Environmental Protection Agency radon risk

The Environmental Protection Agency (EPA) studied increases in lung cancer rates among uranium mine workers. The unit used to measure airborne radon is the picocurie (pico = 10 ) per liter (pCi/L). A curie is defined as 3.7 X 10 ° radioactive disintegrations per second. The EPA examined mine workers exposed to radon levels of about 400 pCi/L. The EPA then used a linear risk-exposure model, which assumes that risk increases linearly with exposure, to estimate the risk associated with the much lower radon levels in homes. For example, by using this model, if 400 pCi/L increased cancer risk in uranium miners by 10%, then 40 pCi/L would increase the risk by 1.0%. The EPA, as shown in Table 8-5, has established that home radon levels above 4 pCi/L pose a significant threat to the occupants. Further studies demonstrated that the risk associated with radon exposure is greater for smokers. 

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