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Daniel Martineau,¹ Karin Lemberger,¹ André Dallaire,¹ Philippe Labelle,¹ Thomas P. Lipscomb,² Pascal Michel,³ and Igor Mikaelian⁴

¹Département de Pathologie et Microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal, St. Hyacinthe, Québec, Canada; ²Department of Veterinary Pathology, Armed Forces Institute of Pathology, Washington, DC, USA; ³Faculté de Médecine Vétérinaire, Université de Montréal, St. Hyacinthe, Québec Canada; ⁴Idexx Veterinary Sciences, West Sacramento, California, USA

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. Key words: aluminum, beluga, cancer, cetaceans, pollution, polycyclic aromatic hydrocarbons, whale, wildlife. Environ Health Perspect 110:285-292 (2002) . [Online 12 February 2002]

http://ehpnet1.niehs.nih.gov/docs/2002/110p285-292martineau/ abstract.html

Address correspondence to D. Martineau, Département de Pathologie et Microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal, St. Hyacinthe, Québec J2S 7C6 Canada. Telephone: (450) 773-8521. Fax: (450) 778-8113. E-mail: martinea@medvet.umontreal.ca

Incidence data were provided to Health Canada from the Canadian Cancer registry at Statistics Canada. We gratefully acknowledge the cooperation of the provincial and territorial cancer registries, which supply the data to Statistics Canada. We thank S. De Guise, S. Lair, R.J. Letcher, L. Measures, and R. Norstrom for helpful discussions. We thank R. Plante and C. Guimont (Filmar) for recovering and transporting carcasses to our facility over the last 15 years, all students who helped with postmortem examinations, and our colleagues at the FMV for their consistent support.

We acknowledge the help of the Centre Océanographique de Rimouski for logistic support, and the financial support of World Wildlife Fund Canada, Alcan, Fisheries and Oceans Canada, Fondation de la Faune du Québec, Société des Parcs du Québec, and NSERC.

Received 25 May 2001 ; accepted 20 September 2001.