Radionuclude Levels in Caribou of Northern Alaska in 1995-96

Caribou (Rangifer tarandus) were sampled (1995-96) from a mortality event near the Project Chariot site (the location of a radiotracer experiment in northwestern Alaska during the 1960s) and reference sites. Radionuclide levels in muscle and bone and the cause(s) of the mortality were determined because of local residents' concerns. Bone gross alpha mean activity (n=65) was 130.0 Bq/kg, and varied significantly (p<0.01) from 73.3 to 168.0 Bq/kg among locations. Bone gross beta mean activity was 510.4, and muscle gross beta mean activity was 9.78 Bq/kg. Bone strontium-90 mean activity (n=58) was 137.8 Bq/kg. Muscle potassium-40 mean activity (n=65) was 83.0 Bq/kg, and varied significantly from 76.0 to 104.4 Bq/kg among locations. Muscle cesium-137 mean activity (n=65) was 6.67 Bq/kg, ranged significantly from 0.74 to 15.6 Bq/kg by location, and increased with increasing body condition score. Bone potassium-40 mean activity ranged from 18.9 to 47.4 Bq/kg, and muscle strontium-90 ranged from 8.89 to 20.0 Bq/kg. Radionuclide concentrations were at expected levels. In some cases, they were low compared to those in Canadian caribou studies.En 1995 et 1996, on a prélevé des échantillons de caribou (Rangifer tarandus) morts accidentellement près de l'emplacement du projet Chariot (N.-O. de l'Alaska), sur les lieux d'une expérience menée avec des radiotraceurs dans les années 1960 et sur des lieux de référence. On a déterminé les niveaux de radionucléides dans les muscles et les os ainsi que la ou les causes de mortalité afin de répondre aux questions que se posaient les résidents de la région. La radioactivité moyenne brute alpha dans les tissus osseux (n = 65) était de 130,0 Bq/kg, et variait largement (p < 0,01), de 73,3 à 168,0 Bq/kg selon les emplacements. La radioactivité moyenne brute bêta dans les tissus osseux était de 510,4 et celle dans les tissus musculaires était de 9,78 Bq/kg. La radioactivité moyenne du strontium 90 (n = 58) était de 137,8 Bq/kg. La radioactivité moyenne du potassium 40 (n = 65) dans les tissus musculaires était de 183,0 Bq/kg, et elle variait largement, de 76,0 à 104,4 Bq/kg selon les emplacements. La radioactivité moyenne du césium 137 (n = 65) dans les tissus musculaires était de 6,67 Bq/kg et variait largement, de 0,74 à 15,6 Bq/kg selon l'emplacement; son augmentation suivait celle de la cote de l'état du corps. La radioactivité moyenne du potassium 40 dans les tissus osseux allait de 18,9 à 47,4 Bq/kg, et celle du strontium 90 dans les tissus musculaires allait de 8,89 à 20,0 Bq/kg. Les niveaux de concentration en radionucléides étaient ceux auxquels on s'attendait. Dans certains cas, ils étaient bas, par rapport à ceux d'études canadiennes sur le caribou

Blood dynamics of mercury and selenium in northern elephant seals during the lactation period

The effects of reproduction and maternal investment (i.e., milk transfer) on trace element levels remain poorly understood in marine mammals. We examined the blood dynamics of mercury (Hg) and selenium (Se) during lactation in the northern elephant seal (Mirounga angustirostris), a top predator from the North Pacific Ocean. Total Hg and Se levels were measured in whole blood and milk of 10 mother-pup pairs on days 5 and 22 of lactation. Both Hg and Se were transferred to offspring through the milk. Results suggested that the maternal transfer of Se was prominent during lactation, whereas the Hg transfer was larger during gestation. The lactation period affected Hg and Se levels in the blood of elephant seal mothers and pups. Physiological processes and their relationship to body condition should be considered carefully when interpreting trace element levels in the framework of biomonitoring.Peer reviewe

Radionuclide Contaminant Burdens in Arctic Marine Mammals Harvested During Subsistence Hunting

