If you check a little deeper into this I think you'll find that all lead based bullets are already banned in parts of California, Nevada, and Arizona. It seems that lead based bullets are thought responsible for weak egg shells from California Condors thereby contributing to their being on the endangered species list. It seems that lead based bullets leave too much lead in the offal from hunting kills and that the birds are ingesting. Of course the Condor has been on that list for the last forty years. This is why you have seen the increase in monolithic bullets in recent years.