Greenwald said the research had been intended to show that lab tests of baseball bats could serve as a good indicator of how bats would perform on the field. Although the study did find that metal bats performed better, nothing in the research indicated they performed so well that they could be lethal.

Some states considering or undertaking a ban on metal bats include:

New Jersey, where a state Assembly committee voted last October to move forward with a bill banning metal and metal-composite bats from league and school baseball games involving children younger than 17. The bill has not yet been considered by the full state legislature.

North Dakota, where the state High School Activities Association has banned any bats not made of wood, starting this spring.

Massachusetts, which has considered a ban for several years but never has passed one.