Synthetic Fiber Sanitary Napkins: Nonnegligible Exposure Source of Organophosphate Esters in Women

The addition of organophosphite antioxidants (OPAs) in synthetic fibers results in potential pollution of OPAs and their oxidation products, OPAs = O, a class of organophosphate esters (OPEs), in sanitary napkins. Although the endocrine-disrupting effects and reproductive toxicity of many OPEs have been reported, the exposure risks of OPAs = O induced by sanitary napkins remain unclear. We detected two major OPAs, tris(2,4-ditert-butylphenyl) phosphite (AO168) and bis(2,4-ditert-butylphenyl) pentaerythritol diphosphite (AO626), and two OPEs, tris(2,4-ditert-butylphenyl) phosphate (AO168 = O) and bis(2,4-ditert-butylphenyl) pentaerythritol diphosphate (AO626 = O₂), in most sanitary napkins with the maximum ∑₄OPs of 516 μg/g in synthetic fiber surface layers and 200 μg/g in absorbent cores. According to the simulated dermal exposure experiment, the estimated dermal intake of ∑₄OPs during menstruation was 805 ng/kg BW/day in the low-absorption scenario and 2240 in the high scenario, which was comparable to dietary intake. Molecular docking analysis revealed that OPAs and OPAs = O may competitively inhibit key steroidogenic enzymes (CYP11A1, CYP17A1, CYP19A1, and 17β-HSD1), exhibiting binding affinities comparable to or greater than those of typical endocrine disruptors (bisphenol A and triphenyl phosphate). This study identifies dermal exposure from synthetic fiber sanitary napkins as a critical pathway for OPAs/OPAs = O, highlighting their potential to disrupt hormonal homeostasis and pose a reproductive health risk.