So how could radiation have a beneficial effect? There is good scientific evidence that while high doses destroy cells, low-dose radiation stimulates the DNA to repair mechanisms that are essential to maintaining cells throughout the lifetime of the organism. Low-dose radiation is also thought to lower the number of free radicals in the cell, substances which damage DNA. In addition, radiation stimulates apoptosis—the process which causes damaged cells to self-destruct and die before they can become malignant and cause cancer. The idea that small doses of radiation may be good for us is known as radiation hormesis.