Microplastics found in human testicles potentially linked to declining sperm counts, says report

Researchers have discovered microplastics in human testicles, potentially contributing to declining sperm counts in men, according to a report by The Guardian. The study found microplastic pollution in every sample tested.

The research, titled ‘Microplastic presence in dog and human testis and its potential association with sperm count and weights of testis and epididymis', involved studying dissolved tissue samples to analyse the remaining plastics.

The study, conducted by researchers at the University of New Mexico in the United States, involved testing 23 human and 47 dog testes. It was published on May 15 in the Toxicological Sciences journal.

Xiaozhong Yu, one of the researchers and authors of the study and a professor at the University of New Mexico, told The Guardian that he was surprised by the findings. “At the beginning, I doubted whether microplastics could penetrate the reproductive system. When I first received the results for dogs, I was surprised. I was even more surprised when I received the results for humans.”

Impact on Sperm Count

The samples were from the New Mexico Office of the Medical Investigator, which routinely collected human testes. The samples were analysed after a seven-year storage period. The human testicles were preserved, so their sperm counts could not be measured. However, the dog testes showed lower sperm counts in samples with higher PVC contamination, per the report.

The study, thus, indicated a “possible link” between microplastics and reduced sperm counts while noting that further research is needed to confirm this theory.

On the likely impact on sperm count, Professor Yu said, “PVC can release a lot of chemicals that interfere with spermatogenesis, and it contains chemicals that cause endocrine disruption.”

Notably, sperm counts in men have been decreasing for decades, with chemical pollution, including pesticides, often blamed. However, microplastics have recently been detected in human blood, placentas, and breast milk, suggesting widespread contamination. While the health impacts are not fully understood, lab studies have shown microplastics can damage human cells.

Environmental Impact

The study noted that microplastics are ubiquitous, found from Mount Everest’s peak to the ocean's depths, and people ingest and inhale these particles daily. These microplastics may then lodge in tissues and cause inflammation or chemicals in the plastics might harm them. In March, doctors also linked microscopic plastics in blood vessels to higher risks of stroke, heart attack, and early death, the report said.

What The Study Found

• Human testicles contained nearly three times the plastic concentration found in dog testes: 330 micrograms per gram of tissue versus 123 micrograms.
• Polyethylene, used in plastic bags and bottles, was the most common microplastic found, followed by PVC.
• The researchers noted that the widespread presence of microplastics and nanoplastics raised concerns about their impact on human reproductive health. They added that PVC releases chemicals that disrupt spermatogenesis and cause endocrine disruption.
• However, they added that limited research exists on microplastics within the human reproductive system and its effect on sperm quality.

Notably, a smaller 2023 study in China also detected microplastics in six human testes and 30 semen samples. Recent mouse studies have also shown that microplastics can reduce sperm count and cause abnormalities and hormone disruptions.