Contrary to popular consumer perception about the risk of chemicals in foods, major hazards associated with foodborne illness are clearly of biological origin (1). The Centers for Disease Control and Prevention (CDC) has published summaries of foodborne diseases by etiology for the years 1993 through 1997 (Table 194.1) (2). CDC groups foodborne disease agents in four categories; bacterial, parasitic, viral, and chemical. Greater than 95% of all reported outbreaks foodborne illnesses are caused by microorganisms or their toxins. Fully 97% of reported cases are likewise linked to a microbial source. Only
around 3% of the outbreaks and less than 1% of cases can be truly linked to chemical (heavy metals, monosodium glutamate, and other chemicals) contamination of foods. Furthermore, 97% of reported deaths are due to microbial sources. These data are from reported outbreaks. CDC estimates for the actual number of cases of foodborne disease caused by microbial agents is much higher due to under reporting (Table 194.2).