COVID 19 - Possible interrelations with respiratory comorbidities caused by occupational exposure to various hazardous bioaerosols. Part I. Occurrence, epidemiology and presumed origin of the pandemic

The occupational bioaerosols containing viruses, bacteria, fungi, microbial toxins and plant or animal particles, may evoke infectious, allergic or immunotoxic diseases which may co-exist as comorbidities with COVID-19 and exacerbate the course of disease. They include hypersensitivity pneumonitis (HP) caused mostly by bacteria, fungi, and particles containing animal proteins, and immunotoxic diseases such as organic dust toxic syndrome (ODTS) and byssinosis, caused mostly by bacterial and fungal toxins. The two most probable scenarios of possible interrelations between these three comorbidities (CM) and COVID-19 are: 1) 'Triggering' - when infection with SARS-CoV-2 triggers severe CM after bioaerosol exposure; 2) 'Reverse triggering' when exposure to bioaerosol exacerbates a symptomless or mild course of COVID-19, and evokes a severe disease. The occupations mostly endangered by COVID-19 as the result of exposure to SARS-CoV-2 bioaerosol, or to other bioaerosols which may exacerbate this disease, include: health care workers, social workers, breeders of fur animals, slaughterhouse workers, workers engaged in the processing and selling of seafood, and probably also agricultural workers, mainly in the developing countries. The authors present a hypothesis for the origin of the present pandemic. It assumes that a mild form of the present SARS-CoV-2 that is supposedly circulating among the Chinese population in the eastern part of the country, mutated under the influence of as yet unknown factor(s) present in the Chinese seafood markets, probably component(s) of bioaerosols, into the virulent and highly contagious form, known as the present SARS-CoV-2, under a scenario similar to that the authors have named 'Reverse triggering'.

Byssinosis and tuberculosis amongst "home-based" powerloom workers in Madhya Pradesh State, India

BACKGROUND

Byssinosis is an occupational lung disease observed among workers exposed to cotton, flax, and hemp dust. The severity and extent of Byssinosis are well recognised in the high-income countries and control measures have been implemented to prevent the disease. In India, there are conflicting evidence on burden estimation of the disease, followed by inadequate prevention and control of Byssinosis.

DESIGN/METHODS

We did a cross-sectional study to assess the prevalence of Byssinosis in "home-based" power-loom workers in Mominpura, an administrative ward of Burhanpur Municipality with 2800 population in the state of Madhya Pradesh, India. 290 adults working from "home-based" power loom units were randomly selected, profiled and screened for Byssinosis like symptoms with the help of a semi-structured questionnaire and simple hand-held peak expiratory flow monitor. For epidemiological purposes the symptoms were classified based on Schilling's classification. Chest x-rays were done for selected subjects. Sputum smear microscopy for detecting TB was done for those who had Byssinosis like symptoms.

RESULTS

Prevalence of Byssinosis among "home based" powerloom workers was found to be 98% [n = 283, 95 CI (95.65-98.96)]. Peak expiratory flow rate (PEFR) was reduced in 44% (n = 124), of which 81 (29%) had more than 50% PEFR reduction, and of these, 69 (29%) were in early stage of Byssinosis (Grade 0.5). 11% of study participants who had Byssinosis like symptoms, also had TB.

CONCLUSIONS

Byssinosis is highly prevalent in "home-based" power loom units in Madhya Pradesh. Adequate advocacy on awareness and prevention; prompt diagnosis and linkages to treatment services in "home-based" power loom units are urgently required to address Byssinosis at an early disease stage.

A large scale gene-centric association study of lung function in newly-hired female cotton textile workers with endotoxin exposure

Background

Occupational exposure to endotoxin is associated with decrements in pulmonary function, but how much variation in this association is explained by genetic variants is not well understood.

Objective

We aimed to identify single nucleotide polymorphisms (SNPs) that are associated with the rate of forced expiratory volume in one second (FEV₁) decline by a large scale genetic association study in newly-hired healthy young female cotton textile workers.

Methods

DNA samples were genotyped using the Illumina Human CVD BeadChip. Change rate in FEV₁ was modeled as a function of each SNP genotype in linear regression model with covariate adjustment. We controlled the type 1 error in study-wide level by permutation method. The false discovery rate (FDR) and the family-wise error rate (FWER) were set to be 0.10 and 0.15 respectively.

Results

Two SNPs were found to be significant (P<6.29×10⁻⁵), including rs1910047 (P = 3.07×10⁻⁵, FDR = 0.0778) and rs9469089 (P = 6.19×10⁻⁵, FDR = 0.0967), as well as other eight suggestive (P<5×10⁻⁴) associated SNPs. Gene-gene and gene-environment interactions were also observed, such as rs1910047 and rs1049970 (P = 0.0418, FDR = 0.0895); rs9469089 and age (P = 0.0161, FDR = 0.0264). Genetic risk score analysis showed that the more risk loci the subjects carried, the larger the rate of FEV₁ decline occurred (P_trend = 3.01×10⁻¹⁸). However, the association was different among age subgroups (P = 7.11×10⁻⁶) and endotoxin subgroups (P = 1.08×10⁻²). Functional network analysis illustrates potential biological connections of all interacted genes.

Conclusions

Genetic variants together with environmental factors interact to affect the rate of FEV₁ decline in cotton textile workers.

The Measurement and Health Impact of Endotoxin Contamination in Organic Dusts from Multiple Sources: Focus on the Cotton Industry

Endotoxin is derived from Gram-negative bacterial membranes, and its inflammatory effects following inhalation are well characterized. The significance of this fact becomes apparent when the wide-ranging environments containing high levels of this microbial product are considered. Endotoxin is present in numerous industrial environments, especially where organic fibers are processed. Microbial contamination of these fibers mainly occurs at the agricultural stage. Materials such as flax and hemp are affected in this way, but the most important product in this context is cotton, from which chronic dust inhalation causes the disease byssinosis. Despite the fact that endotoxin constitutes a significant threat to public health, there are currently no occupational exposure limits for this toxicant. This communication describes the toxicology of endotoxin, and its role in inhalation-induced disease, focusing on measurement of airborne endotoxin in the occupational and domestic environments using the Limulus amebocyte lysate (LAL) enzyme assay. Following the success of the LAL assay for measuring endotoxin in dusts, our laboratory has examined its application to aqueous washes from cotton fibers. Reproducibility of the results was high, and data are presented displaying levels of endotoxin contamination in fibers from different cotton producing countries. Hence, worldwide comparison of industrial endotoxin concentrations can be readily made using this test. It would be highly desirable if the performance of the LAL assay facilitated introduction of industrial endotoxin safety limits, and in spite of minor surmountable shortcomings, the test is accurate, reliable, and well field-tested, so its continued widespread use may achieve this goal.

