Solar ultraviolet radiation and outdoor workers in Canada : a program of research on exposure assessment, sun protection behaviours and prostate cancer risk
Bibliographic record
Abstract
Background: Exposure to solar ultraviolet radiation (UVR) is the main cause of skin cancer, and emerging evidence shows that it may prevent prostate cancer. Understanding the etiology of skin cancer has been challenged by a lack of detailed exposure assessment instruments, and this influences the ability to study the effect of solar radiation on other, more multi-factorial diseases. Methods: In the first study (Chapters 3 and 4), 78 outdoor workers wore UVR dosimetry badges for five work days, and provided information on skin cancer risk factors and sun protective behaviours. This data was used to investigate levels of exposure and prevention behaviours. The second study (Chapters 2 and 5) developed a job exposure matrix (JEM) based on occupation/industry, time spent outdoors and satellite data on available ambient UVR. The JEM was used to investigate the risk of prostate cancer in outdoor workers using a previously conducted population-based case-control study. Results: Over 300 UVR measurements were taken among seventy-three workers. Exposure was variable; the main predictors of exposure were time spent outdoors and meteorology. Outdoor workers relied more on clothing (hats, shirts) than on shade or sunscreen for protection. Sun protection scores showed that fairer people used more protection. The job sites’ clothing requirements also influenced protective behaviours. Based on the JEM, approximately 1.5 million Canadians (82% male) were exposed to solar UVR at work (for ≥2 hours/day). The largest exposed groups were construction workers, farmers and landscapers. Prostate cancer cases (n=1638) were compared to controls (n=1697) using the UVR satellite data-enhanced JEM and case status from national cancer registries. A statistically significant decrease in risk of prostate cancer was found in the highest exposed workers. Conclusions: Outdoor workers in Canada experience high levels of solar UVR exposure. Sun protection was relatively high and was driven by workplace requirements, which suggests company policies requiring hats and shirts could be an effective prevention strategy. JEMs are a key tool for population-level studies, and the addition of objective measures into the matrix for solar UV radiation was an innovation that showed high, long-term occupational exposure to solar UVR is protective for prostate cancer.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.006 |
| Science and technology studies | 0.003 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".