Environmental factors

Abstract

Approximately 50% of the human infertility issues involve male factors. A number of different components may result in reduction of sperm count or motility and affect sperm morphology. The etiology of male infertility is difficult to understand, due to its etiological heterogeneity, complexity, and incomplete knowledge of the underlying causes. In addition, World Health Organization (WHO) recently suggested changes in semen analysis lower limit parameters. In this way, it is not easy, based on the sperm count, to compare male infertility of earlier with the current ones. Most likely, some subfertile and/or infertile individuals under these new numbers would not be screened as such 5 years ago. Moreover, conventional reference values for seminal parameters have little diagnostic value because of their marked biological individuality variations, although seminal parameters may be useful for assessing differences in an individual's serial results, in particular of progressive motility, morphology, and vitality. Not long, we have seen significant refinement regarding male full evaluation combined with new sophisticated diagnostic techniques. Even then, most of the infertile men are described as idiopathic. Therefore, reproductive toxicity has been a topic of increasing interest and concern, as human exposure to a considerable number of potential toxicants is unavoidable due to contamination of air, water, ground, food, beverages, and household. Several lifestyle-related factors such as obesity, smoking, sedentary exposure to traffic exhaust fumes, dioxins, combustion products, cell phone electromagnetic radiations, chronic noise stress, anabolic steroids, illicit drugs, heat, notebooks use, dietary habits, oxidative stress, etc., appear to exhibit some involvement in human reproduction. Apart from this, public concern about adverse effects of environmental chemicals, pesticides, food additives, and persistent pollutants on spermatogenesis in adult men is sometimes not supported by the available data for humans. About 80,000 new chemical compounds have been introduced to human civilization in the last 100 years, and only 145 have been rigorously assessed for their reproductive health effects. The main scope of this chapter is to review some of the most frequent environmental or occupational pollutants in sex hormone levels, birth rates, and human reproduction in view of the fact that male infertility may be a surrogate marker of serious additional underlying medical problems.