The human testicles had been preserved and so their sperm count could not be measured. However, the sperm count in the dogs’ testes could be assessed and was lower in samples with higher contamination with PVC. The study demonstrates a correlation but further research is needed to prove microplastics cause sperm counts to fall.
The testes analysed were obtained from postmortems in 2016, with the men ranging in age from 16 to 88 when they died. “The impact on the younger generation might be more concerning” now that there is more plastic than ever in the environment, Yu said.
The study, published in the journal Toxicological Sciences, involved dissolving the tissue samples and then analysing the plastic that remained. The dogs’ testes were obtained from veterinary practices that conducted neutering operations.
The human testicles had a plastic concentration almost three times higher than that found in the dog testes: 330 micrograms per gram of tissue compared with 123 micrograms. Polyethylene, used in plastic bags and bottles, was the most common microplastic found, followed by PVC.