A longitudinal observation of early pulmonary responses to cotton dust.

AIMS: To examine early adverse pulmonary effects of exposure to cotton dust, and to identify potential risk factors, including atopy for pulmonary responses to cotton dust. METHODS: Spirometry, methacholine challenge testing, and questionnaire; performed among 101 non-smoking newly hired textile workers at baseline (prior to starting work), and at 3, 12, and 18 months after starting work. Concentrations of airborne cotton dust in various work areas were measured at each follow up survey using vertical elutriators. RESULTS: The incidence of non-specific respiratory symptoms was 8% at three months, then diminished afterwards. Substantial acute cross shift drops in FEV(1) at each follow up survey, and longitudinal declines in FVC and FEV(1) after 12 months of exposure were observed. Airway responsiveness to methacholine increased with follow up time, and was more pronounced among atopics. Increasing airway responsiveness was strongly correlated with cross shift drops in FEV(1). In addition, one or more respiratory symptoms at three months was significantly, and pre-existing atopy marginally significantly, associated with cross shift drops in FEV(1) after adjusting for other covariates and confounders. CONCLUSION: Results suggest that non-specific respiratory symptoms, decreasing lung function, and increasing airway responsiveness are early pulmonary responses to cotton dust. In addition, the occurrence of respiratory symptoms and increasing airway responsiveness, as well as atopy, may be important predictors for acute changes in lung function among cotton textile workers.

Increased blood monocyte procoagulant activity in cotton mill workers.

Blood monocyte procoagulant activity has previously been related to delayed type hypersensitivity. In this study, cotton workers exposed to cotton dust containing endotoxin and subjects not exposed to organic dusts, were examined. Blood mononuclear cells from the two groups were incubated with and without endotoxin and the recalcification time was measured. Mononuclear cells from cotton workers had a decreased baseline procoagulant activity but an increased response to endotoxin, suggesting cellular sensitization to the endotoxin present in cotton dust.

Serologic study of guinea pigs exposed for 12 months to cotton dust.

A guinea pig animal model of byssinosis has been described that demonstrates both acute and chronic effects of cotton dust inhalation (Ellakkani et al., 1984, 1987). During the latter study in which guinea pigs were exposed to 21 mg/m3 cotton dust 5 d/wk, 6 h/d for 52 wk, blood samples were taken from animals (20 exposed, 20 sham-exposed) prior to exposure and monthly during the exposure period. Sera were evaluated for quantities of the major protein fractions, and for IgG antibodies to cotton dust components. At the completion of the study, blood was evaluated for total and differential leukocytes. At 6 mo of exposure, each of the five protein fractions was significantly different from the corresponding fraction in the control animals. Antibodies reactive with an aqueous cotton dust extract (ACDE) were prominent by 2 mo of exposure and the titer was increased with continued exposure. The extract was composed of 2.6% protein, 12.8% reducing sugar, and 4.1% nucleic acid, with the remainder being largely simply sugars and inorganic material. A fraction of the antibodies showed reactivity with gram-negative bacteria and specifically with Enterobacter agglomerans, the most prevalent gram-negative microorganism in the dust. Minimal antibody response was detected using lipopolysaccharide from this microorganism or gram-positive bacteria. These results indicate that exposure of guinea pigs to cotton dust resulted in hematologic changes and in specific antibody formation. The presence of antibodies in each of the animals suggests their possible use as an indicator of cotton dust exposure.

Blood histamine levels in cotton-dust exposed workers in a textile mill of Ahmedabad.

Blood histamine levels were measured by the bioassay of histamine (on an isolated strip of guinea pig ileum) in workers exposed to cotton dust in a textile mill in Ahmedabad. Byssinotic subjects showed very high levels of blood histamine as compared to nonbyssinotic and control subjects. The blood histamine levels were not well correlated to the dust concentrations or duration of exposure but rather to the day of the week (ie, first, second, third, etc., after weekend break) on which the samples were collected. The blood histamine levels were high on the first day of the work week, when byssinotics complained most of their symptoms.

Exposure of cotton workers in an experimental cardroom with reference to airborne endotoxins.

Workers from cotton mills were exposed to cotton dust during carding in an experimental cardroom. Cotton from different geographical locations with varying amounts of endotoxin were used. Exposure levels ranged from 0.6 to 3.6 mg dust/m3 (from a vertical elutriator) and from 0.1 to 8.0 micrograms/m3 of endotoxin. No relationship was found between the decrease in FEV1 over the workshift and the amount of airborne dust. Airborne endotoxin correlated with the decrease in FEV1 and the increase in blood neutrophils. The FEV1 decrease was more pronounced among smokers. The data suggest that the amount of airborne endotoxin determines the risk for development of the acute symptoms in the byssinosis syndrome.

Byssinosis: serum immunoglobulin and complement concentrations in cotton mill workers.

In two separate studies (labeled A and B), concentrations of IgC, IgM, IgA, C3, and C4 were determined in the sera of byssinotic and non-byssinotic cotton mill workers. In study A, sera were collected on Monday morning and Monday afternoon and Friday afternoon in order to ascertain if the waning byssinotic response from Monday to Friday correlates with changes in serum immunoglobulin and complement concentrations. In study B, sera was collected on Monday morning and afternoon and was performed primarily to evaluate history of atopy and smoking as complicating factors in byssinosis. In study A, the concentrations of all immunoproteins were found to decrease from Monday morning to to Friday afternoon in all textile workers, and in study B only C3 concentration decreased morning to afternoon. There was, however, no difference between the immunoprotein changes for byssinotic workers when compared to non-byssinotic workers in either study. Due to the fact that hypersensitivity pneumonitis causes a decrease in immunoprotein concentrations in affected workers while no decreases are noticed in normal workers, our data do not support an immune complex etiology for byssinosis. In addition, decreased serum C3 concentrations observed in this study could be caused by complement activation; however, there was no difference in complement levels between byssinotic and non-byssinotic textile workers. Therefore, these data neither support nor eliminate the involvement of antibody-independent complement activation in the pathogenesis of byssinosis.

Role of histamine in the aetiology of byssinosis. I Blood histamine concentrations in workers exposed to cotton and flax dusts.

The formation or the accumulation, or both, of histamine in the lungs may be potentiated by agent(s) present in cotton dust at higher level(s) than in flax dust and negligible in cottonseed dust. It has been suggested that such potentiation may be due to the activation of the ability of the lung to produce histamine and/or produce or recruit mast cells; this may present an acceptable explanation of the mechanism by which the propagation of the chronic effect of the dust proceeds in cotton and flax workers. Histamine accumulated in the lung over the weekend is released on exposure to dust causing the symptoms of byssinosis. The difference in the rate of histamine metabolism relative to the rate of histamine formation in byssinotic subjects leads to a more prolonged histamine accumulation than in symptom free subjects, with the consequent appearance of the symptoms of byssinosis. Continuous exposure to dust, without weekend interruption, leads to equivalent rates of histamine formation and metabolism with non-considerable histamine accumulation in the lungs and consequent absence of the symptoms of byssinosis.