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Aqueous extracts of cotton and other vegetable dusts cause contraction of the isolated ileum and tracheal muscle of the guinea-pig, and of isolated human bronchial muscle. The levels of this contractor activity place the dusts of cotton, flax, and jute in the order of the probable incidence of byssinosis occurring in the mills spinning these fibres.

Extracts of cotton dust possess a histamine-liberating activity and contain a permeability-increasing component. These actions are of plant origin and are found in the pericarp and bracts of the cotton boll. Histamine and 5-hydroxytryptamine have also been found in some cotton dust samples. The formation of histamine by bacterial action in cotton dust does not take place under conditions found in cotton mills. The smooth muscle contractor substance is organic in nature, relatively heat-stable, and dialysable. The relevance of these results to the symptoms of byssinosis is discussed.

Studies of ventilatory capacity change in small groups of employees during a shift in a cotton mill and in three cotton ginneries in Uganda, a sisal factory in Kenya, and a jute mill in England, have demonstrated that an effect is produced by the dust in the cotton mill and in a very dusty ginnery but not in two other less dusty ginneries. No significant effect was detected in the sisal factory or in the jute mill despite much higher dust concentrations than in the cotton mill.

The dust sampling instruments gave the weight in three sizes: Coarse (>2 mm.), medium (7μ to 2 mm.), and fine (<7μ). The samples were analysed for protein, mineral (ash), and cellulose (by difference). The fine and medium sisal and jute dusts contain less protein than cotton dusts. The physiological changes observed in the employees in the cotton mill indicate the need for general dust measurement and control, even when new carding machinery is installed in a new mill.

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Valić, F., and Žuškin, E. (1972).Brit. J. industr. Med.,29, 293-297. Effects of different vegetable dust exposures. In order to establish the rank of biological activity of vegetable dusts, five groups of non-smoking female workers exposed to similar concentrations of hemp, flax, cotton, sisal, and jute airborne dust, respectively, were compared as to the prevalence of byssinosis, chronic respiratory symptoms, and one-second expiratory volume changes over the Monday shift. The groups were selected in such a way as to differ in the distribution of age and length of exposure to the respective dust as little as possible.

The prevalence of byssinosis in hemp and flax workers was approximately equal (44% and 43% respectively), in cotton workers it was considerably lower (27%), while no byssinosis was caused by either sisal or jute dust. The highest prevalence of other chronic respiratory symptoms was recorded in hemp workers (39%), followed by flax (36%) and cotton workers (27%), while in sisal (13%) and jute workers (13%) it was the lowest.

Significant mean FEV1·0 reductions over the shift were recorded in all the groups of textile workers with the largest reductions in hemp workers (19%) followed by flax (11%), cotton (8%), sisal (7%), and jute workers (5%). The application of orciprenaline before the shift diminished the mean acute FEV1·0 falls over the work shift in all the groups studied.

Aqueous extracts prepared from dust collected in the card-rooms of several cotton mills have been prepared and found to contain activity which contracts the smooth muscle of guinea-pig ileum, guinea-pig trachea, rat stomach strip, and rat duodenum. The extracts contained an unknown contractor substance which was dialysable, resistant to boiling for one hour, and not destroyed by the action of proteolytic enzymes. They also contained a small amount of 5-hydroxytryptamine. One of the dust samples also contained histamine, but it could not be detected in the other samples, one of which was known to possess bronchoconstrictor properties in man. The particulate material, even after repeated washing, was found to have some stimulant action on guinea-pig ileum.

There was no evidence for the release of histamine by the extracts in either cats or guinea-pigs, although a very small amount was released in rats. Jute dust is much less active than cotton dust, and the activity differs qualitatively. Cotton dust extracts were found to have pyrogenic activity but it is unlikely that pyrogens were responsible for the smooth-muscle contractor properties. Experiments with whole animals suggest that although smooth-muscle contracting substances were present in the extracts, it is possible that the symptoms of byssinosis are caused by the release of some other active bronchoconstrictor substance in the tissues. The mechanism of the release is not known; it may be caused by a soluble principle in the extract or due to the presence of particulate matter in the dust.

