IT'S an unforgettable image. Julianne Lindemann of Advanced Genetic Sciences, enveloped in ``moon suit'' protective clothing, is spraying genetically altered bacteria on strawberry plants. In the background, news reporters and other onlookers happily down coffee and doughnuts. They seem unconcerned about possible contamination by the microbe that, according to some stories filed that day, was a potential environmental menace. Thus began the field test of so-called ice-minus bacteria. This is a strain of the common field bacterium Pseudomonas syringae, with a gene removed so the microbe no longer promotes frost on plants. The bacteria were released in Brentwood, Calif., April 24, 1987, after four years of sometimes bitter court battles, public hearings, and regulatory delays.
As the first planned release of a genetically engineered organism proposed in the United States, the ice-minus test has become a classic case study. Experimenters and critics alike refer to it when they consider the safety of allowing products of the genetic engineer increasingly to enter our environment.
``That experiment was probably the most highly publicized single experiment in the history of biological science,'' says Arthur Kelman, a University of Wisconsin bacteriologist. ``And yet,'' he adds, ``on the basis of what we knew about that organism, it probably was one of the safest first experiments that have ever been done.''
For biologists such as Professor Kelman, the ``moon suit'' photograph symbolizes both what is rational and what is ridiculous in the field-test safety debate. Scientists felt at the time that only exaggerated fear lay behind the California Department of Health Services order for Dr. Lindemann to wear protective gear. Lindemann's colleague Trevor Suslow wore only a standard dust mask when he applied the bacteria a second time last December. Yet many experts also believe that the extensive environmental studies and highly visible caution which marked the ice-minus experiment were justified in terms of public responsibility. They provided knowledge to help allay concern about this widely misunderstood experiment. Future experiments of comparable safety will probably require much less scrutiny.
The Office of Technology Assessment (OTA) emphasizes this in its recent report to the Congress on field testing gene tailored organisms. Noting that some two dozen such trials have already been held in five countries, it points out that the pace of field testing is accelerating.
More than 300 companies in the United States - let alone universities and government laboratories - are developing genetically engineered products. The eventual applications for field tests would overwhelm government regulators if they tried to consider every case as intensively as they did the ice-minus experiment. OTA suggests that Congress consider a system to regulate field tests according to their degree of risk.
The National Academy of Sciences urged a similar strategy last September. Dr. Kelman, who chaired the academy's study committee, says that this strategy reflects general scientific opinion. At the American Association for the Advancement of Science annual meeting in February, he told the press:
``Even though there appears to be a debate, ... actually the areas of agreement are greater than one might expect. And so if one were to ask even those people who have expressed the deepest concern whether they would agree with the statement that most introductions into the environment represent relatively low risk or no significant risk, I think that you would find there is a consensus on that. You would also find there is a consensus that there may be problems and that these problems have to be recognized.''
To tackle the problems of assessing environmental risks, both the Kelman committee and the OTA distinguish between tests that are inherently safe and those that are inherently risky. They urge regulators to reserve detailed scrutiny for the latter. Field tests in which a small change is made in a known harmless organism, such as a crop plant, which is then put back into its usual environment, need less regulation than does the release of organisms that might become new weeds or pathogens, they say.
Kelman explains: ``Weeds differ from crop plants and pathogens from nonpathogens in a large number of traits. Most weeds grow vigorously, produce large numbers of seeds, germinate readily, and spread over wide areas. Most pathogens have the ability to invade plants or animals, resist defense systems of the organisms they invade, form toxic chemicals that injure or kill cells, reproduce and spread ... rapidly and invade new organisms. They can also survive under adverse conditions in the environment.
``Each of these traits is expressed through several genes or clusters of genes. The transfer of a few individual genes unrelated to characteristics contributing to weedlike attributes or pathogenicity, therefore, are not likely to turn a crop plant into a weed or a harmless microorganism into a pathogen.''
To make the point, he notes: ``If I have a petunia and I transfer a gene for a different color out of a bacterium, that's a big jump from a bacterium to a pe-tunia. ... [But] it's still a petunia. ... It's not going to become a killer petunia.''
Even though scientists can rank field tests according to risk, all tests will need at least some regulation. Scientists still don't know enough to say some categories of tests are so safe they need no supervision at all.
While acknowledging that most projects that can be done today do seem safe, a University of Minnesota biologist, Philip Regal, told a February meeting of the American Association for the Advancement of Science: ``I have yet to see any genetic engineering textbook that deals with safety when it comes to the organisms that are to be released in nature. Maybe it's best they don't. We have a way to go before that chapter could be written responsibly.''
Meanwhile, some research is under way to gain the basic knowledge that, one day, could lead to standardized tests for ecological safety.
For example, Clemson University, in partnership with the Monsanto Company, is field-testing a soil bacterium - Pseudomonas fluorescens - that has two added genes to help in tracking the microbe. These genes enable the bacterium to ``eat'' lactose, something the wild form can't do. This helps distinguish the designer bacterium in analyzing soil samples. Ellis Kline and Horace Skipper are testing this tracking system, which Monsanto scientists David J. Drahoe, Gerard Barry, and Bruce Hemming developed. Their test began at Clemson's field station near Edisto, S.C., last November. If successful, the 18-month trial should give ecologists a useful tool for monitoring bacterial releases.
Dr. Regal sees progress in building the knowledge base. He explains: ``We have been thinking beyond the ice-minus bacteria in California. It is silly to get people concerned about things like that. Dozens of scientists have spent thousands of hours working on more important issues. NSF [the National Science Foundation] and EPA [the Environmental Protection Agency] have awarded millions of dollars for research in an attempt to get some background information. ... Gradually, we are getting molecular biologists and ecologists to work together.''
``We're at a point now where things will develop,'' says Kelman. ``There are permits being issued. There are organisms now out in the field. The Monsanto experiment in South Carolina is in progress. It's slow. It's agonizingly slow. ... But I'm optimistic that it [the safety issue] will be resolved.''