Tests so far have yet to show irradiation to be dangerous. In the early 1980s, eight feeding studies were conducted in China on human volunteers. More than 400 people consumed irradiated food for up to 15 weeks with no sign of abnormal effects, including no abnormal chromosome activity. During the past 20 years, millions of mice, rats and other laboratory animals in the United States and Europe have been bred and reared exclusively on irradiated diets without any signs of cancer or other illnesses that could be attributed to the irradiated foods. While irradiation raises the levels of certain known food carcinogens such as benzene and formaldehyde, it does so minimally.
Many foods naturally carry much higher levels than are found in irradiated foods.
Eggs, for example, have 100 times more naturally occurring benzene than most irradiated foods. Free radicals have also surfaced as a concern in irradiated food. Free radicals are atoms or molecules with unpaired electrons, which make them unstable and very reactive. They're considered to be carcinogenic if ingested in large amounts during long periods. Irradiation produces free radicals in food, but no more than toasting or frying, which is to say small amounts.