A new study published March 1, 2013 in the peer-reviewed journal Environmental Health Perspectives found an association between high level exposure to perfluorooctanoic acid (PFOA) and kidney cancer as well as testicular cancer (Vieira et al 2013). The study’s findings confirm earlier research from animal and occupational mortality studies and are in line with conclusions of the C8 Science Panel (C8 panel).
In their case-control study, the researchers aimed to identify a probable link between between PFOA exposure from drinking water and incidence of testicular and kidney cancers. PFOA is used in the manufacture of Teflon, a non-stick coating of cooking ware, but shall be phased out shortly (FDA, 2012). Earlier animal and occupational mortality studies have linked elevated PFOA exposure to kidney, pancreatic, testicular and liver cancer, yet the biological mechanisms underlying the increases in cancer rates remain unknown.
Based on these previous findings the scientists from the U.S. and the U.K. compared the exposure levels of cases diagnosed with kidney, pancreatic, testicular or liver cancer to those of all other cancer cases in the region (controls). Cases and controls were taken from the cancer registries of the 13 counties surrounding Du Pont’s Washington Works Teflon manufacturing plant. The total population under study amounted to 25 107 people who were registered with 18 types of cancer between 1995 and 2005. The cancer types registered included bladder, brain, female breast, cervix, colon/rectum, kidney, leukemia, liver, lung, melanoma of the skin, multiple myeloma, non-Hodgkin lymphoma, ovary, pancreas, prostate, testis, thyroid, and uterus cancer.
PFOA exposure levels were estimated on the basis of residency within one of six contaminated public water districts. This crude exposure measure was refined using exact addresses of cases and controls, to see whether their houses were connected to the water distribution system with elevated PFOA levels. Further, intake and uptake data was used to estimate PFOA serum levels. Estimates of serum PFOA levels ranged from 5.3 to 125 µg/L in the different districts, with very high exposure levels between 600–4,679 µg/L-years and high exposure levels between 198–599 µg/L-years. The analysis was adjusted for age, sex, diagnosis year, smoking status and insurance provider.
The odds of testicular cancer, kidney cancer, non-Hodgkin lymphoma and prostate cancer were increased in the district with the highest drinking water levels of PFOA. Surprisingly, the crude exposure measure of drinking water levels yielded higher adjusted odds ratios (AORs) than the estimated serum levels. For testicular cancer the AOR was as high as 5.1 (95% CI 1.6, 15.6). For the exposure groups based on estimated serum level, the largest AOR was found for testicular cancer of which cases were 2.8 times as likely to be in the very high exposure category, but only few cases were identified (n=6). Kidney cancer cases were twice as likely in very high and high exposure categories. A smaller or no association was found with other cancers types including non-Hodgkin lymphoma, pancreatic and liver cancer.
The study confirms associations between PFOA and kidney as well as testicular cancer found in previous animal and occupational mortality studies. The study’s weakness lies with the indirect estimates of exposure based on generalized consumption levels of contaminated drinking water. Yet, the analysis offers the advantage of being a human study based on a large sample size and environmental rather than exclusively occupational exposure.
Vieira, V et al. (2013). “Perfluorooctanoic Acid Exposure and Cancer Outcomes in a Contaminated Community: A Geographic Analysis.” Environ Health Perspect 121:318–323 (2013)