Study Finds Evidence of Microplastics in Human Testicles

A new study has found that human and dog testicles contain evidence of microplastics, which could affect sperm count, weight of testes, and other reproductive problems.

Microplastics are tiny plastic particles that are less than 5 millimeters (about 0.2 inches) in diameter, making them barely visible to the human eye. However, these particles are small enough to move from the digestive system into the bloodstream, which can allow them to circulate with the blood flow and become trapped in filtering organs, such as the the lungs, kidneys, spleen, and liver.

In findings published last month in the medical journal Toxicology Sciences, researchers from the University of Mexico warn that these small particles of plastic waste are also pervasive in the male reproductive system, creating potentially serious consequences on male fertility.

“The ubiquitous existence of microplastics and nanoplastics raises concerns about their potential impact on the human reproductive system,” said lead researcher Chelin Jamie Hu, of the UNM Department of Cell Biology and Physiology. “[However], limited data exists on microplastics within the human reproductive system and their potential consequences on sperm quality.”

The new study aimed to measure and analyze the presence and types of microplastics in both canine and human testes, identifying potential links between these microplastics and sperm count, as well as the weights of the testes and epididymis, which is the tube connecting the testes to the rest of the body.

Microplastic Health Concerns

Researchers from Rice University found back in 2021 that microplastics breaking down may be causing bacteria to grow and spread that is resistant to available antibiotics, posing serious health risks for humans. Researchers studied how ultraviolet aging affects microplastics like polystyrene, commonly used in disposable containers.

As these items break down into microplastics, they become breeding grounds for antibiotic-resistant genes (ARGs) due to microbial and chemical contamination. These ARGs, protected by bacterial chromosomes, phages, and plasmids, can spread antibiotic resistance to other environmental items and humans. This spread decreases humans’ ability to fight infections, contributing to the rise of “superbug” infections that are difficult to treat and can have high fatality rates.

Another study, published in 2020 by researchers from Arizona State University, discovered every organ in the body showed the presence of microplastics. Health experts have expressed concern in recent years regarding the widespread use plastics in consumer products and the chemicals used to manufacture those products, which could have a wide range of health effects including diabetes, obesity, sexual dysfunction, and infertility.

Microplastics in Human and Dog Testicles

For this latest study, researchers used advanced pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) to measure 12 types of microplastics in 47 canine and 23 human testes. Data on reproductive organ weights and sperm count in dogs were collected. Statistical analyses were applied to investigate the relationship between microplastics and reproductive functions.

The researchers found microplastics in all canine and human testes, with significant differences between individuals. The average total microplastic levels were 122.63 µg/g in dogs and 328.44 µg/g in humans, with human levels three times higher than dogs. Both humans and dogs had similar proportions of the main types of polymers, with polyethylene (PE) being the most common.

Additionally, a negative correlation was found between certain plastics like PVC and PET and the normalized weight of the testis.

These findings show that microplastics are widespread in the male reproductive system of both dogs and humans, potentially affecting male fertility, the researchers concluded. More research may be needed to determine what those effects are.