Microplastics have crossed so many boundaries it is hard to keep track.
The ‘red flag’ of our consumptive lifestyles, they have reached the limits of the Earth - from the Mariana Trench to the tip of Mount Everest. These tiny particles of decomposed plastic have seeped into clouds, and been found buried in archaeological remains believed to be ‘pristine’.
They have challenged our ideas of bodily inviolability too, infiltrating every organ. What might have been considered the ‘purest’ parts of human life - placentas, babies, breast milk - contain microplastics.
So it comes as little surprise that human testicles have them too, as the most comprehensive study yet on microplastics and the scrotum confirms.
Less is known about what microplastics are doing to our bodies. But in the case of testicles, the new research suggests they could be lowering sperm count.
Every human testicle in the study contained microplastics
“The ubiquitous existence of microplastics and nanoplastics raises concerns about their potential impact on the human reproductive system,” the study, published in the journal Toxicological Sciences, states.
“Limited data exists on microplastics within the human reproductive system and their potential consequences on sperm quality.” To find out more, the scientists tested 23 human testes, and 47 testes from pet dogs. Microplastic pollution was found in all 70 samples - though with “significant inter-individual variability.”
The human testes were taken from postmortems conducted in 2016, with the men ranging in age from 16 to 88 when they died. While the dogs’ testes were obtained after neutering operations at veterinary practices.
The researchers dissolved the tissue samples to see whether any tiny plastic particles remained.
It did - and plastic concentration was revealed to be almost three times higher in human than dog testes, with 330 micrograms per gram of tissue compared to 123 micrograms in dogs.
Polyethylene - the most commonly produced plastic, primarily used for packaging like plastic bags - was, unsurprisingly, the most frequent microplastic found. PVC (polyvinyl chloride), used for everything from plastic bottles to pipes, was next.
Since the human testes had been preserved, no sperm count reading could be taken. But in the dogs’ testes, sperm count was lower in samples with higher contamination of PVC.
Are microplastics lowering men’s sperm count?
Further research is needed to prove the connection, the researchers note, but the signs do point in that direction.
Sperm counts in western men have more than halved in the last few decades, with air pollution and exposure to pesticides frequently cited as factors. One expert believes that pollution is causing penises to shrink, as well as lowering sperm count.
“At the beginning, I doubted whether microplastics could penetrate the reproductive system,” Prof Xiaozhong Yu, one of the authors of the new study told the UK’s Guardian newspaper.
“When I first received the results for dogs I was surprised. I was even more surprised when I received the results for humans.”
“PVC can release a lot of chemicals that interfere with spermatogenesis and it contains chemicals that cause endocrine disruption,” explained Yu, who works at the University of New Mexico in the US.
A smaller study in China last year also found microplastics in six human testes and 30 semen samples.
