Particles of plastic in testicles may affect fertility

Since June is Men’s Health Awareness Month, I was googling around the internet looking for appropriate subjects when I came across several articles about researchers finding tiny shards of plastic in men’s testicles and how they may be affecting fertility.

To be fair, researchers have been looking at the effects of plastics on the human body for some time. An article published in News-Medical.net last month says that “within the human body, microplastics have been retrieved from blood, sputum, liver, heart, lungs, testes, endometrium, placenta and amniotic fluid.”

The issue is that microplastics are everywhere. An article in Scientific American says, “These tiny polymers shed by the 400 million-some metric tons of plastic that humans produce each year, are in the food we eat and the water we drink — and therefore our body. While microplastics’ impacts on human health have not yet been fully established, evidence suggests chemicals in some plastics can disrupt hormone signaling, potentially leading to a wide array of health effects.”

Dr. John Yu is a toxicologist in the College of Nursing at the University of New Mexico and the lead author of the study about testicles which was published in Toxicological Sciences last month. The story about it that I found on NPR.org said, “When he set out to do the study, Yu didn’t expect microplastics would have penetrated the male reproductive system so extensively, given the tight blood-tissue barrier around those organs. To his surprise, the research team unearthed a wide range and heavy concentration of microplastics in the testicles of about two dozen men and close to 50 dogs.”

In case you’re curious, the male testicles were collected from autopsies of people ranging in age from 16 to 88, and from dogs who’d been neutered at local veterinary clinics in New Mexico. 

Yu explained that “dogs can function as ‘sentinel’ animals for disease and harmful chemical exposure because they’re so embedded in the human environment, plus spermatogenesis (the production or development of mature spermatozoa) is more similar to the human process of producing sperm than lab rats.”

Researchers identified twelve different microplastic types in the samples of which the most common was polyethylene (PE) with polyvinyl chloride (PVC) coming in second. They found that the amount of microplastic was about three times greater in men than in the dogs’ reproductive tissue.

“PE is commonly used in packaging, water supply systems, and agricultural films. PVC is also very common, used in construction, medical equipment, packaging, and insulation for electronics,” Medical News Today said.

Researchers examined the dogs’ tissue samples to determine how microplastics influence fertility. “The results suggested that certain microplastic types were associated with decreases in sperm count and declines in testis weight. These results reached a level of statistical significance in the analysis,” MNT reported.

However, and there’s always a however, one type of microplastic was associated with increased sperm count and two were associated with an increase in testis weight, but the researchers called the results “not statistically significant.”

The study has some obvious limitations. The human tissue sample was small, they were taken from just one area of the U.S. and were harvested in 2016 which could have impacted the results.

“Researchers also acknowledge that the humans from which samples came typically did not experience natural deaths, so experts cannot broaden the results to an entire population,” the MNT article explained. “Their approach to analyzing tissue samples also requires further refinement. Furthermore, the study could not account for certain factors that could have impacted the amount and types of microplastics they observed.”

Male infertility accounts for between twenty to thirty percent of infertility cases and that number is increasing. Unlike women who go through menopause, men can remain fertile throughout their lives. Of course, there are extenuating circumstances such as age-related changes, various medical problems, medicines, illegal drugs, and environmental exposure that can affect male reproductive hormones, sperm counts and sperm quality.

In their study, the authors noted that their research “highlights the need to determine the dose-response effects of these microplastics and to conduct mechanistic studies on the reproductive system."

So, although this study adds value to what we’re learning about microplastics, at the end of the day, more research is necessary. 

    Kathy Hubbard
  

Kathy Hubbard is a member of Bonner General Health Foundation Advisory Council. She can be reached at kathyleehubbard@yahoo.com.