Effects of tetrabromobisphenol A (TBBPA) on the reproductive health of male rodents: A systematic review and meta-analysis

Tetrabromobisphenol A (TBBPA) is a type of brominated flame retardant widely detected in the environment and organisms. It has been reported to cause cytotoxicity and disrupt endocrine system of animals. However, the effect of TBBPA on the reproductive system of male rodents is still controversial. Hence, this meta-analysis aims to determine whether TBBPA exposure damage to the reproductive system of male rodents. In this study, a thorough search of literatures was undertaken to select papers published before December 1st, 2020. The standard mean difference (SMD) and 95% confidence interval (CI) were calculated by random model. The results showed a statistically significant association between TBBPA exposure and the reproductive system health of male rodents (SMD = −0.35, 95% CI −0.50 to −0.19). The SMD for the reproductive system index organ weight, sperm quality, hormone levels, and gene expression were 0.03 (95% CI −0.18 to 0.23), −0.47 (95% CI −0.78 to −0.16), −0.51 (95% CI −0.75 to −0.27), and −0.98 (95% CI −1.36 to −0.60), respectively. There was a significant dose-effect relationship between TBBPA exposure and the reproductive health of male rodents, with the SMD values of low, medium, and high doses −0.20 (95% CI −0.34 to −0.05), −0.24 (95% CI −0.56 to 0.07), and −0.48 (95% CI −0.83 to −0.13), respectively. For exposure duration of TBBPA, an exposure time of >10 weeks (SMD = −0.33, 95% CI −0.54 to −0.12) showed more significant effect than an exposure time of ≤10 weeks (SMD = −0.22, 95% CI −0.43 to −0.02). Moreover, TBBPA exposure exhibited significant negative effects on sperm count (SMD = −0.49, 95% CI −0.82 to −0.17) while also reduced the content of triiodothyronine (T3), thyroxine (T4), and thyroid stimulating hormone (TSH) hormones. To summarize, our meta-analysis indicated that TBBPA had a toxicity effect to the reproductive system of male rodents.