COUNCIL FORFOR AGRICULTURALAGRICULTURAL SCIENCE SCIENCE AND AND TECHNOLOGY—1 TECHNOLOGY NUMBER 7 APRIL 1996 RADIATION PASTEURIZATION OF FOOD AUTHORS: DONALD W. THAYER (Cochair), U.S. De- partment of Agriculture, ARS, ERRC, Philadelphia, Pennyslvania; EDWARD S. JOSEPHSON (Cochair), UMMARY cal Association, the Ameri- S Food Science and Nutrition Research Center, Uni- Radiation pasteuriza- can Dietetic Association, the tion of foods with low doses versity of Rhode Island, West Kingston; ARI Institute of Food Technolo- of gamma rays, X-rays, and BRYNJOLFSSON, Wayland, Massachusetts; GEORGE gists, and the health authori- electrons will effectively con- ties of approximately 40 G. GIDDINGS (Deceased), International Atomic En- trol foodborne pathogens on countries. beef, pork, lamb, and fish. As ergy Agency, Vienna, Austria; R EVIEWERS: JULIUS used here radiation pasteur- M. COON, M.D., Jenkinton, Pennsylvania; SANFORD INTRODUCTION ization means the destruction Although largely pre- A. MILLER, Graduate School of Biomedical Science, of pathogenic non-spore ventable, foodborne illness University of Texas Health Science Center of San forming foodborne bacteria remains a serious problem in and parasitic organisms, such Antonio; MORRIS E. POTTER, DVM, Centers for Dis- the United States. A report by as trichina. Radiation pasteur- ease Control and Prevention, Atlanta, Georgia; the Council for Agricultural ization therefore can protect Science and Technology has TANYA ROBERTS, U.S. Department of Agriculture, the public from diseases such estimated that foodborne dis- as salmonellosis, hemorrhag- Ecomonic Research Service; WALTER URBAIN, Sun eases caused by pathogenic ic diarrhea caused by Escher- City, Arizona bacteria such as Campylo- ichia coli O157:H7, and gas- bacter, Escherichia coli troenteritis from Vibrio vulnificus. Irradiation can extend O157:H7, Listeria monocytogenes, Salmonella, and Sta- the shelf lives of fruits and vegetables, and arthropod phylococcus aureus may cause as many as 9,000 deaths pests, e.g., insects and mites, can be sterilized or killed each year and 6.5 to 33 million cases of diarrheal dis- in a more environmentally friendly manner than is pos- ease in the United States. The annual economic losses sible with ozone depleting, highly toxic fumigants. associated with foodborne disease may be as large as $5 Moreover, long-term animal feeding studies have dem- billion to $6 billion. Recent outbreaks of disease caused onstrated that radiation pasteurized or sterilized foods by the ingestion of E. coli O157:H7 in hamburger, par- are safe and nutritious for humans. The process has been ticularly in the northwestern United States where there endorsed by by the U.S. Food and Drug Administration were more than 700 cases and four deaths from a single (FDA), the U.S. Department of Agriculture (USDA), the outbreak, have alarmed the public. Unfortunately, this U.S. Army, the World Health Organization (WHO), the organism may cause 8,000 to 20,000 cases of disease Codex Alimentarius Commission, the American Medi- annually in the United States. COUNCIL FOR AGRICULTURAL SCIENCE AND TECHNOLOGY—2 The most common foodborne bacterial pathogens sae, and the protozoan parasite Toxoplasma gondii. Tri- that may be found on meat and poultry are Campylo- chinella spiralis localizes in the muscles of pigs and bacter jejuni, Escherichia coli O157:H7, Listeria mono- many wild animals and when ingested by humans can cytogenes, various Salmonella spp., and Staphylococcus cause trichinosis. Fortunately, this disease is rare in the aureus. The symptoms of campylobacteriosis caused by United States. Adult tapeworms may be several feet long C. jejuni generally are a mild diarrhea beginning 1 to 7 and occasionally infections may result from attachment days after ingestion of contaminated food and may last of Cysticercus bovis to the wall of the intestine. If the from 1 to 7 days. Infections larvae emerge within the in- from E. coli O157:H7 can testine, they may penetrate cause severe abdominal THE RADIATION PASTEURIZATION the wall; when that happens cramps and pain, bloody diar- the eyes, heart, liver, lungs, PROCESS FOR MANY FOODS HAS BEEN rhea, and occasional renal and brain may become infect- failure starting 3 to 7 days APPROVED OR ENDORSED BY THE ed. Other symptoms of infec- after ingestion of the contam- tion may be abdominal pain, MAJOR AND WORLD AGENCIES inated food, lasting days to U.S. nausea, weakness, weight weeks, and possibly resulting AND ASSOCIATIONS. loss, hunger pains, and ner- in death. Listeriosis caused by vousness. In 1993, T. gondii infection with L. monocytoge- caused 2,056 cases of food- nes is an acute infection of the brain with or without ac- borne illness in the United States at an estimated cost companying persistence of the organism in the blood. of $2.7 billion. In most otherwise healthy individuals, Symptoms appear suddenly and include fever, intense its associated disease usually is mild and self limiting. headache, nausea, and vomiting. The bloodborne form It