Byssinosis: as seen in cotton spinning mill workers of Karachi

OBJECTIVE

To identify Byssinosis in cotton spinning mill workers, probable associations of disease with factors such as different work areas, safety gadget usage and overtime and to ascertain proportions of byssinosis to accidental injuries.

METHODS

This study was conducted in a spinning mill of Karachi in June 2006. Mill workers who had worked for a period of minimum 5 years were selected. A sample size of 83 conveniently selected workers participated in the research study. Data collection was done via questionnaire, and pulmonary function tests.

RESULTS

The mean age of the sample was 30 +/- 6.9 years. Of all the workers 72% used safety gadgets (masks) while working and 50% availed overtime. Smokers amounted to 31% of the total subjects. Around 35% workers complained of having respiratory ailments of which 19% (16 workers) closely matched byssinotic symptoms. Pulmonary Function Tests (PFTs) confirmed 13 of 16 workers to be byssinotics, with the remaining being labeled as Probables. The overall proportion of Byssinotics in the mill was 19.28% (95% C.I. 11-27) and that of accidental injuries was 22.9%. The association of byssinosis with respect to work areas was significantly high in Ring area (O.R. = 2.04) followed by carding (O.R. = 1.3). The association of byssinosis was also high in workers who did not use safety gadgets, e.g. dust masks (O.R = 4.89) and in people who worked overtime (O.R. = 1.82). Associations with respect to duration of employment and smoking could not yield significant results.

CONCLUSION

Results indicate a very high probability of association of disease to non-usage of safety gadgets and overtime working. Studies comprising of a greater sample size would show precisely the overall prevalence of the disease.

Airborne Endotoxin and Its Relationship to Pulmonary Function among Workers in an Indian Jute Mill

Air samples from various processing areas of an Indian jute mill were examined for endotoxin. The authors assessed work-related respiratory symptoms and pulmonary function changes in the dust-exposed workers from the different processing areas using a standard questionnaire and spirometry. Endotoxin was estimated in water extract of jute dust from 3 milling areas, and in outside air, by the Limulus amebocyte lysate gel clot technique. The batching, spinning, and weaving areas of the jute mill showed endotoxin levels of 0.22-4.42 microg/m3, 0.04-1.47 microg/m3, and 0.01-0.07 microg/m3, respectively, values similar to those found in Indian cotton mills. Respiratory morbidities among the workers included typical byssinotic symptoms, along with acute changes in postshift forced expiratory volume in 1 s (FEV1.0) (31.8%). Results of this study demonstrated that increased exposure to bacterial endotoxin in airborne dust is related to byssinotic symptoms among Indian jute mill workers. Findings were similar to those reported previously for workers in the cotton, flax, and hemp industries.

Respiratory symptoms and cotton dust exposure; results of a 15 year follow up observation

AIMS

To determine chronic effects of long term exposure to cotton dust and endotoxin on incidence of respiratory symptoms and the effect of cessation of exposure.

METHODS

Respiratory health in 429 Chinese cotton textile workers (study group) and 449 silk textile workers (control group) was followed prospectively from 1981 to 1996. Byssinosis, chest tightness, and non-specific respiratory symptoms were assessed by means of identical standardised questionnaires at four time points. Exposures to cotton dust and endotoxin were estimated using area samples collected at each survey. Incidence and persistence of symptoms were examined in relation to cumulative exposure and exposure cessation using generalised estimating equations (GEE).

RESULTS

Among cotton workers, the cumulative incidence of byssinosis and chest tightness was 24% and 23%, respectively, and was significantly more common in smokers than in non-smokers. A high proportion of symptoms was found to be intermittent, rather than persistent. Among silk workers, no typical byssinosis was identified; the incidence of chest tightness was 10%. Chronic bronchitis, cough, and dyspnoea were more common and persistent in the cotton group than in the silk group. Significantly lower odds ratios for symptoms were observed in cotton workers who left the cotton mills; risk was also related to years since last worked. Multivariate analysis indicated a trend for higher cumulative exposure to endotoxin in relation to a higher risk for byssinosis.

CONCLUSION

Chronic exposure to cotton dust is related to both work specific and non-specific respiratory symptoms. Byssinosis is more strongly associated with exposure to endotoxin than to dust. Cessation of exposure may improve the respiratory health of cotton textile workers; the improvement appears to increase with time since last exposure.

John Pemberton and the flax industry in Northern Ireland

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Respiratory effects of long-term exposure to cotton dust

Traditionally, the concept of cotton dust-related disease focused on acute airway responses. A possible connection of long-term exposure to cotton dust with chronic obstructive airway disease was not addressed until the past two decades. This review summarizes the latest findings relevant to this topic that were observed from longitudinal cohort studies and discusses the relation between acute airway responses and chronic losses of lung function.

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.

Respiratory symptoms, lung function and cell surface markers in a group of hemp fiber processors

BACKGROUND

Hemp dust exposure is associated with byssinosis and accelerated lung loss in longitudinal studies. The immunological changes associated with hemp dust exposure are less well understood.

METHODS

We studied a small group of current male hemp processors with a mean age of 43 years. Questionnaire data, lung function, serial FEV(1) and blood were collected from all workers.

RESULTS

In total, seven workers (64%) complained of at least one respiratory symptom (one with byssinosis). The mean percentage predicted FEV(1) was 91.5, FVC 97.7, PEF 92.1, and FEF(25-75) 79.5. Serial FEV(1) measurements in the two workers with work-related respiratory symptoms revealed a mean change in FEV(1) on the first working day of -12.9%. This contrasted with +6.25% on the last working day. Respective values for the two workers without work-related symptoms were -1.4 and +3.2%.