We conducted gamma spectrometric analyses on more than 200 arctic marine mammal tissue samples. These samples were primarily provided by subsistence hunters from northern Alaska, with a smaller number of samples from the Resolute region in Canada. The majority of samples (>90%) had detectable levels of the anthropogenic radionuclide 137Cs, with a mean level observed in all samples of 0.67 Bq/kg dry weight ± 0.81 (SD). Converted to wet weight, the mean was 0.21 Bq/kg ± 0.19 SD. The median activity observed was 0.45 Bq/kg dry weight (0.18 Bq/kg wet weight) with a range from detection limits to 6.7 Bq/kg dry weight (1.1 Bq/kg wet weight). These findings confirm expectations that current anthropogenic gamma emitter burdens in marine mammals used in the North American Arctic as subsistence food resources are well below activities that would normally merit public health concern (~1000 Bq/kg wet weight). Some differences among species and tissues were observed. Beluga tissues had slightly higher mean burdens of 137Cs overall, and epidermis and muscle tissues in bowhead and beluga whales typically had higher burdens than other tissues analyzed. Low levels of the neutron activation product 108mAg (half-life 418 yr.), probably bioaccumulated from bomb fallout sources, were observed in 16 of 17 beluga livers analyzed, but were not found in any other tissues of beluga or in any other species sampled. A subset of 39 samples of various tissues was analyzed for the alpha and beta emitters 239,240Pu and 90Sr. Plutonium levels were near the threshold of detectability (~0.1 Bq/kg dry weight) in 6 of the 39 samples; all other samples had no detectable plutonium. A detectable level of 90Sr (10.3 ± 1.0 Bq/kg dry weight) was observed in only one of the 39 samples analyzed, a bowhead epidermis sample. Although the accumulation of 108mAg has not been previously reported in any marine mammal livers, all of our analytical measurements indicate that only very low levels of anthropogenic radioactivity are associated with marine mammals harvested and consumed in the North American Arctic.On a effectué des analyses gamma-spectrométriques sur plus de 200 échantillons de tissus prélevés sur des mammifères marins. La plupart de ces échantillons étaient fournis par des chasseurs de subsistance de l'Alaska septentrional, et un petit nombre venaient de la région de Resolute au Canada. La majorité des échantillons (> 90 p. cent) contenaient des niveaux détectables du radionucléide anthropique 137Cs, avec un niveau moyen observé dans tous les échantillons de 0,67 Bq/kg de poids sec ± 0,81 (écart-type). Convertie en poids frais, la moyenne était de 0,21 Bq/kg ± 0,19 d'écart-type. L'activité médiane observée était de 0,45 Bq/kg de poids sec (0,18 Bq/kg de poids frais) avec une fourchette allant des seuils de détection jusqu'à 6,7 Bq/kg de poids sec (1,1 Bq/kg de poids frais). Ces résultats confirment les réponses prévues, à savoir que les charges actuelles des émetteurs gamma anthropiques présentes chez les mammifères marins utilisés en Amérique du Nord comme ressource de subsistance sont bien inférieures aux niveaux qui voudraient normalement qu'on s'inquiète pour la santé publique (~1000 Bq/kg de poids frais). On a observé certaines différences dans les espèces et les tissus. Dans l'ensemble, les tissus prélevés sur le bélouga contenaient des charges moyennes de 137Cs légèrement plus élevées, et l'épiderme et les tissus musculaires de la baleine boréale et du bélouga avaient généralement des charges supérieures à celles trouvées dans les autres tissus analysés. Dans 16 des 17 foies de bélouga analysés, on a observé de faibles niveaux du produit d'activation neutronique 108mAg (demi-vie 418 années), dont la bioaccumulation est probablement due à des retombées de bombes atomiques, mais on n'en a observé aucune trace dans les autres tissus du bélouga ou de toute autre espèce échantillonnée. On a analysé un sous-ensemble de 39 échantillons provenant de tissus divers pour savoir s'ils contenaient des émetteurs alpha et bêta 239,240Pu et 90Sr. Dans 6 des 39 échantillons, les niveaux de plutonium étaient proches du seuil de détectabilité (~ 0,1 Bq/kg de poids sec), et on n'a pas trouvé de plutonium détectable dans aucun des autres échantillons. On a observé un niveau détectable de 90Sr (10,3 ± 1,0 Bq/kg de poids sec) dans un seul des 39 échantillons analysés, soit un échantillon d'épiderme de baleine boréale. Bien qu'on n'ait jamais rapporté auparavant une accumulation de 108mAg dans le foie d'un mammifère marin, toutes nos mesures analytiques révèlent que les mammifères marins faisant l'objet d'une activité d'exploitation et consommés dans l'Arctique nord-américain ne présentent que de très faibles niveaux de radioactivité anthropique

