Abstract
The objective of this study was to determine the specific botanical ingredients present in respirable raw cotton dust. Significant differences in content of gross leaflike (bract-containing) trash were found between several grade divisions of raw cottons. For example, higher grades of raw cotton (strict low middling=SLM) contained less leaflike trash than lower grade cottons (low middling=LM). The potential for production of fine particulate from botanical trash materials plus lint and linters was determined in the laboratory by an abrasive milling test. Bract and wood fragments were the most friable of all plant materials found in raw cottons whereas seed meat, lint, linters and seed coat were the least friable. Respirable (<10 µm) raw cotton dusts associated with the processing of middling, SLM and LM raw cottons were predicted to contain the following % weight composition of specific vegetable ingredients: leaflike=70–72%, stem=13–18%, bark=3–8%, exocarp-mesocarp=3–6%, endocarp=1–2% and seed=0.5–2%. Bract is the most abundant component in respirable raw cotton dust.