Increased risk of squamous cell carcinoma based on solar ultraviolet radiation measurements from outdoor workers in Lisbon, Portugal

Introduction: Solar ultraviolet radiation (UVR) is one of the main causes of skin cancer, with squamous cell carcinoma (SCC) being particularly prevalent among outdoor workers due to chronic UVR exposure. Despite the increasing incidence of SCC in this group, cases remain under-reported and are not always classified as an occupational disease. Current guidelines for UVR exposure are established for a limit of 30 J/m2 over an 8-h workday, and they are implemented for both solar and artificial UVR (non-specific). This study aimed to calculate the excess risk of SCC among gardeners, gravediggers, pavers, asphalters, sanitation workers, and sailors in Lisbon based on measured solar UVR, in comparison with indoor workers. Methods: A prospective observational study using personal dosimeters was conducted to assess solar UVR in 90 outdoor workers from Lisbon Municipality, from April to October 2023. This data was used to calculate the relative risk (RR) of SCC for each of the investigated occupations as well as for each individual using a formula developed by Milon et al. Results: Solar UVR exposure was associated with an increased risk of developing SCC by values ranging from 22 to 437%, in terms of individual UVR dose assessment. Pavers had an increased risk of developing SCC by 65%, Asphalters by 133%, Sanitation Workers by 179%, Gravediggers by 187%, and Gardeners by 193%. Despite some limitations, a novel approach was tested by using direct UVR dose measurements in real environmental exposure conditions to estimate the risk of developing SCC. Discussion: Outdoor work is associated with a substantially increased risk of SCC. However, the current model needs to be refined to improve the accuracy of risk assessment and to support the development of targeted prevention interventions. The relevance of the study provides valuable insights for health and safety policies in reducing UVR exposure and SCC risk among outdoor workers.