The information available regarding batch kier washed cotton was reviewed, including the 1978 OSHA Cotton Dust Standard, the 1978 complete exception for severely washed cotton, limitations of the 1978 exemption, washed cotton in the 1985 revision of the standard, 1985 exemptions for washed cotton, limitations of the 1985 partial exemptions for mildly washed cotton, recent evaluations of mildly washed cotton, initial studies of modern batch kier washing, and additional studies of open batch kier washing. Studies indicated that, with respect to removal of potential respiratory toxicity, cotton mildly washed in batch kier systems was equivalent to cotton mildly washed on a continuous batch system in a manner acceptable to OSHA under the washed cotton provisions of the current cotton dust standard. Mildly washing cotton in modern batch kier systems using two different systems on two different occasions and using two different worst case cottons resulted in consistent and effective removal of dust from cotton and reduction of endotoxin content in residual dust. The concentration of endotoxin in airborne dust from each worst case cotton that had been mildly washed on each modern batch kier system was less than 12 nanograms of endotoxin per milligram of dust. The Task Force for Byssinosis Prevention concluded that mild washing of cotton in modern batch kier systems will prevent the acute respiratory effects of occupational exposure to cotton dust.