A research team studied nearly 65,000 workers at four British power stations and found nuclear plant workers were more likely to die of a heart attack than of cancer caused by occupational radiation, The Daily Telegraph reported Tuesday.

The finding, published in the International Journal of Epidemiology, said the incidence of heart attacks and other problems were highest among workers with the highest levels of exposure. Researchers, however, said the study did not rule out the possibility that diet, exercise, socioeconomic status, shift work and stress may also be a factor.

The Guardian newspaper said some of the workers began work in the industry as far back as 1946, with those who worked at nuclear sites before 1980 exposed to higher levels of radiation.