Microplastics and sperm: what the research shows, and what it doesn't (2026).

Microplastics are in men: a 2024 study found them in every semen and urine sample from 113 men across three regions of China, and another 2024 study found them in all 23 human testes it examined. Whether they affect sperm is much less settled. The semen study found that men carrying more types of plastic had lower sperm counts, concentration and progressive motility, with PTFE (the non-stick coating polymer) standing out, but it was a one-time snapshot with no measure of dose, and no study has yet shown that lowering your exposure changes a semen analysis. The clearest harms come from mice dosed with polystyrene beads. Bottled water is the one source with a quantified difference: an estimated 90,000 extra particles a year against 4,000 from tap. Motily doesn't score microplastics because there is no behavior with evidence that it changes sperm. Tap water instead of bottled and no heating food in plastic are reasonable, cheap and unproven.

Are microplastics in men?

Yes, and the two best studies found them in everyone they looked at. Zhang and colleagues (eBioMedicine, 2024) collected semen and urine from 113 men aged 24 to 58 in Henan, Shandong and Hubei and found microplastics in every sample of both. They identified eight polymer types, with polystyrene, polypropylene and polyethylene the most common, and a typical man carried three to five of them. Hu and colleagues (Toxicological Sciences, 2024) examined 23 human testes and 47 dog testes and found microplastics in all of them. The human tissue held about 328 micrograms of plastic per gram, roughly 2.7 times the dog tissue, with polyethylene the largest share at 35%. The human testes were archived specimens, so nothing about those men's sperm was measured.

Smaller studies came first. Zhao and colleagues (Science of the Total Environment, 2023) looked at 30 semen samples and 6 testis samples from a Beijing hospital and found microplastics in 11 of the semen samples and 4 of the testes, polystyrene dominant in testis and polyethylene and PVC in semen. Montano and colleagues (Science of the Total Environment, 2023) found 16 fragments of 2 to 6 micrometers in 6 of 10 semen samples from men living in a polluted part of Campania, Italy. Before any of those, Leslie and colleagues (Environment International, 2022) measured plastic in the blood of 22 healthy volunteers for the first time, at an average of 1.6 micrograms per milliliter, with PET (drink bottles), polyethylene and polystyrene the most common.

The methods, particle sizes and units differ from study to study, so the numbers can't be compared with each other. The consistent finding is presence. Plastic particles reach the testes, and by 2024 the detection rate in semen had gone from some samples to all of them, which says as much about better instruments as about exposure.

Do they affect sperm? The human evidence

One study has linked microplastics in semen to semen quality, and it is worth reading closely because it is the source of most of the headlines. In the 113-man study, each additional type of polymer a man carried was associated with a lower total sperm count (about 15 million fewer sperm), a lower concentration (about 7 million per milliliter lower) and lower progressive motility (about 8 percentage points lower), after adjusting for age, BMI, smoking, drinking and study site. PTFE, the non-stick coating polymer, was found in 55% of the men and was the one polymer the authors singled out as significantly associated with lower semen quality.

The authors list the limits themselves. It is a cross-sectional study, "only an association between microplastic exposure and sperm quality", and it "does not establish causation". They recorded only whether each polymer was present or absent, "without specific exposure concentrations, sizes and shapes", so there is no dose to reason about. Nobody has tested a man before and after a change in exposure, and nobody has run a trial. Men who carry more types of plastic may also differ in where they live, what they do for work and what they eat, and a snapshot cannot separate those from the plastic. So the honest summary is: one study, one country, 113 men, a real association, and no evidence yet about cause or about what you can change.

What the animal and lab studies show

The mechanism story comes from mice. Jin and colleagues (Journal of Hazardous Materials, 2021) gave mice polystyrene particles of 0.5, 4 and 10 micrometers for 28 days and found lower sperm quality and testosterone, inflammation in the testes and disruption of the blood-testis barrier, the layer that protects developing sperm from the bloodstream. Xie and colleagues (Ecotoxicology and Environmental Safety, 2020) found polystyrene particles lowered sperm count and motility, raised the share of malformed sperm and cut serum testosterone in mice, with oxidative stress as the likely route.

These studies show that the particles can do harm, and how. They don't show that the particles in a man's semen are doing it. The mice swallowed uniform polystyrene beads at set doses for weeks; men take in a changing mix of polymers, sizes and shapes over decades, at doses nobody has measured. An association in men plus a mechanism in mice is a reason to keep studying, not a verdict.

Can you reduce exposure?

Somewhat, and one source is quantified. Cox and colleagues (Environmental Science & Technology, 2019) combined published particle counts for common foods and drinks with recommended intakes and estimated that a person swallows 39,000 to 52,000 microplastic particles a year, or 74,000 to 121,000 with inhalation, and that these are likely underestimates. The one habit that moved the total a lot was water: someone who meets their daily intake from bottled water alone "may be ingesting an additional 90,000 microplastics annually, compared to 4,000 microplastics for those who consume only tap water".

