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frost damage to commercially significant crops. These mutant bacteria and 
wild-type bacteria have been sprayed on plants at the same test site In 
Individual experiments over the past several years and no environmental harm 
has resulted. Bacteria were applied at the same times of year, with the same 
equipment, at the same concentration, and on the same plant varieties as 
proposed for the field test. Past studies with genetically marked strains 
have shown that the bacteria do not survive well through a full yearly cycle, 
l.e., their populations drop to very low levels during the winter season. 
These epiphytic bacteria do not survive for more than a month in the soil. 
Spray-appl ied INA’ bacteria could not be detected even Immediately adjacent to 
the Inoculated plot. No INA" mutants could be detected in the area In subsequent 
years. The bacteria can survive up to a year In plant debris on the surface of 
the soil, but die rapidly (within a month) when plant debris is incorporated 
into the soil . 
5.3 Effects of the Proposed Field Test 
5.3.1 Risk Assessment 
A. The Method 
An analysis which appeared In Section VII of the October 1977, N I H 
Environmental Impact Statement on NIH Guidelines for Research Involving 
Recombinant ONA Molecules Is paraphrased here. A series of events must occur 
In order for there to be harm from a recombinant DNA experiment; the overall 
probability of a detrimental effect will be the product of the probabilities of 
the Individual steps. If the probability of any one of these essential steps 
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