they cause dry or productive cough of chronic or non - chronic nature , asthma and other respiratory symptoms . however , known effects are mainly altered pulmonary function findings and symptom of chest tightness . cotton dust - induced lung diseases are poised to become a health problem , not only due to already known effects but also because of the emergence of newer findings like occurrence of cotton dust - induced pulmonary fibrosis . it is now believed that cotton fiber per se is not responsible for this pulmonary response . a hypothesis that has commonly emerged , indicate that contamination of the cotton fibers with gram - negative bacteria and/or their endotoxins may be responsible for causing the disease , which shows the symptoms of subjective feeling of chest tightness , shortness of breath , and decrease in pulmonary function . although , in the developed world , there is a significant decline in the prevalence of cotton dust - related lung diseases , studies show an increasing incidence in the developing world . chemicals present in cotton dust , mainly derived from bract extract are being highlighted as the responsible factor . studies exploring the role of occupational factors in respiratory disease and symptoms , found significant role of occupational exposures in asthma , chronic bronchitis , and other respiratory symptoms . exposure to dusts from cotton , wood , metal , and minerals was associated with non - chronic cough and/or phlegm , chronic bronchitis and adult - onset asthma . apart from the classical observations of cotton dust exposure like chest tightness , altered pulmonary functions findings and byssinosis , non - chronic cough or phlegm , chronic dry cough , adult - onset asthma , and other non - specific respiratory symptoms have all been associated with different grades of exposure . changes in lung function and airway reactivity resulting from exposure to cotton dust was reported . obvious cross - shift drops in forced expiratory volume in 1 sec ( fev1 ) , and declines in forced vital capacity ( fvc ) and fev1 over 1 year , were observed . atopic workers had a significantly greater acute drop in fev1 than did non - atopic workers . both atopic and non - atopic workers had slightly increased airway reactivity at 1 year , compared with baseline values . the results suggested that exposure to cotton dust is responsible for acute and longitudinal declines in lung function . interesting findings were observed while examining circadian rhythms in peak expiratory flow rate ( pefr ) of workers exposed to cotton dust . in a study , people working in various departments of cotton spinning and weaving mills measured and recorded their own pefr at regular intervals during three days of the same work week , from waking in the morning throughout the day until going to bed . significant difference was observed in workers having prominent exposure to cotton dust in the working environment . a number of studies have been carried out all over the world to enumerate and evaluate the health effects of cotton dust exposed workers in different processes . however , such studies carried out in ginning industry especially in indian context are scanty . hence this study was initiated to explore occupational and morbidity details and respiratory functional status of the exposed workers as well as to investigate across the working shift pulmonary function changes . this cross - sectional epidemiological study was conducted on workers from three ginning units where principal exposure is from cotton dust . a gin is the place where harvested cotton is taken to a series of process and lint is separated from the seed . the actual process of ginning takes place in gin house where a series of ginning machines and a long conveyer is installed . ginned cotton is transported through one or more gin - lint cleaners to the press house where it is pressed into bales through a semi - automatic procedure . initially the aim of the study was explained to the workers , and informed consent was obtained after which they were enrolled for this study . the participants of this study were subjected to an interview with a predesigned questionnaire to collect occupational and medical history , clinical examination and pulmonary function test . fvc and pefr were recorded by spirovit - sp-10 ( schiller health care ltd , switzerland ) and wright 's peak flow meter . then only the observations were recorded . while recording observations , three recordings were taken in standing posture using nose clip and the best value all volumes obtained were expressed in body temperature on atmospheric pressure of air saturated with water vapor ( btps ) . this equation is based on western india population and our present study was also conducted in western india . the instrument was calibrated every day before starting the experiment . for categorizing pulmonary function impairment , 80% of predicted value of fvc and fev1 /fvc ratio of 0.7 was considered as cut - off marks for determining restrictive and obstructive impairment . one hundred and sixty - eight subjects participated in this study ; however , pulmonary function test could be performed in 154 subjects . subjects with established diagnosed respiratory disease , subjects in prolonged medication , subjects with chest injury / operation , and subjects with simultaneous other industrial / occupational exposure ( ginning job being seasonal ) were excluded for pulmonary function study . pulmonary function test was carried out by experienced technical staffs of national institute of occupational health , ahmedabad , india . twelve subjects had other industrial / occupational exposures and 2 subjects did not cooperate for this examination . analysis of the collected data showed that mean age of the workers was 31.5  11.2 years , mean job duration was 6.8  4.8 years , majority ( 47% ) was of 26 - 45 years of age and 10% subjects had work experience of 15 years or more . among the study subjects , 59% were actual workers , 15% were supervisory staffs , and 26% were allied workers . out of the actual workers , 37% were in gin house , 34% in press , 4% in bagging , and 10% in cotton loading and unloading . mean body height and body weight were 167.6  8.2 cm and 60.2  14.5 kg , respectively [ table 1 ] . general characteristics of the study subjects common health problems among these subjects working in different activities of ginning were backache ( 20% ) , joint pain ( 12% ) , headache ( 4% ) , recurrent cough ( 4% ) , etc . irritation of nose ( 2% ) and