Does bisphenol A disrupt hormones and lower male testosterone?

Bisphenol A (BPA) is an established endocrine-disrupting chemical that interacts with various hormonal signaling pathways. While its ability to modulate estrogenic and non-estrogenic receptors is well-supported by scientific evidence, its specific impact on male testosterone levels in human populations remains a subject of ongoing research with mixed findings.

Mechanistic pathways of endocrine disruption

BPA acts primarily as a xenoestrogen, though its activity extends far beyond classical estrogen signaling.

• Estrogen Receptor (ER) Signaling: BPA functions as a weak agonist for both ERα and ERβ. While its binding affinity is significantly lower than that of endogenous 17β-estradiol (in the micromolar range), it effectively induces estrogen response element (ERE)-mediated transcription. In pancreatic cells, BPA has been shown to disrupt ERα-ERβ heterodimer formation, which interferes with critical anti-apoptotic pathways.
• Non-ER Hormone Pathways: BPA is a high-affinity ligand for the estrogen-related receptor gamma (ERRγ), binding more strongly to it than to classical ERs. It also interacts with the peroxisome proliferator-activated receptor gamma (PPARγ) and the membrane-bound G protein-coupled estrogen receptor (GPER), the latter of which triggers rapid non-genomic signaling.
• Enzymatic Modulation: BPA can disrupt steroidogenesis by altering the expression of key enzymes, including aromatase (CYP19A1) and the steroidogenic acute regulatory protein (StAR), which are essential for maintaining hormonal balance.

Impact on male reproductive hormones

The relationship between BPA and testosterone is supported by strong mechanistic models but shows variability in clinical observations.

• HPT Axis Interference: In animal and in vitro models, BPA interferes with the hypothalamic-pituitary-testicular (HPT) axis. It mimics endogenous hormones to downregulate the secretion of gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH).
• Leydig Cell Function: Preclinical studies demonstrate that BPA inhibits testosterone production in Leydig cells by downregulating enzymes such as CYP11A1 and StAR.
• Human Epidemiological Findings: Human data are inconsistent. While some cross-sectional studies associate BPA exposure with lower testosterone and reduced sperm counts, other research—such as the InCHIANTI population study—has found either no significant association or even a positive association between higher BPA excretion and higher total testosterone levels. These discrepancies are often attributed to differences in exposure levels and study design.

Bottom line

BPA is a multifaceted endocrine disruptor that acts through estrogenic and alternative hormone pathways. While it clearly suppresses testosterone in controlled animal models via HPT axis and Leydig cell disruption, human evidence is currently inconsistent, making the specific association with lower testosterone in men plausible but not yet definitively proven.