Cancer in wildlife, a case study: beluga from the St. Lawrence estuary, Québec, Canada.

Abstract

A population of approximately 650 beluga (Delphinapterus leucas) inhabits a short segment of the St. Lawrence estuary (SLE). Over 17 years (1983-1999), we have examined 129 (or 49%) of 263 SLE beluga carcasses reported stranded. The major primary causes of death were respiratory and gastrointestinal infections with metazoan parasites (22%), cancer (18%), and bacterial, viral, and protozoan infections (17%). We observed cancer in 27% of examined adult animals found dead, a percentage similar to that found in humans. The estimated annual rate (AR) of all cancer types (163/100,000 animals) is much higher than that reported for any other population of cetacean and is similar to that of humans and to that of hospitalized cats and cattle. The AR of cancer of the proximal intestine, a minimum figure of 63 per 100,000 animals, is much higher than that observed in domestic animals and humans, except in sheep in certain parts of the world, where environmental contaminants are believed to be involved in the etiology of this condition. SLE beluga and their environment are contaminated by polycyclic aromatic hydrocarbons (PAHs) produced by the local aluminum smelters. The human population living in proximity of the SLE beluga habitat is affected by rates of cancer higher than those found in people in the rest of Québec and Canada, and some of these cancers have been epidemiologically related to PAHs. Considered with the above observations, the exposure of SLE beluga to PAHs and their contamination by these compounds are consistent with the hypothesis that PAHs are involved in the etiology of cancer in these animals.

Particulate hexavalent chromium is cytotoxic and genotoxic to the North Atlantic right whale (Eubalaena glacialis) lung and skin fibroblasts

“…Particulate Cr(VI)-induced lung cancer is a major concern in humans, but because of the small population of right whales, it is unknown if this is a concern for this species. Cancer has been reported in cetaceans such as the St. Lawrence Estuary (Canada) Beluga whales [Martineau et al, 2002]. These whales are highly contaminated with pollutants, and exposure to PAHs have been suggested as the etiology of cancer [Martineau et al, 2002] but Cr(VI) has not been studied in this species.…”

“…Cancer has been reported in cetaceans such as the St. Lawrence Estuary (Canada) Beluga whales [Martineau et al, 2002]. These whales are highly contaminated with pollutants, and exposure to PAHs have been suggested as the etiology of cancer [Martineau et al, 2002] but Cr(VI) has not been studied in this species. Of greater concern for the right whales is that the Cr(VI) particulates can slowly dissolve over time and release soluble Cr(VI) ions into the body.…”

Infection and cancer in multicellular organisms

“…These infection-associated tumours emphasize the need to consider infectious causation when the tumours are linked to immunosuppressive pollutants, or more generally with human activities (e.g. increased incidences of cancers in whales and fish that are exposed to such pollutants; [139,140]). …”

Primary pheochromocytoma in an Asian Water Buffalo (Bubalus bubalis)

“…Pheochromocytomas are generally enlarged and replaced affected adrenal gland and small ones are completely surrounded by compressed adrenal cortex. They have been reported most frequently in cattle and dogs and rare in other domestic animals (Meuten, 2002), some strains of laboratory rats (Sheehy et al, 1997) and wild animals, which include a wolfdog (Sako et al, 2001), a Nicobar Pigeon (Caloenas nicobarica) (Sonnenfield et al, 2002), callitrichids (Garner, 2001) and spotted dolphins (Stenella frontalis) (Martineau et al, 2002). Adrenal tumors are very rare in wild ruminants.…”