A leading epidemiologist has warned that falling sperm counts and changes in sexual development “threaten human survival” and lead to a fertility crisis.
Writing in a new book, Shanna Swan, an environmental and reproductive epidemiologist at the Icahn School of Medicine in Mount Sinai, New York, warns that the impending fertility crisis poses a global threat comparable to that of the climate crisis.
“The current state of reproductive affairs cannot continue much longer without threatening human survival,” he writes in Count Down.
It comes after a study he co-authored in 2017 found that sperm counts in the west had dropped by 59% between 1973 and 2011, making headlines worldwide.
Now, Swan says, after current projections, the average sperm count is projected to reach zero by 2045. “That’s a little worrying, to say the least,” he told Axios.
In the book, Swan and co-author Stacey Colino explore how modern life endangers sperm count, changes male and female reproductive development, and endangers human life.
It points to exposures to lifestyle and chemicals that change and threaten human sexual development and fertility. Such is the severity of the threats they pose, she said, that humans could become an endangered species.
“Of the five possible criteria for endangering a species,” Swan writes, “only one needs to be met; the current state of affairs for humans meets at least three.”
Swan offers advice on how to protect yourself from harmful chemicals and urges people to “do everything possible to safeguard our fertility, the destiny of humanity and the planet.”
Between 1964 and 2018, the global fertility rate fell from 5.06 births per woman to 2.4. Now, about half of the countries in the world have fertility rates below 2.1, the level of replenishment of the population.
While contraception, cultural changes, and the cost of having children are likely to be contributing factors, Swan warns of indicators that suggest there are also biological reasons, such as rising abortion rates, more genital abnormalities among boys and the earlier puberty of girls.
The swan blames “chemicals everywhere,” found in plastics, cosmetics, and pesticides, that affect endocrines like phthalates and bisphenol-A.
“The chemicals in our environment and unhealthy living practices in our modern world are altering our hormonal balance, causing varying degrees of reproductive damage,” he writes.
He also said factors such as smoking, marijuana and growing obesity play an important role.