Document 2JRzkEgbYD9DNnaV9gQp9yg7r

Instrumenwiion far Dust Measurement PERSONAL DUST SAMPLING WITH THE CIP-10 FOR A BETTER MEDICAL MANAGEMENT OF THE PNEUMOCONIOSIS RISK IN COAL MINES M. ZITTER B. Mahieu E. de Surgy P. Sebastien G. Auburtin A. Mas HouiUeres du Bassin de Lorraine, Freyming-Merlebach, France INTRODUCTION In French coal mines, static sampling is used for regulatory measurements ofambient dust concentrations in workings. In 1983 however, the personal dust sampler CIP-10 became commercially available. This air sampling instrument was designed by CERCHAR (` `Centre d'Etudes et Recherches de Charbonnages de France* ') to measure individual exposures to respirable dust in mining environments. The CIP-10 is a small (18 x 7 x 2.5 cm) and light (300 g) in strument, conveniently worn by die miners. It can be lodged into a chest pocket or into a chest strap. Wearing the CIP-10 is generally well accepted by the workers. The sampler is operating at a flow rate of 101/min and collects die respirable fraction of the dust within a rotary foam. Dust can be ashed or extracted from the foam for laboratory analyses, such as free silica determination. The CIP-10 has enough autonomy to cover a foil 8-hour shift. More technical information on the CIP-10 is available elsewhere (Courbon et al, 1988). Personal sampling greatly modified our existing views on dust exposure in coal mines. Results of a large scale monitoring study ofpersonal exposures to respirable dust in French coal mines have just been reported (Bruyet et al, 1988). Several more specific surveys were carried-out at die request of the occupational physicians from collieries in Lorraine. They pro vided other useful informations, examples ofwhich are given in this report. USEFULNESS OF PERSONAL DUST SAMPUNG Documenting Specific Exposures In French mines, some goafs must be filled-up, especially in the case of flat working, when heating, water irruption or min ing damages are feared. When hydraulic stowing is not possi ble, pneumatic stowing is sometimes used to fill-up the goafs with shales. The shales are collected in the washing plants, sent back underground with successive tubings, belt-conveyed to the face and sprayed out pneumatically from a stowing machine located in the top road. Since it was often found in the career ofpneumoconiotics, this technique was suspected to carry a substantial pneumoconiosis risk. In February 1984, a survey was carried out in a particular working at Wendel mine to measure personal exposures associated with the pneumatic stowing technique. For a period of 10 days, all workers engaged in the operation and two technicians were equipped with a CIP-10. Measurement results are reported in Tables I and n. Concentrations of respirable dust were in the range 11.2-91.5 mg/m3. Such Table I Personal Dust Sampling with the CIP 10 Pneumatic Stowing Technique Wendel Pit, February 1984 Pneumatic T n'138 T n' 139 Stowing Mean Technique S n*140 Ratio S/T 20/2 3.70 6.70 5,20 11,20 115% 21/2 8,00 7,40 7,70 52,50 581% 22/2 15, 30 11,70 13,50 77,70 475% 23/2 9,00 8,80 8,90 39,50 343% 24/2 20, 10 14, 10 17,10 33,50 95% 27/2 6,40 7,10 6,70 22, 10 230% 28/2 7,20 6,70 6,90 55,90 710% 29/2 40,00 37,50 38,70 91,50 136% 1/3 12,50 15,40 14,00 68,50 389% 862 RESULTS OF RESPIRABLE DUST IN HG/H3 T = Technicians S - Stover 440- Table 0 Personal Dust Sampling with the CIP 10 Instrumentationfor Dust Measurement PNEUMATIC STOWING TECHNIQUE VgNDEL PIT FEBRUARY 1984 20/2 21/2 22/2 I TECHNICIANS 23/2 24/2 27/2 28/2 29/2 I STOWER V3 RATIO STOWER / TECHNICIANS 21/2 23/2 27/2 29/2 863 Instrumentationfor Dust Measurement high figures are reported with caution, since a saturation ef fect was observed with the CIP-10 at very high concentrations. The stower was the most exposed. By-standers could be 8 times less exposed. Pneumatic stowing was also affecting the exposures ofpeople at the face. The pneumatic stowing tech nique is not used any more in mines from Lorraine since the end of 1986. Other surveys with the CIP-10 were able to document un suspected exposures, such as those