Why Male Fertility Has Decreased By 50%

Declining male fertility has been a concern of scientists for quite some time. In fact, a seminal 1992 study published in the British Medical Journal found that from 1938 to 1991, the average male sperm count had dropped by nearly half and that semen volume, not just production, had decreased significantly as well. A 2017 clinical review published in the journal Human Reproduction Update looked at hundreds of studies published on male fertility in the previous decades and found that sperm count had indeed decreased by 50% to 60% across the U.S., Europe, Australia, and New Zealand with an average decline of nearly 1.5% per year.

Since declining sperm counts could potentially have devastating consequences for the future of humanity, scientists have been hard at work trying to figure out exactly why this is happening. Recently, more and more evidence is pointing to a possible culprit that lies right at the heart of modern life: exposure to chemicals (via The Conversation). Everything from air pollution to the plastics we use for packaging may be negatively affecting male fertility, and with new 2,000 chemicals released into the human environment each year, it may take decades to identify all the possible causes. 

Many studies already link chemicals that we consider essential in the 21st century to devastating impacts on male fertility. A 2014 study published in the journal Toxicology Letters, for example, found that workplace exposure to pesticides used in agriculture are known to produce reproductive hormonal changes in men and are associated with lower sperm density and mobility as well as reduced testicular weight. A 2018 study published in the journal Reproductive Biology and Endocrinology found that air particulate pollution may be inducing sperm DNA damage and lowering its quality and motility.

"Chemicals in our environment and other lifestyle factors in our modern age have harmed our reproductive health to the extent that, in the future, it may not be possible for most people to reproduce in the old-fashioned way," Shanna Swan, an environmental and reproductive epidemiologist at the Icahn School of Medicine at Mount Sinai recently told USA Today. Author of the book "Count Down: How Our Modern World Is Threatening Sperm Counts, Altering Male and Female Reproductive Development, and Imperiling the Future of the Human Race," Swan also said that we may be fast approaching a reality that we once only relegated to science fiction films like "The Handmaid's Tale" and "Children of Men" if the problem is not addressed.