CONCLUSIONS

Lung function changes and abnormalities in a profile of cell surface activation markers and antibodies were noted to relate to the presence of work-related respiratory symptoms, not seen in the control group.

Pulmonary response of mice to aqueous cotton dust extract

OBJECTIVE

To determine the pulmonary response of mice to acute exposure of aqueous cotton dust extract (CDE).

DESIGN

CDE was made from a standard cotton mill dust. Under mild anaesthesia, 0.05 ml of CDE was instilled intratracheally in balb/c mice. The same volume of sterile isotonic saline was instilled in controls. After 1, 5 and 10, days animals were given an overdose of pentobarbital by intraperitoneal injection, and the upper thorax was opened to expose the trachea. An incision was made and cannulae was inserted. Bronchoalveolar lavage (BAL) was done by instilling, phosphate buffer saline. Total and differential counts were done. The lavage supernatant was assayed for protein.

SETTING

The laboratory of Division of Pulmonary and Critical Care Medicine, Duke University Medical Center, USA.

ANIMALS

Balb/c mice.

MAIN OUTCOME MEASURES

Post-exposure acute effects at bronchoalveolar level.

RESULTS

Total and differential cell counts in BAL fluid were significantly higher in CDE exposed compared to controls (P < 0.01). The total mean values (expressed as cells x 10(4)) after exposure for days 1, 5 and 10 were 193.4 +/- 8.6, 177.8 +/- 7.7 and 113.5 +/- 6.4 respectively versus controls (41.6 +/- 3.4). Differential counts (cell no. x 10(4)) revealed 124.3 +/- 6.8, 94.2 +/- 7.9, 19.9 +/- 3.5 polymorph neutrophils (PNM) and 67.3 +/- 7.1, 81.6 +/- 9.4, 90.2 +/- 8.6 macrophages (AM) on days 1, 5 and 10 respectively compared to controls 2.8 +/- 2.3 (PMN) and 37.2 +/- 1.1 (AM). Analysis of protein (mg/ml BAL fluid) demonstrated a significant increase on exposure for days 5 and 10 (0.8 +/- 0.05 and 0.9 +/- 0.6 respectively versus controls, 0.09 + 0.01, p < 0.01).

CONCLUSION

Acute exposure to CDE causes influx into the air spaces of inflammatory leukocytes accompanied by an increase in lung permeability (evidenced by the presence of protein in BAL fluid). In cotton mill workers, the above factors may contribute to the development of chronic byssinosis by as yet undefined agent(s) in cotton dust.

Byssinosis: role of polymer length on the effect of tannin on the airway beta-adrenergic receptor

Tannin, isolated from cotton bracts and implicated in the pathogenesis of byssinosis, inhibits isoproterenol and forskolin-stimulated cAMP release from airway cells in part by decreasing cell surface beta-adrenergic receptor number and uncoupling the beta-adrenergic receptor from its stimulatory G-protein (Gs) and in part by inhibiting adenylyl cyclase activity. We have hypothesized that cotton tannin, because of its long polymer length, interacts with the hydrophobic binding pocket of the beta-adrenergic receptor and alters beta-adrenergic receptor binding and Gs coupling. In these studies, tannins of three different polymer lengths and molecular masses were isolated from cotton bracts using sequential Amicon ultrafiltration [molecular mass > 10, 000 (YM10 retentate), 1,000-10,000 (YM10 filtrate), and 1,000-5,000 Da (YM2 retentate)]. The YM10 retentate (25 microg/ml) decreased chloride secretion (Jnet = 1.11 +/- 0.28 (control) to 0.59 +/- 0.18 microEq/cm2.h, p < 0.05, n = 6), decreased cell surface beta-adrenergic receptor number (18.0 +/- 1.8 (control) to 10.6 +/- 0.9 fmol/mg protein, p < 0.02, n = 4), and inhibited forskolin-stimulated cAMP release (5,254 +/- 1,290 (control) to 2, 968 +/- 620 pmol/mg protein, p < 0.01, n = 8). In contrast, neither the YM10 filtrate nor the YM2 retentate had any effect on net chloride secretion, beta-adrenergic cell surface receptor number, or forskolin-stimulated cAMP release. We conclude that polymer length is essential for the effect of tannin on the beta-adrenergic receptor and on adenylyl cyclase.

Prevalence and predictors of work related respiratory symptoms in workers exposed to organic dusts

OBJECTIVES

The aims of this study were to document the prevalence of work related upper and lower respiratory tract symptoms in workers exposed to organic dusts and to identify variables predictive of their occurrence.

METHODS

A cross sectional survey with an administered questionnaire (a previously validated adaptation of the Medical Research Council (MRC) respiratory questionnaire) was performed. Symptoms were classified as work related by their periodicity. Demographic data, smoking habits, and occupational histories were recorded. Personal exposures to dust and endotoxin were measured and individual subjects ascribed an exposure value specific to occupation, site and industry. Cox's regression techniques were used to identify variables predictive of work related upper and lower respiratory tract symptoms. Information was stored using Dbase 3 and analysed with SPSS.

RESULTS

1032 Workers (93% of the target population) were studied in nine different industries. The highest prevalences of work related lower respiratory tract symptoms (38.1%), upper respiratory tract symptoms (45.2%), and chronic bronchitis (15.5%) were found among poultry handlers. White workers were significantly more likely to complain of upper and lower respiratory tract symptoms. An individual in the swine confinement industry had a symptom complex compatible with byssinosis. Increasing current personal exposures to dust or endotoxin were found to be predictive of upper and lower respiratory tract symptoms, chronic bronchitis, and byssinosis. In a univariate analysis a relation between current exposures and the organic dust toxic syndrome was found. Present smoking and previously documented respiratory tract illness were significantly predictive of work related lower respiratory tract symptoms. Women were more likely to report work related upper respiratory tract symptoms.

CONCLUSIONS

People exposed to organic dusts may have a high prevalence of work related respiratory tract symptoms which are related to dust exposures and smoking habits. Action should be taken to reduce exposures to dust and endotoxin and stopping smoking should be promoted among workers exposed to organic dusts to reduce morbidity.

