Pathogens

The most important kind of biological hazards to consider are microorganisms. A microorganism is a tiny, usually single-celled organism that can be seen only with a microscope. A microorganism that can cause disease is called a pathogen. Although these organisms sometimes occur in clusters large enough to be seen with the naked eye, they are not usually visible. This is one reason why they can be so dangerous. Just because food looks good doesn’t mean it is safe.