ATOMS FOR THE FUTURE
Published in slightly different form in Tomorrowsf (http://www.tomorrowsf.com), No. 11 (November-December 1998).
Thomas A. Easton
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Robert Zubrin believes that we have the technology to send people to Mars right now. What blocks us is political will and public interest, for given a moderate amount of money--a mere $20 billion--we could build and launch the first Mars ship by 2005. Subsequent launches would cost just $2 billion apiece.
Unfortunately, his Mars-nauts face a vital obstacle: Even if we can build the necessary vehicles, rocket engines, and other necessary bits of apparatus--and there is no real reason other than money and will to think we can't--the space environment is rich with radiation. Space travelers depend on the metal shells of their spacecraft, or barriers of stored water and other materials, to block the cell-destroying electrons, neutrons, and other particles that sleet through the vacuum, never more powerfully than during "solar storms."
The solution may lie with a curious offshoot of nuclear technology called Deinobacter radiodurans.
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Have you heard the promise of a nuclear solution to our space frustrations before? Once upon a time, nuclear technology promised not only space, but also cheap energy, atom-powered cars, trains, planes, and ships.
We got the ships. The cars, trains, and planes never happened. Space? Well, Orion never got off the ground although more modest packages--isotopic generators and tiny nuclear piles--have proved useful for exploratory craft.
The energy turned out to be pricey. It also had worrisome waste-disposal problems (as does every other use of nuclear material), and now many nuclear power plants are being closed down and dismantled well before their time.
The main reason we have rejected the nuclear genie seems to be those worrisome problems much more than price. Ever since Hiroshima, "nuclear" has scared people. It can do a huge amount of damage either quickly (bombs) or slowly (cancer, birth defects, and mutations from exposure to contaminated water, dust, and food). It is scarey stuff. There is no denying that.
Yet nuclear power will return. Environmental scientists assure us that fossil fuels are even scarier, for their use leads to global warming and the inevitable inundation of Nauru and the Marshall Islands in the South Pacific and much of Bangladesh in Asia, as well as other low-lying regions. This isn't going to upset you too badly if you live in Switzerland or Colorado, but if you're a Bangladeshi a little nuclear glow-in-the-dark could seem downright comforting.
Another reason for bringing back nuclear power is that the oil supply is expected to begin its final decline within 10-20 years. When it does, prices will soar and political balances will shift. There may even be wars over the dwindling supply.
And still another is Deinobacter radiodurans. This tiny bacterium came to our attention because of research into the preservation of food by irradiation, which so badly damages the genes (DNA) of most bacteria that they die.
It was only a decade after Wilhelm von Roentgen's discovery of X-rays in 1895 that the first patents were issued for the use of ionizing radiation (such as X-rays) for destroying bacteria in food. During World War II, Massachusetts Institute of Technology researchers showed that ground beef could be preserved by exposing it to X-rays. Further research followed in the late 1940s and 1950s, when every government agency concerned with nuclear technology sought to free "nuclear" and "radiation" of their negative connotations. The rhetoric was of "atoms for peace" and "beating swords into plowshares". In 1958, however, the Food and Drug Administration (FDA) defined radiation sources intended for use in food processing as "food additives" and required safety tests before irradiated food could be marketed.
During the 1960s, FDA regulations approved the use of radiation to preserve canned bacon, kill insects in stored wheat and flour, and inhibit potato sprouting. However, when the Army asked the FDA in 1968 to approve irradiating canned ham to make the food keep longer in tropical areas such as Vietnam, then-FDA commissioner James L. Goddard raised questions about the safety of the process, noting that laboratory animals fed irradiated meat had developed cancers and cataracts and shown slower reproduction. Shortly after that, the FDA rescinded earlier approvals of food irradiation and commercial interest stopped dead for over a decade. In 1980, the FDA concluded that food irradiated at low doses was safe enough not to need extensive tests on laboratory animals.