[Exposure to endotoxins in the environment. Occurrence and health hazards]

Endotoxins are lipopolysaccharides from the outer cell wall of Gram-negative bacteria. Exposure to endotoxins can take place in industries where organic material is handled, in agriculture, in garbage handling, and sewage treatment. Byssinosis defined as Monday chest tightness and slight dyspnoea in the work place has been related to endotoxin exposure in cotton mills, but studies indicate that similar symptoms may be found in other work places. Other symptoms are: Headache, nausea, gastrointestinal symptoms and influenza-like symptoms. Several studies have shown a decrease in FEV1 following exposure to endotoxins. The relationship between exposure to organic dust, microorganisms, endotoxins and other chemicals in the work place and disease needs further research.

Pulmonary reactions to organic dust exposures: development of an animal model

Acute inhalation of organic dusts such as cotton, hay, silage, grain, animal confinement, or compost dust can result in illness characterized by fever, pulmonary inflammation, chest tightness, and airway obstruction. These agricultural materials are complex mixtures of plant, bacterial, and fungal products. Elucidation of the time course of disease onset, the mechanisms of disease progression, and the identity of etiologic agents is essential for effective prevention and treatment. Toward this end, animal models for acute organic dust-induced reactions have been developed and characterized. Information concerning the applicability of various animal models to humans and progress toward elucidation of causative agents and mechanisms of action is presented.

Byssinosis in Guangzhou, China

OBJECTIVES

To study the prevalence of byssinosis and other respiratory abnormalities in workers exposed to cotton dust in Guangzhou in two factories that processed purely cotton.

METHODS

All the 1320 workers exposed were included. The controls were 1306 workers with no history of occupational dust exposure. Total dust and inhalable dust were measured by Chinese total dust sampler and American vertical elutriator respectively. A World Health Organisation questionnaire was used. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were measured by a Vitalograph spirometer.

RESULTS

The median inhalable dust concentrations ranged from 0.41 to 1.51 mg/m3 and median total dust concentrations from 3.04 to 12.32 mg/m3. The prevalence of respiratory abnormalities in the cotton workers were (a) typical Monday symptoms 9.0%; (b) FEV1 fall by > or = 5% after a shift 16.8%; (c) FEV1 fall by > or = 10% after a shift 4.2%; (d) FEV1 < 80% predicted 6.1%; (e) FEV1/FVC < 75% 4.0%; (f) cough or phlegm 18.2%; (g) chronic bronchitis 10.9%; and (h) byssinosis, defined by (a) plus (b) 1.7%. With the exception of (d), most of the prevalences increased with increasing age, duration of exposure, and cumulative inhalable dust exposure. No increasing trends of respiratory abnormalities were found for current total dust, inhalable dust, and cumulative total dust concentrations. Compared with controls, after adjustment for sex and smoking, with the exception of (d), all the pooled relative risks of respiratory abnormalities were raised for cotton exposure.

CONCLUSION

It is concluded that cumulative inhalable cotton is likely to be the cause of byssinotic symptoms, acute lung function decrements, cough, or phlegm, and chronic bronchitis.

Ocular and nasal irritation in operatives in Lancashire cotton and synthetic fibre mills

OBJECTIVES

To document the prevalence of work related ocular (eyeWRI) and nasal (noseWRI) irritation in workers in spinning mills of cotton and synthetic textile fibres and to relate the prevalence of symptoms to atopy, byssinotic symptoms, work history, and measured dust concentrations in the personal breathing zone and work area.

METHODS

A cross sectional study of 1048 cotton workers and 404 synthetic fibre workers was performed. A respiratory questionnaire was given to 1452 workers (95% of the total available population). Atopy was judged by skin prick tests to three common allergens. Work area cotton dust sampling (WAdust) was carried out according to EH25 guidelines in nine of the 11 spinning mills included in the study. Personal breathing zone dust concentrations were assessed with the IOM sampler to derive total dust exposure (PTdust) and a concentration calculated after the removal of fly (Pless).

RESULTS

3.7% of all operatives complained of symptoms of byssinosis, 253 (17.5%) complained of eyeWRI and 165 (11%) of noseWRI. These symptoms did not relate to atopy or byssinosis, or correlate univariately with any measure of cotton dust exposure (noseWRI v WAdust r = 0.153, PTdust r = 0.118, eyeWRI v WAdust r = 0.029, PTdust r = 0.052). Both of these symptoms on logistic regression analysis were related to being of white origin (P < 0.001), female sex (P < 0.001), and younger age (P < 0.001). With regression analysis, there was a negative relation between dust concentration and prevalence of symptoms.

CONCLUSION

Work related ocular and nasal irritation are the most common symptoms complained of by cotton textile workers. There was no relation between these symptoms and atopy, byssinosis, or dust concentration. It is likely that they relate to as yet unidentified agents unrelated to concentration of cotton dust.

Respiratory disease in cotton textile workers: epidemiologic assessment of small airway function

We performed a cross-sectional study of 705 textile workers in two cotton mills and one silk mill in Shanghai, People's Republic of China, to assess small airway function among cotton textile workers and to compare the FEV1 to the FEF25-75 in detecting airflow obstruction in these workers. All workers had at least 2 years of work experience. Environmental sampling was performed with vertical elutriators and revealed that in the cotton mills mean elutriated dust levels were 1.07 +/- 0.23 mg/m3 in mill 1 and 1.01 mg/m3 +/- 0.24 mg/m3 in mill 2. Mean endotoxin levels were 332 +/- 83 ng/m3 in mill 1 and 101 +/- 46 ng/m3 in mill 2. No differences were found in preshift FEV1 or FEF25-75 between cotton and silk workers. Cotton workers had significantly greater declines than silk workers in FEV1 across a workshift, but not in FEF25-75. These acute changes in FEV1 were noted in both byssinotic and nonbyssinotic workers. Although cotton dust may affect both large and small airways, spirometric measures of small airway function (e.g., FEF25-75) add little to the FEV1 and FVC in detecting airflow limitation in cotton dust-exposed workers.

