Service dogs add to the debate over environment and fertility, but what does that mean for humans?

A lab, like the dogs in the study. But a troublemaker, not a service dog.

A study of generations of services dogs raised in identical conditions adds new evidence to the much-debated theory that common chemicals in the environment may impact fertility.

This from a story buried in this morning’s paper. 

From 1988 to 2014, researchers studied between 42 and 97 stud dogs annually. Between 1994 and 2014, they also noticed that the mortality rate of the female puppies, although small, showed a threefold increase. And the incidence of undescended testicles in male puppies, also small, had a 10-fold increase, to 1 percent from 0.1.

When the researchers tested testicular tissue for chemical content (in dogs retired from breeding or neutered for other reasons), they found concentrations of chemicals that had been common in electrical transformers and paint, and others still used in plastics. In additional analyses done in the last three years, researchers found concentrations of the same chemicals in the dogs’ semen. The chemicals include polychlorinated bisphenol (PCB), which, though banned, has a long half-life, and diethylhexyl phthalate (DEHP).

As noted, there is a ferocious debate over this. The researcher at the Silent Spring Institute in Newton have been trying to sort it out. Go here for some of their research. 

Do note that even one of the critics of the research into the links between human health and estrogen-mimicking compounds has this to say about the study:

Peter J. Hansen, a professor of reproductive biology at the University of Florida, describes himself generally as a skeptic of many studies linking chemical exposure to declining sperm quality. Much research on the effect of environmental hazards on humans is typically done by administering doses of hazards to research animals in much greater concentrations than is typically found in water supplies, he said.

But the Nottingham study, he noted, detected the chemicals in the dogs’ tissue and also in the dogs’ food. And researchers did so over decades, tracking a concurrent decline in reproductive markers.

“I think it was very rigorous,” he said. “It’s much more clear from their data that there was a decline over time, which agrees with the human data but doesn’t suffer from the same research problems.”




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