Review date
June 2024
Article publication date
December 2023
Summary
This cohort study examined the association between residential radon exposure and risk of skin cancer (melanoma and squamous cell carcinoma) incidence. The study included 1.3 million adults (aged 20 years and more) from the Swiss National Cohort followed from the year 2000 to (up to) 2011. The data on individual exposures to residential radon (Bq/m3) were estimated by geographic location. Skin cancer incidence data during the same period were collected from regional cancer registries. The association between residential radon exposure and malignant melanoma or squamous cell carcinoma incidence was estimated in terms of the hazard ratio (HR) with 95% confidence interval (CI) per 100 Bq/m3, adjusting for solar ultraviolet (UV) radiation. A total of 4,937 incidences of melanoma were diagnosed during follow-up (average follow-up of nearly nine years). The mean radon exposure was 76.4 Bq/m3. No association was found for melanoma/squamous cell carcinoma incidence [HR (95% CI): 1.03 (0.94-1.13)] across all age groups. However, an association was reported for melanoma incidence [1.68 (1.29-2.19)] in the 20–29 years old age group. The results showed that residential radon exposure was largely not associated with the risk of developing skin cancers.
Link to
Published In
Environmental Research
ARPANSA commentary
The overall conclusion of the study is that there is little association between long-term exposure to residential radon and skin cancer incidence. This conclusion is inconsistent to the evidence from previous Swiss studies (Vienneau et al., 2017; Boz et al., 2022). The association between melanoma and radon exposure in young adults was based on only a small number (2.2%) of all melanoma cases. It is difficult to compare these findings in the Australian context due to a lack of similar evidence for Australia. In fact, according to the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) led nationwide survey of more than 3300 Australian homes, the average radon exposure level in Australian homes is ~ 10 Bq/m3, which is four times lower than the global average (40 Bq m⁻³) and 7.5 times lower than the mean radon level reported in this study. Consequently, residential radon exposure is not expected to be a significant contributor to skin cancer incidence in Australia. On the other hand, ambient UV levels in Australia are much higher compared to those reported in this study.
A major strength of this study is that it used a robust study design, covering most Swiss regions with high geographic variability of radon levels. Contrarily, the relatively small number of melanoma cases is a key limitation, which limits the statistical power of the study. Other limitations include: radon exposure was not directly measured (but estimated); information on the amount of time spent indoors and ventilation practices at home was not available; exposure to ambient UV radiation, which was adjusted in the analysis, was obtained conservatively (i.e. a spatial resolution of 1 × 1 km across the geographic locations). All these contribute to exposure misclassification to some extent, however, this potential misclassification is unlikely to have altered the overall findings of the study.
ARPANSA has a fact sheet on ionising radiation and health including dose levels from natural sources of ionising radiation, including radon. The International Commission on Radiological Protection has published guidance on radiological protection against radon exposure.
