The Wisconsin DNR sponsored a study that looked into lead in venison that found the metal fragmented into far smaller particles than had been previously assumed (especially involving higher velocity rounds), and that in order to avoid long term exposure, the use of non-lead expanding bullets should be considered. The exposure is small, and can be avoided through shot placement, and careful trimming and inspection of the meat during butchering. Generally speaking, though, there is little environmental concern involving lead projectiles except in watershed areas where it can, and does cause problems. Nothing practical delivers energy on target like lead, so it's still a trade off with toxicity and function playing the positions. I use steel shot in my shotgun, and lead core jacketed bullets in my rifles. Just a note, but if you wish to use steel shot, make sure your gun can handle it. I have a number of older guns that are relegated to trap and the occasional upland shoot because they are not constructed of the right alloy or choke dimensions to fire steel shot without the risk of damaging them.