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The prevalence of byssinosis and chronic respiratory symptoms was studied in 117 workers in four Swedish cotton mills. Changes of forced expiratory volume in 0·75 sec. (F.E.V.0·75) during a Monday and a Wednesday were assessed in 64 male workers in four cardrooms in these mills. Dust sampling was performed with weighed millipore filters.

Prevalences of byssinosis as judged from the workers' histories were 68%, 55%, 44%, and 25% in the four mills; the lowest prevalence of 25% was found in a mill spinning both high grade cotton yarn and rayon. Among 67 workers in the mills having a byssinosis prevalence of 68% and 55%, 60% were non-smokers, 70% had chronic cough, and 27% had chronic dyspnoea. The F.E.V.0·75 decreased on Monday in workers who gave a history of Monday dyspnoea, and to a lesser degree, but still significantly, in those who did not.

In spite of marked differences in fine dust (i.e., dust smaller than 2 mm. diameter) concentrations in the four cardrooms, no significant relations between dust content, byssinosis prevalence, and F.E.V.0·75 changes on Monday could be demonstrated.

The prevention and treatment of byssinosis is discussed. Workers at risk should receive a periodical medical examination including at least a spirographical pulmonary function test at intervals of one year or less.

The prevalence of byssinosis and of chronic bronchitis was studied in a questionnaire investigation among workers in bale opening areas, carding rooms, and spinning rooms in five Swedish cotton mills. Airborne dust and Gram-negative bacteria was measured. Nineteen per cent of the interviewed workers reported symptoms of light byssinosis (grade 1/2). The prevalence of symptoms was not related to the duration of employment, and cases of byssinosis were found among people who had worked in cotton mills for only a few years. A significantly higher proportion of male than female workers reported symptoms. No difference in the extent of byssinosis was found between smokers and non-smokers, but the prevalence was significantly higher among those workers who had ceased smoking. The prevalence of byssinosis was related to the number of airborne viable Gram-negative bacteria as well as to the dust level in the different mills.

Valić, F., and Žuškin, E. (1971).Brit. J. industr. Med.,28, 364-368. A comparative study of respiratory function in female non-smoking cotton and jute workers. To compare the effect of cotton and jute dust, respiratory symptoms were studied and respiratory function measured in 60 cotton and 91 jute non-smoking female workers of similar age distribution, similar length of exposure to dust, and exposed to similar respirable airborne dust concentrations. Cotton workers had a significantly higher prevalence of byssinosis, of persistent cough, and of dyspnoea (P < 0·01) than jute workers. Among cotton workers 28·3% were found to have characteristic symptoms of byssinosis, whereas none was found among jute workers.

Exposure to cotton but also to jute dust caused significant reductions of FEV1·0, FVC, and PEF (P < 0·01) over the first working shift in the week. Functional grading of jute and cotton dust effects has shown that about 30% of cotton workers had functional grades F1 and F2, while only 13% of jute workers were found in the same grades (F1). It is concluded that cotton dust may be considered more active than jute though the latter cannot be considered inactive.

The prevalence of byssinosis was measured in a population of 189 male and 780 female workers employed in three coarse and two fine cotton mills. Ninety-eight per cent. of the male and 96% of the female population were seen.

The workers were graded by their histories as follows:

Grade 0—No symptoms of chest tightness or breathlessness on Mondays

Grade ½—Occasional chest tightness on Mondays, or mild symptoms such as irritation of the respiratory tract on Mondays

Grade 1—Chest tightness and/or breathlessness on Mondays only

Grade 2—Chest tightness and/or breathlessness on Mondays and other days

The dust concentrations to which the workers were exposed were measured with a dust-sampling instrument based on the hexhlet. Altogether 505 working places were sampled. In the card-rooms of the coarse mills 63% of the men and 48% of the women had symptoms of byssinosis. In the card-rooms of the fine mills the corresponding prevalences were 7% for the men, and 6% for the women. Prevalences were low in the spinning-rooms in the coarse mills. The mean dust concentrations in the different rooms ranged from 90 mg./100 m.3 in one section of the card-room in a fine mill, to 440 mg./100 m.3 in one of the card-rooms of the coarse spinning mills. The prevalence of byssinosis in the different rooms was closely related to the overall dustiness (r = 0·93). For the three main constituents of the dust, namely, cellulose, protein, and ash, the prevalence of byssinosis correlated most highly with protein, particularly with the protein in the medium-sized dust particles, i.e., approximately 7 microns to 2 mm.

