In their letter,1 Mastrangelo and colleagues argue that our analyses on occupational organic dust exposure and its specific constituents (eg, endotoxin) suffered from inadequacies that hampered their interpretation. They argue that, given that the effect of endotoxin might diminish after cessation of exposure, analyses of ever versus never exposed to endotoxin might fail to identify the protective effect of endotoxin. Furthermore, they argue that the failure to differentiate between livestock/dairy and crop/orchard farmers may have obscured the protective effect as some papers have argued that the effect is contained (largely) to livestock/dairy farmers only.

The main aim of our paper was to study …