A recent study investigated serum PFAS concentrations and their associations with testicular cancer risk among Air Force servicemen. Dr. Mark Purdue presented findings from the study in an EDC Strategies Partnership webinar.
PFAS and testicular cancer
Since the 1970s, the US military has used Aqueous Film-Forming Foam (AFFF) for fighting fires. PFAS (per- and polyflourinated substances) are a key ingredient used in these foams. AFFF used by the Department of Defense contain different formulations of PFAS, including PFOS, PFHxS, and PFOA. DoD has designated PFAS as emerging contaminants due to their long environmental persistence, contamination of drinking water supplies, and potential associations with several health outcomes (including cancer).
In 2016, DoD restricted the use of PFOS-based AFFF. DoD also initiated water testing on military bases. DoD's water testing identified hundreds of bases with known or suspected PFAS release. DoD's testing also found dozens of bases with PFOS/PFOA contamination in the ground and drinking water.
In 2014, the World Health Organization’s International Agency for Research on Cancer (IARC) classified PFOA as a possible human carcinogen, with the strongest evidence for a link between PFOA and cancer of the kidney and testis. In 2023, an updated review of PFOA by IARC classified PFOA as “carcinogenic to humans” (Group 1). Fewer studies have been done on other PFAS, such as PFOS, but it is possible that they pose similar health hazards.
Dr. Purdue’s study investigated the concentrations of PFAS in serum samples from the DoD Serum Repository, and looked for associations between those concentrations and testicular cancer. The serum samples were collected from active-duty servicemen between 1988 and 2017. The records from the repository were linked to a military cancer registry, which identified 530 diagnosed cases of testicular cancer among the servicemen. For controls, each identified case was matched with a control case with similar demographics. The study found the following:
- In early 2000s, higher serum concentrations of PFHxS were found in servicemen vs. serum from NHANES samples of the general population.
- Service-related predictors of elevated serum PFAS:
- Military firefighting work predicted higher levels of PFOS, PFOA, and PFHxS.
- Service on a base with drinking water PFOA/PFAS >70 ppt (PFHxS) predicted higher levels of PFAS.
- Elevated serum PFOS was associated with increased risk of testicular cancer. The study did not find this association with PFHxS.
"These findings are, to our knowledge, the first evidence of a direct association between measured serum PFOS concentrations and testicular cancer."
Purdue also pointed out previous animal studies that found evidence of PFOS-induced male reproductive toxicity.
More concerns and needed research
Purdue highlighted questions for further research, including whether these study findings are replicable, the question of whether short-chain PFAS are safe, and whether PFAS are associated with other health conditions among military personnel and veterans.
Purdue also highlighted the need to study exposures among women.
“Our group recently published findings suggesting that elevated serum levels of PFOS are associated with an elevated risk of ER (estrogen receptor) and PR (progesterone receptor) positive breast cancer, which is a finding that's consistent with a smaller earlier study.”
There are many concerns about the potential health risks of PFAS exposure. PFAS have been nicknamed “forever” chemicals because of their persistence in the environment. Even without a full picture of their health impacts, we can take steps to limit their use and our exposure.
Visit the webinar page to watch the full recording, download the Webinar Highlights fact sheet, and find out more about this important research.
This organizational blog was produced by CHE's Science Writer, Matt Lilley.