ABSTRACT
Due to their infrequency, very uncommon processes are difcult to study using standard epidemiologic techniques, even using case-referent approaches. Only infrequently are potential associations for such diseases amenable to assessments that conform to Bradford-Hill criteria or other rigorous standards of causation. In particular, the links between occupational factors and uncommon respiratory conditions are often rst described in isolated case reports or limited case series. These accounts, even with their acknowledged limitations,
serve to document the potential association between a disease and an exposure scenario and disseminate that information to a wider clinical and academic community.