experienced by the elec tromechanics underground. These people maintain the energy sources and the mining equipment. They generally stand out ofdie face, except in case offailure ofthe machinery. Because not directly involved in coal extraction, they are not con sidered as "exposed" personnel according to regulations. In the period June 10th-June 19th 1987, all electromechanics from a working wore a CIP-10. Their activities were observed and recorded. Tables m and IV present measurements ofper sonal exposures and of ambient concentrations IS m above the working in the top road on die air return. Values for per sonal exposures were linearly related to the time spent at the face or in the top road. The highest exposure reached die stan dard level for regulatory ambient concentration. In another survey, the exposures of 16 workers involved in to heading operations in the seams were measured during 5 days. Three exposure zones were defined: (1) the shearing area, (2) between die shearing area and the deduster and (3) from the back of the deduster up to the entrance of the headings. A total of 55 measurements were done. Among those, 16 were in excess of 2 mg/m3. Interestingly enough, most of die excessive exposures occurred in zone 3, a day when die shearer did not operate. (Tables V and VI). Assessing the Validity of Job Re-allocation In French collieries, medical management of the pneumoconiosis risk is mainly based on job re-allocation. Diagnosed cases are moved to workings known to be less dus ty. The dustiness ofeach working is deducted from the results ofregulatory measurements done by static sampling. A survey was carried out with the CIP-10 in order to check if this way ofre-allocatingjobs was effectively ensuring less severe per sonal exposure for these diagnosed cases. In Summer 1987,40 active miners with a chest X-ray scored 0/1 and 30 active miners compensated for pneumoconiosis were selected. Personal exposures of workers in the two groups were assessed by a total of476 measurements with the CIP-10. Results are reported in Tables VII and VIII. In average, exposures were less for pneumoconiotics (0.63-0.67 mg/m3) than for other re-allocated but uncompensated workers (0.89 mg/m3). Some personal exposures in excess of 2 mg/m3 were, however, detected (Mahieu et al, 1988). These cases were immediately corrected. Table ITT Personal Dust Sampling with die CIP 10 DATE Static Mea sures Entry & Bottom road Day Shift mg/m3 mg/m3 1 l 10/6 3,98 5,15 1 11/6 2 4,17 1,83 12/6 1 1 15/6 2 1 16/6 2 17/6 1 1 18/6 1 i9/6 4,17 4,09 4,99 (0,33) 4,21 5,20 5,79 5,99 1,66 5,23 5,81 4,26 Values Means SEN 14,00 4,63 1,03 1,00 1,66 ,00 EXPOSURE SITES DURING THE SHIFT Bottom road mg/m3 \ Bottom road Coal face 6 Top road mg/m3 % Coal face 6 Top road Top road mg/m3 % mg/m3 % 1,72 4,32 3,30 3,72 2,49 2,53 62,90 93,40 48,30 49, 10 (0,50) 1,94 1,34 1,58 1,32 46,50 73,20 86,30 72, 10 3,80 91,10 4,27 102,30 1,84 44, 10 3 , OO 73,30 4,28 3,85 5,05 102,60 92,30 101,20 2,97 70, 50 2,79 66,20 3,87 3,96 4,04 95,90 2,97 57,10 1,86 3,92 67,70 5,89 5,89 113,20 113,20 3,07 1,83 51,20 5,24 3,72 6,14 62,10 120,50 1,70 3 2,50 4,04 3,54 2,99 77,20 67,60 51,40 4,25 73,50 1,35 1,83 2,85 2,50 1,24 42.90 66.90 5,31 124,60 10,00 1,89 ,60 8,00 57,88 16,78 14,00 2,95 1,05 10,00 60,58 22,45 6,00 3,22 ,63 6,00 70,08 16,56 12,00 4,69 1*7 10,00 102,79 16,80 PERSONAL DUST SAMPLING WITH THE CIP 10 ELECTROMECHANICS MARIENAU PIT Seas ED JUNE 1987 Results of respirable dust in mq/3 Results of individual measures i in the ratio of ambient regu latory measurements (15 m above the wor king in fhe top road on the air return) (*) doubtful values 864 Table IV Personal Dust Sampling with the CIP 10 Instrumentation for Dust Measurement ELECTROMECHANICS MARIENAU PU seam ED JUNE 1987 ENTRY & BOTTOM ROAD BOTTOM ROAD BOTTOM ROAD COALFACE & TOP ROAD COAL FACE & TOP ROAD TOP ROAD SVXtf .!A DISCUSSION According to the governmental directives of December 1975, in the French coal mines the concentration of respirable dust is regularly controlled and measured by static ambient sam pling in