No matter how tightly procedures are controlled, determined perpetrators could still find ways to introduce pathogens or poisons.And natural pathogens such as salmonella are always a concern.

• 不论程序控管多麽严密，有心人士仍找得到方法加入病原体或毒物，而像沙门氏菌之类的自然病原体一直是个问题。