Germ Warfare: A fresh look at irradiation
Zero tolerance: The Federal Meat Inspection Act in 1994 defined the presence of E. coli O157:H7 in hamburger as an adulterant. Recalls of E. coli O157:H7 contaminated meat and related illnesses continued to grow over the next decade. With near regularity, E. coli O157:H7 recalls and illnesses seemed to begin in the spring and peak in late summer and fall.
After 24 million pounds of contaminated beef were recalled in 34 separate incidents in 2002, recalls dropped to just over a million pounds a year for the next three years, and then to just 181,900 pounds in 2006. The U.S. Centers for Disease Control (CDC) saw E. coli O157:H7-related illnesses drop 48 percent between 2000 and 2006. That was encouraging news for the meat industry.
Cause for concern: In April 2009, the CDC published the latest FoodNet data on the incidence of disease caused by pathogens transmitted through food. Citing recent large, multistate foodborne outbreaks as evidence, the report concluded that efforts to reduce foodborne disease in the United States have leveled off since 2004 and that fundamental problems with bacterial and parasitic contamination are not being resolved.
The CDC report should not be a surprise, since the latest data from the U.S. Department of Agriculture (USDA) show that E. coli contamination rates for ground beef are on the rise and at the highest levels since 2003. In 2008, 0.47 percent of ground beef samples tested positive for E. coli O157:H7 up from 0.24 percent in 2007. The percent of positive samples in 2006 was 0.17 percent compared to 0.16 percent in 2005. During the past two years, about 40 million pounds of beef have been recalled in at least 40 incidents due to E. coli O157:H7. Experts don’t seem to agree on reasons for the increase.
Hot and hazy days of summer: The hot and often humid days of summer almost always bring an increased incidence of E. coli O157:H7. The question is, which year will 2009 resemble? Will it be like 2005 and 2006, or like 2007 and 2008?
A review of E. coli O157:H7 diarrhea in the U.S. by Slutsker et al (1997) found that E. coli O157:H7 was isolated most frequently from patients during the summer months. An epidemiological review of E. coli O157:H7 outbreaks in the U.S. (1982-2002) showed that outbreaks involving ground beef peaked in summer months (Rangel et al, 2005) and in a review of non-O157 STEC infections in the U.S. from 1983-2002, Brooks et al 2005, revealed that these infections also were most frequent during the summer.
Pre-harvest interventions: Much has been written about best management practices from “farm to fork” to reduce contamination. Since 1993, beef producers alone have invested more than $27 million of their checkoff dollars in beef safety research, and the industry as a whole invests $350 million annually on safety interventions. Steve Kay, editor and publisher of Cattle Buyer Weekly, estimated that between 1993 and 2003, the 10 largest packing companies invested more than $400 million on new food-safety equipment and added $250 million to their operating costs to fight E. coli O157:H7.
Interventions currently being used include on-farm sanitation, steam, hot water and organic acids. These technologies can reduce bacteria by two to three logs (99 to 99 percent). Recent approval of E. coli vaccines shows promise. However, vaccines are costly and producers will need to have an incentive to use them.
Testing: We often hear calls for increased product testing. The International Commission on Microbiological Specification for Foods in 2002 (Book 7), concluded the following, “No feasible sampling plan can ensure complete absence of a pathogen … It cannot be guaranteed that the lot is completely free of the organism, no matter how large the number of sample units.”
Irradiation: Despite our best efforts at every stage of beef production, harmful bacteria continue to plague the industry. Eventually the food-safety discussion gets around to irradiation.
What is food irradiation?
Food irradiation, sometimes referred to as “cold pasteurization,” is the process of exposing food to an ionizing energy (gamma rays, X-rays or electron beams) to kill bacteria and extend shelf life without cooking or changing the food. Amounts of energy used are measured in kiloGrays (kGy). A dose of below one to 10kGy is usually sufficient to rid a product of harmful bacteria in most products.
The major benefit of food irradiation is greatly reducing, or even eliminating, the number of harmful organisms in a product. From a food-safety standpoint, irradiation is comparable to pasteurization of milk. Other benefits include helping to keep meat, poultry and seafood fresh longer, and helping to reduce the need for chemical fumigants in foods by eliminating insects.
In fact, certain items, like tropical fruits arriving from India, Mexico, Thailand and several other countries must be irradiated to gain access to the U.S. Framework Equivalency Work Plans (FEWP’s) have been signed with nine countries including India, Mexico, Thailand, Vietnam, Laos, South Africa, Pakistan, Philippines and Malaysia. These agreements allow importation into the U.S. of produce from cooperating countries that was previously prohibited due to the risk of importing pests along with the produce. Irradiation prevents foreign fruit flies from damaging domestic product and allows consumers to enjoy items like imported mango, mangosteen, longans and papaya.
Mangoes from India have been available at select stores in the U.S. since 2007. Irradiated mangosteen from Thailand and dragonfruit from Vietnam are also starting to appear at Asian specialty stores nationwide. In early 2009, Mexico began to export irradiated guavas to the U.S. after that product received USDA approval in October 2008. Irradiated mangoes from Mexico began to enter the U.S. market in early 2009. Certain specialty mangoes cannot stand hot water treatment phytosanitary procedures and as a consequence must be irradiated.
The availability of irradiated produce will increase dramatically in the future because of food-safety concerns involving green leafy vegetables such as spinach and lettuce and an expanding market for exotic produce from Asian countries.
How effective is irradiation?