eye ( 2.5% ) as well as chest tightness ( 1.5% ) was experienced by some workers . as far as pulmonary function is concerned , it was observed that all the relevant parameters showed a declining trend with increasing experience of job . similar trend was observed in majority of parameters with increasing age of the study subjects and smoking status . however , no significant difference of pulmonary function parameters was observed when compared between actual workers , supervisory staffs , and allied workers ( univariate analysis ) [ table 2 ] . on multivariate analysis when adjustment for age and height was taken up , it was observed that job experience had no significant effect although age and height showed significant effects . however , in case of smoking , it was observed that smokers had significantly lower values of fvc , fev1 , and pef after adjustment for age and height . distribution of pulmonary function parameters of the subjects across the working shift , changes in pulmonary function was also examined in some workers . in general , no such significant across - the - shift deterioration of values was observed [ table 3 ] . out of 154 workers examined for pulmonary function test , four subjects had obstructive abnormality and nine workers had restrictive abnormality . circadian rhythm of pefr values ( three times / day ) of 22 healthy volunteers was obtained for consecutive two days after initiation of exposure to cotton dust ( first two working days of the week ) . one - way anova with post hoc test ( tukey hsd ) was applied on the obtained data , which showed no significant difference at any level [ table 4 ] . across the shift changes of pulmonary function parameters of the subjects distribution of pefr values for first two consecutive working days of the week the role of occupational exposures in asthma , chronic bronchitis , and respiratory symptoms is already explored . moreover , non - specific respiratory symptoms in isolation or in combination with respiratory functional impairments with or without symptoms may also be related to such exposures . cotton dust exposure produces a unique condition named byssinosis that produces symptoms like chest tightness mostly on resuming work after an absence , altered pulmonary functions findings , etc . , circadian rhythms in peak expiratory flow rate following cotton dust exposure showed interesting new findings . common health problems among the subjects in this study were backache , joint pain , headache , recurrent cough etc . so far as pulmonary function is concerned , it was observed that all the relevant parameters showed a declining trend with increasing experience of job . similar trend was observed in majority of parameters with increasing age of the study subjects and smoking status ( univariate analysis ) . on multivariate analysis smokers had significantly lower pft values after adjustment for age and height although job experience had no significant effect . distribution of pefr data obtained at regular intervals on first two working days of the week showed no significant difference at any level . studies on cotton textile workers have also shown cross shift and chronic decline of fev1 values . however , such studies carried out in ginning industry particularly in india are scanty . in this present study , no cross - shift significant changes in relation to pefr and fev1 values however , chronic effect on lung function is observed in a few subjects and declining trend of values was observed with increasing job duration . a study conducted in turkey on cottonseed workers came out with similar findings like our study and concluded that smoking appears to be the main factor responsible for respiratory symptoms among such workers . this difference of observation in case of ginning activities compared to other cotton dust exposures may be explained by non - continuous and seasonal nature of exposure in case of ginning . the activity of ginning is undertaken in a seasonal manner for a period of 3 - 4 months only in a year and the activity is not continuous and interrupted by different factors . exposure from other sources and confounding effect of age might also have contributed in the findings observed in the study subjects . periodic relevant examination ( clinical examination and lung function test ) and industrial hygiene survey ( periodic monitoring of dust and toxicants like gram - negative bacteria , endotoxins ) at regular intervals is recommended . prevalence of backache and joint pain during work in a good number of workers reflects that manual work of the industry might be causing some discomfort for the workers . training on proper method of manual material handling may also prove useful for these workers .
background : known respiratory health effects of exposure to cotton dust are mainly altered pulmonary function findings and symptom of chest tightness . 
 a number of studies have been carried out all over the world to enumerate and evaluate the health effects of cotton dust exposed workers in different processes . 
 however , such studies carried out in ginning industry especially in indian context are scanty.objectives:this study was initiated to explore occupational and morbidity details and respiratory functional status of the exposed workers as well as to investigate across the working shift pulmonary function changes.materials and methods : a cross - sectional study was conducted including workers from ginning units where principal exposure is from cotton dust . 
 all the workers of the selected ginning units were subjected to an interview with a predesigned questionnaire to collect occupational and medical history , clinical examination and pulmonary function test.results:in this present study , no cross - shift significant change in relation to pefr and fev1 values is observed . 
 however , chronic effect on lung function is observed in a few subjects and declining trend of values was observed with increasing job duration as well as age of workers and among smokers . 
 other health problems among these subjects were backache and joint pain.conclusions:studies on cotton textile workers have shown both cross - shift and chronic decline of values . in this study on ginning workers , 
 chronic effect only is observed . 
 this difference of observation may be explained by different nature of exposure in case of ginning . 
 this study recommends regular periodic clinical examination , lung function test and monitoring of dust , gram - negative bacteria and endotoxins in such workplaces .