Falling sperm counts ‘as big a threat to humans as climate change’

SPERM counts are falling at a rate that threatens the long-term survival of the human race, a leading epidemiologist has warned.

In a new book, Prof Shanna Swan, an environmental and reproductive epidemiologist at Icahn School of Medicine in New York, warns there is a looming fertility crisis comparable in its impact to climate change.

She projects that if sperm counts continue to fall at current rates they will reach “zero” by 2045.

To blame, she says, are lifestyle changes that alter hormone balances, and exposure to “everywhere chemicals” that impair the endocrine system of chemical messaging in the body. Additional factors are smoking tobacco and cannabis and increased obesity.

In a paper published in 2017, Prof Swan found total sperm count in the West had fallen by 59 per cent between 1973 and 2011. “If you look at the curve on sperm count and project it forward – which is always risky – it reaches zero in 2045,” she told Axios, a US news site.

Her new book, Count Down, expands on that research and argues that the fertility crisis is as serious as climate change. “The climate crisis has been accepted – at least by most people – as a real threat. My hope is that the same will happen with the reproductive turmoil that’s upon us,” Prof Swan writes. Fertility rates globally have been falling for decades, with the average number of children born per woman falling from 5.06 in 1964 to 2.4 in 2018.

Much of that fall is associated with the positive results of economic development. But Prof Swan writes that there is clear evidence of biological factors at play, and not just socioeconomic ones. She also identifies increased rates of miscarriages and impaired fecundity, a term for conception difficulties, as evidence of a broader problem in the West.

She blames “everywhere chemicals” such as phthalates and bisphenol-a, found in cosmetics, pesticides and plastics, as well as lifestyle changes.