A hazard may be an unacceptable level of disease-causing micro-organisms or products of microbial activity (i.e. toxins). Hazards may also be caused by chemical substances that reach food inadvertently through various environmental sources, or during food processing, preparation or storage. Hazards can result from food additives that are used in excess of functional or culinary needs; or from materials that leach into highly acidic food from containers, pipes or their toxic coatings.