Environmental Hazards and Male Fertility: Why Don't We Know More?

Nearly all (97%) the studies in the recent literature addressing the relationship between environmental hazards and male fertility use at least one of three common study design strategies: recruiting men presenting to fertility centers (53%), evaluating only one environmental exposure at a time (87%), and using conventional semen quality parameters as the only study outcome (45%). While each of these study design features is logical, defensible, and has generated an enormous amount of information regarding the impact of the environment on male reproductive function, they may also be barriers to furthering our understanding. In this article, we examine in which ways each of these study design features limits progress on male fertility research and propose strategies to go beyond them. Rather than abandoning these strategies, we propose that they should be a starting point instead of the default strategy for the future of male fertility research to more fully understand how men's environmental exposures impact human fertility and human reproduction more generally.