Polar bears are being heavily affected by pollution in the environment and it's not just about unfavorable living conditions. Researchers have found that exposure to chemicals put polar bears at risk of having weaker penile bones, resulting in a reduced ability to mate. This is a problem given the dwindling numbers of polar bears in the world.

In a study published in the journal Environmental Research, researchers analyzed mineral density in the penile bones in 279 polar bear samples from eight subpopulations. Endocrine disrupting chemicals are not found in the same concentrations in polar bear populations so the researchers compared the results of the bone mineral density tests with available information on chemical concentrations in the areas the subpopulations were from. According to findings, where there are large amounts of endocrine disrupting chemicals found in an area, polar bears from that location also had low mineral density in their penile bones.

How did researchers get so many penile bones together? They enlisted the aid of hunters. As the actual sign of having shot and hunted a bear, the penile bone is taken by hunters as trophies. The penile bones were then examined via x-ray to determine calcium density.

Out of the subpopulations tested, Western Hudson bears had the highest mineral density in penile bones while those from North East Greenland variety had the lowest. Low bone density has overall effects on health but weak penile bones are mostly associated with unsuccessful mating or fertilization failure.

"Based on this, future studies should assess how polar bear subpopulations respond upon EDC [endocrine disrupting chemicals] exposure since information and understanding about their circumpolar reproductive health is vital for future conservation," recommended the researchers.

Endocrine disrupting chemicals like polychlorinated biphenyls were in heavy use from the late 1920s until they were banned in 2001 by a United Nations treaty. Unfortunately, the chemicals break down slowly so they accumulated in the environment.

The Arctic region has particularly high levels of pollutants because chemicals are absorbed by the atmosphere and then deposited in polar areas through the cold air. As such, animals in the Arctic suffer more exposure than their counterparts in equatorial or more temperate regions.

Researchers from the Aarhus University Arctic Research Centre, the Wildlife Management Division of the Government of Nunavut in Canada, the University Hospital of Hvidovre, the Carleton University's National Wildlife Research Center, and the Center for GeoGenetics at the University of Copenhagen's Natural History Museum of Denmark participated in the study.