Our modern environment and lifestyle has exposed people to...

Our modern environment and lifestyle has exposed people to increasing levels of radiation from the built environment, (it is possible to get a reading from a concrete wall or a road because of the radioactivity present in some of the quarried materials), increasing air travel and medical procedures. Whilst air pollution and diet are also suspected to play a roll, The increase in cancer rates cannot be explained by the ageing population as rates in children and adolescents is increasing at an alarming rate.
Medical science believes that no radiation dose is "safe", because as radiation is cumulative, every subsequent exposure increases risk. This is why doctors and even dentists carefully weigh the risks against the benefits before recommending X-rays. In most cases CT scans for children are not recommended because of their higher dose.
Pilots and air crew are considered to have double the risk than those in the general public because of their exposure to cosmic radiation.

https://www.cancer.org/healthy/cancer-causes/radiation-exposure/x-rays-gamma-rays/do-xrays-and-gamma-rays-cause-cancer.html