Residential radon and COPD. An ecological study in Galicia, Spain

Abstract

Purpose: Radon is a human lung carcinogen but it might be linked with other respiratory diseases. We aimed to assess the relationship between residential radon exposure and COPD (chronic obstructive pulmonary disease) prevalence and hospital admissions at a municipal level.

Materials and methods: We designed an ecological study where we included those municipalities with at least three radon measurements. Using mixed Poisson regression models, we calculated the relative risk (RR) for COPD for each 100 Bq/m³ of increase in radon concentration and also the relative risk for COPD using a cut-off point of 50 Bq/m³. We did not have individual data on cigarette smoking and therefore we used a proxy (bladder cancer standardized mortality rate) that has proved to account for tobacco consumption. We performed separate analyses for sex and also sensitivity analysis considering age and rurality.

Results: A total of 3040 radon measurements and 49,393 COPD cases were included. The relative risk for COPD prevalence was 0.95 (95% CI: 0.92–0.97) while for hospital admissions the RR was 1.04 (95% CI: 1.00–1.10) for each 100 Bq/m³. Relative risks were higher for women compared to men. Using a categorical analysis with a cut-off point of 50 Bq/m³, the RR for COPD prevalence was 1.06 (95% CI: 1.02–1.10) and for hospital admissions it was 1.08 (95% CI: 1.00–1.17) for women living in municipalities with more than 50 Bq/m³. All risks were also higher for women. No relevant differences were observed for age, rurality or other categories for radon exposure.

Conclusion: While the influence of radon on COPD prevalence is unclear depending on the approach used, it seems that residential radon might increase the risk of hospital admissions in COPD patients. Women have a higher risk than men in all situations. Since this is an ecological study, results should be interpreted cautiously.

Keywords:

• Chronic obstructive
• ecological study
• pulmonary disease
• radon
• Spain

Acknowledgements

This research work has not received direct competitive funding. The Galician Radon Map previously received research-project funding from the Galician Regional Authority (Xunta de Galicia) (PGIDT01MAM20801PR) and the Nuclear Safety Council (SRA/1391/2005/748). The case-control studies received competitive funding from the Xunta de Galicia: 10CSA208057PR and the Carlos III Institute of Health, Ministry of Science & Innovation (PI03/1248). We are grateful to the Galician Health Service for the information provided on COPD data that made possible this study. Part of this work has been performed during a Fulbright grant for Senior Researchers awarded to Alberto Ruano-Ravina at Brown University (Providence, Rhode Island, USA) (REF PRX14/00365). This grant is awarded by the US Department of State in collaboration with the Spanish Ministry of Education. This paper forms part of Raquel Barbosa Lorenzo’s doctoral thesis.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.