In 1986, the FDA issued regulations permitting irradiation of fruits, vegetables, and pork at doses under 1 kiloGray (a Gray--a measure of absorbed dose of radiation--is 100 rads; 1 kiloGray is over 100 times as much radiation as it would take to kill a human being; click here for definitions) and of dried spices and herbs at doses up to 30 kiloGrays and requiring that irradiated foods be appropriately labeled. In 1990, the FDA approved the irradiation of poultry at doses up to 3 kiloGrays.
The 1990 approval was welcomed by the poultry industry, for it had recently suffered bad publicity over bacterial contamination of its products. More recently, similar bad publicity has afflicted fast-food chains and supermarket meat distributors, and by the end of 1997, the FDA had approved low-dose irradiation of beef with gamma rays.
One might expect that any technological development that promised to end fears of fatal food poisoning attacks would be welcomed with open arms, especially since food irradiation produces no detectable difference in the taste of the meat (according to taste tests performed by the USA Weekend Sunday supplement [Jan 23-25, 1998]). It has also been a success with astronauts, whose food has been preserved in this way for many years.
Unfortunately, the critics remain vocal. They speak disparagingly of nuking the cheeseburgers loved by patriotic Americans. Continuing protests keep many food manufacturers and marketers from having anything to do with food irradiation, at least, in the words of Quaker Oats public relations director Ron Bottrell, "until consumer confidence in the process reaches a level where we feel more comfortable with it." The Grocery Manufacturers of America have a similar attitude though they also seem to favor the technique.
Consumer comfort may be slow in coming. In September 1990, Jacques Leslie wrote in The Atlantic that "Most opposition ... starts from the assumption that radiation, frequently a lethal agent, cannot possibly affect food in safe ways.... [T]he dispute thus chiefly pits experts who support food irradiation against laymen who oppose it. Instead of grappling with the details of scientific inquiry, the coalition of anti-nuclear activists, organic-food advocates, and holistic-health practitioners who compose the organized opposition to food irradiation habitually make startling but invariably hollow claims of conspiracy.... Of the hundreds of scientists in this country who have done extensive research on the wholesomeness of food irradiation, only a few have publicly expressed opposition to it, and the several other scientists who are actively against food irradiation are not experienced in the field.... [T]he preponderance of evidence refutes the opposition's claims." The article is well worth reading for its detailed refutations of a number of objections to food irradiation. See also here.
It seems inevitable that you will eventually see a great many irradiated products at the grocery. The technique works, it seems safe despite the fears of some, and there is a very real danger from nonirradiated food. But I find food irradiation more interesting because it doesn't always work. Even very large doses of radiation don't always sterilize food successfully. Some bugs just don't die. Fortunately, they're rare, they don't cause disease, and they stink. They also may prove useful for cleaning up toxic waste sites.
Back in 1956, when the food irradiation process was still relatively new, a can of irradiated meat spoiled. Researchers discovered that the culprit was the bacterium now known as Deinococcus radiodurans. It belongs to a group of five species distinguished by "being the most radiation-resistant of vegetative cells. Certain strains have survived as much as 5 Mrad [50 kiloGrays--5000 times as much radiation as it would take to kill a human being; 3 kilograys is supposed to be enough to sterilize meat] of gamma radiation. An important component of this radiation resistance is the ability to repair damage to chromosomal DNA. Chromosomes can be completely broken apart and reconstituted." The bacteria are not normally found in high-radiation environments, but rather in ordinary soil, and they are also "highly resistant to the effects of desiccation, the mutagenic effects of UV radiation, most chemical DNA damaging agents and ... the effects of organic solvents." Its gene-set or genome is being analyzed by the Institute for Genomic Research (TIGR) in Rockville, Maryland. Click here to see its place in the bacterial family tree.
Currently researchers are working to develop Deinococcus radiodurans as a way to clean up "DOE waste sites [where] about 32% of soils and 45% of groundwaters ... contain radionuclides and metals plus an organic toxin class. The most commonly reported combinations of these hazardous compounds [are] radionuclides and metals (e.g. U, Pu, Cs, Pb, Cr, As) plus chlorinated hydrocarbons (e.g., trichlorethylene), fuel hydrocarbons (e.g., toluene), or polychlorinated biphenyls." The idea is to introduce genes for breaking down organic toxins and tolerating heavy metals and test the resulting bacterial strains for their ability to function in a radioactive environment where bacteria that might be able to clean up a nonradioactive toxic waste site would die. Very similar work is aimed at producing Deinococcus radiodurans strains that could thrive in and clean up DOE's "mixed waste streams" before they contaminate soil and groundwater.
