From this story on wishtv.com:
Indiana State Police are warning hunters to stay away from trash left behind by those making methamphetamine, saying it may contain chemicals that are toxic, flammable, corrosive and acidic. Police say the combination of the chemicals could cause an explosion, fire or burns. Police say among the items hunters should be wary of are 1.5 gallon gas cans, battery casings, plastic bags, empty blister packs, soda bottles and other types of containers. Police also warn that hunters should be aware of backpacks and nylon or plastic bags found in an odd place because they could contain toxic vapors.