Follow-up study of respiratory function in hemp workers

A 3-year follow-up study was performed on 38 women and 28 men from the originally studied textile workers employed in a soft hemp processing mill. Acute and chronic respiratory symptoms and ventilatory capacity were recorded during the cross-sectional and the follow-up studies. Maximum expiratory flow-volume (MEFV) curves were obtained on these workers, and forced vital capacity (FVC), 1-second forced expiratory volume (FEV1) and flow rates at 50% and at 25% of the VC (FEF50, FEF25) were measured. High prevalences of acute and chronic respiratory symptoms persisted at the follow-up study. In particular, high prevalences of byssinosis were documented at both studies (women: 47.4% and 47.4%; men: 64.3% and 67.9%, respectively). Statistically significant mean across-shift reductions were recorded for all ventilatory capacity tests at the initial study. A large mean annual decline was calculated for FEV1 in women and for all ventilatory capacity parameters in men; these declines were greater for workers with symptoms of byssinosis than for those without. The accelerated decline in FEV1 noted in the women workers, who were predominantly nonsmokers, suggests an independent hemp effect. Exposures in the work environment were measured with Hexhlet filters and revealed very high dust concentrations (mean total: 21.4 mg/m3, 22.4 mg/m3; respirable: 8.4 mg/m3, 9.9 mg/m3) at both initial and follow-up studies. These levels are much higher than those found in mills processing organic materials in North America. Our data demonstrate that work in the hemp industry, particularly in small poorly regulated mills, continues to have deleterious effects on respiratory function.

Low normal alpha-1-antitrypsin serum concentrations and MZ-phenotype are associated with byssinosis and familial allergy in cotton mill workers

Recent studies have shown a close association between byssinosis and airborne endotoxin concentrations. Endotoxin might induce byssinosis through the release of biochemical mediators as the broncheoalveolar surface. Alpha-1-antitrypsin (alpha-1-A) which neutralizes enzymes released by granulocytes is known to be important. This study evaluates the possible importance of alpha-1-A concentration and the heterozygosity (Pi-S and Pi-Z alleles), in the prevalence of byssinosis and familial allergy. 253 cotton workers were interviewed and clinically studied to identify persons with the cotton lung disease, byssinosis, and atopic disease. Serum was available for alpha-1-A concentration determination in 226 individuals, and for Pi phenotyping in 206. The overall prevalence of byssinosis was 30/226 (13%). In the group with alpha-1-A < or = 35 mumol l-1 the prevalence was 5/18 (28%), versus the prevalence 25/208 (12%) in the group with alpha-1-A > 35 mumol l-1 (p < 0.1, Fishers exact test). MZ phenotype was associated with an increased prevalence of byssinosis compared with the MM-group: 3/8 (38%) and 25/187 (13%), p < 0.1, Fishers exact test. An association between MZ-phenotype and familial allergy was found: 4/8 (50%) contra 23/187 (12%), p < 0.05, Fishers exact test. In a logistic regression model controlling for confounding by endotoxin, tobacco exposure, sex, and age, the odds ratio for byssinosis in the MZ-phenotype group was significantly elevated 5.8 (1.1-30.3). Odds ratio for familial allergy was also significantly elevated in the MZ-group 2.8 (1.3-5.9).(ABSTRACT TRUNCATED AT 250 WORDS)

Cotton dust and across-shift change in FEV1 as predictors of annual change in FEV1

In this report of a 5-yr longitudinal study of workers employed at six cotton textile mills, exposure and across-shift FEV1 change were evaluated as possible predictors of the annual change in FEV1 for yarn manufacturing workers. A total of 611 workers had three repeatable spirometric tests, over at least 3 yr, and at least one (average of three) across-shift test, while always working the same shift. The "same shift" criterion controlled for the effect of diurnal variation. Average exposure was determined from measures of lint-free elutriated cotton dust in combination with job histories. This study found a significant association between the acute and chronic effects of cotton dust exposure. Both exposure and across-shift change proved to be significant predictors of annual change, and excess annual declines in FEV1 were predicted even for exposures of 200 micrograms/m3 and across-shift drops in FEV1 of 200 ml. These results suggest that, to prevent dust-related chronic decline in lung function, current smokers should be excluded from yarn manufacturing work and exposures should be reduced below 200 micrograms/m3, to approximately 100 micrograms/m3.

[Effects of jute, ramee, flax dusts on rabbit alveolar macrophages in vitro]

The effects of jute, ramee, flax dusts on alveolar macrophage (AM) were observed by cell culture. The results indicated that AM could be damaged by all of the three kinds of dusts. The viability was decreased. The activity of lactic dehydrogenase (LDH) and acid phosphatase (AcP) in the culture supernatant was increased. The morphology of AM was damaged. But the toxicity effect of the three dusts was less than that of SiO2 and chrysotile asbestos (CH) in the same dosage. Meanwhile, the functions of AM were changed. The levels of IgG, immunocomplex (IC) and histamine (HIS) were increased. As to the degree of toxicity and ability of stimulating AM to secrete biomedium by the three dusts, the effect of flax was weakest.

Women's respiratory health in the cotton textile industry: an analysis of respiratory symptoms in 973 non-smoking female workers

As part of a 1992 survey of both environmental and occupational determinants of health, 973 non-smoking women aged 20-40 years who were employed in three comparable modern Chinese cotton textile mills were given a questionnaire that included questions on standard respiratory history and symptoms. All women had some potential exposure to cotton dust; mean employment was 8.7 years. Comparisons were made between those with lowest or no current exposure (job classification in administration, quality control, and testing, n = 112) and those in the more heavily exposed classifications (yarn production areas, n = 861). Association of symptoms with job was tested by logistic regression, adjusting for age, passive smoking at home, and the use of home coal burning stoves. Odds ratios for prevalence of current frequent symptoms in those working in production jobs, after adjustment for home exposure to passive tobacco smoke and coal heating, were frequent cough 2.23 (95% confidence interval (95% CI) 1.05-4.75), frequent phlegm 3.24 (1.54-6.84), shortness of breath 4.54 (1.40-14.72), and wheeze 2.96 (1.16-7.55). Nine cases with grade I byssinosis (chest tightness or shortness of breath on return to work after two days off) were found; all were in production jobs. In these non-smoking women textile workers, chronic respiratory symptoms were associated with job category after correction for domestic indoor air quality. These data support evidence for an increased prevalence of respiratory disease in populations exposed to cotton dust.