well-defined locations. The respirable dust is collected using the CPM3 air sampling instrument (Fabries et al., 1987). Workings are ranked according to their dustiness. Stan dard levels are in terms of gravimetric concentration of respirable dust (as collected by the CPM3) in the ambient air. The observed differences in die pneumoconiotic risk among coal fields (Amoudru, 1987) have been taken into account to define standard levels which are specific to each coal field. In Lorraine, the standard level is at 4.5 mg/m3 below 1% free silica, and gradually decreases above 1%. All the work ings are regularly classified according to this level. Also the regulations impose for any worker exposed an an nual medical examination and a chest X-ray. At the term of that examination, every year the occupational physician defines for each worker die types ofworkings in which he can be employed, essentially in function of the data of the chest radiography. So the sound subject (Aptitude 1) will be able to work everywhere (workings ranked O, A, B, C, D, E) and the serious pneumoconiotics (aptitude 5) will only be author ized to work in non dusty working places (rank O); in general they are re-allocated in surface jobs. We know now that there is a heterogeneity ofexposures within die workings. This one could have been in the past at the origin of some cases of early and/or severe pneumoconiosis. Re allocation must also take into account this heterogeneity. In ternal procedures are now in place for a better protection of active miners with slight X-ray changes (score 0/1): their ex posures are followed to limit under 5 g the annual cumulative inhaled dose according to their work loads. Another advantage of personal sampling in coal mines is the ability to detect unsuspected high exposures. The surveys among electromechanics and among workers engaged in heading operations beautifully illustrated this point. Those different studies carried out with the CIP-10 on the in dications of the occupational physician have brought useful contributions to the improvement ofthe technical and medical prevention of pneumoconiosis in our coal mines. The CIP-10 has been found to be a reliable instrument. Personal sampling is considered useful to identify needs for appropriate control measures and to follow cases at risk. 865 Instrumentation for Dust Measurement REFERENCES 1. Amoudru, C. (1987). Les pneumoconioses: dimension actuelle des proble'mes CoUoque INSERM, 155:3-40. 2. Bruyet, B., P. Courbon, and P. Sdnstien, (1988). Personal exposures to respirable dust in French coal mines. Presented at the symposium on pneumoconiosis, Shen Yang, China, May 30-June 2 1988. 3. Courbon, P., R. Wrobel, and J.F. Fabrics, (1988). A new individual dust sampler: the CIP-lOA/in. Occup. Hyg. 32:1, 129-143. 4. Fabries, J.F., R. Wrobel, and P. Courbon (1987). A compact high- flowrate respirable dust sampler: the CPM3 Ann. Occup. Hyg. 3V2 195-209. 5. Mahieu, B., E. deSurgy, and M. Zitter, (1988). Surveillance des agents suspects de Pneumoconiose par capteur individuel de poussieres <fan< les mines de charbon. Presented at the 20th Joumees Nationales de Me'decine du Travail Toulouse, France, May 18-21, 1988. Table V Personal Dust .Sampling with the CIP 10 Heading Workings Marienau Pit SDS June 1988 EMPLOYMENT | 13/6 14/6 16/6 17/6 Overman iTi. 1,63 iTi. ,59 iTi. (13,0) iTi. 1,67 Haulager Z3 (3,10) Haulager Z3 1,66 "Debloqueur" Z+ 1,88 Z+ 2,99 Z+ 1,83 Z+ 1,61 Annexes Z3 2,68 Z2 1,39 Piper Z2 1,40 Z3 2,85 Z3 1,40 Z3 1,66 Piper Z2 1,14 Z3 1,27 Z3 2,64 Z3 1,61 "Resserrage bride" Z3 2,42 Divers Z3 1,74 Z3 1,04 Z3 1,00 Divers Z3 1,67 Z3 1,18 Z3 1,85 Hewer Hewer Hewer Z2 ( , 08) Z2 1,04 Z2 1,06 Z2 Z1 Z2 1,48 1,96 2,57 Z2 Z2 Z2 1,13 ,11 1,21 Z2 Z1 Z2 1,41 1,41 1,06 Hewer Cutterman Z2 ,93 Z2 1,01 Z2 ,80 Z2 ( ,01) Z1 1,58 Z1 2,52 Cutterman (*) doubtful values Z1 ( ,18) Z1 1,75 Z1 1,34 Z1 1,85 Results of respirable dust in mg/m3 Activity and localisation of workers during the shift 20/6 Z3 1,12 Z3 ( ,92) Z3 2,51 Z+ 3,64 Z3 ,50 Z2 (1,15) Z3 2,81 Z3 1,04 Z2 1,56 Z3 4,26 Z3 4,35 Z3 3,14 Z3 3,69 