Microplastics and Testosterone: What the Testicle Study Found, and What It Didn't

In May 2024 a headline went round the world: microplastics had been found in every human testicle researchers tested. Within a week, supplement companies were selling "detox" protocols, and men were throwing out their plastic chopping boards.

The study was real. The finding was real. What most of the coverage left out was how small the study was, what it could not measure, and the fact that nobody yet knows whether those particles do anything to a man's testosterone.

This is what the research actually shows, where the evidence is solid, where it is speculation, and the handful of changes that are worth making regardless.

What the testicle study found

Researchers at the University of New Mexico, led by Xiaozhong Yu, examined 23 human testes collected at post-mortem and 47 dog testes from routine neutering. They found microplastics in every sample.

The concentrations were striking. Human tissue averaged about 330 micrograms of plastic per gram of tissue, nearly three times the level in dogs. Polyethylene, the plastic used in carrier bags and bottles, was the most common type in both species.

In the dogs, the researchers could also count sperm. Higher levels of PVC in the tissue went with lower sperm counts. That is the finding most often quoted as proof that microplastics harm male fertility.

What it could not tell us

Three limits matter.

The human samples could not be tested for sperm. They had been preserved chemically, so the sperm link comes only from dogs. Dogs share our homes and some of our exposure, but they are not men.

Nobody measured testosterone. The study says nothing at all about hormone levels in the men whose tissue was examined.

The method has been questioned. In 2025 a group of scientists published a critique in the same journal. They argued that the chemical method used to dissolve tissue can leave fatty residues that look like polyethylene to the instrument, and that the particles were not confirmed by a second, visual technique. The authors defended their method, pointing out that the visual techniques cannot see the smallest nanoplastics, which may matter most. The honest position is that the exact numbers are uncertain, even if the presence of plastic is not.

Microplastics elsewhere in the body

The testicle study did not appear in isolation. Microplastics have now been reported in blood, placenta, semen and arterial plaque.

The study that worried cardiologists most was published in the New England Journal of Medicine in 2024. Marfella and colleagues examined plaque removed from the neck arteries of 257 patients. Polyethylene was detected in 58 per cent of them. Over the next three years or so, those with plastic in their plaque were about four and a half times more likely to have a heart attack, stroke or die than those without.

That sounds alarming, and it may turn out to be important. But it is an association, not proof. People with more plastic in their arteries may differ in many other ways, such as diet, income, where they live and how much processed food they eat. The authors themselves said confounding could not be ruled out.

A 2024 multi-site study in China also found microplastics in men's semen and urine and linked higher levels to poorer sperm quality. Again, it is observational.

So do microplastics lower testosterone?

In animals, there is a reasonable body of evidence that they can. Rodent studies have found that high doses of microplastics damage the Leydig cells, the cells in the testes that make testosterone, and lower testosterone levels.

In humans, there is not yet any good study showing that microplastics themselves lower testosterone. The animal doses are often far higher than people are thought to be exposed to, and nobody has measured both microplastic levels and testosterone in a large group of men.

Anyone who tells you otherwise is getting ahead of the evidence.

The chemicals that ride along are a different story

Here the evidence is stronger, and it is the part most often overlooked.

Plastics contain additives that leach out, particularly phthalates, used to make plastic soft, and bisphenols such as BPA, used in hard plastics and can linings. These have been studied in people for much longer.

Using data from 2,208 people in the American NHANES survey, Meeker and Ferguson found that higher levels of phthalate breakdown products in urine went with lower testosterone in men, women and children. The strongest links were in boys aged 6 to 12, where the highest exposure went with testosterone roughly a quarter to a third lower. The study was cross-sectional, so it cannot prove cause, but it fits a long line of animal work showing that some phthalates interfere with testosterone production.

So the more defensible way to frame this is not "microplastics lower testosterone" but "plastics expose you to chemicals, some of which have measurable links to lower testosterone". Our hormone disruptors guide goes through each family of chemicals in more detail.

Where your exposure comes from

You cannot avoid plastic altogether, and nobody should try. But exposure is not spread evenly, and a few sources account for a lot of it.

