Thirty volunteer subjects were exposed to controlled amounts of respirable dust generated by the carding of cotton in an experimental cardroom. Eighteen exposures each lasting six hours were performed while carding unwashed and washed cottons from the three major growing regions of the United States. Elutriated dust was analysed gravimetrically and was comparable (059 mg/mi3 + 004) for all exposures. Spirometry was recorded before and after each exposure. California cotton resulted in a significantly smaller fall in FEV, than cotton of the same grade from Texas or Mississippi. All washed cottons resulted in reduced declines when compared with unwashed cottons. For 17 subjects breathing zone personal total dust samples were analysed for airborne endotoxin and compared with the individual's pulmonary function response. A significant correlation between endotoxin exposure and acute decrease in FEV, was seen. The effect on FEV, per nanogram of airborne endotoxin was greater for Mississippi cotton than for cotton from the other regions. Airborne endotoxin appears to be an important determinant of acute pulmonary effects of cotton dust. Water washing of cotton results in reduced airborne endotoxin and less bronchoconstriction.Certain workers employed in the processing of cotton, flax, and hemp fibres develop acute and chronic respiratory symptoms generically called byssinosis.'In different reports the prevalence rates of byssinosis range from 2% to 90%.2 In addition to typical symptoms, acute and chronic ventilatory declines have been shown in people exposed to cotton dust.2 The variability of human responses to the inhalation of textile dusts has been related both to constitutional (individual susceptibility) and environmental factors. Increased responses to cotton dust and cotton dust extracts have been reported in cigarette smokers3 and individuals with atopy.4 Epidemiological and experimental studies have related symptom prevalence and ventilatory declines to airborne respirable dust levels.5'-Even after accounting for dust levels, pronounced differences exist between mills,5 and within mills at different work areas.

The chemical compositions of four cottons from a 1982 washed cotton study conducted by the Industry/Government/Union Task Force for Byssinosis Prevention were established by proximate and elemental analyses. The four cotton samples were an unwashed control grown in Mississippi and the corresponding washed, bleached, and scoured/bleached processed cottons. The proximate analyses consisted of serial solvent extractions that furnished data on moisture, water extractables, ethanol extractables, ethanolamine extractables, cellulose, and insoluble residue. Ash production was also measured for the four cotton lint samples. Elemental analyses were performed by x-ray fluorescence for potassium, calcium, magnesium, silicon, phosphorus, and sulfur, and by Kjeldahl analysis for nitrogen. The analyses demonstrate that the water wash and the scouring procedure are responsible for substantially increasing the purity of the cotton fiber. The level of water extractables was reduced by the water washing process, while the level of ethanolamine extractables was reduced by the scouring process. The washed cotton sample contained much smaller amounts of potassium and magnesium compounds than the unwashed control. Ash was reduced to approximately the same level by each of the washing processes.The nitrogen and calcium contents dropped steadily with increasing severity of processing conditions. The changes in chemical composition of cotton lint on processing are related to the layered structured of the cotton fiber. The Cotton Quality Research Station, USDA, and the Division of Respiratory Disease Studies, NIOSH, have determined the effects that dusts from these cottons have on pulmonary function in a group of human volunteers through measurements of the change in forced expiratory volume in one second (FEV 1 ) on exposure to dust generated by carding the cotton samples. All three processed cottons were considerably less active than the unwashed control. Many of the chemical composition parameters showed a marked decrease with water washing alone.In 1973, Merchant and co-workers reported a series oaf experiments demonstrating that thorough washing of cotton prior to carding in a textile mill completely eliminated the biological activity of card dust in a human panel [30]. They also found that carding washed cotton generated a lower fine dust concentration (0.16 mg/m3) than carding raw cotton (0.89 Mg/M3), but the washed cotton was difficult to process in the mill. Since that time, human challenge experiments with dust from a variety of washed and raw cottons have shown that washing cotton prior to carding substantially reduces its ability to cause lung function decrements [ 1, 2, 3, 4, 9, 31, 34, 39], while processing experiments have corroborated the work of Merchant et al. in decreased dust production by washed cotton [5, 23, 26, 27, 36, , 37, 39, 45]. The Cotton Quality Research Station, USDA, Clemson, South Carolina and the Division of Respiratory Disease Studies, NIOSH, Morgantown, West Virginia, have conducted several washed c...

Acute spirometric responses to inhaled cotton dust were examined in a population of 226 healthy, non-asthmatic adults whose atopic status had been evaluated by skin prick tests to 10 common environmental allergens. Exposure to cotton dust occurred in model cardrooms where elutriated dust levels were carefully controlled (1.02 mg/m3). Atopy, defined as positive prick tests to at least two allergens, was observed in 26% of subjects. Significant forced expiratory volume in one second (FEV1) decrements occurred after exposure to cotton dust independent of atopic status (p< 0.001). The mean FEV1 decline in atopic subjects, however, was significantly greater than in non-atopic subjects (p < 0.05). Degree of atopy, as measured by number of positive skin tests, also exhibited a significant association with cotton induced decrements in FEV, (p< 0.05). These data suggest that atopy may be an important determinant of the magnitude of the acute pulmonary response to cotton dust. This may reflect the non-specific airways hyperresponsiveness that has been described in non-asthmatic, atopic individuals.Acute decrements in lung function have been observed in cotton textile workers and in previously unexposed individuals after exposure to cotton dust.' 2 This response has been related to concentrations of total and respirable dust, and to grade, microbial, and endotoxin content of cotton.36 The precise role of the atopic state in acute pulmonary responses to cotton dust is the subject of considerable speculation but may be of great importance if acute declines in lung function are found to be related to the chronic respiratory disease described in cotton textile workers. '8 During the course of selecting volunteer subjects for a study of the pulmonary effects of dust from pretreated cotton, atopic status was evaluated by performing prick tests to common inhalant allergens. Skin tests were used to examine the relation between atopy and acute spirometric responses to controlled concentrations of untreated cotton dust. We report here the results of this investigation.

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