The symptoms of byssinosis may be caused by something in the plant débris which affects the respiratory tract above the level of the terminal bronchioles. This is the site where the medium-sized dust deposits. The possible importance of the fine dust is discussed.

For routine measurements in industry, it is necessary to have a method of assessing dustiness in which the sampling equipment is simple and assessment rapid. As total dust concentration is relatively easy to measure, and correlates closely with the prevalence of byssinosis, permissible levels of dustiness have been expressed in terms of total dust. On comparing the prevalence of byssinosis among workers with short and long exposures and low and high concentrations (Table 11), it appears that a mill with a concentration of 100 mg./100 m.3 or less would be reasonably safe, but in dusty card-rooms it seems that such levels are not possible to achieve at present. As it is necessary to adopt a realistic target that can be achieved, it is suggested that dust concentrations in cotton mills should be less than 250 mg./100 m.3 and that periodic medical examinations should be adopted to protect susceptible workers who can be advised to leave their dusty environment before they are permanently disabled.

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The results are given of environmental and clinical investigations in four card rooms where one of the latest systems of exhaust ventilation to control dust has been installed. The concentration of air-borne coarse dust particles, larger than 2 mm., was reduced by between 80% and 90% around the carding engines. The card rooms consequently looked less dusty. However, the concentrations of medium and fine sized dust particles were not always reduced and were actually increased in some places. In one mill, when the new control system had been running for three years, there was found to be no reduction in the prevalence of non-specific chest symptoms, and there was an increase in the number of those with chest tightness on Mondays, a symptom characteristic of byssinosis. Evidence is given of a similar failure to reduce the dust sufficiently in three other mills where the same exhaust system is installed.

There is an urgent need to extend the limited investigations reported here to a larger number of mills. Meanwhile there is a continuing morbidity and mortality from byssinosis. Until work in card rooms has been made safe and proved to be so, it is necessary to have regular measurement of dust conditions and for the workers to have periodical medical examinations to enable managements to be advised about the hazards in their mills and advice to be given to the individuals affected by the dust.

In a mill spinning coarse cotton the prevalence of byssinosis and other respiratory symptoms, and the F.E.V.1·0, were measured in a group of 29 men and 117 women employed in the winding room. All the men and 95% of the women at risk were included.

Dust concentrations, measured with a modified Hexhlet at various work points in the winding room, ranged from 1·65 to 6·05 mg./m.3 total dust. These concentrations are higher than 1·0 mg./m.3, which is the threshold limit value for cotton dust recommended by the American Conference of Governmental Industrial Hygienists. The mean dust concentration was 3·48 mg./m.3 compared with 2·85 mg./m.3 in the card room of the same mill.

The prevalence of byssinosis was 18·8% among the women and 13·8% among the men. A comparison among the women showed that those with symptoms of byssinosis had, on the average, significantly lower F.E.V.s than women of similar age without such symptoms. Four women and one man with moderately severe symptoms of byssinosis showed evidence of permanent respiratory disability with effort intolerance and a substantial diminution in F.E.V.1·0. Further studies should be carried out in other winding rooms because, if these findings are repeated elsewhere, they would indicate the necessity for medical surveillance, dust control, and extending the compensation scheme to include winding room workers.

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Berry, G., Molyneux, M. K. B., and Tombleson, J. B. L. (1974). British Journal of Industrial Medicine,31, 18-27. Relationships between dust level and byssinosis and bronchitis in Lancashire cotton mills. A prospective survey of workers in 14 cotton and two man-made fibre spinning mills was carried out. A questionnaire on respiratory symptoms was completed at the start of the survey by 1 359 cotton workers and 227 workers in man-made fibre mills and again two years later by about half of these workers. Dust measurements were available for 772 women and 234 men cotton workers.

The prevalence of bronchitis was found to be unrelated to dust level but for women was related to years of exposure. The change in symptoms of bronchitis was unrelated to dust level or to length of exposure. There was, however, an increased prevalence of bronchitis in the cotton mills when compared with the man-made fibre mills, and also over the two-year period a greater proportion of symptom-free workers developed symptoms and a lower proportion of those with symptoms lost their symptoms in the cotton mills than in the man-made fibre mills.

