To measure tissue levels of bisphenol A (BPA) in uterine leiomyoma (ULM), adjacent myometrium (Myo-F), and
normal myometrium (Myo-N). Also, we tested the effect of BPA treatment on rat myometrium. Methods: Uterine leiomyomas
and Myo-F tissues were isolated from hysterectomy specimens done to treat symptomatic ULMs (N ¼ 30). Normal myometrium
is isolated from hysterectomies done on ULM-free uteri for other benign indications (N ¼ 25). Bisphenol A was measured in 1 g of
tissue using solid-phase extraction and high-performance liquid chromatography, with fluorescence detectors. Experimentally,
adult female rats were fed BPA orally at a dose of 50 mg/kg/d for 90 days. Animals were killed, and their myometrial thickness and
proliferating cell nuclear antigen (PCNA) immunostaining were evaluated. Results: Tissue concentration of BPA in each of ULM
(12.3 + 2.8 mg/g) and Myo-F (10.1 + 0.2 mg/g) was significantly higher than that of Myo-N (0.58 + 0.2 mg/g). There was no
statistically significant difference in BPA level between ULM and Myo-F within submucous or interstitial/subserous fibroid groups.
Compared to control rats, BPA-treated animals showed significantly higher myometrial thickness (168.67+5.7 mm and 281.6+
20.32 mm, respectively, P ¼ .003) and increased myometrial PCNA immunoscores (1.5 + 0.37 and 10.38 + 0.67, respectively,
P  .001). Conclusion: Bisphenol A concentrates in human ULM tissue and its adjacent Myo-F compared to Myo-N. No significant
difference is detected in BPA content of ULM tissue of different subtypes. Bisphenol A increases thickness and induces
cellular proliferation in rat myometrium. Taken together, our results support a role of BPA in ULM development/growth.