**Abstract**

Endocrine-disrupting chemicals (EDCs) are exogenous compounds with natural or anthropogenic origin omnipresent in the environment. These compounds disrupt endocrine function through interaction with hormone receptor or alteration of hormone synthesis. Humans are environmentally exposed to EDCs through the air, water, food and occupation. During the last decades, there has been a concern that exposure to EDCs may contribute to an impairment of human reproductive function. EDCs affect male fertility at multiple levels, from sperm production and quality to the morphology and histology of the male reproductive system. It has been proposed that exposure to EDCs may contribute to an impairment of sperm motility, concentration, volume and morphology and an increase in the sperm DNA damage. Moreover, EDCs exert reproductive toxicity inducing structural damage on the testis vasculature and blood-testis barrier and cytotoxicity on Sertoli and Leydig cells. This chapter will explore the effects of EDCs in male reproductive system and in the decline of male fertility.

**Keywords:** endocrine-disrupting chemicals, male infertility, lifestyle, environmental pollutants, body burden

## **1. Introduction**

Endocrine-disrupting chemicals (EDCs) are exogenous substances or mixtures of chemicals that can disrupt male and female endocrine function through the interaction with hormone receptors. They lead to alterations in hormone action, synthesis, transport and metabolic processes [1]. Several compounds such as dioxins, plastic contaminants (e.g., bisphenols (BP)), triclosan (TCS), pesticides and herbicides (e.g., diphenyl-dichloro-trichloroethane (DDT)), metals and others are known EDCs [2].

Humans may be exposed to EDCs due to contamination of water and food chain, inhalation of contaminated house dust and through occupational exposure [2]. Although, in some westernized countries the use of certain EDCs has been banned, there are cases that human exposure to these chemicals is inevitable. Thus, during the past decades, human exposure to EDCs has received increased attention, and particular focus has been given to the harmful effects of EDCs to the male reproductive system. Evidences suggest that EDCs may have significant adverse

effects on human health and are contributing to the trends in occurrence of male reproductive health problems and the decline in male fertility [3]. According to the literature, male reproductive decline may result from a combination of morphological, functional and molecular alterations in the reproductive organs, often due to exposure to EDCs. Most studies are focused either on the evaluation of basic seminal parameters or reproductive outcomes, but there are evidences that EDCs may impact at the level of the reproductive and endocrine systems. For example, there are evidences that TCS has a tendency to bioaccumulate in the epididymis [4]. Bisphenol A (BPA) has been reported to have both estrogenic and antiandrogenic effects [5–7]. It has been also negatively associated with sperm quality [8–10]. Toxicological studies showed that BPA caused adverse reproductive outcomes, namely, decreased epididymal weight, daily sperm production and testosterone (T) levels in rodents [11–13]. Recently, our group performed a systematic review regarding the effect of exposure to mercury (Hg) on human fertility [14]. Results revealed that higher levels of Hg in blood and hair were associated with male subfertility or infertility status.

This chapter summarizes the effects of male exposure to EDCs on markers of male fertility. The agents discussed here, which include TCS, BPA, metals (such as cadmium (Cd) and Hg), polychlorinated biphenyls (PCBs) and others were chosen based on their human exposure prevalence and adverse effects on human reproductive health.
