Microplastics found in human and dog testicles may threaten fertility

Scientists from the University of New Mexico in the United States researched the testicles of dozens of humans and dogs. The study discovered worryingly large amounts of microplastics. Preliminary results suggest that these could hurt fertility, but experts emphasize that further research in this area is necessary.

The research team consisted of scientists who thoroughly examined 23 human testicles and 47 dog testicles. These studies aimed to check whether microplastics can be found in these organs. The researchers noted the presence of "significant amounts" of this material in the samples studied.

"Our study demonstrated the presence of microplastics in all the human and dog testicles examined," said Prof. Xiaozhong "John" Yu, the author of the work published in the journal "Toxicological Sciences".

Professor Yu is an expert who specializes in studying the impact of various factors on fertility. His studies have shown that the number of sperm produced by men can be affected by heavy metals, pesticides, or substances that disrupt hormone function. The noticeable global decline in male fertility in recent years prompted him to search for a new harmful factor.

In the research, scientists used human tissues obtained from autopsies and dog tissues. For dogs, the researchers found an average of 67 micrograms of plastic per kilogram of tissue, and for humans, 184 micrograms per kilogram.

- Initially, I doubted that microplastics could penetrate the reproductive system. When I received the first results regarding dogs, I was surprised. I was even more surprised by the results concerning humans – said Prof. Yu.

Thanks to the latest analytical methods, scientists were able to precisely determine not only the amount but also the types of plastics present in the examined tissues. The most commonly found plastic is polyethylene (PE), which is used, for example, to make plastic bags and bottles. The second most common was polyvinyl chloride (PVC), which is used to produce, among other things, flooring, window and door frames, packaging, and components of various devices. Experiments on dogs showed that a decrease in sperm count accompanied polyvinyl chloride.

"The type of plastic matters. PVC can release large amounts of substances that affect spermatogenesis. It also contains compounds that disrupt hormone function," warns Prof. Yu.

Dogs were chosen for the research for two reasons – they live closely with humans, and their bodies are significantly similar to humans. Physically, their spermatogenesis is closer to humans, and the sperm concentration is similar. Prof. Yu said that humans and dogs share common environmental factors contributing to the decline in sperm count.

Researchers remind us that microplastics come from various plastic-made objects that gradually degrade in the environment. These particles are carried by wind and water and are now practically everywhere.

The average age of the men whose tissues were examined was 35 years, indicating that exposure to plastic began decades ago when there was less plastic in the environment than there is now. This is not good news.

"The impact on younger generations could be even more concerning now that there is more plastic in the environment than ever before," warns the specialist.

The results indicate the need for further research to determine how microplastics might affect sperm production in the testicles. Scientists still do not know the long-term effects of microplastics on the body.