Environmental contaminants found in home and diet have the same adverse effects on male fertility both in humans and domestic dogs, finds a new study highlighting the decline in sperm quality in both the species over the past few years.

The findings, published in the journal Scientific Reports, showed the chemicals -- at concentrations relevant to environmental exposure -- have the same damaging effect on sperm of both man and dog. "We know 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," said co-author Rebecca Sumner, postdoctoral student at the University of Nottingham, Britain.

"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," Sumner said.

For the study, the team tested the effects of two man-made chemicals -- the common plasticiser DEHP, widely used in the home (e.g. carpets, clothes, toys) and the industrial chemical polychlorinated biphenyl 153, which although banned globally, remains widely detectable in the environment, including food.

The researchers carried out identical experiments for both species using samples of sperm from donor men and stud dogs, living in the same region. "This new study supports our theory that the domestic dog is indeed a 'sentinel' or mirror for human male reproductive decline. Our findings suggest man-made chemicals, widely used in home and working environment, may be responsible for the decline in sperm quality," lead author Richard Lea from the varsity noted.