Male infertility continues to be a worldwide problem, but it is not always clear what factors contribute to it.

Due to increasing evidence that microplastics have found their way into different biological systems, from blood to lungs, researchers have become interested in identifying and understanding the potential impact of microplastics on reproductive systems, as well.

A study recently published in Toxicological Sciences has examined microplastics and their presence in male reproductive organs.

Researchers identified 12 different microplastic types in dog and human testis samples. In dogs, researchers found that higher amounts of certain microplastics were associated with reduced sperm counts and testis weight.

As research moves forward, experts hope to better understand how the presence of microplastics may contribute to declines in male fertility.

InfertilityTrusted Source involves the inability to conceive after 1 year of unprotected sex. Male infertility accounts for about 20% of infertility cases.

There are many potential causes of male infertility, including endocrine disorders, genetics, and even certain medications. Exposure to environmental toxins can also cause male infertility.

Male infertility can be a significant struggle and can take a particularly heavy psychological toll.

James A. Kashanian, MD, director of Male Sexual Health in the Department of Urology at Weill Cornell Medicine, not involved in the current research, noted the following to Medical News Today:

There are times when doctors have no idea what is causing male infertility, making it even more challenging to decide the best course of action. In recent decades, there has also been a noted decline in sperm counts worldwide.

Experts are interested in addressing how the environment impacts male fertility and what changes can potentially lead to better fertility rates.

The researchers behind the current study wanted to understand more about the relationship between microplastics and male reproductive systems.

They looked at testis tissues from dogs and men. They obtained canine testis tissues from routine dog neuter surgeries and anonymized samples from men via the New Mexico Office of the Medical Investigator. Altogether, the research included samples from 47 dogs and 23 men.

Researchers identified 12 different microplastic types in the dog and human testis samples. They found that the amount of microplastics in men was about three times higher than in dog reproductive tissue.

Among humans and dogs, the most common type of polymer was polyethylene (PE), and the second most common was polyvinyl chloride (PVC).

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.

Tracey Woodruff, PhD, professor and director of Environmental Research and Translation for Health (EaRTH) Center at the University of California, San Francisco, also not involved in the study, explained to MNT that:

Researchers were able to examine the dog tissue samples further to determine more about how the presence of microplastics influenced 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.

One microplastic type was associated with an increase in sperm count, and two were associated with an increase in testis weight. However, these results were not statistically significant.

Interestingly, researchers did not find an association between PE and the observed properties, though PVC was associated with decreases in testis weight. Thus, it is possible that microplastics negatively affect male fertility, but more research is required.