Heat and wear on plastic are plausible sources with measurements but no human health data. Hussain and colleagues (Environmental Science & Technology, 2023) microwaved polypropylene containers and polyethylene food pouches for three minutes and measured up to 4.22 million microplastic and 2.11 billion nanoplastic particles released per square centimeter, more from the pouches than the containers. Luo and colleagues (Science of the Total Environment, 2022) simulated cooking with non-stick pans and estimated that "thousands to millions" of PTFE particles can be released, about 9,100 from a single scratch and 2.3 million from a broken coating on the authors' figures. Given that PTFE was the polymer the semen study singled out, a scratched non-stick pan is the swap with the most circumstantial support. It is still circumstantial: nobody has compared the semen of men who cook on damaged pans with men who don't.

For balance, the World Health Organization's 2019 review of microplastics in drinking water concluded that "based on the limited information we have, microplastics in drinking water don't appear to pose a health risk at current levels", noting that particles larger than 150 micrometers are unlikely to be absorbed while data on the smallest particles was "extremely limited", and called for more research. That was before the semen and testis studies, and it was about water, not sperm, but it is the most careful public-health assessment there is.

Why Motily doesn't score it

Every one of the eight habits in the daily check-in has the same chain behind it: a behavior you can log, a measurable change it causes in the body, and a change in sperm parameters that has been shown in at least moderate evidence, which is what sets the weights on the science page. Microplastics don't have that chain yet, on three counts.

• Exposure is near-universal. The 2024 studies found plastic in every man. A score that is the same for everybody measures nothing.
• It can't be self-reported. You know whether you had a sauna today. You don't know how many particles you swallowed, and no study has shown that any question about your day predicts what is in your semen.
• No habit change has been shown to change sperm. The human evidence is a single cross-sectional association. There is no study in which men reduced their exposure and their semen analysis moved.

Putting a microplastics item in the check-in would turn a guess into a number and imply a precision the research doesn't have. If a trial shows that a specific swap changes semen quality, it can be added with a weight that reflects the evidence. Until then it is a guide, not a score.

What to do

• Drink tap water rather than bottled. It is the one swap with a quantified difference in particles, and it costs nothing. Reasonable, not proven.
• Move food out of plastic before heating it, and use glass or ceramic in the microwave. Reasonable, not proven.
• Replace a non-stick pan once the coating is scratched or flaking. PTFE was the polymer the semen study singled out. Reasonable, not proven.
• Keep the changes with real evidence first: smoking, weight, heat, alcohol and sleep. None of the swaps above should displace them.
• Skip anything sold as a microplastics detox, cleanse or test. There is no proven way to remove the particles and no threshold to test against.
• If a semen analysis came back low, work through the main guide and talk to a doctor. Microplastics are not a diagnosis.

Common questions

Related guides

• Every factor ranked
• Heat
• Phones, laptops and Wi-Fi
• Diet
• Supplements
• How Motily scores each habit

Sources

1. Zhang C, et al. Association of mixed exposure to microplastics with sperm dysfunction: a multi-site study in China. eBioMedicine, 2024.
2. Hu CJ, et al. Microplastic presence in dog and human testis and its potential association with sperm count and weights of testis and epididymis. Toxicological Sciences, 2024.
3. Zhao Q, et al. Detection and characterization of microplastics in the human testis and semen. Science of the Total Environment, 2023.
4. Montano L, et al. Raman microspectroscopy evidence of microplastics in human semen. Science of the Total Environment, 2023.
5. Leslie HA, et al. Discovery and quantification of plastic particle pollution in human blood. Environment International, 2022.
6. Jin H, et al. Polystyrene microplastics induced male reproductive toxicity in mice. Journal of Hazardous Materials, 2021.
7. Xie X, et al. Exposure to polystyrene microplastics causes reproductive toxicity through oxidative stress and activation of the p38 MAPK signaling pathway. Ecotoxicology and Environmental Safety, 2020.
8. Cox KD, et al. Human consumption of microplastics. Environmental Science & Technology, 2019.
9. Hussain KA, et al. Assessing the release of microplastics and nanoplastics from plastic containers and reusable food pouches: implications for human health. Environmental Science & Technology, 2023.
10. Luo Y, et al. Raman imaging for the identification of Teflon microplastics and nanoplastics released from non-stick cookware. Science of the Total Environment, 2022.
11. World Health Organization. WHO calls for more research into microplastics and a crackdown on plastic pollution. 22 August 2019.

Correction, 8 October 2026. A common question said every study had found microplastics in every sample. Only the two largest did; the page's own figures for the smaller studies were right.