Investigation of Heavy Metals in a Large Mortality Event in Caribou of Northern Alaska

We measured element concentrations (As, Cd, Cu, Pb, Zn, Fe) and body condition (gross and histologic endpoints) of animals from a caribou (Rangifer tarandus) mortality event that occurred in Alaska, in the area of Point Hope and Cape Thompson (including the Chariot site), in 1995. These were compared to results from hunter-killed caribou from reference sites (Barrow and Teshekpuk Lake, Alaska) and from the area of a mine (Red Dog Mine) to determine whether heavy metals had played a role in the mortality event or whether any elements were at concentrations of concern for human consumers. Starvation and malnutrition were major factors leading to death or severe weakness, as very little or no fat (very low body condition scores) and serous atrophy of fat (observed as watery contents of the marrow cavity, with no apparent fat, and histologically) were more prevalent in caribou associated with the mortality event than in hunter-killed animals from reference sites. Accumulation of hepatic (liver) hemosiderin in Kupffer cells (macrophages) was noted as an indicator of cachexia. Concentrations of lead in feces and liver, copper in the rumen contents, and arsenic in muscle were higher in caribou harvested near Red Dog Mine, as might be expected in that mineral-rich area, but were not at levels of concern for toxicoses. Kidney concentrations of cadmium, which increased significantly with increasing age, present a potential concern for human consumers, and this is an expected finding. We concluded that caribou had starved and that heavy metals had played no role in the mortality event. Further investigation of regional mineral differences is required to understand the sources and transport mechanisms that explain these findings and to properly address mining activity. Mortality events on the north slope of Alaska are common and likely involve starvation as described here, but in most cases they are not investigated, even though recent industrial activities have heightened concern among some local residents and wildlife managers.On a mesuré la concentration en éléments (As, Cd, Cu, Pb, Zn, Fe) et l'état corporel (points limites bruts et histologiques) de caribous (Rangifer tarandus) prélevés lors d'un épisode de mortalité qui s'est produit en 1995 en Alaska, dans la région de Point Hope et de Cape Thompson (y compris le site Chariot). On a comparé ces résultats à ceux de caribous tués par des chasseurs à des emplacements témoins (Barrow et Teshekpuk Lake, en Alaska) et à proximité d'une mine (Red Dog Mine) pour trouver si les métaux lourds avaient joué un rôle dans l'épisode de mortalité ou si la concentration d'un ou plusieurs éléments pouvait constituer un risque pour la consommation humaine. La famine et la malnutrition étaient des facteurs majeurs ayant causé la mort ou une extrême faiblesse, vu que la présence minime ou l'absence de graisse (très basses notes d'état corporel) et une atrophie séreuse de la graisse (observée sous forme de contenu aqueux de la cavité médullaire, sans graisse visible, et à la suite de l'examen histologique) étaient plus courantes chez le caribou associé à l'épisode de mortalité que chez les animaux des emplacements témoins tués par les chasseurs. On a noté dans le foie une accumulation d'hémosidérine hépatique des cellules de Kupffer (cellules macrophages) témoignant d'une cachexie. La concentration de plomb dans les matières fécales et le foie, de cuivre dans le rumen et d'arsenic dans le tissu musculaire était plus élevée chez le caribou provenant de Red Dog Mine, comme on pouvait s'y attendre dans cette zone riche en minéraux, mais cette concentration n'atteignait pas un niveau pouvant provoquer des toxicoses. La concentration de cadmium dans le rein, qui augmentait de façon significative avec l'âge, pourrait constituer un risque pour la consommation humaine, ce qui n'est pas surprenant. On a conclu que les caribous étaient morts de faim et que les métaux lourds n'avaient joué aucun rôle dans l'épisode de mortalité. Il faudrait effectuer des recherches plus poussées sur les différences régionales en minéraux afin de comprendre les mécanismes d'origine et de transport qui expliquent ces résultats et d'aborder comme il le faut les activités minières. Les épisodes de mortalité sont courants sur le versant Nord de l'Alaska et sont probablement liés à la famine, comme le décrit cet article, mais dans la plupart des cas ils ne font pas l'objet d'une enquête, même si l'activité industrielle récente est un sujet qui préoccupe de plus en plus certains résidents et gestionnaires locaux de la faune

