Does perfluorooctanoic acid (PFOS) cause early menopause and reduced kidney function

HI all…with comments due to Health Canada on ‘Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonate (PFOS) in Drinking Water’ guidelines on Sept 2, a new article reveals that two reported potential health effects of these compounds (early menopause and reduced kidney function) are actually a result of having those conditions rather than being the cause. This isn’t to suggest there shouldn’t be drinking water guidelines or standards for perfluorinated compounds. It is only to illustrate the importance of doing good science.

(PFOA and PFOS are also included on the USEPA’s draft Drinking Water Chemical Contaminant Candidate [CCL4] list and one or both could be regulated in the US in the not too distant future- https://www.epa.gov/ccl/chemical-contaminants-ccl-4)

Bill

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A Study of Reverse Causation: Examining the Associations of Perfluorooctanoic Acid Serum Levels with Two Outcomes

Radhika Dhingra, Andrea Winquist, Lyndsey A. Darrow, Mitchel Klein, and Kyle Steenland

Environ Health Perspect; http://dx.doi.org/10.1289/EHP273

http://ehp.niehs.nih.gov/EHP273/

“Background: Impaired kidney function and earlier menopause were associated with perfluorooctanoic acid (PFOA) serum levels in prior cross-sectional studies. Reverse causation, whereby health outcomes increase serum PFOA, may underlie these associations.

Objective: We compared measured (subject to reverse causation) vs. modeled (unaffected by reverse causation) serum PFOA in association with these outcomes, to examine the possible role of reverse causation in these associations.

Methods: In cross-sectional analyses, we analyzed PFOA in relation to self-reported menopause among women (N=9,192) aged 30-65, and kidney function among adults aged 20+ (N=29,499) in a highly-exposed Mid-Ohio Valley cohort. Estimated glomerular filtration rate (eGFR, a marker of kidney function) and serum PFOA concentration were measured in blood samples collected during 2005/06. Retrospective year-specific serum PFOA estimates were modeled independently of measured PFOA, based on residential history and plant emissions. Using measured and modeled PFOA in 2005/06 (predictor variables), cross-sectional associations were assessed for eGFR and menopause (yes/no). We also analyzed measured PFOA (dependent variable) in relation to the number of years since menopause.

Results: Menopause and eGFR were significantly associated with measured (trend tests: p=0.013, p=0.0005, respectively) but not modeled serum PFOA (p=0.50, p=0.76, respectively). Measured PFOA levels increased for the first seven years after menopause (trend test, p<0.0001), providing further evidence that the observed association between measured PFOA and menopause is subject to reverse causation for this outcome.

Conclusion: Our results support the conjecture that in prior studies, early menopause and reduced kidney function are the causes rather than the results of increased measured.”