At least 20 school children developed symptoms of ammonia poisoning after drinking carton milk served at their schools. The milk was produced by a Wisconsin milk producer. Five days previous to the illnesses, the producer had noted an ammonia leak in one of its cooling chambers. The ammonia had sprayed about the storage tank and cartons. After tasting and smelling about 75 of the remaining 250,000 milk cartons, the processor determined that the milk was safe. The Wisconsin Department of Agriculture found high levels of ammonia in milk containers.