Phthalates as the silent saboteurs of male fertility via changes in semen quality: a systematic review

Phthalates, which are commonly used as plasticizers, are pervasive in modern environments. The potential effects of endocrine-disrupting chemicals (EDCs) on human reproductive health have raised concerns. Among the various health risks, a significant focus has been on male fertility, particularly the relationship between phthalate exposure and a reduced sperm count. Di-(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DBP) are two of the most studied phthalates because of their wide use in products such as plastics, cosmetics and medical devices. Growing evidence suggests that they may impair sperm production, viability, and quality, contributing to male infertility. This review synthesizes epidemiological and experimental evidence on the reproductive toxicity governed by phthalates in semen parameters. This systematic review was conducted following the SWiM (synthesis without meta-analysis) guidelines. A comprehensive search across three major databases was conducted to capture literature on phthalate exposure and semen parameters, including sperm concentration, morphology and motility, published between 2014 and 14/10/2024. Two independent researchers screened and selected studies. The risk of bias in the included studies was assessed via ROBINS-E tool. A meta-analysis was not performed due to variability in the study designs. 38 studies met the eligibility criteria and were included in this review. Human phthalate exposure has shown that semen parameters are altered, such as a decrease in the sperm concentration. Research suggests that high exposure to phthalates such as MEHP, DEHP and DBP is associated with reduced sperm concentration, motility, and overall semen quality. Phthalates remain a potential contributing factor in male fertility issues, but the variability in findings across populations and exposure levels in these populations indicate that more research is needed to understand this relationship. Phthalates, particularly MEHP, DEHP and DBP, negatively affect sperm concentration and affect sperm morphology, likely through endocrine disruption and impairment of testicular function via oxidative stress. The certainty of the evidence is graded as low to moderate, primarily due to the observational nature of the included studies. However, given the potential risks to reproductive health, the evidence supports a precautionary approach advocating stricter regulation of phthalate exposure in everyday products.