Lead free shot as well as slugs are readily available if lead toxicity is a concern. steel, bismuth, copper. CCI even makes a lead free .22 cartridge. A less than lethal shotgun shell, bean bag, rubber ball, stinger plastic balls at chicken coup range would be devastating for small vermin. If we are just talking about the occasional dispatch of a delinquent racoon on a homestead, I am not sure that lead toxicity would be a significant measurable danger. The studies I have found about lead toxicity and grazing animals most often mention the animals being on the recieving end of pellets piercing the skin. The OP's original question on a model 60 Marlin which is number 2 after the Ruger 10-22 in number of purchases would be a good entry level firearm.