Leukaemia and occupation: a New Zealand Cancer Registry-based case–control Study

BACKGROUND: To examine the association between occupation and leukaemia. METHODS: We interviewed 225 cases (aged 20-75 years) notified to the New Zealand Cancer Registry during 2003-04, and 471 controls randomly selected from the Electoral Roll collecting demographic details, information on potential confounders and a comprehensive employment history. Associations between occupation and leukaemia were analysed using logistic regression adjusted for gender, age, ethnicity and smoking. RESULTS: Elevated odds ratios (ORs) were observed in agricultural sectors including horticulture/fruit growing (OR: 2.62, 95% confidence interval (CI): 1.51, 4.55), plant nurseries (OR: 7.51, 95% CI: 1.85, 30.38) and vegetable growing (OR: 3.14, 95% CI: 1.18, 8.40); and appeared greater in women (ORs: 4.71, 7.75 and 7.98, respectively). Elevated ORs were also observed in market farmers/crop growers (OR: 1.84, 95% CI: 1.12, 3.02), field crop/vegetable growers (OR: 3.98, 95% CI: 1.46, 10.85), market gardeners (OR: 5.50, 95% CI: 1.59, 19.02), and nursery growers/workers (OR: 4.23, 95% CI: 1.34, 13.35); also greater in women (ORs: 3.48, 7.62, 15.74 and 11.70, respectively). These elevated ORs were predominantly for chronic lymphocytic leukaemia (CLL). Several associations persisted after semi-Bayes adjustment. Elevated ORs were observed in rubber/plastics products machine operators (OR: 3.76, 95% CI: 1.08, 13.08), predominantly in plastic product manufacturing. CLL was also elevated in tailors and dressmakers (OR: 7.01, 95% CI: 1.78, 27.68), cleaners (OR: 2.04, 95% CI: 1.00, 4.14) and builder's labourers (OR: 4.03, 95% CI: 1.30, 12.53). CONCLUSIONS: These findings suggest increased leukaemia risks associated with certain agricultural, manufacturing, construction and service occupations in New Zealand.