Avian exposure and bronchogenic carcinoma.

OBJECTIVE To investigate the association between bird keeping and risk of lung cancer. DESIGN Case-control study asking detailed questions on exposure to domestic birds and other pets, smoking, and various demographic and potentially confounding variables. SETTING District general hospital; current admissions interviewed in hospital or recent admissions interviewed at home. PATIENTS 143 patients with lung cancer, 143 controls with heart disease, and 143 controls with orthopaedic conditions individually matched for age, sex, date of admission, and current or past admission. MAIN OUTCOME MEASURES Odds ratios for lung cancer in relation to various aspects of bird keeping, after adjustment for smoking and other relevant confounding variables. RESULTS Risk of lung cancer was not significantly associated with household exposure to pet birds at any time or at various specific periods in life, or to keeping large numbers of birds. For specific types of birds no association was seen for living in households with budgerigars or canaries but risk was significantly associated with keeping pigeons (odds ratio 3.53, 95% confidence interval 1.56 to 7.98). This remained significant after regression analysis to account for confounding variables (3.9, 1.2 to 12.62) in both sexes and all age groups. CONCLUSION Bird keeping may confer some risk of lung cancer but the relation is not as strong as previously reported.