New study suggests that microplastics are stored in the balls

The origins of the mythical "Pee is stored in the balls" meme are largely unknown. But the origin of the microplastics that, according to a recent study, are actually stored in the balls? That is, unfortunately, much easier to trace. Published last week in the journal of Toxicological Sciences, the scientific paper titled "Microplastic presence in dog and human testis and its potential association with sperm count and weights of testis and epididymis" presents evidence suggesting that those of us with testicles may very likely have a bunch of plastic in our balls.

From the article summary in The Guardian:

The scientists tested 23 human testes, as well as 47 testes from pet dogs. They found microplastic pollution in every sample.

The human testicles had been preserved and so their sperm count could not be measured. However, the sperm count in the dogs' testes could be assessed and was lower in samples with higher contamination with PVC. The study demonstrates a correlation but further research is needed to prove microplastics cause sperm counts to fall.


The human testicles had a plastic concentration almost three times higher than that found in the dog testes: 330 micrograms per gram of tissue compared with 123 micrograms. Polyethylene, used in plastic bags and bottles, was the most common microplastic found, followed by PVC.

While the sample size — as in the quantity of testes involved in the study, not the physical size of the testes involved in the study — was rather smaller, the researchers believe this could help explain declining sperm rates (along with the pesticides that have also been implicated).

Also worth noting is that The Guardian's headline of "Microplastics found in every human testicle in study" fits frighteningly well with the cadence of Gilbert & Sullivan's musical theatre classic, "The Modern Major General." Fortunately, the fine folks on Bluesky are on it:

Microplastics found in every human testicle in study [Damian Carrington / The Guardian]

Microplastic presence in dog and human testis and its potential association with sperm count and weights of testis and epididymis [Chelin Jamie Hu, Marcus A Garcia, Alexander Nihart, Rui Liu, Lei Yin, Natalie Adolphi, Daniel F Gallego, Huining Kang, Matthew J Campen, Xiaozhong Yu / Toxicological Sciences]

Previously: A golf club you can pee in