The Putnam County Public Library District will host a free screening of the PBS documentary “Poison Squad” at 1 p.m. Tuesday, Oct. 21, at the library’s Granville branch, 214 S. McCoy St.

The 110-minute documentary explores how chemist Harvey Wiley, M.D., led a campaign to remove dangerous substances from the nation’s food. Wiley led various on 12 volunteers to prove the substance’s harm. The documentary is based on the book “The Poison Squad” by Deborah Blum. “The Poison Squad” is not rated.

For more information, call 815-339-2038.