Lead exposure is associated with increased lead bioaccumulation and a decline in semen quality: a systematic review and meta-analysis

Abstract

OBJECTIVE: This systematic review and meta-analysis aimed to assess the impact and associated mechanisms of lead on human semen quality. METHODS: A systematic search was conducted from March 18th to April 30th, 2024, utilizing Google Scholar, PubMed, and Scopus, and applying the PECOS model to identify relevant studies. RESULTS: A total of seventeen studies fulfilled the inclusion criteria. The results of our analysis indicated that blood lead levels were markedly elevated in men exposed to lead compared to control subjects (SMD -7.06 [95% CI: -9.03, -5.08], p<0.00001), with analogous results observed for semen lead levels (SMD -3.42 [95% CI: -5.22, -1.62], p=0.0002). Lead exposure was linked to significant decreases in ejaculate volume (SMD 0.81 [95% CI: 0.16, 1.45], p=0.02), sperm count (SMD 2.10 [95% CI: 1.11, 3.09], p<0.0001), sperm concentration (SMD 0.77 [95% CI: 0.09, 1.44], p=0.03), and total motility (SMD 2.20 [95% CI: 1.28, 3.11], p<0.00001), as well as an increase in abnormal sperm morphology (SMD -3.29 [95% CI: -4.87, -1.71], p<0.0001). While reductions in testosterone levels and elevations in semen malondialdehyde were noted, these changes did not reach statistical significance. CONCLUSIONS: This study demonstrates that lead exposure is associated with reduced sperm quality. The present findings highlight the urgent need for strategies to reduce lead exposure and emphasize the importance of further research into potential mitigating interventions.