LUNG CANCER AND PET BIRDS

Determining whether an exposure causes a disease in an individual is difficult, but such determination can be supported by demonstrating biological plausibility. Unfortunately, the mechanisms suggested by Kohlmeier et al. are not consistent with all available information. Although inhalation of avian antigens may cause hypersensitivity pneumonitis, neither hypersensitivity pneumonitis nor pulmonary fibrosis, which occasionally results, is associated with lung cancer. In addition, avian particulates, owing to their size, are not likely to reach the alveoli, nor have they been proven to be carcinogenic. Finally a mycologic pathway is unlikely, given that pet birds seldom are a source of Cryptococcus neoformans, even among immunosuppressed individuals, because few birds shed this organism and there is little aerosolization from feces.