ok heres some info. the EPA has classified nephthalene as a high priority PBT Chemical. It doen't break down but goes into the ground water, which then gets into the food chain. Water treatment plants do n't remove PBT's. Even inhaling the fumes given off by moth balls is toxic.
I've lost eggs to skunks, possums, rats, racoons. If you must use moth balls make sure you use proper safety measures. Very toxic to you, pets animals etc...