Microplastics Found in Human and Dog Testicles Linked to Lower Sperm Counts

Evidence of Microplastic Accumulation in Reproductive Tissue

Microplastics—defined as plastic debris smaller than 5 millimeters—have been identified in nearly every organ and fluid in the human body, including stool, blood, and ejaculate. Recent research has brought the focus to reproductive health. A study published this year in Toxicologic Sciences examined 23 human and 47 dog testicles, finding microplastics in every single sample. According to the findings, dog testicles with higher concentrations of certain microplastics tended to have lower sperm counts.

Despite the prevalence of these particles, the biological mechanism for how they interact with human cells remains under study. Urologist Chris Deibert, MD, notes that while microplastics are ubiquitous, there is a distinction in their localization. “We’ve found microplastics in testicles, and there’s some evidence for it in semen – seminal fluid – but not so much in sperm itself,” Dr. Deibert explains. The concern, according to experts, lies not just in the plastic particles themselves but in the chemical additives they carry into the body.

Chemical Additives and Exposure Routes

Researchers are increasingly interested in the health risks posed by chemical additives in microplastics, such as polybrominated diphenyl ethers (PBDEs). Study authors note that many of these additives, particularly in the flame retardant and plasticizer categories, have been linked to adverse health effects including endocrine disruption, reproductive toxicity, neurotoxicity, hepatotoxicity, and cancer.

A study published in Environment International examined how certain flame retardants added to plastics can be absorbed through the skin. Using 3D human skin-equivalent models, researchers found that the skin could absorb up to 8% of the exposure dose, though specific amounts varied. The study also noted that sweaty skin was more likely to absorb some flame retardants than dry skin. While the amount of additives that became available to circulate in the bloodstream did not exceed 0.14% of what was initially present in the microplastics, the findings suggest that skin absorption is a viable exposure route.

These particles are effectively impossible to avoid, as they are found in the air, food, and water. Some researchers estimate that individuals may be consuming a credit card’s worth of microplastics each week. Dr. Suzhao Li, an associate research professor at the University of Colorado Anschutz Medical Campus who specializes in infectious disease and inflammation immunology, notes that microplastics are foreign to the human body. When these foreign materials enter, immune cells attempt to process them, though the long-term consequences are still being researched.

Reducing Exposure and Clinical Context

As science races to catch up with the rising global concern, evidence has suggested potential links between microplastics and a variety of conditions, including cancer, heart disease, kidney disease, and Alzheimer’s disease. Given the lack of medical interventions to remove these particles once they have entered the body, experts emphasize preventative measures to reduce exposure.

Dr. Deibert suggests several practical steps to minimize contact with microplastics and associated chemicals, such as phthalates, which are typically found in contaminated food. These recommendations include:

• Eliminating the practice of microwaving food in plastic containers.
• Avoiding the use of plastic water bottles.
• Minimizing the amount of food prepared outside the home.
• Advocating for regulatory bodies, such as the EPA, to set limits on specific plastics, similar to past efforts to limit fluorocarbons.

Readers should understand that while the ubiquity of microplastics is well-documented, the full scope of their impact on human health is an ongoing area of scientific inquiry.

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