Microplastics and Sperm Quality: What Studies Show
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TL;DR
- Global research suggests total sperm counts have fallen by roughly 62% since the 1970s, and the decline may be accelerating.
- Scientists have now detected microplastics in human semen, testes, and penile tissue.
- Human studies have reported associations between microplastic exposure and semen-quality measures including sperm concentration and progressive motility.
- While this does not prove that microplastics are causing the decades-long decline in sperm counts, detection in reproductive tissue, human associations, and laboratory evidence showing biologically plausible mechanisms have made the question increasingly difficult to ignore.
The bigger story starts before microplastics
Something has been happening to male reproductive health for decades.
A landmark 2017 systematic review analyzed semen data from 42,935 men across 185 studies. Among men in North America, Europe, Australia and New Zealand who had not been selected based on fertility status, average sperm concentration fell from an estimated 99 million sperm per milliliter in 1973 to 47.1 million in 2011.
That is a 52.4% decline.
Total sperm count fell even further: 59.3% over the same period. Levine et al. (2017) Then researchers updated the analysis. Using data through 2018 and expanding the geographic coverage, researchers estimated that among unselected men globally:
Sperm concentration fell 51.6%.
Total sperm count fell 62.3%.
Perhaps most strikingly, the estimated annual rate of decline in sperm concentration was more than twice as steep when researchers restricted their analysis to the period after 2000. Levine et al. (2023)
Separately, the World Health Organization estimates that roughly 1 in 6 people worldwide experience infertility at some point in their lives. Those statistics do not tell us why sperm counts have declined – researchers have investigated numerous potential contributors, including obesity, smoking, heat exposure, diet, pesticides, endocrine-disrupting chemicals and other environmental exposures.
Microplastics are now part of that investigation. And the reason is increasingly straightforward: scientists keep finding plastic where sperm are made, stored and released.
Scientists found microplastics in every human testicle they examined
In 2024, researchers at the University of New Mexico analyzed testicular tissue from 23 human cadavers using pyrolysis gas chromatography-mass spectrometry. Microplastics were detected in all 23 human testes. The average concentration was approximately 328 micrograms of plastic per gram of tissue, with polyethylene, one of the world's most widely used plastics, the dominant polymer. Hu et al. (2024)
The study also examined dogs, where researchers had access to reproductive measurements unavailable in the human cadaver samples. In the canine data, concentrations of certain plastics were associated with reproductive measures including sperm count and testicular weight.
That distinction matters: the study established that microplastics were present in human testes, but it did not establish that those particles reduced sperm counts in the human subjects. Still, the location is hard to ignore. The testes are where sperm are produced.
Then researchers started finding microplastics in semen
A 2024 multi-site study in China recruited 113 men from reproductive medicine centers and measured eight types of microplastics in semen and urine. Among samples successfully analyzed for microplastics, researchers reported widespread mixed exposure, with most men carrying three to five different plastic types.
The more interesting finding was not simply that plastic was present. It was the relationship with semen quality.
Exposure to PTFE, a polymer commonly associated with non-stick coatings, was associated with reduced sperm concentration. Researchers also reported a dose-response pattern: for every additional type of microplastic detected, the odds of reduced sperm concentration were 3.22 times higher in their statistical model. Zhang et al. (2024)
This was a cross-sectional study of men attending reproductive medicine centers. Researchers measured exposure and semen quality at roughly the same time. That means the study can identify an association, but it cannot tell us that microplastics caused the sperm differences.
Another study found a potentially striking difference in sperm motility
A separate 2025 study analyzed semen from 45 men attending a fertility center. Microplastics were detected in 34 of the 45 samples, or about 76%. In this, one finding stood out in particular: Among men whose semen contained PET microplastics, average progressive sperm motility was:
20.6% with PET detected
versus
34.9% without PET detected
Progressive motility is essentially a measure of how many sperm are moving forward effectively, an important part of normal sperm function. While a striking difference, the study was small, so researchers said more research is needed Guo et al. (2025). What researchers can confidently say is that microplastics are showing up in human semen, and researchers are beginning to see potentially meaningful differences in sperm function that warrant much larger studies.
Plastic has even been detected in human penile tissue
In another study, researchers analyzed penile tissue collected from men undergoing penile prosthesis surgery. Microplastics were identified by infrared imaging in 80% of the analyzed samples. PET and polypropylene were the most common polymers identified. Codrington et al. (2024) Again, the study was tiny and involved a very specific group of patients. It cannot tell us whether microplastics contribute to erectile dysfunction. But considered alongside the semen and testicular findings, it adds to an increasingly unusual picture: plastic particles have now been directly detected throughout multiple parts of the male reproductive system.
So could microplastics be contributing to declining sperm counts?
The honest answer is: it's possible, but we don't know for sure just yet.
The global decline in sperm counts is well documented, but there is currently no human study demonstrating that microplastics caused that decline. What researchers increasingly have is an evidence chain:
- Exposure: Microplastics are ubiquitous in food, water and air.
- Internal exposure: They have been detected in blood and numerous human tissues.
- Reproductive exposure: Researchers have now detected them in testes and semen.
- Human associations: Several early observational studies have reported relationships between particular microplastic exposures and semen-quality measures.
