Epidemiologist Shanna Swan projects that on current trends sperm counts will reach zero by 2045. That shocking conclusion comes from a new book by Swan and her colleague Stacey Colino. Is this nature's way of bringing human population under control? (More on that later.)
In a 2017 study Swan and colleagues looked at "244 estimates of SC [sperm concentration] and TSC [total sperm count] from 185 studies of 42,935 men who provided semen samples in 1973–2011" in North America, Europe, Australia and New Zealand. Men elsewhere may fare better, but the causes of this trend suggest that it is worldwide.
Swan told The Guardian that she blames so-called "'everywhere chemicals', found in plastics, cosmetics and pesticides, that affect endocrines such as phthalates and bisphenol-A." She also pointed to unhealthy lifestyle choices including use of tobacco and marijuana and to rising obesity. Obesity itself has been linked to increasing human endocrine disruption from these same chemicals.