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

To examine the association between occupation and leukaemia.

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.

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).

These findings suggest increased leukaemia risks associated with certain agricultural, manufacturing, construction and service occupations in New Zealand.