Background
The occupational lung cancer risk in manufacturing and repair of shoes was studied by pooling of two major case-control studies from Germany.
Methods
Some 4184 incident hospital-based cases of primary lung cancer and 4253 population controls, matched for sex, age, and region of residence were intensively interviewed with respect to their occupational and smoking history. Based on the occupational coding and a free text search, all individuals who had ever worked in shoe manufacturing or repair for at least half a year were identified. Shoemaker-years were calculated as the cumulated duration of working in shoe manufacturing or repair. Odds ratios (OR) and 95% confidence intervals (CI) were calculated via conditional logistic regression. Additional adjustment for smoking and occupational asbestos exposure was used.
Results
Seventy-six cases and 42 controls who had ever worked in shoe manufacture or repair (OR = 1.89, 95% CI: 1.29–2.78). After adjustment for smoking, this risk was lowered to 1.69 (95% CI: 1.09–2.62). Further adjustment for asbestos exposure only slightly changed the risk estimates upwards. The smoking adjusted OR in males was 1.50 (95% CI: 0.93–2.41) and 2.91 (95% CI: 0.90–9.44) in females. Logistic regression modeling showed a positive dose–effect relationship between duration of exposure in shoe manufacture and repair and lung cancer risk. The odds ratio for 30 years of exposure varied between 1.98 and 2.24 depending on the model specified.
Conclusions
The study demonstrates an increased lung cancer risk for shoemakers and workers in shoe manufacturing. The risk seems to double after being 30 years in these occupations.