Multivariate analysis of byssinosis risk assessment

Multiple logistic regression model was used considering byssinosis as an independent variable, and dustiness, smoking, exposure years and age as explanatory variables. Dustiness and length of exposure to the dust were found to be the most important contributory factors to byssinosis prevalence. The risk of byssinosis among workers in card room, blow room and waste plant sections and those who had exposure of more than 5 years was nearly three times than that among workers of other sections of the mill and/or with less than 5 years of exposure.

Alteration in the modulatory role of respiratory epithelium after exposure of guinea pigs to respirable cotton dust

Chest tightness may occur after inhalation of cotton dust. To understand the origins of this symptom of byssinosis, we exposed guinea pigs to respirable cotton dust and determined whether the resulting pulmonary obstruction was associated with alterations in the in vitro reactivity of the trachea to methacholine. The isolated, perfused trachea preparation was utilized because it allows a comparison of airway smooth muscle responses to drugs after they are applied separately to the mucosal or serosal surfaces. In epithelium-containing control tracheae, mucosally applied methacholine was less potent and elicited smaller maximum contractile responses than those obtained when it was applied to the serosal compartment. After a 6-h inhalation exposure to 30 mg/m3 respirable cotton dust, the mucosal maximum response to methacholine was substantially increased immediately (0 h) after the end of the exposure, but it was decreased 18 h postexposure. A dust level of 10 mg/m3 produced modest increases in the mucosal maximum responses at both postexposure periods, elevating them to the magnitude of the extraluminal maximum response. The potency of serosally applied methacholine was not affected by any cotton dust exposure. Mechanical epithelium removal increased mucosal reactivity to the serosal level in both control and cotton (30 mg/m3)-exposed groups, and abolished the effects of dust on mucosal reactivity to methacholine. Our findings suggest that the modulatory effect of the epithelium may be inhibitory or excitatory. The balance between the two influences may be altered by inhaled cotton dust.

Is a low serum concentration of alpha 1-antitrypsin associated with an increased susceptibility for byssinosis in cotton mill workers? Considerations regarding analytical quality requirements and economical consequences

We have previously demonstrated an association between development of the cotton lung disease byssinosis and endotoxin concentrations in the work environment. Endotoxin has been shown to exert its effects through granulocyte activation and hence release of elastase and other proteases at the bronchoalveolar surface. alpha 1-Antitrypsin is a protease inhibitor, and hence, alpha 1-Antitrypsin concentrations in the blood and then on the alveolar surface might be important for the protection against endotoxin effects. Airborne endotoxin concentrations in the work place and S-alpha 1-Antitrypsin (a1A) was measured in 226 workers in cotton mills in Vejle and of these 206 were further phenotyped. The following models were considered: Model 1. The S-a1A concentration is determining the risk for development of byssinosis. The lower the concentration, the higher the risk. Model 2. The degree of exposure to endotoxin is determining. The higher the airborne concentration and the longer time working in that, the higher is the risk. Model 3. The phenotype of a1-A is determining. Only MS and/or MZ phenotypes represent a risk disposition. The goals for analytical quality for a1-A measurements were estimated in the two relevant models. The specifications are: Regarding model 1: analytical coefficient of variation CVA < 3% and analytical bias--1 mumol/L < BA < +1 mumol/L. Model 2: a1-A is not of significant importance and specifications cannot be evaluated. Regarding model 3: There is a direct relationship between cut-off point and analytical performance, e.g. an imprecision of SA 3 mumol/L and cut-off of 38 mumol/L will allow for a BA of -1 mumol/L.

Diseases associated with exposure to plant dusts: focus on cotton dust

Research during recent years has made clear that pulmonary disease and certain general symptoms caused by organic dusts are far more common than previously suspected. To the traditional environments of cotton dust and moldy hay has been added a series of environments, such as swine confinement buildings, sewage treatment stations and industrial fermentation plants. It has been suggested that, rather than linking clinical disease with a specific environment (farmer's lung, byssinosis, etc), symptoms should be related to the relevant pulmonary cellular reactions, particularly inflammation. In so doing, a more homogenous picture of the various clinical entities has emerged. It is now understood that symptoms once considered to be unique to one particular environment, such as chest tightness in cotton mills, are also present in other organic dust environments. New models for organic dust-induced disease have been established using the criteria developed for disease among workers in cotton mills and swine confinements buildings. This has led to uniform methods for diagnosis, description of symptomatology and understanding of pathogenesis. Employing this experience on an international basis, provides an important background for dealing with new problems in this important area of occupational health and is a prerequisite for the establishment of treatment and prevention programs.

Respiratory disorders and atopy in cotton, wool, and other textile mill workers in Denmark

A cross-sectional study of respiratory disorders and atopy in Danish textile industry workers was conducted to survey respiratory symptoms throughout the textile industry, to estimate the association of these disorders with atopy, and to study dose-response relationships within the cotton industry. Workers at cotton mills, a wool mill, and a man-made fiber (MMF) mill were examined. Four hundred nine (90%) of the 445 workers participated in this survey, i.e., 253, 62, and 94 workers at the cotton mills, the wool mill, and the MMF mill, respectively. An interview designed to assess the prevalence of common respiratory and allergic symptoms was given to all workers willing to participate, and blood samples were drawn. Lung function measurements determined a baseline FEV1, FVC and the change in FEV1 and FVC during work hours on a Monday. The working environment was examined for dust, bacteria, endotoxins, and molds, and the exposure was estimated for each participant. The mean personal samples of airborne respirable dust and respirable endotoxin were highest in the cotton industry, i.e., 0.17-0.50 mg/m3 and 9.0-126 ng/m3 respectively, whereas mold spores were found in the highest concentrations in the wool mill: 280-791 colony-forming units (cfu)/m3. Only small concentrations of microorganisms were found in the MMF mill. The mean change in FEV1% and FVC% was greatest among atopic individuals in both cotton and wool industry and other textile industries although the differences were not significant. FEV1% and FVC% in the cotton workers were significantly associated with the cumulative exposure to respirable endotoxin. Byssinosis was diagnosed only in the cotton industry. We found a dose-response relationship between endotoxin exposure and byssinosis, and a significant association between A-1-A serum concentrations less than or equal to 35 mumol/liter and byssinosis, a finding we are further evaluating in subsequent studies.