- Biological plausibility: Laboratory and animal studies have identified mechanisms capable of affecting male reproductive function.
How could microplastics affect sperm?
Most of the mechanistic evidence comes from animals and laboratory models, so it should not be treated as proof of what occurs at ordinary human exposure levels. But scientists have identified several pathways worth investigating.
One is oxidative stress. Excess reactive oxygen species can damage cellular membranes, mitochondria and DNA, all of which matter for sperm development and motility.
Experimental studies have also reported changes involving the blood-testis barrier, germ-cell apoptosis and sperm energy metabolism, including reduced activity of enzymes involved in cellular energy production.
Another potential pathway involves testosterone production.
In mice chronically exposed to polystyrene microplastics, researchers have reported suppression of the LH/LHR/cAMP/PKA/StAR signaling pathway in Leydig cells, the cells responsible for producing testosterone.
There is also a second issue that is easy to confuse with the particles themselves: plastics can contain or interact with chemicals such as BPA and phthalates, some of which already have substantial research histories as endocrine-disrupting chemicals.
The biological story is therefore unlikely to be as simple as "plastic particle equals lower sperm count." Particle size, polymer, surface chemistry, additives, dose, route of exposure and duration may all matter.
The most important question still hasn't been answered
Imagine two groups of otherwise similar men followed for years, with rigorously measured microplastic exposure and repeated measures of sperm concentration, motility, hormones and fertility outcomes. We do not yet have that study. Most of today's human evidence is observational, cross-sectional and relatively small. That is why headlines claiming that microplastics cause infertility are ahead of the science.
But dismissing the research because causation has not yet been proven goes too far in the opposite direction. Sperm counts have declined dramatically over the last several decades. Microplastics are now demonstrably present in the human reproductive system. And early epidemiological and experimental evidence gives researchers legitimate reasons to investigate whether those facts are connected.
What can you actually do?
You are not going to eliminate plastic exposure completely.
Microplastics have been detected in food, drinking water and air, so the realistic goal is reducing repeated, unnecessary exposure rather than trying to create a plastic-free life.
Simple changes include using glass or stainless steel for hot foods and beverages when practical, avoiding heating food in plastic containers, replacing heavily scratched or degraded plastic foodware, reducing unnecessary bottled-water consumption, and controlling household dust.
None of these steps has been demonstrated to increase sperm count or improve fertility.
They are simply reasonable ways of reducing avoidable exposure while the science catches up.
Where Sifts fits
There are really two sides to managing microplastic exposure:
Reduce what you take in, and support what your body naturally eliminates. Sifts is designed around the second. Its key ingredient is chitosan, a non-digestible dietary fiber studied for its interaction with microplastic particles in the gastrointestinal tract and its potential to support their elimination through normal digestion.*
For us, that is the appropriate frame: support the body's natural handling of dietary microplastic exposure while researchers continue working out what long-term exposure may mean for human health.*
Because when plastic is being detected in blood, organs, testes and semen, the question is no longer whether humans are exposed. The question is what that exposure ultimately does to us.
FAQ
Have sperm counts really fallen by more than 60%?
A large updated meta-analysis estimated that total sperm count among unselected men worldwide declined by approximately 62.3% between 1973 and 2018. The research documents a population-level trend, but it does not identify one specific cause for the decline.
Have microplastics been found in human semen and testes?
Yes. Researchers have detected microplastics in human semen and testicular tissue. One 2024 study detected microplastics in all 23 human testes examined, while a 2025 study detected microplastics in 34 of 45 semen samples. Detection establishes exposure, but it does not by itself establish harm.
Do microplastics cause infertility or lower sperm count?
Current human evidence does not establish that microplastics cause infertility or the long-term decline in sperm counts. Early observational studies have reported associations with sperm concentration and motility, while animal and laboratory studies provide possible biological mechanisms. Larger and longer-term human studies are still needed.
Can I reduce my exposure to microplastics?
Yes. You cannot completely avoid microplastics, but you can reduce unnecessary exposure by avoiding heating food in plastic, using glass or stainless steel for hot foods and drinks, replacing heavily scratched plastic containers, and reducing unnecessary bottled-water use.
Sources
Levine et al. (2017), Temporal trends in sperm count: a systematic review and meta-regression analysis; Levine et al. (2023), Temporal trends in sperm count: a systematic review and meta-regression analysis of samples collected globally in the 20th and 21st centuries; World Health Organization, 1 in 6 people globally affected by infertility; Hu et al. (2024), Microplastic presence in dog and human testis and its potential association with sperm count and weights of testes and epididymis; Zhang et al. (2024), Association of mixed exposure to microplastics with sperm dysfunction; Guo et al. (2025), The Presence of Microplastics in Human Semen and Their Associations with Semen Quality; Codrington et al. (2024), Detection of microplastics in the human penis; Casella et al. (2025), Preliminary Study on PCC-Chitosan's Ability to Enhance Microplastic Excretion in Human Stools from Healthy Volunteers; Cornelli et al. (2026), Reduction in Circulating Microplastics in Humans Following Gastrointestinal Sequestration by Chitosan.
Disclaimer: The information in this article is for educational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.