Food safety can be threatened by hazards of both a chemical or microbiological nature. There are many possible reasons why food may be unsafe. Over time, knowledge has evolved about how to keep food safe through the phases of production, storage, preparation and consumption. In spite of this, incidents are reported on a daily basis in which food intake leads to health-related problems.
Chemicals may be natural or manufactured. Chemical safety is concerned with the effect of human exposure to chemicals in natural environment settings as well as with chemicals in industrial extraction, synthesis, production, transport and use. Most industrial chemicals have the potential to be hazardous to human health if not managed appropriately. Safe disposal of chemical waste poses a particular challenge.