The prevalence of byssinosis was related to smoking habits, the smokers having about 1·4 times as much byssinosis as the non- and ex-smokers after allowing for exposure. Byssinosis was associated with the dust level and years of exposure, more so for the women, and an association between the incidence of new cases over the two years and dust level was also found. After allowing for dust level, years of exposure, and smoking there were still differences between the occupational groups in byssinosis prevalence. Strippers and grinders had the highest prevalence followed by drawframe tenters. Speedframe tenters, card tenters, and comber tenters had similar prevalences and ring spinners the lowest.

The effect of airborne dust on the guinea-pig ileum was studied. Tyrode extracts of airborne dust collected freshly in the cardroom of a cotton mill, and extracts of air pollutant samples drawn on the roof of the mill and of the local town hall were all found to induce the guinea-pig ileum to contract when applied in a tissue-bath. However, the force of contraction with air pollutants was rather greater than that with the cardroom dust. Considering the variables involved, the ileum response to the cardroom dust may have been due to ordinary air pollutants which constitute a significant part of the dust. It is concluded that this pharmacological phenomenon is probably not relevant in the context of byssinosis.

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The principal causative agent of byssinosis lies in the dust of cotton mills. This dust contains bacteria and fungi. An attempt has been made to determine whether any association could be established between the numbers of viable bacteria and fungi in the air of two cotton and two jute mills, and the prevalence of byssinosis. No association was found except between the numbers of live organisms of B. pumilus and B. subtilis, and the occurrence of byssinosis. This association does not establish a causal relationship, but it is suggested that an attempt should be made to produce typical symptoms in byssinotic subjects by means of organisms of the genus Bacillus. A subsequent paper presents the results of some observations of this kind.

Four hundred and eighty-six textile workers in three cotton mills and one wool/synthetic mill were studied for symptoms and functional effects of workroom exposure to dust. Byssinosis was found in 5.7% of 386 cotton workers, with an apparent threshold level of 0.5 mg cotton dust/m3 of air. Mean post-shift functional declines were greater in workers exposed to greater than or equal to 0.2 mg/m3. Workers with byssinosis were unequally distributed, however, with respect to job category and mill; and these variables, rather than current dust exposure levels, accounted for the observed distribution of byssinosis prevalence rates. Variation in biological potency of different samples of cotton dust could be responsible for 'mill effect', the residual variation in response rates by mill after controlling for variation due to dust exposure. A number of other potential influencing variables that are likely to be distributed unequally by mill should also be considered. Mill effect should be assessed in large-scale studies of byssinosis, most of which have analysed biological response rates by combining mill and other variables to examine first-order effects of dust dosage. In such analyses, much of the observed variability may be due to factors other than dust dosage.

The problem of byssinosis has plagued cotton textile mills for hundreds of years, and it is still a problem today. With the regulations on airborne raw cotton dust set by OSHA and the ACGIH, research regarding the measurement of cotton dust in lint fiber is a necessity. A procedure known as the mass concentration particle size distribution (MCPSD) technique, developed at Texas A&M University, was used to measure the characteristics of cotton dust as affected by harvesting method and genotype. Cotton genotypes from three harvest seasons were analyzed by using a Coulter Counter, Model TAII, to obtain the mass concentrations and particle size distributions of dust present in the lint fiber. The genotypes were subjected to both hand harvesting and conventional spindle harvesting for comparison purposes. Results from the dust concentration analyses of particles less than 100 micron, 16 micron, and 8 micron in diameter, respectively, are presented. Also, a proposed procedure to obtain large quantities of "cotton dust" from gin trash material is discussed.

This study was conducted to investigate the prevalence of respiratory problems, in particular byssinosis, and to explore factors associated with their occurrence among a group of 595 randomly selected workers representing 40.5% of those exposed to dusty operations in a typical Ethiopian cotton textile mill. A standard questionnaire on respiration was administered and pre and postshift forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were determined for each worker; workers found to have byssinosis and other respiratory diseases were compared with workers having no respiratory diseases in terms of the level and duration of exposure to cotton dust and other variables. Multiple area air samples from different sections were analysed for elutriated cotton dust concentrations (0.86-3.52 mg/m3). The prevalence of byssinosis was 43.2% among blowers and 37.5% in carders in comparison with four to 24% among workers in other sections. Prevalence of chronic bronchitis ranged from 17.6 to 47.7% and bronchial asthma from 8.5 to 20.5% across all sections. Significant across shift decrements in FEV1 and FVC were seen in those workers with respiratory tract diseases compared with those workers without such diseases. A significant dose response relation for pulmonary function and respiratory illnesses was also found by regression analysis. Preventive measures are proposed. Further research including a nationwide survey of textile mills is suggested. This is the first epidemiological study of the textile industry in Ethiopia.

