Some points for you to ponder:
1. The fragemnts you can't see, can travel upwards of 20" from the entrance. You can't trim all that out.
2. Any amount of lead ingested is bad.
3. A full grown adult is not as susceptible to your young child who is fed venison harvested with lead bullletts, over several years.
4. There have been studies (WV and MI, I believe) that measured lead levels in hunters vs general public and its not been appreciatively larger. Take that for what its worth.
Personally, I switched after I went on a raptor study were we caught eagles and Buteos and they all had lead in their systems. As a falconer, that got me on the path to lead free.
If you really want to know more, you should look into:
Ingestion of Lead from Spent
Ammunition.
I agree with Chris Parrish that we are better of self-regulating and encouraging other hunters to make the switch on their own. But if we are truly going to champion the title and cause of conservationist, I don't see how you don't make the switch to lead-free.