Black tail deer on Alaska’s Kodiak island have shown high rates of cryptorchidism (undescended testicles) since at least the mid 1990s. These cases have been concentrated to the low lands at the South end of Kodiak island. Many of the affected deer inhabited low land areas and it was proposed that an estrogenic compound, possibly in seaweed consumed by these deer could be responsible for the cryptorchidism. Testicular malformations of deer have been observed for the last 20 years in WA and OR where pesticide use has been shown to have occurred. In a 1993 U.S. Dept. of Agriculture study of the Bering Sea. Chlorothalonil was found in every fog sample collected, and in several of the sea water samples collected. One of those pesticides found was Endosulfan.

Endosulfan is also a xenoestrogen—a synthetic substance that imitates or enhances the effect of estrogens—and it can act as an endocrine disruptor, causing reproductive and developmental damage in both animals and humans”  Endosulfan has been shown to be correlated to cryptorchidism.

Besides the potential for ocean and fog carried pesticide exposure, another and possibly related route for pesticides to enter this environment could be the transport of herbicide treated drift wood from forestry operations some distance away. persistent herbicides contaminate compost.

Also, the Kodiak National Wildlife Refuge has used Clopyralid, and uses Aminopyralid on the refuge, included in their management plan is the area of affected deer. Clopyralide and Aminopyralid belong to the same family of herbicides as Picloram, and are chemically very similar. Picloram has been shown to cause testicular atrophy in rats.  All three of these pesticides are very persistent in the environment.

“Elk, goat, marten, red squirrel, muskrat, and beaver do not occur in any areas known to support invasive plants. On the other hand, field observations indicated that deer and hare have used areas that support invasive plants for foraging and, in some cases cover, including sites subjected to active management.” Active management meaning pesticide application. Deer on Kodiak island have been observed ingesting plants treated with herbicides.