Reproduction

Are Nanoplastics Causing Fertility Problems?

By Adam Marcus

Plastic particles have turned up pretty much everywhere. They’re also in virtually everything we eat and drink, so it should come as no surprise that they also contaminate the food we feed to animals, including hay.

Exposure to micro- and nanoplastics, defined as those less than 1 mcm, have been linked to an array of health concerns. Gastrointestinal illnesses, cardiovascular issues and reproductive problems have been associated with exposure. A new study suggests nanoplastics can significantly disrupt equine sperm and potentially undermine fertility.

The findings come from a laboratory analysis and must be confirmed. But Jose M. Ortiz-Rodriguez, DMV, PhD, of the Dipartimento di Scienze Mediche Veterinarie at the Università di Bologna, in Italy, who helped conduct the research, said the study raises red flags. “The changes we observed in motility parameters and oxidative status were measurable, but we cannot directly conclude that they would impair fertility in vivo,” Dr. Ortiz-Rodriguez told The Modern Equine Vet. “These effects are within the range of what we see with other mild stressors or known disruptors, but without in vivo exposure data we should be cautious about any broader interpretation.”

Dr. Ortiz-Rodriguez and his colleagues exposed previously frozen equine sperm from 5 stallions to 30-nanometer polystyrene particles, a common microplastic found in the environment. Particles of that size or smaller are believed to be capable of penetrating into a cell nucleus and its mitochondria, potentially disrupting cellular function. The samples were assessed for viability, motility and other characteristics using flow cytometry and computer-assisted semen analysis. The researchers determined how avidly sperm absorbed fluorescent-tagged nanoplastic particles.

They found that sperm cells exposed to nanoparticles took up the particles, particularly the post-acromal section immediately behind the head of the cells, and in the mid-piece below that region. After 1 hour of incubation, those sperm showed reduced motility and viability, and a reduction in mitochondrial activity. The effect was pronounced when sperm were exposed to higher concentrations of the plastics, and when the exposure was prolonged, they reported, which “may impair mitochondrial function, an effect likely more pronounced in horses, whose sperm motility relies heavily on mitochondrial metabolism,” the researchers wrote.

Although the effects on equine sperm function remain theoretical and must be replicated in future studies, the ubiquity of nanoplastics is no longer in question.

“Several recent studies have reported nanoplastics in different animal tissues, including testicular tissue in humans and dogs, which suggests systemic exposure is possible in many species, horses included,” Dr. Ortiz-Rodriguez told The Modern Equine Vet. MeV

For more information:
Dindo S, Tovar-Pascual L, Balassarro VA, et al. Nanoplastics internalization impairs mitochondrial activity in equine sperm. Theriogenology 2026;250:117711
https://www.sciencedirect.com/science/article/pii/S0093691X25004376