Early-life exposure to bisphenol A and reproductive-related outcomes in rodent models: a systematic review and meta-analysis

We performed this meta-analysis to elucidate the associations between early-life BPA exposure and reproductive-related outcome indicators. The standardized mean differences (SMDs) and its 95% confidence intervals (CIs) were measured by fixed-effects or random-effects models. The results revealed that BPA exposure at extremely-high dose (>50mg/kg/day) was significantly associated with negative reproductive-related outcomes (Prostate weight: SMD: -4.21; 95% Cl: -5.97, -2.44; Testis weight: SMD: -1.92; 95% Cl: -2.61, -1.23; Epididymis weight: SMD: -2.16; 95% Cl: -3.47, -0.86; Daily sperm production; SMD: -1.90; 95% Cl: -3.27, -0.53; Epididymal sperm count; SMD: -3.42; 95% Cl: -3.87, -2.97). Meanwhile, regardless of the dose, early-life BPA exposure could result in an adverse effect on sperm parameters of F1 generation male rodents at any period. Also, we found the non-monotonic dose response curves of BPA in specific tissues or organs, which may challenge the traditional mindset of "safe dose". This study demonstrated that bisphenol A exposure was relevant to adverse reproductive-related outcomes at specially appointed dose and period of life. Yet the assumption that no adverse effects can occur below the "safe" dose is suspected.