Toxin production by Bacillus pumilus

Two strains of Bacillus pumilus (M11 and M38) and one strain each of Bacillus cereus (M27), Bacillus subtilis (M67), and Enterobacter agglomerans (M14) were identified from the air of Lancashire cotton mills. These strains were tested for cytopathic effects in Vero cells; B pumilus and B cereus strains were also examined for haemolytic activity, lecithinase production, and proteolytic action on casein. Rounding and clumping of the Vero cells occurred after the addition of supernatants prepared from B pumilus and B cereus strains; finger-like projections developed in the cells treated with B pumilus supernatants. Minimal effects occurred with B subtilis and E agglomerans. After two hours of exposure B pumilus (M11) produced the greatest effect, but treatment with trypan blue showed that most cells exposed to the M11 strain were still alive after 96 hours of exposure; those exposed to the supernatant prepared from the M38 strain of B pumilus were dead. Sheep erythrocytes were lysed more rapidly by B cereus than by B pumilus, B cereus (strongly positive) had a greater effect on lecithin than either of the B pumilus strains (M38 weakly positive, M11 negative). All hydrolised casein but the effect was more rapid with one of the B pumilus (M11) strains. It is concluded that not only do the toxins of B pumilus differ from those of B cereus, but there are also differences between the toxins produced by the two strains of B pumilus (M11 and M38).

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.

Byssinosis in cotton textile workers of Kishangarh

Byssinosis is an occupational hazard for the workers exposed to cotton dust. In this study 616 cotton textile workers were studied; out of which 149 had byssinosis; 37 (24.7%) had grade-1/2, 78 (52.7%) grade-1, 25 (16.6%) grade-2 and 9 (6.0%) of grade-3 byssinosis. Majority of the byssinotics were of age group between 36-40 years and had developed disease after 16 years of exposure. Disease was more common among smokers and severe, in whom consumption was more than 15 cigarettes/bidis per day for more than 10 years. Ventilatory function tests were markedly abnormal compared with non-byssinotic. On clinical examination and laboratory investigation (specially eosinophilia) and, radiological investigation (x-ray chest) no positive finding was detected. The high prevalence rate of the disease in this study was apparently due to poor working conditions of the workers.

[The echocardiographic indices of patients with chronic bronchopulmonary diseases due to exposure to jute, flax and kenaf dusts]

Chronic bronchopulmonary diseases without concomitant diseases in 32 workers contacting with dust of jute, flax, kenaf were not accompanied by abnormal echocardiographic findings. Patients with byssinosis and chronic bronchitis showed a statistically valid increase of the stroke volume indicating potential possibility of functional loads of the myocardium and its structural sequels during advance of bronchopulmonary diseases.

Inhibition of alveolar macrophage spreading and phagocytosis by cotton bract tannin. A potential mechanism in the pathogenesis of byssinosis

One of the major host-defense functions of alveolar macrophages is the phagocytosis and clearance of inhaled particles deposited in the lower airways and alveolar spaces. Recent studies have indicated that the condensed tannins present in cotton mill dust stimulate the secretion of neutrophil chemotactic factor and arachidonic acid from resident rabbit alveolar macrophages and that these responses may contribute to the acute pulmonary inflammatory reaction associated with byssinosis. To characterize further the effect of tannin on macrophage function, the ability of tannin to modulate alveolar macrophage spreading and phagocytosis in vitro was examined. Tannin caused a dose-dependent inhibition of alveolar macrophage spreading with nearly complete inhibition occurring at concentrations of 12.5 micrograms/ml. This inhibitory effect of tannin was not reversed with removal of tannin. Furthermore addition of tannin to previously spread macrophages actively caused the macrophages to round up. Examination of the structure of alveolar macrophages exposed to tannin by scanning and transmission electron microscopy revealed blebs on the surface of the cells and the loss of most of the cellular organelle structure, as compared to control macrophages. Tannin also modulated the ability of the alveolar macrophages to phagocytize unopsonized latex microspheres. The effect of tannin was biphasic. At the lowest concentration examined (3 micrograms/ml), tannin significantly enhanced phagocytosis of the latex microspheres. However, as the concentration was increased, phagocytosis decreased almost exponentially until at 50 micrograms/ml phagocytosis was significantly inhibited compared to control macrophages. These data indicate that tannin present in inhaled cotton mill dust could significantly decrease the ability of resident alveolar macrophages to phagocytize and thereby clear inhaled dust particles. This inhibitory effect would increase the time that particles remain exposed in the lower airway and alveolar spaces and thereby increase the time that potentially toxic compounds in the dust have to exert their biologic effect. This inhibition of macrophage function may therefore contribute to the pathogenesis of byssinosis.

Toxicity of intratracheally instilled cotton dust, cellulose, and endotoxin

Cotton dust includes respirable particles containing endotoxin and elastase, agents associated with emphysema. To examine whether a respirable fraction of cotton dust could produce emphysema in an animal model, we intratracheally instilled hamsters with respirable cotton dust particles (0.75 mg/100-g animal), mass median aerodynamic diameter less than or equal to 4.8 microns, twice weekly for 6 wk. We also examined whether instilled endotoxin (255 micrograms/100-g animal) could produce emphysema in hamsters and whether cellulose (0.75 mg/100-g animal) is an appropriate inert comparison dust. A saline-instilled group was the control. Hamsters were killed 8 wk after the last instillation. Static pressure-volume deflation curves of air-filled excised lungs were analyzed to measure lung distensibility. Lungs were fixed in inflation using glutaraldehyde and were examined morphometrically to obtain surface area and numbers of granulomata. Endotoxin-treated animals had increased distensibility, reduced surface-to-volume (S/V) ratio, and morphologically apparent mild centrilobular emphysema. Cellulose-treated animals had decreased distensibility, normal S/V ratio, and significant numbers of granulomata with patchy areas of thickened interalveolar septa. Cotton-dust-instilled animals had normal distensibility, reduced S/V ratio, significant numbers of granulomata, and mild centrilobular emphysema. These data suggest that cotton dust produces a significant parenchymal lesion with elements similar to both the emphysematous response to endotoxin and the fibrotic nodular response to cellulose.

