Risk comparisons between limit values for ionizing radiation, PAH, and benzene in Sweden

The background of regulatory limit values for carcinogenic agents in Sweden is discussed and exemplified with the ambient and occupational air pollutants benzene and PAH (especially benzo[a]pyrene, BaP), ionizing radiation, and radon. The estimated cancer risks at different limit values are compared, as is the estimated number of cancer cases annually due to existing pollutant levels. Although the individual lifetime cancer risks are much higher at the occupational limit values for benzene and BaP than what is recommended for the general public, the estimated number of cancer cases annually is lower at existing pollutant levels. The individual cancer risk at the occupational dose limit for ionizing radiation is comparable to the occupational cancer risk with BaP, but higher than the one for benzene. At the dose limit for the general public, the radiation risk would be higher than what is recommended for individual air pollutants. However, doses from man-made radiation are usually much lower than the dose limit due to optimization. Thus, the estimated number of cancer cases annually due to radiation is low and comparable to the estimated number due to the chemical air pollutants discussed. In contrast, the lung cancer risk with radon in dwellings both at limit values and existing levels is high and comparable to occupational limits for the chemical carcinogens and for radiation. The estimated number of cancer cases annually at existing radon concentrations (1100 cases) is much higher than for the other discussed pollutants (0.03-7 cases each) and also higher than the estimated number of lung cancer cases due to total air pollution (approximately 100 cases).