Although this issue has been discussed before here, the context has been about the decline of the sperm quality of Western men, which a recent study concluded has fallen by more than 50 percent in 40 years, and is not slowing down:
How is that for a URL reference – somewhat self-defeating I think. Here is the old-fashioned reference:
H. Levine (et al.), “Temporal Trends in Sperm Count: A Systematic Review and Meta-Regression Analysis,” Human Reproduction Update, 2017, pp. 1-14.

     Now this research has been quoted in the media as allegedly showing that Western sperm quality is undergoing decline. Gloating non-Whites, primarily Muslims have ground it in. Yet as Mike Adams has noted   there is still evidence that the decline in sperm quality is worldwide, and not exclusively due to factors such as diet, although that may be a contributing factor. The analysis had some indication that the decline in sperm quality was worldwide, including in still developing countries.

     Earlier studies had indicated that there was in fact a worldwide trend in the decline of sperm quality:
S. Swan (et al.), “The Question of Declining Sperm Density Revisited: An Analysis of 101 Studies Published 1934-1996,” Environmental Health Perspectives, vol. 108, 2000, pp. 961-966.

     Adams and others hypothesise that the crash of sperm may be due to chemical pollution through estrogenic-type chemicals which act as hormone disruptors:
Fish have become transgender due to the effects of the human contraceptive pill being flushed down drains:

     It would be a miracle if the high tech toxic environment which modern consumer culture swims in, does not have the same effect on humans.  Perhaps the present lack of masculinity in “men” may have a chemical explanation, since testosterone levels across the world are also crashing:

     This problem alone could finish off the human race, if it is not already too late. Investigate ways of minimising the use of hormone disrupting chemicals, eat organic, and hope and pray for the best. We are certainly in for a rough ride.