by Alex Brooks
The New York State Department of Health has completed and released a study of cancer incidence in Hoosick Falls. It found no statistically significant elevations of cancer incidence for any of the cancer types associated with PFOA exposure.[private] The only cancer found to have a statistically significant elevation was lung cancer, which has not been associated with PFOA exposure in any study.
Although the study’s finding is good news as far as it goes, environmental health experts have been quick to point out the limited scope of this study. The source of the data is the New York State Cancer Registry. All cancer cases occurring in New York State are required to be reported to the cancer registry (even if the hospital where it is diagnosed is in Vermont – it is based on the place of residence at the time of diagnosis). The study used data from residents of Hoosick Falls from 1995 through 2014. The population of Hoosick Falls is about 3,400, which is statistically a fairly small sample. The C-8 study which came out of the DuPont litigation in Ohio and West Virginia, for instance, studied about 70,000 people who were exposed to PFOA.
The actual incidence of cancer among residents of Hoosick Falls during this period was compared to the average number of cancers found per capita in the entire white population of upstate New York. The two kinds of cancer most closely linked to PFOA exposure are testicular cancer and kidney cancer. Both of these had a lower incidence in Hoosick Falls than they did in the general upstate NY population.
Some associations have been shown between PFOA exposure and incidence of bladder and prostate cancers, but the evidence is a bit weaker. Bladder cancer incidence in Hoosick Falls was slightly lower than expected and prostate cancer slightly higher than expected, but the difference was small enough that neither of these was considered statistically significant. Bladder cancer was 22 cases versus 26 expected, and prostate cancer was 61 cases versus 56 expected over the 20 year period of the study.
The study found higher than expected incidence of lung cancer, prostate cancer, colorectal cancer, melanoma, stomach cancer and liver cancer, but the only one of these considered statistically significant was lung cancer, of which there were 91 cases over the 20 year period, versus 65 expected.
There were a total of 480 cancers diagnosed over the 20 year period, versus 453 expected. Thus overall there were about 6% more cancer cases than expected, but the evidence does not link those additional cancer cases to PFOA exposure.
The study does not conclusively answer questions about the effect of PFOA exposure on the local population, because it has significant limitations. It does not include assessment of health effects other than cancer. It does not assess people who worked at plants handling PFOA in Hoosick Falls who did not live in the Village. It does not assess long-time residents of Hoosick Falls who moved away. Cancers diagnosed when people resided somewhere else, after living in Hoosick Falls for a long time, would not show up in this study. What percentage of the exposed population may have moved away, and what their health outcomes may have been, are not within the purview of this study.
The NYS Health Department has made a commitment to update and review cancer incidence data for the village in three to five years to check for any changes in the “comparative cancer profile” of Village residents, and to continue to do blood-testing to monitor the reduction of PFOA blood levels among local residents now that the water is clean. They did not make commitments to do a more definitive study, or to implement the kind of comprehensive medical monitoring program championed by Senator Gillibrand at a PFOA forum at the Hoosick Falls High School in July of 2016. [/private]