Together, toxins and climate change pose a significant threat to fertility rates in species around the world
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Combined exposure to toxic chemicals and climate change’s impacts likely increases reproductive harm, and may be contributing to the broad global drop in fertility – according to new peer-reviewed research which looked at a total of 177 studies.
The research considers how chemicals found in plastic, coupled with the effects of climate change – such as heat stress – are linked to reductions in fertility and fecundity (the physical ability to produce offspring) across global species, including in humans, wildlife and invertebrates.
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On their own, the reproductive harms of each of these issues is well-studied, but there is little research on what happens when organisms are subject to both. Together, these two issues have an ‘alarming’ additive effect, said study lead author and courtesy faculty at Oregon State University Susanne Brander.
‘You’re not just getting exposed to one – but two – stressors at the same time that both may affect your fertility, and in turn the overall impact is going to be a bit worse,’ said Brander.
Co-author of the paper, Shanna Swan, co-produced a study back in 2017 that found sperm levels among men in Western countries had dropped by more than 50 per cent across four decades. Other research has also shown similar trends.
In particular, this new study focused on the impacts of hormone-disrupting chemicals and substances, such as microplastics, bisphenol, phthalates, and PFAs. These are believed to be a potential driver of the fertility decline recorded worldwide.
Phthalates have been linked to altered sperm shape in invertebrates and reduced sperm counts in humans. In a similar vein, PFAs are believed to impact sperm quality, and are both linked to hormone disruption. These chemicals are readily found in consumer goods, so exposure is frequent.
The new research looked at studies showing how heat stress, lower oxygen levels and other issues associated with climate change may worsen infertility. Heat waves have been known to damage sperm in insects, and a similar impact has been observed in humans.
To combat the issues caused by these stressors, scientists urge corporations and organisations to reduce the use of toxic chemicals, as well as tackle climate change.
‘There is enough evidence in both areas to act to reduce our impact on the planet,’ said Brander.
