Bracts collected from cotton plants after the first killing freeze contained higher levels of endotoxin and gram negative bacteria (GNB) than bracts obtained earlier in the growing season. Large numbers of GNB and considerable endotoxin were still present on some bracts even after 5 years of dry storage. Dusts from senescent bracts were contaminated with significantly more GNB and endotoxin than dusts from green bracts. Higher levels of microbial contaminants were found in dusts from senescent bracts collected from capsules that matured after the first killing freeze as compared to senescent bracts from early-maturing capsules. Experiments were carried out in which bracts were removed from cotton plants in the field or the amount of bract in the harvested crop was reduced by utilizing a species (Gossypium herbaceum L. with a semi-closed capsule. A reduction in the number of GNB or in the amount of endotoxin in raw ginned lint was not demonstrated by these approaches.