sequences, acute toxicities of dietary origin appear to pose a relatively small population health burden. Acute food toxicities may be very severe, but they generally affect much smaller numbers of people and can be associated rapidly with the food source, so that they usually can be controlled relatively easily.

FOOD SAFETY HAZARDS IN FOOD PRODUCTS

General Hazards from Foods

A variety of safety hazards are associated with foods produced by any method. These can be categorized from greatest to least hazardous by their probability to cause an adverse health effect as:

  • pathogenic microorganisms,

  • nutrient imbalances,

  • naturally occurring toxicants,

  • environmental and industrial chemicals, including pesticides,

  • food and feed additives,

  • food alterations associated with genetic modification.

This categorization was first proposed by Wodicka (1982).

Pathogens

Types of Pathogenic Microorganisms

Pathogenic microorganisms in food include: viruses, bacteria, toxin-producers, and parasites. Food-borne pathogens are often particularly risky for children, the elderly, and the immune-suppressed. There are millions of people stricken by food-borne illness every year in the United States and an estimated 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths per year, mostly among the elderly and the very young (CDC, 2003).

In the United States, the Norovirus is the most commonly found cause of food-borne illness; other viruses (rotavirus and astrovirus), as well as parasites (Giardia) and bacteria (Campylobacter), play a major role. Three pathogens, Salmonella, Listeria monocytogenes, and Toxoplasma gondii, are responsible for 1,500 deaths each year; other pathogens that also contribute to morbidity and mortality due to food-borne pathogens include Norovirus, Campylobacter, and Escherichia coli O157:H7.

It is estimated that unknown pathogenic agents account for 81 percent of illnesses and hospitalizations and 64 percent of deaths due to food-borne illness (Mead et al., 1999). These numbers are far lower than in the past; in the United



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