A new study notes that exposure to radiation puts adults at equal risk of developing cancer as children. The study by Columbia University researchers counters some previous studies suggesting that as people age; their vulnerability to radiation-induced cancer diminishes.

The report says “Overall, the weight of the epidemiological evidence suggests that for adult exposures, radiation risks do not generally decrease with increasing age at exposure.”

The study's conclusion was based on a review of data concerning Japanese survivors of the atomic bomb. The study authors tracked the ensuing incidence of cancer looking at the age of the survivors at the time the bomb was dropped. They used the same statistical framework to predict cancer risk by age of radiation exposure among people aged 30 to 60 in the U.S. population.

They found that some types of cancer tumors appear to increase following radiation exposure -- a discovery they said could have practical implications, since most X-ray procedures and jobs requiring radiation exposure involve middle-aged people.

In an accompanying editorial, John D. Boice of the International Epidemiology Institute in Rockville, Md., and Vanderbilt University in Nashville, noted that prior studies contradict the current findings and that generalizing the Japanese data to the U.S. population may be problematic.

He noted that the present study “raises provocative hypotheses and conclusions that -- although preliminary -- draw attention to the continued importance of low-dose radiation exposures in our society.”

The findings are published in the Oct. 25 online issue of the Journal of the National Cancer Institute.