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 diVerent 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. (Occup Environ Med 1998;55:668-672)

Abstractsignificant for both FEV 1 (p<0.01) and FVC (p<0.05). Background -Exposure to cotton is knownConclusions -Chronic bronchitis is more to produce a specific occupational disease prevalent in cotton workers than in those known as byssinosis. A large population of working with man-made fibre and extextile workers was investigated to deterposure is additive to the effect of smoking. mine whether such exposure was also asThe diagnosis of chronic bronchitis is associated with chronic bronchitis once sociated with a small but significant decreother possible aetiological factors had been ment in lung function. accounted for. (Thorax 1997;52:22-27) Methods -A total of 2991 workers were investigated for the presence of symptoms Keywords: cotton, man-made fibre, chronic bronchitis, smoking, lung function. compatible with chronic bronchitis. An MRC adapted respiratory questionnaire Chronic bronchitis is a disease of the respiratory and MRC definition of chronic bronchitis system related to cigarette smoking. It is charwere used for diagnostic labelling. Current acterised by the presence of a cough with spuand lifetime exposure to dust was estum production which is chronic and persistent. timated by personal and work area It has been described as such and can be sampling, and the use of records of retro-investigated using questionnaire techniques in spective dust levels previously measured epidemiological studies. It has recently been accepted that chronic endotoxin exposure was measured using bronchitis may occur more commonly in some a quantitative turbidometric assay. Lung occupational groups, notably coal mining. 2 function tests were performed to measure There is also some evidence to suggest that forced expiratory volume in one second there may be an excess of disease in foundry (FEV 1 ) and forced vital capacity (FVC). A workers 3 and steel workers. 4 The study of these control group of workers exposed to man-working populations has been made more difficult because of the confounding effect of made fibre textiles was identified. The smoking which remains clearly the most imcomparative prevalence of chronic bronportant aetiological factor. In the occupational chitis in the two populations was assessed, groups where chronic bronchitis may occur as allowing for sex, age, smoking habit, and a result of industrial exposure to dust, smoking ethnic origin. Two case referent studies is prevalent among the work force and idenwere also performed; cases of chronic tifying sufficient numbers of workers who are bronchitis were separately matched with lifelong non-smokers is difficult. Until smoking controls from the cotton and control popu-is adequately accounted for it is impossible to lations to determine the effect of the symp-ascribe aetiological roles to occupational factors tomatic state on lung function.in the occurrence of bronchitis. Results -After controlling for smokingWe have studied nearly 3000 workers on (pack years), workers in a cotton en-their first entry into a five year longitudinal vironment were sig...

This study of workers naive to cotton dust exposure has demonstrated that respiratory symptoms and acute airway responses develop early following first exposure, and a tolerance effect develops in those workers with the continued exposure. Current smoking and increasing exposure predicts the development of work-related lower respiratory tract symptoms, while early symptoms and acute airway changes across the working week predict the longitudinal loss of lung function at 1 year.

Objective: This longitudinal study aimed to identify the predictors of leaving during the first year of employment from the cotton spinning mill environment in newly hired workers. Methods: One hundred and ninety eight consecutively appointed new employees were investigated by questionnaire, lung function test, and skin test. They were examined before employment and at the end of the 1st week, and the 1st, 3rd, 6th, and 12th month after starting work and when possible before leaving their job. 572 personal dust sampling and 191 endotoxin measurements were performed to assess the environmental exposure. For the univariate analysis x 2 , Student t tests, ANOVA, and Kruskall Wallis tests were used. Cox proportional hazards analysis was used to identify factors associated with leaving the job. Results: Fifty three per cent of workers left the mill environment during their first working year. Work related lower respiratory tract symptoms reported at the third month were associated with an increase rate of leaving the industry compared to those remaining in the industry (25% v 4.8%; p,0.005). Having respiratory symptoms at the first month of work predicted those leaving the industry at some point in the next 11 months. According to the Cox model, increasing age and having work related lower respiratory tract symptoms were found to be predictors for leaving job at the first working year. Atopic status, dust and endotoxin levels, and lung function changes were not consistently predictive of workers who left the industry in the follow up period. Conclusion: This study demonstrated that work related respiratory symptoms can predict workers likely to leave the cotton mill environment during the first year of employment, but atopy or acute lung function changes do not.

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