Menstrual product use and variation in organophosphate pesticide exposure by menstrual cycle timing among menstruating-age women: National Health and Nutrition Examination Survey 2001–2004

This presentation examines whether the type of menstrual product a woman uses, and the timing of her menstrual cycle, are associated with urinary concentrations of OrganoPhosphate (OP) pesticide metabolites. OP pesticides remain among the most widely used insecticides in U.S. agriculture, and menstrual absorbent products—commonly made from cotton, a pesticide-intensive crop—represent a plausible but largely unexamined route of exposure for reproductive-aged women. Using pooled NHANES data from 2001–2004, I will present findings from an analysis of 868 menstruating-age women, examining five urinary OP metabolites in relation to self-reported days since menstrual onset and self-reported menstrual product use (tampons, sanitary napkins, both, or neither). I will walk through the statistical approach used to address a key data challenge: A substantial share of metabolite measurements fell below the laboratory's detection limit, which required Tobit-type modeling to avoid the bias introduced by conventional substitution methods. I will also describe the use of flexible, non-linear regression models to test whether metabolite concentrations vary in a curved, rather than strictly linear, pattern across the menstrual cycle. I will share the central finding: Among women who use sanitary napkins, several OP metabolites show a distinct pattern across the cycle—concentrations are highest near the start of menstruation, decline to a low point roughly two to three weeks later, and rise again by the end of the cycle. This late-cycle rise was not explained by product use to manage menstrual bleeding, prompting a secondary hypothesis I will discuss: That panty liners, commonly used for non-menstrual discharge around ovulation, may contribute to this pattern. I will present supporting evidence for this hypothesis, including an age-based comparison motivated by the fact that ovulation is less consistent in younger women, and will discuss where this evidence is strong versus where it remains preliminary. I will close by discussing the public health implications of an underrecognized exposure route, along with the limitations of a cross-sectional design for testing a mechanism tied to individual-level menstrual cycle timing, and directions for future research that could more directly test this hypothesis.

Phyllis Mugadza is a PhD candidate in Population Health Sciences at Harvard University, specializing in environmental epidemiology. In the Weisskopf Lab, she develops exposure assessment methods to quantify the body burden of chemicals from personal care products, with a focus on menstrual products. She holds a BS in Mechanical Engineering and an MPH in Health Care Management from Yale University. She is also the inventor of a patented reusable menstrual disc and was named one of ten global innovators in MIT Solve's inaugural Solv[ED] cohort. Her work advances menstrual health equity through environmental exposure science.