In 2024, a team of researchers from Peking University highlighted the cruel lack of data concerning the exact impact of microplastics on human health. In their meta-study, they highlighted the toxic and inflammatory effects of these particles on the respiratory, digestive, nervous, cardiovascular, immune and reproductive systems.
This time, a Spanish team examined the follicular fluid of 29 women and the seminal fluid of 22 men, secretions that both play an essential role in natural conception and assisted reproduction.
Scientists have unsurprisingly detected microplastics in human reproductive fluids, an observation that raises important questions about potential risks to fertility and reproductive health. Their findings are published in the journal Human Reproduction.
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"We were struck by their frequency."
A microplastic is a small piece of plastic measuring less than 5 millimeters, most often resulting from the degradation of plastic waste (packaging, bags, bottles). While these have been proven to pose a threat to the environment, their danger to public health is less widely recognized.
"Previous studies have already shown that microplastics can migrate into various human organs (blood, placenta, editor's note). So we weren't totally surprised to find microplastics in human reproductive fluids, but we were struck by their frequency," says Emilio Gomez-Sanchez, first author of the study and director of the IVF laboratory at Next Fertility Murcia (Spain).
Microplastics were present in 69 % of the follicular fluid samples analyzed, and in 55% of the seminal fluid samples. A range of commonly used microplastic polymers were detected. Polytetrafluoroethylene (PTFE), found in non-stick pan coatings, was notably present in 31% to 41% of the samples.
Polystyrene (disposable food packaging), polyethylene terephthalate (plastic bottles) and polypropylene (caps and containers) were also identified in both groups.
To detect them, the researchers used laser direct infrared (LDIR) imaging technology. In short, LDIR is an advanced technique used to detect and analyze microplastics in environmental samples. It combines infrared spectroscopy and laser imaging to identify the size, shape, and chemical composition of plastic particles.
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Understanding the consequences on fertility
"Very few studies have been published on this subject. It is assumed that microplastics cause inflammatory reactions that can lead to changes in many biological processes, such as triggering apoptosis in cells (the ability of cells to self-destruct), continues Emilio Gomez-Sanchez. They can also act as endocrine disruptors, introduce chemicals into the body or cause infections"One of the main hypotheses is that microplastics harm the quality of eggs and sperm in humans. But current data is not sufficient to confirm this.
This study on a small cohort does not allow conclusions to be drawn about the consequences of microplastics on fertility and reproductive health, but their detection highlights the need for further research. Subsequent phases of the project will explore the potential relationship between the presence of microplastics and the quality of oocytes and spermatozoa, in a larger number of cases.
“ There is no cause for alarm at this stage.Microplastics are just one of many factors that may play a role in fertility, along with age and genetics,” adds the study author. Nevertheless, simple measures, such as using glass containers to store and reheat food, choosing stainless steel utensils, or limiting the amount of water consumed in bottles, can help minimize our exposure.
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