Cancer rates in Gros-Mécatina no higher than rest of Quebec: report

Quebec public health officials are reassuring residents of a Lower North Shore municipality that they don't run a higher risk of getting cancer, just because of where they live.

However, Dr. Stéphane Trépanier, the head of public health for the province's North Shore, said that because officials don't have clear answers to explain a recent cluster of brain cancer deaths in Gros-Mécatina, they will continue to monitor reports of any new cases and investigate further if need be.

A comparative analysis of overall rates of cancer carried out by public health has found that the rate is no greater in the municipality of Gros-Mécatina, a small community located about 537 kilometres east of Sept-Îles, than it is in North Shore communities generally or across Quebec.

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For some cancers, such as breast cancer, the rate is actually lower. For others, such as non-Hodgkin's lymphoma, and colorectal and prostate cancer, the rate is higher.

Trépanier held a public meeting Tuesday with residents in La Tabatière, a village part of Gros-Mécatina, to present two reports — one on the rate of all cancers in the village and one on brain cancers specifically.

Over a 10-year period, four cases of brain cancer were reported in the small municipality, where the population is about 458 people — a much higher rate than in the general Quebec population.

That's what led the municipality to call for an investigation last year and residents to start asking questions because of worries about possible environmental contamination. There's also been a much higher rate there of non-Hodgkin's lymphoma than elsewhere on the North Shore or across Quebec.

"We're so small and everybody knows everybody, and it seemed to us that a lot of people were passing away due to cancer," said Gros-Mécatina Mayor Randy Jones, adding that it was a great strain on the community.

"But yes, I think for the most part people felt reassured, just knowing someone is looking at it. Twice he's [Dr. Trépanier] been here and met with the public. And he promised to get more sampling done to see if people were exposed at one time or another to pollutants. But some of the cancers we have are rare, and that's where the problem is," Jones said.

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In the report on brain cancer, public health concluded that "all the evidence suggests that there is no more current exposition to environmental risk factors for brain cancer in La Tabatière".

Residents could have been exposed to certain contaminants in the past, the report said, "but nearly all those contaminant sources don't exist anymore." Moreover, "the cancers are very unlikely explained by those expositions given the weakness of the studies trying to find a link with brain cancer."

Trépanier also said it's possible the cluster of cases could simply be a coincidence.

Environmental factors not to blame

The public health investigation looked at a range of possible factors, including environmental contamination.

As part of the report, investigators also conducted air and water sampling, and residents were asked to fill out a questionnaire about lifestyle issues and family medical history.

In the 1990's, studies showed levels of polychlorinated biphenyls (PCBs), once used in Hydro-Québec transformers, and mercury were seven times higher among people from La Tabatière than elsewhere in Quebec. 

That contamination came mainly from the consumption of seabird eggs, as well as mussels and clams.

But the report said there has never been any conclusive studies linking those environmental factors with brain cancer, and levels of those contaminants have dropped off.

"The only recognized environmental risk factor is radiation," the report said, adding "no source was identified."