Exposure standards, cotton dust

The criteria document (j.) for a recommended standard for occupational exposure to cotton dust defines cotton dust as dust generated into the atmosphere as a result of the processing of cotton fibers combined with any naturally occurring materials such as stems, leaves, bracts, and inorganic matter which may have accumulated on the cotton fibers during the growing or harvesting period. 

Further assessment of atopy in the pathogenesis of the acute byssinotic reaction necessitates purification of well characterized and standardized cotton dust antigens, and the development of an allergy specific test (HAST) to measure serum IgE antibodies to cotton dust allergens. Such developments would allow correlation of skin tests, clinical history, dust exposure, FEVj and serum IgE level with specific IgE to cotton dust allergens. 

With the promulgation of the OSHA mandatory standards for exposure to cotton dust ( ), it is now assumed that prolonged exposure to cotton dust is a cause of chronic respiratory effects. Thus, there seems to have been a straightforward interpretation of complex and conflicting medical literature. This paper presents a review of the literature with emphasis on cause and effect relationship consistent with reported epidemiological data. 

The OSHA standard establishes a permissible exposure limit of 200 ug/m for yarn manufacturing, 750 ug/m for slashing and weaving, and 500 pg/m for all other processes in the cotton industry and for nontextile industries where there is exposure to cotton dust (1). The standard specifies that concentration is... 

National Institute for Occupational Safety and Health Criteria for a Recommended Standard... Occupational Exposure to Cotton Dust. DHEW (NIOSH) Pub No 75-118, pp 12-60. Washington, DC, US Government Printing Office, 1974... 

Department of Labor Standard for exposure to cotton dust. Fed Reg 41 56498-56525, 1976... 

The standard presents OSHA s determination that exposure to cotton dust presents a significant health hazard to employees and establishes permissible exposure limits for selected processes in the cotton industry and for non-textile industries where there is exposure to cotton dust. The cotton dust standard also provides for employee exposure monitoring, engineering controls and work practices, respirators, employee training, medical surveillance, signs and record keeping. 

Similarly, the standard for Exposure to Cotton Dust in Cotton Gins, 1010.1046, the following sign must be posted in each work area where there is potential employee exposure to cotton dust. 

Table I is an attempt to compare the responses in lung function we observe with our naive subjects on exposure to cotton bract extracts with the responses reported in literature of both naive subjects and workers exposed to cotton dust. The comparison suffers from the fact that neither the exposure time or concentration nor the post-exposure time of FEV. q readings are standardized for the different investigating laboratories. The various cotton dusts or extracts are not standardized either and the airway constrictor potency varies with the dusts. Bracts also vary in their potency. We have observed variations in potency with harvest year from the same location (Lubbock, Texas).

In contrast to the documented effect of cotton dust on acute responses, the causation of chronic respiratory effects in occupationally exposed subjects has not been established. The OSHA cotton dust standard is based on the premise that sustained exposure may result in chronic respiratory problems. To test this hypothesis, the pertinent literature is reviewed and discussed in an attempt to decide if convincing epidemiological documentation exists to support a cause and effect connection between prolonged dust exposure and chronic respiratory impairment. There appears to be a need for additional studies to clarify this important aspect of occupational medicine. 

Special instmctions depend upon the hazards of the specific CMR and may vary among experts. Instmctions will emphasize the serious nature of exposure and will generally follow precautions found in OSHA s substance-specific standards. Twenty-eight (28) of OSHA s 30 substance-specific standards are direct CMRs. The other two, bloodbome pathogens and cotton dust, are related indirectly (HBV may cause liver cancer and cotton dust includes pesticide residues). 

Most OSHA standards require firms install specific types of safety equipment or institute specific safety programs. Besides specification standards OSHA also uses performance standards to set maximum levels of exposure to particular hazards. Both specification and performance standards impose considerable financial burdens on firms. The National Association of Manufacturers calculated OSHA standards cost about 103,000 (1993 dollars) for an average firm with 1-100 employees and 1,026,000 for an average firm with 501-1,000 employees (Smith 1976). Within certain industries the costs are even larger. The 1978 cotton dust standard, for instance, increased operating expenses in the textile mill products industry by more than 50 million per year (Viscusi 1992). Clearly, only if regulations are backed by financial penalties for noncompliance will firms install the safety equipment or institute the safety programs dictated by OSHA. 

Unknown concentrations, or those above 3600 ppm, required an open-circuit, self-contained breathing apparatus, pressure-demand type, with full facepiece. In the Cotton Dust Standard section (1910.1043), OSHA used the level of exposure ratio to specify the type of protection required. 

The occupational exposure standard for cotton dust is 0.5 mg/m total dust less fly, using area samplers, although personal sampling may be adopted in the near future. 

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