If you live in Chernobyl the total radiation dose you get each year is 390 millirem. That's natural plus residual from the accident and fire. In Denver, Colorado, the natural dose is over 1000 millirem/year. Denver gets more than 2.56 times as much radiation as Chernobyl! But Denver has a low cancer rate.
Calculate your annual radiation dose:
Average American gets 361 millirems/year. Smokers add 280 millirems/year from lead210. Radon accounts for 200 mrem/year.
Although radiation may cause cancers at high doses and high dose rates, currently there are no data to unequivocally establish the occurrence of cancer following exposure to low doses and dose rates -- below about 10,000 mrem (100 mSv). Those people living in areas having high levels of background radiation -- above 1,000 mrem (10 mSv) per year-- such as Denver, Colorado have shown no adverse biological effects.
Calculations based on data from NCRP reports show that the average level of natural background radiation (NBR) in Rocky Mountain states is 3.2 times that in Gulf Coast states. However, data from the American Cancer Society show that age-adjusted overall cancer death in Gulf Coast states is actually 1.26 times higher than in Rocky Mountain states. The difference from proportionality is a factor of 4.0. This is a clear negative correlation of NBR with overall cancer death. It is also shown that, comparing 3 Rocky Mountain states and 3 Gulf Coast states, there is a strong negative correlation of estimated lung cancer mortality with natural radon levels (factors of 5.7 to 7.5).