What Otters' Penis Shrinkage Could Mean for Humans

Scientists are concerned about the deformed sex organs of England's otters — and what it might mean for humans.

The furry mammals are found in rivers throughout Britain, but male otters aren't what they used to be. An alarming number of them now have shrunken penis bones (baculum), as well as undescended testicles (cryptorchidism) and cysts on sperm-carrying tubes, according to a new report written by Cardiff University scientists.

The results are based on analyses of samples from 755 otter carcasses collected around England and Wales between 1992 and 2009.

"We were surprised to see the reduction in the baculum weight," Elizabeth Chadwick, project manager at the Cardiff University Otter Project, told the BBC. "[It's] certainly something that needs further investigation."

Though scientists aren't yet able to identify a single cause for the deformed sex organs, one leading suspect is a class of chemical pollutants known as endocrine disruptors.

Endocrine-disrupting chemicals (EDCs) alter the hormone balance of humans and animals. An unborn fetus is particularly vulnerable to the effects of endocrine disruptors, since the development of sex organs in the womb is largely controlled by hormones such as testosterone and estrogen.

The plastic additive Bisphenol A, or BPA is one hormone disruptor that's consistently been cited as a concern for women of childbearing age and their babies. Other endocrine-disrupting compounds are found in pharmaceuticals, pesticides and other common household products.

Though scientists are still sifting through the evidence, there are many researchers who believe the prevalence of endocrine disruptors might be linked to a worldwide drop in sperm quality and quantity in humans. [Sexy Swimmers: 7 Odd Facts About Sperm]

As the top predator in England's rivers and lakes, the BBC reports, otters are an indicator species whose health reveals much about the well-being of the entire aquatic ecosystem. Health problems discovered in otters, Chadwick said, "could be a warning for all mammals really, which include us humans."

"These findings highlight that it is time to end the complacency about the effects of pollutants on male reproductive health," Gwynne Lyons, director of Chemicals, Health and Environment Monitoring Trust (CHEM), which co-authored the report with Cardiff University, said in a statement, "particularly as some of the effects reported in otters may be caused by the same EDCs that are suspected to contribute to the declining trends in men's reproductive health and cause testicular cancer, undescended testes and low sperm count."

Contact Marc Lallanilla at mlallanilla@techmedianetwork.com. Follow him on Twitter @MarcLallanilla. Follow LiveScience on Twitter @livescience. We're also on Facebook & Google+.