Are Dangerous Bacteria Lurking Inside Your Organic Produce Dennis T. Avery CHURCHVILLE, VA A new study finds that the most dangerous bacteria in Americas food supply, E. coli O157:H7, can actually get inside the tissues of such food plants as lettuce and spinach, where it cant be washed off. This is bad news for organic food buyers. The major reservoir of O157 bacteria is cattle manureand organic farmers use large amounts of cattle manure to provide the nitrogen fertilizer necessary for their crops to grow. (Conventional farmers prefer to use pure nitrogen, taken from the air, on food crops, using animal manure only for feed corn and other nonfood crops.) Dr. Ethan Solomon reports in Applied and Environmental Biology (Jan. 2002) that his research team found E. coli O157:H7 entering lettuce plants through the root system (from either manure-contaminated soil or irrigation water) and migrating throughout the edible portion of the plant. Research has demonstrated the long-term survival of O157:H7 in manure held under a variety of conditions, so even a strict adherence to the [organic] guideline may result in the application of manure containing culturable E. coli O157:H7 to production fields, says Solomons new report. Direct contact between the leaves and contamination source is not required for the organism to become integrated into edible lettuce tissue. Solomons team tested only lettuce. Given the political correctness and expanding sales of organic foods, more research obviously needs to be done on other food crops to determine the extent of the danger. Of course, few organic farmers put raw manure directly on their crops. But composting is an erratic process, and achieving high enough temperatures long enough to kill the tough bacteria is critical. Another study, published in the same journal in 1998 by Kudva, Blanch and Hovde, found that E. coli O157:H survived for 21 months in a manure pile under fluctuating environmental conditions. The bacterium survived at least 100 days in bovine manure frozen at 20 C., and survived 21 to 40 days under a wide variety of conditions. Dr. Dean Cliver, a professor of food safety at the University of California/Davis, told York Times columnist John Tierney, in November, 2000, We know that animals are shedding bacteria that can make people sick if the manure hasnt been treated properly. Personally, if I knew something was grown with conventional chemical fertilizers, I would feel it was extra safe. We have two virulent new foodborne microbes (E. coli O157 and Salmonella typhimurium) associated with animal manure. An increasing percentage of our food sales are organicwith a logically higher risk of bacterial infection. The Centers for Disease Control estimate that E. coli O157 sickens more than 60,000 American per year, hospitalizes nearly 2,000, and kills 50. The virulent new strains of E. coli and Salmonella attack the strong as well as infants and the elderly. O157 can inflict permanent damage on even its survivors internal organs, especially the kidneys of children. The U.S. Department of Agriculture, in its proposal to establish the new National Organic Program stated, Applications of raw manure are a hazardous, threatening pathogenic contamination of food products, notwithstanding the use of composted manure, which can carry similar hazards. Dr. Robert V. Tauxe, then head of the CDCs Foodborne Illness Branch, stated in a 1997 letter to the Journal of the American Medical Association that . . . adequate composting of manure should in principle eliminate pathogens from manure. Unfortunately, knowledge of the critical times and temperatures needed to make [them] microbiologically safe is incomplete, and the regulatory approach is . . . patchy at best. Despite all this, a CDC spokesperson said in 1999 that it had not studied the risks of organic food, and was not planning to, because such research was not warranted. More recently, the CDC says it has initiated a study comparing the bacterial risks of organic and conventional produce, but the results are still pending. The USDA organic standards currently forbid raw manure from being applied to the organic food crops less than 120 days before harvest for food crops whose edible portion has direct contact with the soil surface, or less than 90 days before harvest of a product whose edible portion does not have direct contact with the soil surface or soil particles. But these guidelines were written before the Solomon teams research showed that E. coli O157 could travel into the plants through the root systems. Perhaps the USDA organic standards need to be revised on the basis of the new findings. Is it time to restrict animal manure to feed crops only? Many food safety professionals think the only reasonable alternative would be electronic irradiation. Irradiation would not only kill virtually all the pathogenic bacteria, but also keep the food fresher-tasting since it kills many of the bacteria and fungi which cause food to rot. This article was published by Knight Ridder Tribune Dennis T. Avery is based in Churchville, Va., and is director of global food issues for the Hudson Institute of Indianapolis.