On the basis of these observations and the results of controlled exposures of human volunteers, the Task Force concludes that mild washing of cotton in modern batch kier systems will prevent the acute respiratory effects of occupational exposure to cotton dust. Because results of epidemiological observations of cotton textile mill workers have indicated a significant association between acute and chronic effects (see Appendix), the Task Force further concludes that mild washing of cotton in modern batch kier systems can also be expected to prevent the chronic effects of occupational exposure to cotton dust.
(n) Washed Cotton2. Where feasible, users of raw cotton should consider washed cotton substitution, either complete or in part (as a blend), as an adjunct means to achieve compliance with the current OSHA PEL for cotton dust when other engineering controls have not been entirely effective. In addition, even if compliance with the OSHA PEL has been achieved, washed cotton substitution should be considered as a means to further reduce potential risk of occupational respiratory disorders among workers exposed to cotton dust.
. . . . . . .
(4) Higher grade washed cotton. The handling and processing of cotton classed as "low middling light spotted or better" (color grade code 52 or better and leaf grade code 5 or better according to the current USDA classification system begun in 1993) which has been washed:
(A) On a continuous batt system or a rayon rinse system
(i) With water,
(ii) At a temperature of no less than 60°C,
(iii) With a water-to-fiber ratio of no less than 40:1, and
(iv) With bacterial levels in the wash water controlled to limit bacterial contamination of the cotton.(B) On a batch kier washing system*
(i) With water,
(ii) With cotton fiber mechanically opened and thoroughly prewet before forming the cake,
(iii) For low-temperature process, at a temperature of no less than 60o C with a water-to-fiber ratio of no less than 40:1; or, for high-temperature process at a temperature of no less than 93o C with a water-to-fiber ratio of no less than 15:1, and
(iv) With a minimum of one wash cycle followed by two rinse cycles for each batch, using fresh water in each cycle.
3. Research should be conducted to optimize textile processing of mildly washed cotton and, as commercial experience is gained, information should be disseminated regarding applications in which washed cotton can be feasibly substituted for unwashed cotton. Dissemination of this information may serve to promote voluntary substitution of mildly washed cotton for unwashed cotton by cotton-consuming companies as a prevention strategy.