Banning lead ammunition was previously mentioned. It was actually started during the Clinton years.
They were getting the Army & National Guard to use compressed powdered tungston projectiles rather than lead. It was made law on certain military bases, with the idea that it would be expanded as a later environmental provision nationally. You cannot make tungston bullets at home, and they wear out a barrel after several hundred rounds (so the Clintons would get a twofor).
Anyway, they found out that the powdered tungston was breaking down and leaching into the water table faster than lead, and is more damaging than lead. Once the lead gets a coating of lead oxide on the outside, it's fairly stable and inert.
To check on this, do a Google check on
"tungston ammunition massachusets".