Swedish climate activist Greta Thunberg is pictured during a ‘Fridays for Future’ protest in front of the Swedish Parliament Riksdagen last year.

Forget playing to the hearts and minds of climate-change inactivists, says Thunberg. This research may just hit ’em where it counts.

Thunberg has 4.9 million Twitter followers. The wink-wink tweet had logged some 61,000 likes and counting by Thursday afternoon. Her Friday school strikes began a handful of years ago with a solo sit-in at Sweden’s parliament and grew to an international movement; she has since addressed the United Nations and more.

Thunberg recognizes, of course, that reproduction concerns are serious for all humankind.

In Swan’s widely reviewed book, “Count Down: How Our Modern World Is Altering Male and Female Reproductive Development, Threatening Sperm Counts, and Imperiling the Future of the Human Race,” the researcher shares her multi-year, peer-reviewed findings that she says show how chemicals called phthalates are causing human babies to be born with malformed genitals.

Swan says humanity is facing an “existential crisis” in fertility rates as a result of phthalates, which are used when trying to make plastics more flexible. The chemical emits a pollution that impacts the hormone-producing endocrine system, tricking the body during sexual development, her research suggests. The most recently tested chemical had actually replaced another found to raise health concerns.

Moving on from early animal studies, Swan, who is a professor in environmental medicine and public health at Mount Sinai Hospital in New York, discovered that male human babies who had been exposed to the phthalates in the womb had a shorter anogenital distance, something that correlated with penile volume.

What’s more, one related report published in 2017 found that sperm levels among men in Western countries have dropped by more than 50% over the past 40 years, after examining 185 studies involving some 45,000 healthy men.

The future of plastics — whose uses range from life-saving medical-device breakthroughs to food preservation — remains one of the more contentious issues in environmental and climate-change policy-making.