Environmental and Molecular Determinants of Polycystic Ovary Syndrome: Evidence from Cosmetic-Derived Endocrine Disruption in Nigerian Women

Background Polycystic ovary syndrome (PCOS) affects 5–10% of reproductive-age women globally, with rising prevalence suggesting environmental contributions beyond genetic predisposition. This study investigated cosmetic-derived endocrine disrupting chemical (EDC) exposure as a modifiable environmental risk factor for PCOS. Methods We conducted a case-control analysis nested within a cross-sectional study of 126 women in Edo State, Nigeria. Cases were cosmetic users with PCOS (n = 42), while controls included cosmetic users without PCOS (n = 42) and non-cosmetic users (n = 42). Environmental exposure patterns, hormonal profiles, and genetic markers were analyzed to identify risk factors for PCOS development. Results PCOS prevalence among cosmetic users was 50% (42/84), representing a 4-fold increase over population estimates (12–14%) in Nigeria. Cosmetic use duration > 3 years was associated with increased PCOS risk (OR = 3.8, 95% CI: 1.9–7.6, p < 0.001). Daily use of > 5 products further elevated risk (OR = 2.7, 95% CI: 1.4–5.2, p = 0.003). Androgen receptor gene upregulation was equally prevalent in PCOS and non-PCOS cosmetic users (61.9%), suggesting early molecular changes preceding clinical manifestations. Conclusion Cosmetic-derived EDC exposure represents a significant modifiable environmental risk factor for PCOS. These findings support targeted prevention strategies and regulatory oversight of cosmetic ingredients to reduce disease burden.