Microplastics have been found on the summit of Mount Everest, deep in the Mariana Trench in the Pacific Ocean and now in men’s testicles.
Researchers from the University of New Mexico found 12 types of microplastics in all 23 human testicles examined.
Data has shown that sperm counts have declined by 59 percent in recent decades, with other culprits ranging from cell phones in pockets to vape pens.
“We don’t want to scare people,” said the study’s lead author. ‘We want to provide the data scientifically and make people aware.’
Microplastics have been found on the summit of Mount Everest, deep in the Mariana Trench in the Pacific Ocean and now in the testicular tissue of men. Researchers found 12 types of microplastics in 23 human testicles, suggesting the tiny particles may play a role in sperm quality
Graph shows: The rate at which sperm concentrations are declining worldwide is evident from samples collected between 1972 and 2000 (orange) and since 2000 (red)
The team found that the most common of the twelve microplastics was a polymer material, polyethylene, used in plastic bags and bottles.
The average human concentration was 329.44 micrograms per gram of tissue – much more than recent studies on human bloodwhich amounted to only tens of micrograms per gram.
Microplastics, smaller than five millimeters in length, enter our bodies through plastic packaging, certain foods, tap water and even the air we breathe – and have been linked to cancer and fertility problems.
“There are a lot of microplastics,” noted the study’s lead author, Dr. Xiaozhong John Yu. ‘We can make our own choices to better avoid exposure, change our lifestyle and change our behavior.’
Dr. Yu was inspired to lead the project after a colleague, a professor at the university’s pharmacy school named Matthew Campen, discovered alarming levels of microplastics in human placentas.
The presence of this invisible contaminant in placentas, so close to unborn children during pregnancy, Dr. Yu, led them to wonder how else microplastics might affect reproduction.
According to Dr. Yu, Campen asked him, “Have you thought about why there is this decline in reproductive potential recently? There must be something new.’
Dr. Yu and his team found that the concentration of microplastics in human male testicular tissue was significantly higher than the average Campen found in placental tissue.
In one of the more disturbing findings of the study, the researchers determined, based on testicular samples from male dogs, that the volume of microscopic polyvinyl chloride (PVC) plastic, commonly found in pipes, directly scaled to lower sperm counts in dogs .
For ethical reasons, anonymized human male testicular tissue was obtained from the New Mexico Office of the Medical Investigator for the new study.
The state coroners collect this tissue material during perform autopsies and then store the material frozen for potential forensic purposes for up to seven years before it can be legally disposed of.
Preservation methods used to store the human tissue prevented the team from calculating the men’s sperm counts.
To fill this gap, the study also looked at tissue from dogs, showing that the amount of microplastics was directly scaled up to reduce sperm counts in dogs.
“At first I doubted whether microplastics could enter the reproductive system,” said Dr. Yu about his research, published in the journal Toxicological Sciences,
‘When I first got the results for dogs, I was surprised. I was even more surprised when I received the results for people.’
A 2022 report warned that the decline in male sperm counts amounts to a global crisis that could “jeopardize the survival of humanity.” New research this month points the finger at microplastics
Health professionals have been concerned about declining sperm counts in men for years, although the causes appear to be related to multiple environmental factors.
A November 2022 study in the journal Human reproduction updateA study summarizing data from men in 53 countries found that average sperm counts fell by 51.6 percent globally between 1973 and 2018.
To analyze their samples, Dr. Yu and his team first chemically stripped both the human and dog tissues of organic matter, fats and proteins, leaving only contaminants, such as the microplastics, to study.
Spinning the samples in an ultracentrifuge produced individual plastic pellets that could then be identified using traditional laboratory methods, such as mass spectrometry.
Dr. Yu explained that the presence of PVC plastic was particularly alarming: “PVC can release many chemicals that disrupt spermatogenesis (the production of sperm in the testicles) and it contains chemicals that disrupt hormone balance.”
Disruptions of the endocrine system are known to cause problems with sex and reproductive hormones in humans, fish and other species.
The health implications of microplastics in humans have received increased attention in recent years, as research has shown that the particles appear to contribute to inflammatory bowel disease, pancreatic cancer and Alzheimer’s disease.
Amid growing concerns about microplastics in our bodies and in the environment, 175 UN member states have agreed to come up with a plan this year to end plastic pollution: a global plastics treaty.
Nevertheless, Dr. Yu expressed caution in rushing to worst-case scenario conclusions and said he hopes more scientists will study the links between microplastics and reproductive health.
“We have a lot of unknowns,” he said.
‘We really need to look at what the potential long-term effect (could be). Are microplastics one of the factors contributing to this decline?’