Increases of 1000 times the normal amount of radioactivity in Cambridge's tap water have been recorded by the Sanitary Engineering Department since the beginning of experimental nuclear detonations, Harold A. Thomas, associate professor of Sanitary Engineering, said recently. However, this amount would have to be multiplied 30,000 times before it would become medically important, he added.

A Geiger counter test on evaporated rain water in the Yard this past winter "sounded like a bobcat backing into a thorn bush," continued Thomas. "Most of the radiation that comes in rain or snow never gets beyond the roof, though any radioactive material that does get in decays very rapidly. There is no significant accumulation of irradiation of any amount in the water," he concluded.

Geneticists' questions on the effect of radiation on the human race have not yet been settled. "A certain amount of radioactivity causes genes, to mutate," said R. Paul Levine, assistant professor of Biology, "but only time will tell whether the additional amounts of radioactivity present in the air will affect future generations."

"Genetic mutations will definitely occur, as soon as they cross the threshold into the radioactive danger zone," said Paul M. Doty, associate professor of Chemistry.