Reproduction: Household pollutants impair fertility in dogs as well as in humans

According to new research, environmental contaminants found in the home and in food have the same harmful effects on canine fertility as they do on human fertility. Male infertility has been on the rise for several decades, with studies showing an overall 50% decline in sperm quality over the past 80 years, between 1938 and 2011.

A new study, conducted by the University of Nottingham (United Kingdom), suggests that chemicals commonly used in the home have similar harmful effects on human and canine health. Found in typical home environments, these indoor pollutants—many of which are also endocrine disruptors—are at least partly responsible for the decline in fertility observed in both humans and dogs. As a result, canine sperm motility has decreased by 30% over a period of twenty-six years.

British researchers tested the in vitro effects of two known pollutants on human and canine sperm: di-2-ethylhexyl phthalate (DEHP), a plasticizer commonly found in the home (carpets, flooring, upholstery, clothing, metal wires, and toys), and polychlorinated biphenyl 153 (PCB153), an industrial chemical that, although banned in most parts of the world, continues to persist in the environment, including in food. DEHP and PCB153, considered risk factors for reproductive function, have been detected in tissues and fluids ranging from human breast milk to sheep livers, as well as in dry and wet dog food.

Identical experiments were conducted in both species, using human and canine semen samples from the same region of the United Kingdom. To assess ejaculate quality, sperm motility and the proportion of spermatozoa exhibiting DNA fragmentation were measured. The results show reduced motility and increased DNA fragmentation induced by both environmental pollutants, indicating similar sensitivity in both species. The chemicals tested, at concentrations corresponding to in vivo environmental exposure, had the

the same harmful effect on human and canine sperm.

This new study confirms the downward trend in sperm quality observed in both humans and dogs, due to common environmental factors. As a result, in the context of future research, dogs can serve as “sentinels” for human exposure to such factors, since they share the same environment. In addition, external influences such as diet are more easily controlled in the canine model.