The team found 12 types of microplastics in 47 canine and 23 human testes. According to Dr. Yu, it’s likely that there are microplastics in more dogs than not. “Our study revealed the presence of microplastics in all human and canine testes,” Yu said.
Using a novel analytical method, his team quantified the amount of microplastics in the tissue samples, and found correlations between specific types of plastic and reduced sperm count in the dog samples.
Dr. Yu specializes in the impact of environmental factors on reproductive health, and has previously studied the effects of heavy metals, pesticides, and endocrine-disrupting chemicals on sperm count and quality. According to Dr. Yu, a conversation with his colleague, Dr. Matthew Campen, who is a professor in the UNM College of Pharmacy, and who found microplastics in human placentas, inspired Yu to explore their presence in the reproductive tissues of dogs as well.
The research team got canine tissue from Albuquerque animal shelters and veterinary clinics. The samples were chemically treated to isolate the microplastics, which were then analyzed using a mass spectrometer.
In dogs, the average concentration of microplastics in testicular tissue was 122.63 micrograms per gram of tissue, while in human tissue, it was 329.44 micrograms per gram. The most prevalent polymer found in both human and canine tissue was polyethylene (PE), a microplastic commonly used in plastic bags and bottles. In dogs, PVC, used in plumbing and various applications, was the second most prevalent polymer and was correlated with lower sperm counts.
“The type of plastic makes a difference,” Yu said. “PVC can release chemicals that interfere with spermatogenesis and cause endocrine disruption.”
The study compared human and canine tissue because dogs share their environment with humans and have similar biological characteristics. “Compared to rats and other animals, dogs are closer to humans,” Yu said. “Physically, their spermatogenesis is closer to humans, and their concentration has more similarity to humans.”
Microplastics are formed when plastics degrade under ultraviolet radiation and other environmental conditions, and are now basically found everywhere and in everything. Yu pointed out that the men in the study, who averaged to be about 35 years old, were exposed to less plastic than today’s younger generations, and suggested that the impact on the future could be even more severe.
Dr. Yu believes we need more research because microplastic presence is so prevalent. “We have a lot of unknowns. We need to understand the potential long-term effects. Are microplastics contributing to this decline in fertility?” Yu wondered.
Despite these concerns, Yu said it’s more important to share informed awareness than panic just yet. “We want to scientifically provide the data and make people aware of the prevalence of microplastics. We can make choices to reduce exposures, change our lifestyle, and behavior,” he concluded.
This study also shows how the shared environmental factors between humans and dogs and the potential reproductive risks posed by microplastics, are important to address for the health of all of us.
