Capillary gas chromatography of cotton dusts associated with human pulmonary function studies.

The effects of geographical area of growth and cotton variety on pulmonary activity have been evaluated through human volunteer exposure studies conducted by NIOSH and USDA at the Cotton Quality Research Station, Clemson, S.C. These studies demonstrate that carding California cottons releases dust with less human pulmonary activity than dust released from the corresponding Mississippi cottons. Dust released from Texas cottons grown in 1982 was considerably less active than the dust from Texas cottons grown in 1983. Distinct differences in the chemical compositions of the Mississippi, Texas, and California cardroom dusts were found. Aqueous extracts of the dusts were freeze-dried and then derivatized. Capillary gas chromatography revealed that the California dust extracts and the 1982 Texas dust extract were characterized by relatively higher levels of malic acid, whereas the Mississippi dust extracts and the 1983 Texas dust extracts were characterized by relatively higher mannitol levels.

Human ventilatory response to washed and unwashed cottons from different growing areas.

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 (0.59 mg/m3 +/- 0.04) for all exposures. Spirometry was recorded before and after each exposure. California cotton resulted in a significantly smaller fall in FEV1 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 FEV1 was seen. The effect on FEV1 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.

Cotton induced bronchoconstriction detected by a forced random noise oscillator.

Lung function responses to inhaled cotton dust were evaluated in a group of 58 healthy subjects by spirometry (MEFV curves) and forced random noise impedance parameters. Twenty-one of these subjects were also examined by body plethysmography to assess changes in airway resistance (Raw). For the study group as a whole, alterations in lung mechanical function after exposure to cotton dust were detected by maximal expiratory volumes and flows (p less than 0.001) and impedance parameters (p less than 0.01) but not by Raw. Subjects showing responses in MEFV curves also showed increases in Thevenin or effective resistance at low frequencies (R1, R5-9, R5-9/R20-24), suggesting that the limitation of flow occurred predominantly in the peripheral airways. By contrast, non-responders on MEFV measurements were found to have significant increases in effective resistance both at low and at high frequencies (R1, R5-9, R20-24), suggesting a central airways effect. MEFV curve non-responders also exhibited a significantly lower baseline effective resistance profile than MEFV curve responders. The data indicate that under the conditions of the experiment measures of the Thevenin resistance (real part of impedence) by the forced random noise method are reliable indicators of cotton induced bronchoconstriction. Measurement variability, however, suggests that, at present, these are more appropriate for group studies and should remain adjuncts to standard tests of lung function such as spirometry.

Acute lung function response to cotton dust in atopic and non-atopic individuals.

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 less than 0.001). The mean FEV1 decline in atopic subjects, however, was significantly greater than in non-atopic subjects (p less than 0.05). Degree of atopy, as measured by number of positive skin tests, also exhibited a significant association with cotton induced decrements in FEV1 (p less than 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 bronchoconstriction induced by cotton dust: dose-related responses to endotoxin and other dust factors.

Fifty-four healthy humans, selected for their acute airway responsiveness to cotton dust, had spirometric tests immediately before and after 6 hours of exposure to card-generated cotton dust from seven different cottons (of several grades and growing regions). During exposures, we measured airborne concentrations of viable fungi and bacteria (total and gram negative), vertically elutriated gravimetric dust, and vertically elutriated endotoxin. Correlation between each of these five exposure indices and exposure-related acute changes in forced expiratory volume in 1 s showed a statistically significant relationship between all of the indices except concentration of viable fungi. Of the other four indices, endotoxin was the most highly correlated (r = -0.94; p less than 0.00001), and gravimetric dust was the least correlated (r = -0.34; p less than 0.05). These findings suggest that gram-negative endotoxin may play a major role in the acute pulmonary response to inhaled cotton dust.

Dust levels and particle-size distributions in high-capacity cotton gins.

Dust samples were collected inside high-capacity cotton gins with the personal, stationary personal, and the vertical elutriator cotton dust samplers. Dust particles collected on the filters were sized with a particle measurement computer system. Particle-distribution data revealed that gin dust contains a high percentage of dust particles larger than 20 micrometers in diameter.