Liver and renal histopathology of North Atlantic long-finned pilot whales (Globicephala melas) contaminated with heavy metals and organochlorine compounds

Abstract

Long-finned pilot whales (Globicephala melas) from the Faroe Islands are known to be heavily polluted with contaminants, such as mercury (Hg) and organochlorine compounds (OC). This is postulated to exert adverse health effects on whales as well as the human population who rely on its meat and blubber as food sources. It was therefore decided to conduct a screening pilot study to determine contaminant concentrations and histopathology of liver and renal tissues in a total of 14 specimens from this subpopulation. In blubber, the mean ∑OC concentration was 31,887 ng g−1 lw (range: 18,170–47,425 ng g−1 lw) of which ∑PCB concentration was 23,416 ng g−1 lw (range: 13,947–34,543 ng g−1 lw; n = 3). In liver, mean Hg concentration was 138 µg−1 ww (range: 54–351 µg g−1 ww; n = 7) and mean cadmium (Cd) concentration 15 µg g−1 ww (range: 7–31 µg g−1 ww; n = 7). In the kidney, the mean Cd concentration was 36 µg g−1 ww (range: 23–47 µg g−1 ww; n = 7). Of the liver Hg concentrations, two were at the suggested toxic threshold levels of 60 µg g−1 ww and five were 2–6-fold above. Liver selenium (Se) : Hg was on average 1.11 (range: 0.97–1.41; n = 7) indicating that Se was in excess, which decreased the risk of acute Hg poisoning. Histopathological examinations showed high prevalence (>35%) of renal glomerular arteriosclerosis, glomerular capillary dilatation, dilatation and hyalinization of Bowman's space/capsule and tubular hyaline casts. In liver tissue, high prevalence was found for portal cell infiltrates, lipid granulomas, hepatocytic lipid accumulation, bile duct proliferation, lipid-filled Ito cells, and focal necrosis. In a single juvenile male, 4 of 8 renal and 3 of 7 liver lesions were present. Cadmium concentrations increased significantly in the presence of glomerular arteriosclerosis and a similar trend was found for tubular hyaline casts. Based on these findings, as well as the nature of the lesions, data indicate that the histopathological changes were a result of age and that contaminants are likely to be the co-factors in the development in at least three renal and four liver lesions.