Study type | Target population | Main purpose of the study | Method of radon dosimetry | Major finding/conclusions |
Cohort studies | Miners/occupational exposure | Determine the risk of lung cancer morality in exposed miners | Radiation exposure was estimated using job-exposure matrix (JEM) which provides exposure values for potential alpha energy from radon and its progeny in working level months (WLM) | High levels of radon exposure were associated with increased cancer risk. |
Case control studies | The public/residential exposure | Determine the risk of lung cancer in residential setting | Year-long residential radon levels were measured by a-track detectors and were used to estimate exposure in the 25 years prior to the index date. | Most studies reported small insignificant association between residential radon exposure and lung cancer, some studies found negative association. |
Pooled analysis of the cohort studies on miners | Obtain summary estimates of the risk of lung cancer in radon-exposed miners using large sample size. | A summary of the WLM exposure was obtained for the total subjects using reported exposure levels in the individual studies. | A summary of the WLM exposure was obtained for the total subjects using reported exposure levels in the individual studies. | A consistent linear relationship for cumulative radon progeny and lung cancer was observed in the range of miner exposures |
Combined analysis of case-control studies | The general public/residential exposure in Europe and North America | Obtain accurate estimates of lung cancer risk from residential radon exposure by reducing incertainity in radon dosimetry | Available radon measurements form individual studies were used to estimate radon exposure for the total individuals in all homes occupied over the past 5 - 30 years. | A significant increase in risk of lung cancer was associated with increased radon exposures with seemingly linear dose-response relationship. |