Isolated and Combined Exposure to Polystyrene Nanoplastics and a Phthalate Metabolite Mixture Disrupt Antral Follicle Growth and Function of Mice In Vitro.

Abstract

Polystyrene nanoplastics (PS-NPs) are small particles derived from plastic degradation that have been detected in several human tissues. Phthalates are ubiquitous plasticizers used to increase flexibility in polymers which act as endocrine disruptors, impacting hormonal homeostasis. Considering that both pollutants have been detected in human follicular fluid, there is increasing concern regarding their potential effects on female reproductive health. This study evaluated the isolated and combined effects of environmentally relevant doses of PS-NPs and a phthalate metabolite mixture (MM) on antral follicle growth, hormone production, and the expression of genes involved in apoptosis, oxidative stress, steroidogenesis, and hormone receptor signaling. Antral follicles from adult CD-1 mice were cultured with vehicle control (DMSO and water), metabolite mixture (0.01, 0.1, 1, and 10 μg/mL), or PSNPs (5, 25, 50, and 100 μg/mL) or MM + PS-NPs (5 µg/mL PS-NPs + 0.01 µg/mL MM; 100 μg/mL PS-NPs + 10 μg/mL MM). Follicle growth was monitored every 24 h for 96 h. PS-NPs and MM were internalized by follicles and they inhibited follicle growth alone and in co-exposure. Both pollutants altered the expression of apoptosis-related (Casp3, Casp8, Bcl2) and oxidative stress-related (Cat, Nrf2, Gpx1) genes without significantly affecting steroid hormone levels. Co-exposure also reduced Esr2 and Ar expression, demonstrating more pronounced effects under low-dose combined exposure. Altogether, these findings indicate that environmentally relevant exposure to PS-NPs and phthalate mixtures impairs antral follicle growth and disrupts molecular pathways essential for ovarian function, highlighting potential pathways and the importance of understanding combined exposures in reproductive toxicity.

Key Findings

• Polystyrene nanoplastics (PS-NPs) and phthalate metabolite mixtures (MM) were internalized by antral follicles and inhibited follicle growth both alone and in combination.
• Exposure to PS-NPs and MM altered the expression of apoptosis-related genes (Casp3, Casp8, Bcl2) and oxidative stress-related genes (Cat, Nrf2, Gpx1).
• Combined low-dose exposure reduced expression of hormone receptor genes Esr2 and Ar, indicating more pronounced effects on ovarian function.

Clinical Significance

Citation

Souza Patrick V, Santacruz-Márquez Ramsés, Laws Mary Jet al.. Isolated and Combined Exposure to Polystyrene Nanoplastics and a Phthalate Metabolite Mixture Disrupt Antral Follicle Growth and Function of Mice In Vitro. Toxicological sciences : an official journal of the Society of Toxicology. 2026-Mar-22.