(Montreal) Three recent studies detected microplastic particles in the semen of at least half of the subjects studied.
The most recent study, by Chinese researchers, found particles in the semen of all 40 healthy men who underwent a premarital health assessment.
Another Chinese study detected it in half of the 25 samples analyzed, and an Italian study in six of the ten samples studied.
“The question for me is how microplastics get to the sperm, commented the scientific director of the Nature sector.
The authors of the most recent study report in the journal Science of the Total Environment that all of the semen samples analyzed contained microplastics.
Polystyrene was the most common of the eight polymers identified, followed by polyethylene (which is used to make plastic bags) and PVC.
“The effects of exposure to different microplastic polymers on progressive sperm motility were variable, highlighting the need for further research into how microplastics affect male fertility due to their ubiquity and potential toxicity to reproduction,” add the Chinese scientists.
The authors of the Italian study raise the hypothesis that the particles can pass into the sperm via the epididymis (a component of the male reproductive system) and also from the seminal vesicles (glands which, together with sperm, produce the fluid which constitutes sperm), which are the most sensitive to inflammation.
Inflammation will have the effect of opening cellular barriers that would otherwise remain closed, such as the blood-testis barrier.
“That means that there is something in microplastics that makes them capable of entering an organ (the testicles) which is normally very selective and which in any case protects itself enormously,” recalled Ms. Bailey.
The Chinese authors of the most recent study do not seem to have measured any significant impact of microplastics on sperm motility, underlines Ms. Bailey. On the other hand, she points out that all the subjects came from a region with little pollution; While this makes the results more relevant to the general population, she adds, they don’t tell us anything about which men would be more exposed to pollution.
Microplastics could also interfere with characteristics other than motility that were not measured in this study, recalled Ms. Bailey, especially since the relevance of sperm motility as an indicator is limited.
Fertility crisis
Sperm counts have been in free fall for several years, without us really understanding why. Several studies, however, have pointed the finger in the direction of chemical pollution.
And if microplastics are found in semen, added Ms. Bailey, we cannot exclude that they are transmitted to women during sexual intercourse and that they also have deleterious effects on them.
“It’s another piece of the puzzle,” she said. We know that there is a crisis in male reproduction. This is a very complex question. »
Micro and nanoplastic particles come from the breakdown of larger plastic items. Microplastics range in size from one micrometer (one millionth of a meter) to about five millimeters. Nanoplastics are measured in billionths of a meter. For comparison, the circumference of a human hair is about 70 micrometers.
Nanoplastic particles are so tiny that they can enter the bloodstream (for example, by crossing the intestinal barrier) and travel directly to organs.
These particles have so far been detected in every nook and cranny of the body, from the brain to the placenta.
The impact of these particles on human health is still poorly understood, but they possibly interfere with the functioning of certain organs and that of the reproductive system. They could also have carcinogenic properties, be a source of oxidative stress and imitate the action of certain hormones (so-called endocrine disruptors). Other studies implicate them in inflammatory bowel diseases.