Heated plastic

Heat speeds up the release of both particles and additives. Microwaving food in plastic tubs, pouring boiling water into plastic, and leaving plastic bottles in a hot car all increase what ends up in what you eat and drink.

Bottled water

A 2024 study in PNAS by Qian and colleagues used a new imaging technique to count particles in bottled water and found an average of about 240,000 plastic particles per litre, around 90 per cent of them nanoplastics too small to see with older methods. Tap water is not free of plastic either, but bottled water is a large and easily avoided source.

Food packaging and processed food

Phthalates migrate into fatty foods from packaging, tubing and gloves used in processing. Diets high in fast food and ultra-processed food are consistently linked to higher phthalate levels, which is another reason, beyond calories, that ultra-processed food works against you.

Fragranced products

Some phthalates are used to carry fragrance in aftershave, deodorant, air fresheners and laundry products. "Fragrance" or "parfum" on a label can hide them.

What is actually worth doing

None of these steps is expensive, and none depends on the microplastics research being right, because they also cut exposure to the additives with stronger evidence.

• Stop heating food in plastic. Use glass or ceramic in the microwave, and let food cool before putting it into plastic boxes.
• Drink tap water from a glass or steel bottle rather than buying bottled water.
• Eat less ultra-processed and fast food. This is the change with the most other benefits as well.
• Choose fragrance-free toiletries and cleaning products where you can.
• Replace scratched non-stick pans and worn plastic chopping boards when they wear out, rather than all at once.

What is not worth doing: buying "microplastic detox" supplements, chelation, or sauna protocols sold as a way to sweat out plastic. There is no evidence any of these remove microplastics from the body, and the sauna in particular can harm sperm, as we explain in sperm count: what lowers it, what raises it.

Keep it in proportion

Testosterone in men has been falling across generations, and plastics are one of several suspects, as we discuss in why testosterone is falling across generations. But for an individual man, the factors with by far the biggest measured effect are still body fat, sleep, alcohol, medication and illness.

If your testosterone is low, start with those. Our guide to what causes low testosterone lists them in order of how common they are, and a proper testosterone test tells you where you actually stand.

Common questions

Were microplastics really found in every human testicle tested?

Yes, in all 23 human samples in the 2024 study. But it was a small study of post-mortem tissue, it did not measure testosterone, and its method has been questioned, so the exact amounts are uncertain.

Do microplastics lower testosterone?

In animals, high doses can. In humans there is no good study yet showing that microplastics themselves lower testosterone. The chemicals that leach from plastics, especially phthalates, have stronger links to lower testosterone.

Is bottled water worse than tap water?

A 2024 study found an average of about 240,000 plastic particles per litre of bottled water, mostly nanoplastics. Tap water from a glass or steel bottle is a simple way to cut a major source.

Can you detox microplastics?

There is no evidence that any supplement, cleanse or sweating protocol removes microplastics from the body. Reducing new exposure is the only approach with any logic behind it.

Should I stop using plastic altogether?

No. Focus on the biggest sources: heating food in plastic, bottled water, ultra-processed food and fragranced products.

Sources: Hu CJ et al., Microplastic presence in dog and human testis and its potential association with sperm count and weights of testis and epididymis, Toxicol Sci 2024;200(2):235-40 · Response to comment on the above, Toxicol Sci 2025;206(2):458-9 · Marfella R et al., Microplastics and nanoplastics in atheromas and cardiovascular events, N Engl J Med 2024;390(10):900-10 · Meeker JD, Ferguson KK, Urinary phthalate metabolites are associated with decreased serum testosterone in men, women, and children from NHANES 2011-2012, J Clin Endocrinol Metab 2014;99(11):4346-52 · Qian N et al., Rapid single-particle chemical imaging of nanoplastics by SRS microscopy, Proc Natl Acad Sci USA 2024;121(3):e2300582121 · Association of mixed exposure to microplastics with sperm dysfunction: a multi-site study in China, eBioMedicine 2024 · Educational only, not medical advice.

Keep reading: Hormone disruptors guide · Phthalates · Why testosterone is falling across generations · Sperm count: what lowers it, what raises it · Foods crushing your testosterone · Home hormone audit