Exposure To Crude Oil And Ultraviolet Radiation And Risk Of Skin Cancer In 25 000 Offshore Oil Industry Worker

Tom GRIMSRUD, Cancer Registry of Norway, Norway
STENEHJEM J. 1 , BRÅTVEIT M. 2 , SAMUELSEN S. 3 , KIRKELEIT J. 4,5 , ROBSAHM T. 1

1 Department of Research, Cancer Registry of Norway, Oslo, Norway
2 Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway
3 Department of Mathematics, University of Oslo, Oslo, Norway
4 Department of Clinical Science, University of Bergen, Bergen, Norway
5 Department of Occupational Medicine, Haukeland University Hospital, Bergen, Norway

Purpose
To examine prospectively the risk of skin cancer by anatomical site according to dermal exposure to crude oil, benzene, mineral oil, and ultraviolet radiation in 25 000 offshore oil industry workers traced in the Cancer Registry of Norway 1999–2012.
 
Methods
Different metrics of exposure were developed according to expert-based intensity estimates (job‑exposure matrices) covering dermal exposure to crude oil, mineral oil, and dermal and inhalatory exposure to benzene, and according to self-reported solar exposure. Hazard ratios (HRs) were derived by Cox regressions adapted to a stratified case-cohort design with 95% confidence intervals.
 
Results
A total of 112 cases of cutaneous melanoma and 63 cases of squamous cell carcinoma were observed. Dose-related risk patterns were seen for skin cancer on the hand (melanoma and non-melanoma combined, 1 melanoma and 7 squamous cell carcinomas) according to duration of exposure to crude oil, or according to duration of benzene exposure. For the highest exposed tertile (15 years+ of crude oil exposure) compared with the unexposed, the HR was 5.4 (95% CI 0.8–39, 4 cases), and the Ptrend across categories was 0.029, adjusted for sunburns and education. No such trend was found for mineral oil. When anatomical site was disregarded, those reporting ≥ 4 sunburns/year compared to none had increased risks of melanoma (HR 4.5, 95% CI 1.4–15, 4 cases) and squamous cell carcinoma (HR 8.1, 95% CI 1.9–33, 3 cases).
 
Conclusions
Our study suggests that skin cancer can be induced by dermal exposure to crude oil in the upstream oil industry.
 
Funding sources
The Research Council of Norway’s PETROMAKS program (grant no. 220782)
The Statoil Fund for Research in Occupational Medicine
Cancer Registry of Norway Research Fund