Owen White of TIGR is collaborating on a project to map the genes of Deinococcus radiodurans. The project description notes that this bacterium's resistance to radiation is due to having several copies of its genetic material and "an efficient DNA repair mechanism" that can take genetic strands or chromosomes that have been broken into numerous pieces by radiation, ultraviolet light, or toxic chemicals and stitch them back together. "This is a serendipitous result of their ability to survive periods of severe dehydration, which also fragments DNA. Complete sequencing of the genome ... is currently underway [and] will facilitate identification of its novel DNA repair mechanisms."
And this is where the story gets most interesting to me. We're talking nailing down genes that make an organism effectively immune to radiation. We're talking genetic engineering. And it is not much of a leap at all to say that we are talking putting anti-radiation genes in other organisms, perhaps even humans.
The old Cold Warriors would have loved the idea! Laugh off fallout! Nuke the enemy, and send in the genetically engineered infantry while the ground is still glowing! Wow! (Not that these genes will do much to help you survive a nuclear winter.)
The same genes would provide resistance to the effects of increased ultraviolet light (thanks to ozone depletion) and of toxic chemicals in water and food. Since those effects are dominated by cancer, we're talking a genetically engineered resistance to canceras well as to radiation. That's a Wow! too.
But I'm not done. As I said above, a major hazard for space travelers is radiation; on prolonged interplanetary space flights, astronauts may absorb radiation doses hundreds of times greater than those anyone receives on Earth. Indeed, one of the things generally neglected in science fiction is the need for protective measures--not just during emergencies such as solar storms, but routinely. And here is this little package of radiation-immunity genes, just waiting for us to notice it and figure out how to make its tricks our own. Perhaps we will learn from it how to make a radiation-resistance drug. Better yet, perhaps the gengineers will in a few years be able to say, "Want your kid to be able to go to space? Then make your kid zap-proof now! Buy our handy-dandy little Fit-for-Space (TM) gene kit! Only $2995.95!"
That may sound silly, but I do expect that kind of gengineering to appear before too many more years have passed. Once it does, this is precisely the sort of genetic change that some people will think highly desirable. Without it, after all, radiation hazards may well keep us from long-distance space travel. With it--the stars are ours!
And to think it will all have come from nuking a burger!
More seriously, if we had never tried to develop nuclear technologies, if we had never tried food irradiation, if we had let the anti-nuclear, anti-food irradiation, and anti-genetic engineering protestors stop the research, we wouldn't even know this intriguing possibility existed. We would still be thinking of protecting astronauts from space radiation with massive shielding or feeling that we had no escape from Earth.
Radiation protection may also be a nice example of how the best results of research are sometimes not expected or planned. They come instead as serendipitous side-effects, and they are missed by researchers who must keep their eyes too firmly on a previously defined target. Research pays off best when it is most free to explore.
It may also pay off best when it is multi-disciplinary. This case certainly is, for it begins with nuclear physics, moves to food science, shifts to bacteriology, genetic engineering, and toxic waste clean-up, and finally turns a corner to find a niche at NASA.
Dr. Thomas A. Easton is Professor of Life Sciences at Thomas College in Waterville, Maine. He has been the Analog book columnist for almost 20 years. His latest novel, Unto the Last Generation, is available only on-line, from Mind's Eye Fiction. Last year's Silicon Karma (White Wolf, 1997) was well received; copies are now available from the author. His latest nonfiction books are Taking Sides: Clashing Views on Controversial Issues in Science, Technology, and Society (Dushkin Publishing Group, 1995, 2nd ed., 1997, 3rd ed., 1998) and Periodic Stars: An Overview of Recent Science Fiction (Borgo Books, 1997).
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