Radionuclide Contaminant Burdens in Arctic Marine Mammals Harvested During Subsistence Hunting

We conducted gamma spectrometric analyses on more than 200 arctic marine mammal tissue samples. These samples were primarily provided by subsistence hunters from northern Alaska, with a smaller number of samples from the Resolute region in Canada. The majority of samples (>90%) had detectable levels of the anthropogenic radionuclide 137Cs, with a mean level observed in all samples of 0.67 Bq/kg dry weight ± 0.81 (SD). Converted to wet weight, the mean was 0.21 Bq/kg ± 0.19 SD. The median activity observed was 0.45 Bq/kg dry weight (0.18 Bq/kg wet weight) with a range from detection limits to 6.7 Bq/kg dry weight (1.1 Bq/kg wet weight). These findings confirm expectations that current anthropogenic gamma emitter burdens in marine mammals used in the North American Arctic as subsistence food resources are well below activities that would normally merit public health concern (~1000 Bq/kg wet weight). Some differences among species and tissues were observed. Beluga tissues had slightly higher mean burdens of 137Cs overall, and epidermis and muscle tissues in bowhead and beluga whales typically had higher burdens than other tissues analyzed. Low levels of the neutron activation product 108mAg (half-life 418 yr.), probably bioaccumulated from bomb fallout sources, were observed in 16 of 17 beluga livers analyzed, but were not found in any other tissues of beluga or in any other species sampled. A subset of 39 samples of various tissues was analyzed for the alpha and beta emitters 239,240Pu and 90Sr. Plutonium levels were near the threshold of detectability (~0.1 Bq/kg dry weight) in 6 of the 39 samples; all other samples had no detectable plutonium. A detectable level of 90Sr (10.3 ± 1.0 Bq/kg dry weight) was observed in only one of the 39 samples analyzed, a bowhead epidermis sample. Although the accumulation of 108mAg has not been previously reported in any marine mammal livers, all of our analytical measurements indicate that only very low levels of anthropogenic radioactivity are associated with marine mammals harvested and consumed in the North American Arctic.On a effectué des analyses gamma-spectrométriques sur plus de 200 échantillons de tissus prélevés sur des mammifères marins. La plupart de ces échantillons étaient fournis par des chasseurs de subsistance de l'Alaska septentrional, et un petit nombre venaient de la région de Resolute au Canada. La majorité des échantillons (> 90 p. cent) contenaient des niveaux détectables du radionucléide anthropique 137Cs, avec un niveau moyen observé dans tous les échantillons de 0,67 Bq/kg de poids sec ± 0,81 (écart-type). Convertie en poids frais, la moyenne était de 0,21 Bq/kg ± 0,19 d'écart-type. L'activité médiane observée était de 0,45 Bq/kg de poids sec (0,18 Bq/kg de poids frais) avec une fourchette allant des seuils de détection jusqu'à 6,7 Bq/kg de poids sec (1,1 Bq/kg de poids frais). Ces résultats confirment les réponses prévues, à savoir que les charges actuelles des émetteurs gamma anthropiques présentes chez les mammifères marins utilisés en Amérique du Nord comme ressource de subsistance sont bien inférieures aux niveaux qui voudraient normalement qu'on s'inquiète pour la santé publique (~1000 Bq/kg de poids frais). On a observé certaines différences dans les espèces et les tissus. Dans l'ensemble, les tissus prélevés sur le bélouga contenaient des charges moyennes de 137Cs légèrement plus élevées, et l'épiderme et les tissus musculaires de la baleine boréale et du bélouga avaient généralement des charges supérieures à celles trouvées dans les autres tissus analysés. Dans 16 des 17 foies de bélouga analysés, on a observé de faibles niveaux du produit d'activation neutronique 108mAg (demi-vie 418 années), dont la bioaccumulation est probablement due à des retombées de bombes atomiques, mais on n'en a observé aucune trace dans les autres tissus du bélouga ou de toute autre espèce échantillonnée. On a analysé un sous-ensemble de 39 échantillons provenant de tissus divers pour savoir s'ils contenaient des émetteurs alpha et bêta 239,240Pu et 90Sr. Dans 6 des 39 échantillons, les niveaux de plutonium étaient proches du seuil de détectabilité (~ 0,1 Bq/kg de poids sec), et on n'a pas trouvé de plutonium détectable dans aucun des autres échantillons. On a observé un niveau détectable de 90Sr (10,3 ± 1,0 Bq/kg de poids sec) dans un seul des 39 échantillons analysés, soit un échantillon d'épiderme de baleine boréale. Bien qu'on n'ait jamais rapporté auparavant une accumulation de 108mAg dans le foie d'un mammifère marin, toutes nos mesures analytiques révèlent que les mammifères marins faisant l'objet d'une activité d'exploitation et consommés dans l'Arctique nord-américain ne présentent que de très faibles niveaux de radioactivité anthropique

