The Police Department on Saturday is giving residents another opportunity to safely dispose of their unwanted and unused prescription drugs. From 8 a.m. to 8 p.m., the public is invited to bring medications for disposal in a special kiosk at the police station, 918 Main St. The service is free and anonymous, with no questions asked. The event is the latest in a series of drop-off days the department has held in collaboration with the federal Drug Enforcement Administration to help combat prescription drug abuse and theft. Participating residents are asked to remove pills from prescription bottles and seal them in a plastic bag before arriving at the station. No liquids or sharp objects will be accepted. For information on how or where to dispose of those items, contact the Board of Health at 978-640-4473.