Original sentence: Because of concerns of lead poisoning, many manufacturers now cast minis exclusively in a more-expensive lead-free pewter (an alloy of tin, copper, and antimony).These minis were most commonly cast in white metal (an alloy of lead and tin, with a small amount of antimony, which improves the alloy's ability to take fine detail)
Edited sentence: Following some (unfounded) concerns about the safety of white metal, many manufacturers now cast minis exclusively in a more-expensive lead-free pewter (an alloy of tin, copper, and antimony).These minis were most commonly cast in white metal (an alloy of lead and tin, with a small amount of antimony, which improves the alloys ability to take fine detail)