The role of melano‐macrophage aggregates in the storage of mercury and other metals: An example from yelloweye rockfish (Sebastes ruberrimus)

Melano‐macrophage aggregates, collections of specialized cells of the innate immune system of fish, are considered a general biomarker for contaminant toxicity. To elucidate further the relationship between macrophage aggregates and metals exposure, yelloweye rockfish (Sebastes ruberrimus), a long‐lived species, were sampled from the east and west coasts of Prince of Wales Island, Alaska. Metals concentrations in livers (inorganic Hg, methyl mercury, Se, Ni, Cd, Cu, Zn) and spleens (inorganic Hg and methyl mercury) were determined, as well as their correlations with melano‐macrophage aggregate area. Sections of liver tissue were analyzed by laser ablation‐inductively coupled plasma–mass spectrometry to determine how metals were spatially distributed between hepatocytes and macrophage aggregates. The concentration of inorganic Hg in whole tissue was the best predictor of macrophage area in yelloweye livers and spleens. Macrophage aggregates had higher relative concentrations than most metals compared with the surrounding hepatocytes. However, not all metals were accumulated to the same degree, as evidenced by differences in the ratios of metals in macrophages compared with hepatocytes. Laser ablation data were corroborated with the results of X‐ray synchrotron fluorescence imaging of a yelloweye liver section. Hepatic macrophage aggregates in yelloweye rockfish may play an important role in the detoxification and storage of Hg and other metals. Environ Toxicol Chem 2015;34:1918–1925. © 2015 SETACPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112257/1/etc3009.pd

Mercury toxicity in livers of northern pike (Esox lucius) from Isle Royale, USA

Author Posting. © Elsevier B.V., 2007. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology 147 (2008): 331-338, doi:10.1016/j.cbpc.2007.12.003.Many laboratory studies have documented that mercury can be toxic to fish, but it is largely unknown if mercury is toxic to fish in their natural environments. The objective of our study was to investigate the toxic effects of mercury on northern pike (Esox lucius) at Isle Royale, Michigan. In 124 northern pike from eight inland lakes, concentrations of total mercury in skin-on fillets ranged from 0.069 to 0.622 µg/g wet wt. Concentrations of total mercury in livers increased exponentially compared with concentrations in fillets, to a maximum of 3.1 µg/g wet wt. Methylmercury constituted a majority of the mercury in livers with total mercury concentrations <0.5 µg/g wet wt, but declined to 28-51% of the mercury in livers with total mercury concentrations >0.5 µg/g wet wt. Liver color (absorbance at 400 nm) varied among northern pike and was positively related to liver total mercury concentration. The pigment causing variation in liver color was identified as lipofuscin, which results from lipid peroxidation of membranous organelles. An analysis of covariance revealed lipofuscin accumulation was primarily associated with mercury exposure, and this association obscured any normal accumulation from aging. We also documented decreased lipid reserves in livers and poor condition factors of northern pike with high liver total mercury concentrations. Our results suggest (i) northern pike at Isle Royale are experiencing toxicity at concentrations of total mercury common for northern pike and other piscivorous fish elsewhere in North America and (ii) liver color may be useful for indicating mercury exposure and effects in northern pike at Isle Royale and possibly other aquatic ecosystems and other fish species.Financial support was provided by the U.S. Environmental Protection Agency STAR Graduate Fellowship Program to P.E.D

Stable isotope food-web analysis and mercury biomagnification in polar bears ( Ursus maritimus )