Other than cooking, irradiation is the most effective technology available to reduce or eliminate pathogenic bacteria. At doses that are commonly used to irradiate ground beef, we can expect the following levels of pathogen reduction:
- E. coli O157:H7 -- 99.99% to 99.9999%
- Salmonella -- 99% to 99.9%
- Listeria -- 99.9% to 99.99%
Despite widespread media attention from food recalls, serious illness and death, food irradiation technology remains underutilized and sometimes misunderstood. An increasing number of food-industry leaders are asking the question; is it time to take a fresh look at irradiation?
The list of foods approved for irradiation is growing and now includes spinach, iceberg lettuce, herbs and spices, sprouts, shellfish, meat and poultry for bacterial reduction, and fruits and vegetables for disinfestations. Spices have been commercially irradiated since 1986. Approximately one-third of the commercial spices consumed in the United States â€” some 80,000 metric tons (175,000,000 lbs.) â€” are irradiated annually. NASA has served our astronauts irradiated meat products for many years.
During the past decade a steadily increasing amount of irradiated food has entered commercial channels. Although irradiated fruits, vegetables and poultry have been available commercially on a limited basis since the early 1990s, the introduction of irradiated ground beef in Minnesota during May 2000 significantly increased awareness and interest in the technology. Estimates are that approximately 15 million to 18 million pounds of irradiated ground beef and poultry were marketed in the United States during 2008. The volume of irradiated meat and poultry sold in the U.S. has remained steady during recent years. Irradiated ground beef is available from several retail outlets including Wegman’s Food Markets in the Northeast USA, Publix in the Southeast, and nationally through Schwan’s home delivery service and by mail order and retail sale through Nebraska-based Omaha Steaks. Omaha Steaks, Schwan’s and Wegman’s have recently expanded their offering of irradiated ground beef. Schwan’s began selling irradiated ground beef in 2000; it has three ground beef offerings and recently introduced an irradiated breakfast steak. All Schwan’s raw ground beef is irradiated for safety. Omaha Steaks also irradiates all of its raw ground beef and has seen ground beef sales double since it began to use irradiation.
Dr. Robert Tauxe of the CDC estimates that if 50 percent of poultry, ground beef, pork and processed meats in the U.S. were irradiated, the benefit would be a 25 percent reduction in the morbidity and mortality rate caused by these infections, as well as prevention of nearly 900,000 cases of infection, more than 6,000 catastrophic illnesses and more than 400 deaths annually. Dr. Tauxe is currently updating his study but does not anticipate a significant change. The study does not include the cost and disability burden resulting from foodborne illness, hospitalization and litigation.
A recent development that will likely increase the use of irradiation as a food-safety intervention is the recent decision by USDA/FSIS to evaluate irradiation for purposes of carcass sterilization. The American Meat Institute (AMI) petitioned FSIS to accept irradiation as a “processing aid.” The petition calls for surface pasteurization of beef carcasses at depths of mere millimeters. Should FSIS approve the petition, which argues that irradiation of chilled beef carcasses should be considered a “processing aid” and therefore not subject to labeling requirements, meatpackers will have another powerful weapon to combat deadly bacteria.
Currently there is much of the momentum for irradiation use in produce. Highly publicized recalls of spinach, lettuce, tomatoes, jalapeño peppers, sprouts and even peanut paste have caused produce growers and marketers to seek permanent solutions. Research shows that irradiation is very effective at reducing bacteria in many produce items such as spinach and iceberg lettuce without compromising quality.
Estimates indicate some 15 million pounds of irradiated fruits and vegetables â€” mainly mango, mangosteen, longans, papaya and guava â€” are sold annually by U.S. retailers. Hawaii Pride, based in Keeau, Hawaii, exports more than 8 million pounds of irradiated produce annually, including papayas, rambutan, star fruit, purple sweet potatoes and bananas annually to major supermarkets on the mainland.
The irradiation process has become especially helpful in less-developed countries, where spoilage threatens a large percentage of the food supply. According to the World Health Organization, food irradiation can help ensure a safer and more plentiful food supply when established guidelines and procedures are followed.
Irradiation will help do more to alleviate hunger and suffering than any other technology we have available. It extends shelf life, prevents infestation of pests, and opens markets for products produced in countries that haven’t been able to export to the U.S. in almost two decades. Currently, there are more than 30 food irradiation facilities mostly in Asia and Latin America, planned, being built or being renovated for the purpose of accessing the U.S. market.
Sidebar: Irradiation Increase
Why the amount of irradiated food in the United States will significantly increase:
- Food safety concerns in produce, especially with leafy vegetables such as spinach and lettuce.
- Incidence of E. coli in ground beef has increased during each of the past four years; 0.16 percent to 0.47 percent.
- U.S. market access (Framework Equivalency Work Plans) with India, Thailand, Mexico & more.
- Rapidly expanding Asian & Hispanic populations will increase demand for exotic produce.
- Emphasis on “Eating Healthy” will increase fruit & vegetable consumption.
- Irradiation will decrease the “carbon footprint” by reducing harvested crop destruction by preventing larvae from hatching, extending freshness and slowing the ripening process which will allow transport by sea and rail instead of air.
- Is it “Farm to Fork” or “Turf to Tort”? Who’s Next? Litigation is the frequent outcome of recalls and food-safety incidents. If processors do not believe that and are willing to takefurther chances, search the Internet for the word “Marler” for proof.
-- Ronald Eustice