can, however, cause diseases ranging from a rash to of the disease is an acute, mild illness with influenza like hepatitis in adults. Babies may be infected before birth symptoms, which in pregnant women usually results in by cross infection from the mother. These congenital infection of the fetus and miscarriage. Most foodborne infections sometimes lead to infections of the brain with cases of listeriosis occur among individuals with sup- death occurring in 5 to 10% of the cases. In those per- pressed immune systems. In these individuals the mor- sons whose immune systems are not functioning at nor- tality rate may reach 43%; overall it is 30%. Listeria mal levels, previously benign infections of Toxoplasma monocytogenes can multiply in foods stored at refriger- gondii may progress to encephalitis and other infections ation temperatures, so risk may increase during storage, of the central nervous system. despite proper refrigeration. Salmonellosis, caused by infection with any of over 2,500 different strains of Sal- THE ISSUE monella, is characterized by a mild to severe acute gas- Radiation pasteurization when used in conjunction troenteritis starting 6 to 72 hours after ingestion of con- with proper food processing and preparation techniques, taminated food and lasting for days to weeks, and greatly decreases the probability that foodborne patho- causing fever, pain, diarrhea, nausea, and vomiting. Sta- gens associated with meat, poultry, and other foods will phylococcus aureus can produce a heat-stable toxin in reach consumers. improperly stored food that, if ingested, will produce mild to severe symptoms of nausea, cramps, vomiting, SOURCES OF IONIZING RADIATION APPROVED diarrhea, and prostration in 2 to 7 hours lasting 1 to 2 FOR FOOD IRRADIATION days. The FDA has approved the following sources of Beef, pork, and other meats sometimes are con- ionizing radiation for the treatment of foods: gamma rays taminated by parasitic organisms that may cause disease produced by the natural decay of radioactive isotopes in humans when ingested. Among these are the parasit- of cobalt-60 or cesium-137, x-rays with a maximum ic nematode Trichinella spiralis, the bovine and pork energy of five million electron volts (MeV), and elec- tapeworms Cysticercus bovis and Cysticercus cellulo- trons with a maximum energy of 10 MeV. (The elec- COUNCIL FOR AGRICULTURAL SCIENCE AND TECHNOLOGY—3 tron volt [eV] is the amount of energy acquired by an ported before consumption. Most spices are dried in the electron when it is accelerated by one volt in a vacu- open air and become severely contaminated by air- and um.) X-rays are produced when high energy electrons soil-borne bacteria, fungi, and insects. Bacterial plate strike a thin metal film and are identical in their action counts of one to 100 million per gram of spice are not to gamma rays. The term ionizing means that this form unusual. Many commercial food processors therefore of radiation has sufficient energy to create positive and fumigate spices with methyl bromide to eliminate insects negative charges leading to the death of bacteria and or with ethylene oxide to eliminate bacteria and mold. other pathogens in food. Other forms of radiant energy Both methyl bromide and ethylene oxide are extremely include light, heat, microwave, and radio waves. toxic, and methyl bromide is potentially capable of de- pleting the atmospheric ozone layer. Ethylene oxide has SAFETY been banned in Europe because of safety and environ- While food is being irradiated it is never in con- mental concerns, and its use for the treatment of ground tact with any radioactive material, and the gamma rays, spice has been revoked in the United States. The U.S. x-rays, or electrons used to treat it cannot make it ra- Clean Air Act and the Montreal Protocol of the Vienna dioactive. Readers can relate Convention require that any this to personal experience substance listed as ozone de- from exposure to sunlight or MULTIGENERATION STUDIES WITH pleting be withdrawn from to being x-rayed. Although production and use by the ANIMALS HAVE DEMONSTRATED THAT excessive exposure to sun- year 2001. light and to x-rays can be INGESTION OF IRRADIATED FOODS IS In the United States, harmful, appropriate expo- spices, herbs, and dry vegeta- COMPLETELY SAFE AND THAT THE sure to radiation can be used ble seasonings currently are to kill rapidly growing cells NUTRITIVE VALUE REMAINS treated with ionizing radia- such as those in cancers. It is tion to eliminate both insects ESSENTIALLY UNALTERED. the rapidly growing cells of and bacteria. The FDA has insects or spoilage and patho- approved ionizing radiation genic bacteria that are killed when food is irradiated. doses not to exceed 30 kilogray (kGy) for microbial There is little effect on the food itself because its cells decontamination of dry or dehydrated herbs, spices, and are not multiplying. There are minor effects of radiation vegetable seasonings that are used in small amounts as on some very sensitive vitamins, e.g., B1 in pork.