The Camden City School District changed its milk sub-vendor last week after more than 30 students were sickened from cartons of Guida’s Dairy milk found to be contaminated with a sanitizer at the end of March, a school official confirmed Monday. A peroxyacetic sanitizer was found in Guida’s 1% low fat milk March 30 at the Early Childhood Development Center, a pre-K school in Camden. School officials previously said 95 cartons of Guida’s milk were pulled from shelves and eight were contaminated with the substance, made by Vortexx. “It was determined that the substance found in the milk cartons …