Saint-Hyacinthe, February 25 2002 - The beluga population in the St. Lawrence Estuary is affected by an abnormally high incidence of cancer. This finding emerges from a study by Dr. Daniel Martineau of the Université de Montréal Faculty of Veterinary Medicine, which will soon be published in the journal Environmental Health Perspective.
From 1983 to 1999, 263 beluga carcasses found on the shores of the St. Lawrence were reported to Fisheries and Oceans Canada; 129 carcasses were examined at the Faculty of Veterinary Medicine and of these 100 were reasonably well preserved. Dr. Martineau and his team found that cancer was the cause of death of 18% of young belugas and 27% of adult belugas. The cancer rate in this population, and especially the rate of cancer of the digestive system, is much higher than the rates reported in domestic animals. "Percentages like this have never been observed in a population of wild animals anywhere in the world," notes Daniel Martineau. "To the best of our knowledge, this is the first time a rate of cancer comparable to the rates found in humans has been documented in mammals."
The researchers establish a link between these findings and polycyclic aromatic hydrocarbons (PAHs), compounds that include powerful carcinogens, found in the sediments of the Saguenay. It has been shown that these compounds are produced by the aluminum smelters located at the source of the Saguenay River. The production of one ton of aluminium generates roughly one-half a ton of PAHs. According to Alcan the actual quantity of PAHs produced and released into the air by the five aluminium smelters in the Saguenay was 1488 tons in 1990 and 313 tons in 1997.
UdeM researchers, working in conjunction with the Oak Ridge, Tennessee toxicology laboratory, have already shown that tissues from St. Lawrence beluga are contaminated with PAHs. Belugas, mammals that can dive to extreme depths, are one of the few toothwhales that feed significantly on invertebrates which live in sediments.
Aluminum workers from the Saguenay-Lac Saint Jean region are affected by a high incidence of bladder and lung cancers. In 1984, researchers at McGill University demonstrated that exposure to the PAHs generated within the smelters were most likely
responsible for these cancers. Researchers at Université de Montréal note that the incidence of cancer of the digestive system in people living in the Saguenay Lac Saint-Jean area is elevated significantly over the rest of Canada and Quebec. Drinking water used by the towns located along the Saguenay River is taken from surface waters exposed to airborne PAH contamination.
Two researchers at Fisheries and Oceans Canada had earlier identified the amplitude and the persistence of this threat for public health. In 1990, the two researchers estimated that 40,000 tons of PAH produced by the aluminium smelters had accumulated in the Saguenay watershed over the years, of which 20 tons are released into the Saguenay River annually.
The abstract of the study done by the Faculty of Veterinary Medicine at UdeM is available online at: http://ehpnet1.niehs.nih.gov/docs/2002/110p285-292martineau/abstract.html and the full text will appear in the March edition of the review Environmental Health Perspectives.
Université de Montréal ranks second among Canadian universities in terms of research grants and contracts. With its two affiliated schools, the École Polytechnique and the École des HEC, it offers undergraduate, master's and doctorate programs of study in almost all fields of knowledge. It has a student body of close to 50,000 and awards more than 2,500 master's and doctorate degrees each year.
Dr. Daniel Martineau will be available to answer questions Monday, February 25, between 3pm and 4pm.
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Information:
Sophie Langlois
Press Agent
Université de Montréal
(514) 343-7704
sophie.langlois@umontreal.ca