Z3 3,10 866 Table VI Personal Dust Sampling with the CIP 10 Instrumentation for Dust Measurement HEADING WORKINGS MARIENAU PIT SDS JUNE 1988 = AMBIENT DUST RESULTS ^ PERSONAL DUST RESULTS <5 DOUBTFUL VALUES REPARTITION ACCORDING TO THE ZONES AND TO THE DAYS 867 Instrumentation for Dust Measurement Table VH Personal Dust Sampling with the CIP 10 E mg / m3 A RE-ALLOCATION OF PNEUMOCONIOTIC MINERS CONTROL JULY 1987 APTITUDE 2 (CHEST X-RAY SCORED CM - ILO 1980) /MEAN; 0,$$> 3 -I 2 -I l J i: ;i i m *. -f i <* .' t *3 j r. {111! ; 11 i i i i i i ii if i i i i i f it i i i I n i i i i ri i m i i i i ii i i 868 mg l m3 si Instrumentation for Dust Measurement Table VIII Personal Dust Sampling with the CIP 10 RE-ALLOCATION OF PNEUMOCONIOTIC MINERS CONTROL JULY 1987 ' APTITUDE 3 APTITUDE 4 (CHEST X-RAY SCORED VO OR MORE - ILO 1980) 4A MZAfti ; 0,63 JStfAN ; C\b7 3A 2A lA nA 869 Epidemiology--Silica & Asbestos PULMONARY FUNCTION CHANGES IN VERMONT GRANITE WORKERS WILLIAM G.B. GRAHAM Sheila Weaver Taka Ashikaga David Hemenway Robert O'Grady Depts. of Medicine, Biostatistics, and Engineering, University of Vermont and the Vermont State Health Department, Burlington, VT, USA ABSTRACT Previous studies have suggested that excessive losses of FVC and FEVj were occurring in Vermont granite workers despite the fact that quartz levels existing in the industry were below the current OSHA standards. We re-examined these losses in granite workers over an eight year period, testing the workforce semiannual ly from 1979 to 1987. All workers, including stone shed, quarry and office were offered forced spirometry using a 10 L. Collins water sealed spirometer. In the peak year of participation (1983), 887 workers out of a total ofapproximately 1400 were tested. Estimates oflongitudinal loss were based on711 workers who par ticipated in at least 3 ofthe surveys. The mean age ofthis group was 42.9 years, and the mean years employed was 19.3 yrs. 21.4% were non-smokers (NS), 34.2% ex-smokers (ES), and 44.4% current smokers (CS). Average annual losses ofFVC were .025 .055 L. (CS: .032L.;NS: .014L.;ES: .024 L.). Average annual losses of FEVj were .036 .040 L. (CS: .044 L.; NS: .027 L.; ES: .033 L.). Analysis of covariance in dicated that losses were related to die initial values for FVC or FEVjo, height, age, and smoking history. The losses of both FVC and FEVjo were not correlated with years employed in the granite industry. The losses ofpulmonary function were significantly smaller than those estimated previously, which were .070-.080 L in FVC, and .050-.070 in FEVjo- We conclude that current dust levels in the Vermont granite industry do not accelerate pulmonary function loss. BACKGROUND A cross-sectional analysis ofpulmonary function loss in Ver mont granite workers suggested a small loss in the forced vital capacity (FVC) and FEVi due to dust exposure, amounting to 2 ml/year, compared with a 30 ml loss annually due to ag ing, and a 9 ml loss due to smoking.1 Although these results were criticized as resulting in a negligible loss over a work ing lifetime,2 a later longitudinal study3 stated that annual losses of FEVj were between 50-70 ml, and FVC losses were between 70-80 ml. These studies suggesting excessive pulmonary function loss related to granite dust exposure (average dust-year 523 micrograms/cubic meter, average quartz year ofexposure 50 micrograms/cubic meter) were in fluential in the current NIOSH recommended exposure limit of 50 micrograms/cubic meter for crystalline silica. The operative OSHA limit is 100 micrograms/cubic meter. In 1981, we published data4 concluding that die predicted losses of pulmonary function had not occurred, based on a follow-up study ofdie same individual workers who had been tested previously. Large increases had occurred in vital capacity values (106 ml year), and there were essentially no losses annually in FEVi values. The authors of die previous papers agreed5 that the FVC measurements were invalid because of short expiratory times, though the decrements of FEVj values continue to be discussed.6 This study