In the summer of 1995, a school teacher in northern Minnesota took her class on a field trip in the town of Henderson. Soon several frogs had been caught with extra legs, missing legs, and other deformaties. The teacher alerted a local wildlife biologist, and soon the Minnesota Pollution Control Agency was involved. Over the next two months deformed frogs were found in more than 100 sites in 54 of Minnesota's 87 counties, as well as in Wisconsin and Quebec.
Scientists expect that some environmental contaminant is causing the problem.
Moreover, this class of herbicides are known to adversely affect thyroid function and fetal development, which is why similar human drugs used for treating diabetes are not prescribed to women of child bearing age. It is known that frogs are extraordinarily sensitive to anything that disrupts thyroid function, and that the outcome is deformities of the kind observed. Some wonder how these chemicals could be reaching some of the isolated lakes where the deformed frogs have been found. Many scientists are now actively studying the problem and hopefully the cause will soon be determined. If pesticides are playing a role, there will be another reason to reassess weed management systems.