Radiation: Some Thoughts for Food

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Whether the end result is a deadly illness or a striking change in the next generation, the impact of genetic mutations caused by radiation is not fully understood. To learn more about these effects, Cornell University Scientists Richard Holsten, Michiyasu Sugii and Frederick Steward conducted an experiment of elegant simplicity. They irradiated single carrot cells in a growth-stimulating broth of coconut milk, planning to grow them into complete plants. Thus any mutations that showed up on the complete plan could be traced back with assurance to radiation-caused changes in the chromosomes of a single microscopic cell.

To make doubly sure that no other influences were affecting their carrots, the cautious scientists ran an ingenious check: they irradiated the coconut milk and in it they grew cell tissue from a normal cell. When they examined the tissue cells, however, they were startled to find that the chromosomes were damaged. And this time they could not blame the result on direct radiation.

Abandoning their original experiment, they concentrated on analyzing the coconut milk, hoping they would be able to isolate whatever had produced the radiation-like effects.

Feeding Fruit Flies. Their long search, the three Cornell researchers report in Nature, turned up six still-unidentified chemical compounds that apparently had been produced by the irradiation of the sugar found in coconut milk. To confirm their unexpected finding, they irradiated pure sugar and fed it to the buds and roots of other plants and to fruit flies. Again, although the sugar itself was not radioactive, it produced radiation-like results in both the experimental plants and insects; normal growth was noticeably stunted and damaged or altered chromosomes were found.

An immediate result of the Cornell discovery was to raise some serious second thoughts about the preservation of food by radiation, a practice that is gradually gaining acceptance. Relatively heavy doses of radiation have been used to kill microorganisms that cause decay in food; lighter doses prevent potatoes from sprouting and kill insects that infest flour and cereals. The U.S. Food and Drug Administration considers the process safe enough to have cleared irradiated bacon, wheat and potatoes for public consumption, and the U.S. Army has already served some irradiated food in its mess halls. In Canada, the world's first private, commercial food-irradiation plant is now in operation.

But what if irradiated foods contain large amounts of sugar or other carbohydrates that could give rise to the strange compounds that showed up in the Cornell experiments? Would the mysterious chemicals cause harmful, radiation-like effects in humans? Further investigation should be made, warn the Cornell scientists, "before there is widespread use of radiation-sterilized foods that contain sugar."