Mercury (Hg) biomagnification occurs in many ecosystems, resulting in a greater potential for toxicological effects in higher-level trophic feeders. However, Hg transport pathways through different food-web channels are not well known, particularly in high-latitude systems affected by the atmospheric Hg deposition associated with snow and ice. Here, we report on stable carbon and nitrogen isotope ratios, and Hg concentrations, determined for 26, late 19th and early 20th century, polar bear ( Ursus maritimus ) hair specimens, collected from catalogued museum collections. These data elucidate relationships between the high-latitude marine food-web structure and Hg concentrations in polar bears. The carbon isotope compositions of polar bear hairs suggest that polar bears derive nutrition from coupled food-web channels, based in pelagic and sympagic primary producers, whereas the nitrogen isotope compositions indicate that polar bears occupy > fourth-level trophic positions. Our results show a positive correlation between polar bear hair Hg concentrations and δ 15 N. Interpretation of the stable isotope data in combination with Hg concentrations tentatively suggests that polar bears participating in predominantly pelagic food webs exhibit higher mercury concentrations than polar bears participating in predominantly sympagic food webs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73930/1/j.1751-8369.2009.00114.x.pd

Are liver and renal lesions in East Greenland polar bears (Ursus maritimus) associated with high mercury levels?

BACKGROUND: In the Arctic, polar bears (Ursus maritimus) bio-accumulate mercury as they prey on polluted ringed seals (Phoca hispida) and bearded seals (Erignathus barbatus). Studies have shown that polar bears from East Greenland are among the most mercury polluted species in the Arctic. It is unknown whether these levels are toxic to liver and kidney tissue. METHODS: We investigated the histopathological impact from anthropogenic long-range transported mercury on East Greenland polar bear liver (n = 59) and kidney (n = 57) tissues. RESULTS: Liver mercury levels ranged from 1.1–35.6 μg/g wet weight and renal levels ranged from 1–50 μg/g wet weight, of which 2 liver values and 9 kidney values were above known toxic threshold level of 30 μg/g wet weight in terrestrial mammals. Evaluated from age-correcting ANCOVA analyses, liver mercury levels were significantly higher in individuals with visible Ito cells (p < 0.02) and a similar trend was found for lipid granulomas (p = 0.07). Liver mercury levels were significantly lower in individuals with portal bile duct proliferation/fibrosis (p = 0.007) and a similar trend was found for proximal convoluted tubular hyalinisation in renal tissue (p = 0.07). CONCLUSION: Based on these relationships and the nature of the chronic inflammation we conclude that the lesions were likely a result of recurrent infections and ageing but that long-term exposure to mercury could not be excluded as a co-factor. The information is important as it is likely that tropospheric mercury depletion events will continue to increase the concentrations of this toxic heavy metal in the Sub Arctic and Arctic marine food webs

Sometimes Sperm Whales (Physeter macrocephalus) Cannot Find Their Way Back to the High Seas: A Multidisciplinary Study on a Mass Stranding

BACKGROUND: Mass strandings of sperm whales (Physeter macrocephalus) remain peculiar and rather unexplained events, which rarely occur in the Mediterranean Sea. Solar cycles and related changes in the geomagnetic field, variations in water temperature and weather conditions, coast geographical features and human activities have been proposed as possible causes. In December 2009, a pod of seven male sperm whales stranded along the Adriatic coast of Southern Italy. This is the sixth instance from 1555 in this basin. METHODOLOGY/PRINCIPAL FINDINGS: Complete necropsies were performed on three whales whose bodies were in good condition, carrying out on sampled tissues histopathology, virology, bacteriology, parasitology, and screening of veins looking for gas emboli. Furthermore, samples for age determination, genetic studies, gastric content evaluation, stable isotopes and toxicology were taken from all the seven specimens. The animals were part of the same group and determined by genetic and photo-identification to be part of the Mediterranean population. Causes of death did not include biological agents, or the "gas and fat embolic syndrome", associated with direct sonar exposure. Environmental pollutant tissue concentrations were relatively high, in particular organochlorinated xenobiotics. Gastric content and morphologic tissue examinations showed a prolonged starvation, which likely caused, at its turn, the mobilization of lipophilic contaminants from the adipose tissue. Chemical compounds subsequently entered the blood circulation and may have impaired immune and nervous functions. CONCLUSIONS/SIGNIFICANCE: A multi-factorial cause underlying this sperm whales' mass stranding is proposed herein based upon the results of postmortem investigations as well as of the detailed analyses of the geographical and historical background. The seven sperm whales took the same "wrong way" into the Adriatic Sea, a potentially dangerous trap for Mediterranean sperm whales. Seismic surveys should be also regarded as potential co-factors, even if no evidence of direct impact has been detected