Pollution blamed for cancer ravaging Quebecs whales
NewScientist.com news service
Over a quarter of all the deaths of endangered adult beluga whales in Canada's Saint Lawrence Estuary are caused by cancer, local researchers have found.
Such high rates of cancer are unprecedented in wild animals, apart from fish. Industrial pollution is the most likely cause, the veterinary pathologists claim.
Beluga whales live entirely in the Arctic and sub-Arctic. There are approximately 70,000 worldwide and about 650 of these live in a small region of the St Lawrence Estuary in Quebec. Between 1983 and 1999, 263 dead whales were reported and Daniel Martineau of the University of Montreal and his team conducted were able to conduct 100 autopsies.
He found that cancer, particularly cancer of the digestive tract, was the cause of death of 18 per cent of juvenile belugas and 27 per cent of the adults.
"Cancer in wildlife is not very well studied but such a percentage has never been observed among wild animals anywhere else in the world," he says. "In dolphins and terrestrial animals, the figure is closer to two per cent." The cancers found in Saint Lawrence beluga represent about 40 per cent of all cancers ever reported in cetaceans worldwide, he says.
The autopsies revealed evidence for a high level of exposure to carcinogenic polycyclic aromatic hydrocarbons (PAHs). Most PAHs in the St Lawrence Estuary region originate from an aluminium plant upstream, Martineau says.
The belugas are exposed because they dig around in contaminated sediments, and eat invertebrates that live in these sediments.
Martineau also found high levels of PCBs, another carcinogen, in the adult Lawrence Estuary belugas, as well as heavy metals, which weaken the immune system. People living in the region suffer higher rates of lung, urinary and digestive cancers than those living elsewhere in Quebec and Canada. Martineau says the aluminium company should pay for research into the effects of PAHs on the whales' health.
A spokesman for the Alcan aluminium plant says it has been working hard to slash its PAH output. "We've reduced PAH emissions in the air by 82 per cent, and new technology introduced last year will reduce it by a further 35 per cent. We are concerned and we've worked to improve the situation."