Mortality of workers in the British cotton industry in 1968-1984

The mortality of 3458 cotton industry workers originally enrolled in a study of respiratory symptoms in the period 1968-1970 was followed to the end of 1984. Both the total mortality and the mortality from respiratory disease were less than expected, and they both decreased as length of service increased. However, for the subjects who initially reported byssinotic symptoms, the mortality from respiratory disease was slightly raised overall, and it increased with length of service. These patterns of mortality indicate a survivor effect (ie, a tendency for those with respiratory weakness to leave the industry), together with a long-term effect reflected in respiratory mortality on the health of those workers susceptible to the effects of cotton dust. The mortality from lung cancer was lower than expected, and it decreased with length of service. This finding is consistent with other observations that exposure to cotton dust may reduce the risk of lung cancer.

Acute and chronic changes in pulmonary functions among Indian textile workers

An epidemiological study was carried out in three textile mills of Ahmedabad. A total of 214 cotton dust exposed and 184 control subjects were examined for pulmonary function tests. Pulmonary function tests included forced vital capacity and forced expiratory volume in one second. The pulmonary function tests were carried out before starting the shift and after 7 hours of exposure on a vitalograph spirometer. The study shows that among the cotton dust exposed workers byssinotics behave distinctly and show the maximum acute and chronic changes in pulmonary functions. It seems that the effect of cotton dust exposure on the byssinotic subjects is more predominant than the effect of smoking.

Relationship of byssinosis to the generation of oxygen radicals by bract tissues of cotton plants

Byssinosis is a hazardous respiratory disorder of workers in natural fiber processing industries and, in the case of cotton, is caused by exposure to respirable dust generated from leafy trash associated with raw fibers. To understand the chemical characteristics of involucral trash components that might contribute to bysinosis, we examined the human airway constricting activity and oxygen radical generating activity of dry, frost-killed cotton bracts. In response to inhalation of aerosolized bract extracts, the expiratory flow rates of human volunteers at 40% of vital capacity during partial forced expiration decreased by 3 to 32%. These values enabled us to identify two potentially byssinogenically active bract specimens, a specimen virtually inactive, and a fourth intermediately so. Using spin trapping techniques of electron spin resonance spectrometry, we found that all specimens catalyzed the generation of hydroxyl (preponderantly) and superoxide radicals from hydrogen peroxide. However, the weakest constrictor was the most potent catalyst, and vice versa. This was consistent with transition metal content of the specimens; the most potent catalyst also contained the largest amounts of those metals, suggesting a Fenton-type reaction mechanisms. Other possibilities for the inverse relationship of airway constricting (byssinogenic) activity with oxygen radical generation are discussed. We also found that neither aflatoxin nor endotoxin, contingent contaminants of bracts, catalyzed oxygen radical production from hydrogen peroxide.

Evaluation of the contribution of tannin to the acute pulmonary inflammatory response against inhaled cotton mill dust

Anesthetized, intubated, and mechanically ventilated rabbits were exposed to aerosolized saline, cotton dust extract (CDE), or tannin for 5 minutes and lavaged 4 hours after exposure. Cell numbers and types present in the bronchoalveolar lavage fluid (BALF) were determined and the concentrations of thromboxane A2 (TxA2) and prostaglandin F2-alpha (PGF2-alpha) in the BALF were also analyzed. The saline control animals had increased numbers and percentage of polymorphonuclear leukocytes (PMN) in the BALF as well as increased levels of TxB2 and PGF2-alpha compared with unexposed animals. Exposure to CDE further increased the number and percentage of PMN and the level of PGF2-alpha but had no effect on TxA2 levels when compared with control animals. Tannin exposure increased PGF2-alpha levels to the same extent as CDE exposure. PMN also increased but to a lesser extent than with CDE. These results indicate that the inflammatory response to CDE is only partially due to the tannin present in CDE.

Plant constituents of cotton dust and lung effects after inhalation

Experiments were performed to assess pulmonary reactions after inhalation of cotton dusts with different levels of tannins, terpenoid aldehydes and bacterial endotoxins. Guinea-pigs were exposed to cotton dust. Free lung cells were obtained by lavage 24 h later. A dose-response relationship was found between the number of neutrophils and the amount of endotoxin in the dust. No influence of terpenoid aldehyde or tannin levels could be detected. Cotton mill workers were exposed to dust from glanded and glandless cottons in an experimental cardroom. The average decreases in forced expiratory volume in one second (FEV1) over the workday after carding the two cottons were the same, although levels of dust, tannin or terpenoid aldehydes were different. The level of airborne endotoxin was, however, equal. The results support observations from other studies on the importance of endotoxin for the development of the acute reactions observed after cotton dust exposure.

Enterobacter agglomerans lipopolysaccharide-induced changes in pulmonary surfactant as a factor in the pathogenesis of byssinosis

Lipopolysaccharide (LPS) from Enterobacter agglomerans and pulmonary surfactant mixtures were centrifuged in discontinuous sucrose gradients to determine whether LPS bound to surfactant and examined in a Langmuir trough with a Wilhelmy balance to determine whether LPS altered the surface activity of surfactant. The LPS was found to bind to the surfactant and altered its surface tension properties. The binding of LPS to surfactant in the lung may change the physiological properties of surfactant and be a possible mechanism for the pathogenesis of byssinosis.

Cotton bract tannin: a novel human T-lymphocyte mitogen and a possible causative agent of byssinosis

Cotton bract tannin, a major organic component of cotton dust, was tested for mitogenic activity upon human T lymphocytes. Tannin caused polyclonal activation of human T lymphocytes in vitro. The pattern of T-cell response to tannin was similar to the pattern seen in lymphocytes stimulated with the well-known plant lectin T-cell mitogens, PHA and ConA. The response to tannin was shown to be dependent upon tannin dose and presence of monocytes. The maximum response occurred after 3-4 days in culture with the magnitude comparable to the one achieved by ConA. Lipopolysaccharide from Enterobacter agglomerans, a major contaminant of cotton dust, was shown not to be a mediator of tannin mitogenicity in vitro. A role for tannin as a polyclonal cell activator and, therefore, a possible etiologic agent of byssinosis is suggested by these observations.