Žuškin, E., and Valíc, F. (1973).British Journal of Industrial Medicine,30, 375-380. Respiratory response in simultaneous exposure to flax and hemp dust. The effect of exposure to high concentrations of mixtures of hemp and flax dust was studied in 124 workers in two textile mills (mill A: 65-70% hemp and the rest flax, mean dust concentration 13·9 mg/m3; and mill B: about 35% hemp and the rest flax, mean dust concentration 15·8 mg/m3). A high prevalence of byssinosis was found in both mills (80% in mill B; 46·8% in mill A) after a mean exposure of no more than 13 years. In both mills, byssinotics had a higher prevalence of all chronic respiratory symptoms than non-byssinotics. This difference was more pronounced in mill A. Forty-eight percent of byssinotic women and 43% of byssinotic men had byssinosis of grade 2 or 3. Significant mean acute reductions in FEV1·0 and ˙Vmax 50% VC on Monday were recorded in subjects with and without byssinosis with a significantly larger mean reduction in byssinotics (FEV1·0, P < 0·01; ˙Vmax 50% VC, P < 0·05). ˙Vmax 50% VC proved to be a more sensitive test for detecting acute effects of vegetable dust than FEV1·0. The acute respiratory response of the subjects exposed to similar concentrations of flax and mixtures of two different proportions of flax and hemp dust was found to be equal.

The association between the prevalence of both byssinosis and chronic bronchitis and the level of airborne dust was examined in workers in preparing departments in flax mills in Northern Ireland. A weak association between the dust level and byssinosis was found but not between the dust level and chronic bronchitis. It is suggested that the disparity of these associations may have arisen because the diagnosis of byssinosis, as in most recent published studies, was based on relatively acute and reversible symptoms which are more likely to be closely related to the current dust levels than the slowly developing symptoms on which the diagnosis of chronic bronchitis was based. Furthermore an association between chronic bronchitis and the dust levels is likely to be obscured to some extent by the effects of other non-industrial respiratory irritants such as tobacco smoke. Some hypotheses of the basic aetiology of byssinosis are discussed.

This paper is of some historical interest. It describes an investigation to determine whether byssinosis occurred among workers in the waste cotton industry. It was undertaken in 1950 at the instigation of the Minister of National Insurance.

The materials used in the industry were (1) cotton that had been previously spun, and (2) waste material discarded during the preparations for spinning higher grades of yarn. A proportion of raw cotton was sometimes blended with the waste.

Twenty-two mills, representative of the industry, were surveyed. All the men in these mills, who were over 35 years of age and with at least 10 years' exposure to cotton dust, were seen. The investigations included a work history, a clinical examination, an assessment of effort dyspnoea, and a chest radiograph.

There were 140 men who had never been exposed to any dust hazard other than waste cotton. In this group were found seven (5%) men with disabling byssinosis and 35 (25%) men with lesser degrees of the same disease. There were also 15 (11%) men with bronchitis or emphysema without byssinosis.

Thus it was established that byssinosis did occur in the waste cotton industry. Insurance cover, under the National Insurance (Industrial Injuries) Act, 1946, was subsequently extended to workers in the waste cotton industry.

The survey provided no evidence that either the type of waste cotton processed or an admixture of raw cotton played a significant part in the aetiology or incidence of the disease.

Fourteen subjects of whom 12 were cotton mill blow- or card-room workers were exposed in a plastic tent for periods of three or four hours to airborne mill dust either of unrestricted size distribution (total dust) or containing only particles of less than 7μ(fine dust).

A significant fall in indirect maximum breathing capacity followed exposure to either total or fine dust in most experiments. The response to total dust usually appeared a little larger than to fine but the concentration of fine particles in the unfiltered air was rather higher. The changes in the single-breath nitrogen clearance index and the inspiratory airways resistance were less constant, but the general pattern followed that of the ventilatory capacity.

