Environmental contaminants and male infertility: Effects and mechanisms

Abstract

The global incidence of infertility has risen to 15% in contrast to 7%-8% in the early 1960s (Mascarenhas, Flaxman, Boerma, Vanderpoel, & Stevens, 2012). Over the past several decades, a significant deterioration in male reproductive health has been reported in association with increased industrialisation, which has contributed to a massive release of synthetic pollutants into the environment (Rim, 2017; Skakkebaek et al., 2016). The concerns over declining male reproductive health were elicited by one of the landmark publications by Carlsen et al., which revealed a worldwide reduction in the average sperm count to half between 1940 and 1990 (Carlsen, Giwercman, Keiding, & Skakkebaek, 1992). These findings prompted several scientists, mainly Swan et al. to re-evaluate the trend in semen quality over time in different regions throughout the world and eventually confirmed a significant decrease in sperm concentration in western countries (Swan, Elkin, & Fenster, 1997). Incidentally, a parallel increase in the occurrence of testicular cancer and congenital abnormalities (cryptorchidism and hypospadias) were reported in several countries (Ferguson & Agoulnik, 2013; Hutson, 2000). These observations prompted researchers to explore the potential role of common environmental factors in causing a decline in male reproductive health. In 1993, it was hypothesised that the growing incidence of male reproductive anomalies could be due to exposure to chemicals possessing oestrogenic property (Sharpe & Skakkebaek, 1993).

The Toxic Effect of Bisphenol A on Albino Rat Testicles and the Possible Protective Value of Vitamin E and Melatonin

“…Testosterone plays a key role in the initiation and maintenance of spermatogenesis, differentiation of male genital organs, and the production of secondary sexual characteristics. Any factor affecting the viability of Leydig cells and/or interfering with testicular steroidogenesis may cause endocrine regulation of spermatogenesis to be disrupted and impair fertility (Selvaraju et al, 2020).…”

The current perspective on genetic and epigenetic factors in sperm maturation in the epididymis

“…After exposure to environmental contaminants, the epididymal epithelium is degenerates and the blood–epididymal barrier cannot control intraluminal microenvironment. Change in the micro‐architecture of the epididymis, accompanied by an increase in reactive oxygen species, impairs sperm maturation (Selvaraju et al., 2020). Maamar et al.…”

Impact of environmental factors on human semen quality and male fertility: a narrative review

“…Semen quality is the major predictor of male fertility outcome [6]. It was observed that environmental pollution unfavorably affects semen quality by impairing the process of spermatogenesis, steroidogenesis, Sertoli cell, and sperm functions, thereby leading to decreased male fertility [7,8]. Furthermore, there are numerous natural and man-made chemicals that are released into the environment daily and have deleterious impacts on human fertility.…”