The public often has a misconception that any amount of radiation can cause cancer. This is known as radiophobia, and it is not justified, as the real risk of radiation-induced cancer is very low. Low-energy, non-ionizing forms of radiation, such as visible light and cell phone energy, have not been found to cause cancer in people. Ionizing radiation, such as gamma rays, x-rays, and radioactive particles, can cause cancer by damaging DNA.
However, it is not known how this occurs or how many tumors are caused by radiation damage. A very large amount of radiation is needed to cause cancer. The lungs and heart are likely to receive a scattered amount of radiation during radiation therapy for breast cancers, since they are below the irradiated area. There is evidence that radiation from medical images (such as x-rays) slightly increases the risk of cancer. This amount of radiation was selected as a starting point to illustrate that when 700 joules of radiation are administered to a single 70 kg male, a lethal dose of 10 Gy is obtained. To determine the amount of radiation needed to produce excess total cancer in a population, it is important to expand this observation.
This illustrates how much total radiation energy (158,000 J) is required to produce a significant increase in cancer frequency. Studies conducted in high background radiation zones of Yangjiang, China during the period from 1979 to 1995 did not find any statistically significant difference in cancer mortality between the control area and the zone of high natural radiation. Unlike high-dose ionizing radiation, the cancer risk assessment of more frequent or prolonged radiation exposure is still under debate and uncertainty. A study conducted in Australia on radiation exposure from CT scans in childhood and adolescence found that after an average of approximately 9 ½ years, people who underwent a CT scan had a 24% cancer risk because cancers caused by radiation take years to develop. Radiation can cause cancer in most parts of the body, in all animals, and at any age. Radiation-induced solid tumors usually take 10 to 15 years to become clinically manifest, and radiation-induced leukemias usually take 2 to 9 years to appear.
Mutational signatures could be a diagnostic tool for both individual cases and groups of cancers, and could help us find out what types of cancer are caused by radiation. In conclusion, although radiation can cause cancer at high doses and high dose rates, public health data related to lower levels of exposure, below about 10 mSv (1000 mrem), are more difficult to interpret. To monitor your exposure to radiation, we suggest wearing dosimetry badges or having area monitors available in your office area.