It is concluded that the fine fraction (under 7μ) of cotton mill dust produces changes in respiratory function and may be alone responsible. The findings suggest a direct action by the dust on the smaller air passages and imply that to be completely effective dust suppression measures in cotton mills should remove fine dust.

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An epidemiological survey of 414 English and 980 Dutch male cotton workers was undertaken to determine the prevalence of byssinosis and respiratory symptoms, and to compare the ventilatory capacities in the two populations, with particular reference to the influence of air pollution. The English workers were employed in six mills in Lancashire and the Dutch workers in three mills in Almelo spinning similar grades of cotton.

The methods used included a questionnaire on respiratory symptoms and illnesses, the collection and examination of sputum, and the measurement of the forced expiratory volume over 0·75 sec. Concentrations of smoke and sulphur dioxide were measured in the English and Dutch towns.

The crude rates for byssinosis were similar, 13·5% and 17% respectively in the English and Dutch card and blow rooms, and 1·5% and 1·6% respectively in the spinning rooms. The English workers had significantly higher prevalences of persistent cough and persistent phlegm and significantly lower indirect maximum breathing capacities. These findings were supported by the results of a sputum survey. Nearly twice as many English produced specimens, and the mean volume of sputum was greater for the English workers.

The prevalence of bronchitis, defined as persistent phlegm and at least one chest illness during the past three years, causing absence from work, was higher in the English than in the Dutch workers in both types of work room, but not significantly so after standardizing for differences in age. Since there are important differences in the social security systems of the two countries, which may encourage more absence from illness among the Dutch, a comparison of bronchitis thus defined is likely to be invalid.

The higher prevalences of respiratory symptoms and lower ventilatory capacities in the English are unlikely to be due to observer error. They are discussed in relation to smoking habits, exposure to cotton dust, and air pollution. The most likely explanation of the unfavourable picture presented by the English workers is the much higher level of air pollution in Lancashire.

Bulk cotton samples and airborne vertical elutriated cotton dusts were obtained from textile mills in Shanghai, People's Republic of China. Analysis of endotoxin contents revealed that baled cottons which were grown in different countries varied in endotoxin contamination. The two textile mills, which operated at similar overall airborne dust levels, differed markedly in the levels of airborne endotoxins. The data suggest that the biological activity or "toxicity" of airborne cotton dusts may not be correlated directly with gravimetric dust levels.

In an epidemiological study carried out in three textile mills at Ahmedabad, India, 929 workers were examined from the spinning departments. The mean prevalence of byssinosis in the blow section was 29.62%, whereas in the card section it was 37.83%. The concentrations of cotton dust (dust less fly) were high in the blow and card sections (4.00 mg/m3 in the blow and 3.06 mg/m3 in the card section). This study suggests that the prevalence of byssinosis is not low in the textile mills of India as reported in many earlier Indian studies.

Data presented in this study support the finding that cotton and flax dusts contain agents which potentiate the formation or accumulation of histamine or both in the lungs of guinea pigs exposed to dust, and that such agents are present at much higher levels in cotton dust than in flax dust. The potentiating effect may be through the recruitment of mast cells into the lung. Both cotton and flax dusts contain methylating enzyme inhibitory agents, whereas cotton dust also contains agents that inhibit histaminase activity; flax dust contains agents potentiating histamine activity. These agents working together result in the accumulation or depletion of histamine observed in the different groups of animals exposed to either cotton or flax dust in this study.

Manual flax processing originated in Egypt in 2 000 BC. In the present study a representative sample of the workers involved in this trade, where flax is processed in small workshops or homes, was examined, and their dust exposure was evaluated. The study showed that workers handling and processing flax are exposed to high concentrations of dust; the levels of dust at hackling and combing are considerably higher than at batting and spinning. Byssinosis prevailed in 22-9% of the examined workers, and 18-4% of them had their forced expiratory volume in one second reduced by more than 10% at the end of the first morning work period (4 hours) of the week. Both the rates and the grades of these syndromes increased with duration of exposure. Smoking appeared to be one of the important contributory factors in the production of byssinosis. The relationship between dust concentration and prevalence of byssinosis seems to be curvilinear.

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