听力原文： Government officials have ordered a plant of Japan's largest diary producer to halt production indefinitely after batches of its milk left more than 8,000 people with food poisoning. The victims in eight western Japan prefectures suffered symptoms such as stomach pains, vomiting and diarrhoea after drinking low -fat milk produced by Snow Brand Milk Products Co. Ltd. The number of people affected had reached 8,282 by Monday afternoon. Some 100 people have been taken to hospital since late last week after drinking the milk, with about 40 still in hospital on Sunday, health officials said. Snow Brand said the contaminated cartons of milk were made between June 23 and 28. The company halted milk production at the plant from Thursday and recalled the prod- nets. The western Japan region suffered a deadly food poisoning outbreak caused by the O - 157 bacteria in the summer of 1996, killing 11 people and leaving more than 9,500 others ill. Government officials ordered a plant in Japan to halt production because ______.