Objective To determine the risk of lung cancer associated with exposure at home to the radioactive disintegration products of naturally occurring radon gas Design Collaborative analysis of individual data from 13 case-control studies of residential radon and lung cancer. Setting Nine European countries. Subjects 7148 cases of lung cancer and 14 208 controls. Main outcome measures Relative risks of lung cancer and radon gas concentrations in homes inhabited during the previous 5-34 years measured in becquerels (radon disintegrations per second) per cubic metre (Bq/m 3 ) of household air. Results The mean measured radon concentration in homes of people in the control group was 97 Bq/m 3 , with 11% measuring > 200 and 4% measuring > 400 Bq/m 3 . For cases of lung cancer the mean concentration was 104 Bq/m 3 . The risk of lung cancer increased by 8.4% (95% confidence interval 3.0% to 15.8%) per 100 Bq/m 3 increase in measured radon (P = 0.0007). This corresponds to an increase of 16% (5% to 31%) per 100 Bq/m 3 increase in usual radon-that is, after correction for the dilution caused by random uncertainties in measuring radon concentrations. The dose-response relation seemed to be linear with no threshold and remained significant (P = 0.04) in analyses limited to individuals from homes with measured radon < 200 Bq/m 3 . The proportionate excess risk did not differ significantly with study, age, sex, or smoking. In the absence of other causes of death, the absolute risks of lung cancer by age 75 years at usual radon concentrations of 0, 100, and 400 Bq/m 3 would be about 0.4%, 0.5%, and 0.7%, respectively, for lifelong non-smokers, and about 25 times greater (10%, 12%, and 16%) for cigarette smokers. Conclusions Collectively, though not separately, these studies show appreciable hazards from residential radon, particularly for smokers and recent ex-smokers, and indicate that it is responsible for about 2% of all deaths from cancer in Europe.

No abstract

Residential exposure to radon is an important cause of lung cancer in the general population. The risks appear consistent with earlier estimates based on data in miners.

Arid Mediterranean regions that shelter unique biodiversity are threatened by increasing anthropogenic pressures, such as urbanization, overgrazing and climate change. In Morocco, one of the main bush species in arid areas, the jujube (Ziziphus lotus), suffers from officially promoted programmes of removal. The Moorish tortoise (Testudo graeca soussensis) is threatened by such habitat loss. Like most animals, the Moorish tortoise must navigate between microhabitats to find essential feeding resources and thermal refuges. This study combined radio-tracking of free-ranging individuals, microhabitat temperature monitoring and transects in a range of habitats. Tortoises were found to depend on the occurrence of large and relatively abundant bushes to escape lethal overheating. Thus, (1) current official encouragements for the destruction of the jujube bushes should be reappraised; (2) habitat restoration relying on replanting jujube bush should be encouraged; and (3) large-scale monitoring of critical bush densities should be used to better organize conservation plans (protection and/or restoration of areas) for the Moorish tortoise.