; and sheefish muscle in Se. TDIL was exceeded in a 100 g serving of seal for THg in raw and fried liver and boiled kidney; MeHg in dried muscle and raw and fried liver; Cd in raw and boiled kidney; and As in raw and rendered blubber. Arsenic exceeded TDIL in sheefish muscle. However, toxicity potential is likely reduced by the element form (i.e., organic As, inorganic Hg) and the presence of protective nutrients such as Se. CONCLUSIONS: Preparation methods alter wildlife tissues from their raw state, significantly affecting element concentrations. Direct evaluation of actual food items is warranted to determine risk-benefit ratios of traditional diets. Traditional foods provide many essential nutrients with a very limited risk from contaminants. We encourage continued consumption of traditional foods, and urge public health agencies to develop applicable models for providing consumption advice, incorporating food processing considerations.