Male reproductive health in relation to occupational exposure to endocrine disrupting and other potent chemicals, a review of the epidemiologic literature

The line of research focusing on the human, especially male, reproductive system in relation to occupational exposure has diversified since the infiltration of the concept of endocrine disrupting chemicals (EDC), early in the 1990s. The main stream, until then, was the study of reproductive toxicity caused by single albeit relatively heavy exposures to chemicals of limited range (conventional scheme). The new and increasingly important stem is the search for a wider range of chemicals with endocrine disrupting potential, and health effects due to multiple low-dose exposures of potent chemicals (new scheme). There are also studies having aspects of both the conventional and new schemes. For studies with the new scheme, progress has been made in areas such as adherence to standardized techniques in evaluating male reproductive function and more sensitive study designs. Indeed, some studies have suggested the presence of EDCs in the occupational setting. However, epidemiological findings are still constrained by difficulties in the identification of occupationally-exposed populations and evaluation of exposure. There is thus a need for convergence of knowledge and a widening of the scope of epidemiological research targeting occupationally exposed populations under a carefully-designed protocol.