In people under age 30, radiation is a risk factor for a type of brain tumor called a meningioma, a study has found. Researchers analyzed records of 35 patients who were diagnosed with meningiomas before age 30. Five had been exposed to ionizing radiation earlier in their lives. They include two patients who received radiation for leukemia at ages 5 and 6; one who received radiation at age 3 for a brain tumor known as a medulloblastoma; and one who received radiation for an earlier skull base tumor that appeared to be a meningioma. The fifth patient had been exposed at age 9 to radiation from the Chernobyl nuclear power plant disaster in Ukraine.