Researchers at the University of Nottingham have found that exposure to chemical pollutants in the home environment can degrade fertility in both human men and domesticated dogs. Their findings, published in Science Advances, may explain the 50% global drop in sperm quality over the past 80 years.
The team focused in on the effects of two man-made chemicals — DEHP, found home products and features like carpets, flooring, upholstery, clothes, wires, and toys, and polychlorinated biphenyl 153, which has been banned globally, however it is still widely detectable in the environment, including food.
Using donated sperm from sample males and stud dogs living within a specific region in the UK, the researchers found that the chemicals had a clear damaging effect on both sperm samples.
“This new study supports our theory that the domestic dog is indeed a ‘sentinel’ or mirror for human male reproductive decline and our findings suggest that man-made chemicals that have been widely used in the home and working environment may be responsible for the fall in sperm quality reported in both man and dog that share the same environment,” said lead researcher Richard Lea, Associate Professor and Reader in Reproductive Biology at the School of Veterinary Medicine and Science.
“Our previous study in dogs showed that the chemical pollutants found in the sperm of adult dogs, and in some pet foods, had a detrimental effect on sperm function at the concentrations previously found in the male reproductive tract,” Lea continued. “This new study is the first to test the effect of two known environmental contaminants, DEHP and PCB153, on both dog and human sperm in vitro, in the same concentrations as found in vivo.”
Team member Rebecca Sumner, PhD, said that the aforementioned chemicals caused reduced sperm motility and increased DNA fragmentation.
“We know that when human sperm motility is poor, DNA fragmentation is increased and that human male infertility is linked to increased levels of DNA damage in sperm,” Dr. Sumner said. “We now believe this is the same in pet dogs because they live in the same domestic environment and are exposed to the same household contaminants. This means that dogs may be an effective model for future research into the effects of pollutants on declining fertility, particularly because external influences such as diet are more easily controlled than in humans.”
Next, the team will focus on region to see if location also impacts sperm vitality in both men and dogs.