Reading the 91 page Alberta Cancer Board study on cancer rates in Fort Chipewyan one has to remember what the stated limitation of the study were to be sure you have an accurate context.
Those limitations were the small population size, the small number of cancer incidences in the study, migration patterns and impacts were not considered nor was any specific matters of potential unique characteristics of First Nations people in Fort Chip. Finally the study was not designed to determine the causes of cancers in Fort Chip nor if living in Fort Chip elevated cancer levels.
That said, the study found the incidence of overall cancer was higher than expected but could not say if is was due to chance of increased risk in the community. This could be determined by tracking more residents who have lived in the community for the past 20 to 30 years. Such a study would analyze risk factors form lifestyle, family history, occupational and environmental exposures.(emphasis added)
It is interesting that Fort McKay did not want to be used as a comparator in the study. They actually want their own comprehensive health study. They are closer to the oil sand action than Fort Chip is. The other comparison communities had some interesting findings. While Fort Chip had 51 cancer incidences against a statistically expected 39 cases, Fort McMurray and the Northern Lights Health Region had “significantly lower number of cancer cases than expected.” The women in Fort Chip had the same rates of cancer as women in the rest of Alberta but the men had higher incidences.
Detailed study showed that 2 out of the 6 rare kinds of cancer of concern to Dr. O’Connor were confirmed and three of 12 suspected colon cancers were confirmed. The others were not Ft. Chip residents, not cancer or different types of cancer. There were no childhood cancers found, no increases in middle aged or young adult cancers. All the increased incidences were in the 55+ age group and that is a larger than average portion of the Ft. Chip population.
Leukemia and diabetes rates were found to be significantly higher in Ft. Chip residents. Leukemia is 3 times higher than the expected rate. Age again is a factor as is family history. Studies have reported higher incidences of certain kinds of Leukemia where exposure to chemicals for workers in the petroleum, rubber, mining and agriculture industries where they are exposed to solvents, styrene, butadiene and ethylene oxides. Other studies did not report excesses of cancers with such exposure so there is nothing conclusive about these possible causes. Incidences of colon cancer in Ft. Chip were found to be within expected levels.
Other interesting findings from cancer studies that were reported in this study referenced comparing First Nations cancer rates with non-First Nations Alberta. There is no difference between the groups for lung and colon cancer. The lung cancer finding is surprising considering the rate of smoking amongst First Nations Albertans is twice the rate of non-First Nation Albertans. Something else that is counterintuitive is the fact that First Nation Albertans have “…significantly lower rates that non-First Nations for all cancer, leukemia and breast cancer. Conversely, the rate for cholangiocarcinoma, the rare cancers that caused the stir in Ft. Chip in the first place, was found to be “significantly higher” for First Nations than non-First Nations Albertans.
The report goes on to compare U.S. and Ontario studies comparing First Nations and non-First Nations cancer incidences. Interesting stuff that just serves to confirm the Alberta findings in the report. It is noted that a current study on the cancer incidences in Alberta based on this culture difference is in the final stages and will be published next year. That will be interesting reading I am sure.
So we know there are significantly higher cancer incidences, including the rare kind, in Ft. Chip. So what are the reasons? The report says they can and may include all three of chance, increased detection and risk due to lifestyle, occupational and environmental exposures. In discussing increased risk the report notes that Canadian studies up to 2004 showed one in two Canadians will develop cancer in their lifetime. Risk of cancer increases with age and people are living longer and therefore more likely to be diagnosed with cancer. That said, Ft. Chip has a lower proportion of residents in the 55+ age cohort than Alberta as a whole and the aging pattern in Ft. Chip is similar to the rest of the province. So age and even sex cannot explain why there are higher than expected cancer rates.
Lifestyle, socio-economic factors, nutrition and work and environmental exposures all contribute to cancer rates but this study did not deal with any of those causal factors specifically to account for the differences.
So the question of does the oil sands and even uranium deposits in the area contribute to increased incidences of cancer in Ft. Chip is still open. The report references some studies from the International Agency for Research on Cancer and says there is “inadequate evidence to classify crude oil as a human carcinogen, however, there is limited evidence for the carcinogenicity of crude oil in experimental animals.” That same source notes that two types of certain complex volatile organic compounds of petrochemical hydrocarbons, the stuff of crude oil, “…are probably carcinogenic to humans” and others in this group of organic compounds are also “…possibly carcinogenic to humans.” The reports notes that exposure to these potential carcinogens is usually by “…inhalation, ingestion and skin contact.” The most common non-occupational exposure to this stuff is by tobacco smoke and urban air inhalation.
That said, the report states that few epidemiological studies on cancer risks exist amongst petrochemical workers and residents living in close proximity to oil refineries and no studies exists in reference to oil sands mining. “Information about the occupational history of Fort Chipewyan residents and their possible exposures at work could be very important; however, this could not be collect at this stage of the investigation. Future studies should evaluate the occupational history and employment-related migration pattern of the cancer patients in the community.
Next steps call for on-going monitoring of Ft. Chip residences to see if the past increased incidences were random variances or if there is more to it. Given the extent and the long term nature of oil sands exploitation it seems to me that commitment for on-going monitoring and a deeper and more extensive set of studies is the appropriate course of action.
Dr. O’Connor may feel vindicated on the issue of higher incidences and the rare cancers. At the very least the College ought to get off his back. The community will likely be unconvinced and to a point they are entitled to hold that position because we have insufficient evidence to be conclusive about the causes and context of higher cancer incidences. Lifestyle and environmental/ occupational concerns seem to be the unknowns and worth pursuing for more information. All in all the report is a great start.