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1.  Asbestosis: a study of dose-response relationships in an asbestos textile factory 
ABSTRACT A group of 379 men who had worked at an asbestos textile factory for at least 10 years has been followed up. The prevalence of crepitations, 'possible asbestosis', certified asbestosis, small opacities in the chest radiograph and values of lung function have been related to dust levels. The type of asbestos processed was predominantly chrysotile although a substantial amount of crocidolite had also been used in the past. There was a higher prevalence of crepitations than had been observed previously at the same factory. The presence of crepitations is not a specific effect of asbestos exposure and 'possible asbestosis', a combined judgement of two physicians on whether a man had developed signs which might be attributable to early asbestosis, was preferred. Fifty per cent of men with a diagnosis of possible asbestosis were certified as suffering from asbestosis by the pneumoconiosis Medical Panel within 3-5 yr. The most reliable data relate to men first employed after 1950; 6·6% of men in this group had possible asbestosis after an average length of follow-up of 16 yr and an average exposure to 5 fibre/cm3 where the dust levels were determined by static area samplers. The forced expiratory volume and forced vital capacity declined significantly with exposure, after allowing for age and height, but there was no decline in the total lung capacity. The transfer factor also declined with exposure, but not to a statistically significant extent. The non-smokers and light smokers as a group had less crepitations, asbestosis and small opacities on the chest radiograph than heavier smokers with similar exposure. Combining dust concentrations to form the cumulative dose may not be completely satisfactory, and a family of measures was investigated which allows for elimination of dust from the lungs and includes the cumulative dose as a special case. Because the rate of elimination of dust from the lungs is unknown and cannot be estimated from the data, this approach leads to a wide range of possible interpretations of the data; for example the concentration such that possible asbestosis occurs in no more than 1% of men after 40 years' exposure could be as high as 1·1 fibres/cm3 or may have to be as low as 0·3 fibres/cm3. This range is wide because the data relate to higher dust levels, and a shorter period of follow-up. Until data are available on groups exposed to lower levels it will not be possible to assess the effects of the current standard with any certainty. However, the results of this study show that it is important to continue to reduce dust levels to values as low as possible.
PMCID: PMC1008524  PMID: 465379
5.  Byssinosis among Winders in the Cotton Industry 
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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PMCID: PMC1008542  PMID: 6023077
7.  Dust in Card Rooms: A Continuing Problem in the Cotton-Spinning Industry 
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.
PMCID: PMC1038353  PMID: 14180475
9.  The Size of Cotton Dust Particles Causing Byssinosis: An Environmental and Physiological Study 
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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PMCID: PMC1038125
10.  Byssinosis: The Acute Effect on Ventilatory Capacity of Dusts in Cotton Ginneries, Cotton, Sisal, and Jute Mills 
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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PMCID: PMC1038126  PMID: 13898707
12.  A Clinical and Environmental Study of Byssinosis in the Lancashire Cotton Industry 
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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PMCID: PMC1039177  PMID: 14437722
13.  Measuring Dust Exposure with the Thermal Precipitator in Collieries and Foundries 
The standard thermal precipitator has been modified for field surveys of airborne dust exposure so as to make it more portable. A microprojector is used when assessing the samples and for coal-mine dusts the counts are restricted to the range 0·5 to 5 microns.
In industrial environments the dust concentration appears to vary with a standard deviation of more than 50% of the mean. Part of this variability is due to errors of the thermal precipitator. The standard error of a count of a sample is about 10% to 15% in practical work and the combined effect of this and other errors is that the standard error of a single result is about 15%. However, in practice this can be neglected since the dust concentration itself is so variable. A more important source of error is the bias, due to overlapping among the particles on the cover glasses. The count may give a serious underestimate of the number of airborne particles if high sample densities are used.
The product of average concentration and duration of exposure is probably a good index of the dose of dust retained in a man's lungs. The duration of exposure is measured by a simple time study made at the same time as the concentration is measured.
Samples are taken near workers chosen at random to give unbiased estimates of the dust exposure. Ideally successive samples are taken alongside different workers. However, in a survey at a colliery it was not possible to do this and each day had to be spent with one collier. The mean dust exposure of the coal-getters was 2,860 particle-hours per shift, of those on stone work 2,250 particle-hours per shift, and the remainder had a mean dust exposure of 1,010 particle-hours per shift.
In a survey at a steel works successive samples could be taken alongside different workers. It was found that the dustiness was unrelated to the apparently dusty processes and as the dust was very fine it was suspected that it was the normal atmospheric pollution of the neighbourhood. This was confirmed by samples taken outside.
The cost of such surveys is found to lie between £1 and £2 per sample taken and consequently alternative instruments are being developed which can run unattended for long periods. In future research studies respiratory ventilation as well as dust exposure may be measured over many years, which, combined with periodic medical examinations, would enable the relation between dust exposure and its effects on the men to be determined.
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PMCID: PMC1037902  PMID: 13651553

Results 1-17 (17)