A growing number of military veterans are reporting medical problems they and their doctors say were caused by exposure to toxic smoke from massive trash-burning pits near miltary bases in Iraq and Afghanistan.  U. S. military and veterans affairs leaders say they don't believe the trash-burning created health dangers.  We discussed the issue with Melissa Bryant of the group Iraq and Afghanistan Veterans of America; Greg Lovett, producer of a documentary about burn pit exposure titled Delay, Deny, Hope You Die; and Jesse Baca, a Navy and Air National Guard veteran whose doctors tell him the serious diseases he's facing were likely caused by burn pit exposure.