Hazards or contaminants come in three types: chemical, psychical, and biological. Contamination is the word used when foreign objects, bacteria, parasites, viruses, chemical or other microorganisms come into contact with a food product. Chemical contamination refers to a food product coming into contact with cleaning products, such as; detergents, degreasers, or sanitizers; pesticides or insecticides sprayed on produce; or toxic metals from open cans and old or damaged cookware. Physical contamination comes in three types as well: environmental, from food sources, or from people. Examples of an environmental physical contamination are: wood, dirt, twigs, metal, glass, insects, or other foreign objects. Contaminants from people may include earrings, body piercings, bandages, hair or fingernails. A food source contaminant describes an item that is already within the food itself, such as scales, feathers, or bones.
The most common and dangerous form of biological contamination is when harmful microorganisms, which are also referred to as pathogens, meaning a disease-causing microorganism or bacteria, contaminates food. Some sources of biological contaminants are derived from the soil, livestock, produce or the environment in general. And obviously, humans can also spread pathogens. This form of contamination is the most dangerous since microorganisms are such small life forms that it is impossible to detect them with the naked eye. Parasites, protozoa, bacteria, viruses, moulds and yeasts are all examples of microorganisms. Other objects such as insects, equipment, animals and people can all be carriers of microorganisms that could potentially contaminate food.