presents further longitudinal data on pulmonary 870 function losses in the Vermont granite population. The initial survey, done in 1979, was the basis for our 1981 publication. Follow-up industry-wide surveys were carried out semi-annually to 1987, giving an eight year period of observation. The purpose ofthe study was to characterize the rate ofpulmonary function change and to determine whether exposure to the relatively low levels of granite dust prevail ing in die industry significantly affect pulmonary function loss. METHODS All employees in die Vermont granite industry, which includes approximately 70 stone sheds and 6 quarries in 5 different communities, were offered forced spirometry semiannually from 1979 to 1987. hi 1983 these tests were carried out in con junction with a chest radiographic survey. Job categories in cluded the various stone shed jobs (polisher, cutter, planer, wire saw, etc.) as well as outdoor quarry workers and office workers. Spirometry was performed on a 10 L. water-sealed Collins spirometer according to recommendations of die Epidemiology Standardization Project.7 Values for FVC and FEVj, ambient temperature, age, years employed in die in dustry, and smoking history were recorded for each worker. In addition, analysis oftotal gravimetric dust levels was car ried out using personal breathing zone samplers. Data were analyzed using basic univariate analysis, as well as analysis of covariance. RESULTS The numbers ofworkers tested in the semi-annual surveys is given in Table 1. The numbers listed for 1979 are artifactually low, since the initial 150 workers tested were excluded because they had been tested on a different instrument which was not precisely calibrated. Subsequent spirometries were performed on the Collins spirometer used by the previous workers from 1970-74. In addition, approximately 100 trac ings have been lost and are not available for analysis. Only 173 workers were tested on all five occasions over an eight year period, reflecting the fact that new workers were com ing into the work force, others were retiring or were unavailable for testing because of vacation, sick leave or a mobile van at die work place for the first time since 1976. There were 711 workers who were tested 3 times or more. The basic statistics of this group are listed in Table II. Near ly 80% of the workers were either ex-smokers or current smokers; only 21.4% were never smokers. The average number of years in granite was nearly 20. Longitudinal pulmonary function changes are based on die 711 subjects, both shed and quarry workers, who were tested three or more times. This data is summarized in Table HI. Yearly decrements in FEVj, FVC and FEVi/FVC x 100 were esti mated for each worker as the slope of the fitted least squares regression line for each individual. These slopes were approx imately normally distributed and smokers exhibited more function loss than non-smokers and ex-smokers. Overall an nual losses were .025 L.for FVC, .036 L. for FEVi, and 0.37% for the FEV|/FVC ratio. Non-smokers have die low est losses, ex-smokers intermediate, and current smokers die highest losses. Within different smoking categories (non smoker, ex-smoker, and current smoker), there was no differ ence in losses between exposure categories we presume to be different, i.e. office, shed and quarry workers. Decrements in lung function appear to be similar to those reported in other working populations not exposed to dust in the occupational Epidemiology--Silica & Asbestos environment, and are clearly far lower than the estimates of longitudinal loss reported previously among Vermont granite workers. To separate out the effects ofindependent variables (age, value of initial measurement, smoking status and granite working history), we carried out an analysis of covariance. For the FVC and FEVj, the independent variables of initial FVC, height, age and smoking had a significant effect on pulmonary function changes (p<.001 or less), whereas "years in granite," used as an index ofgranite exposure, had no signifi cant effect (p=.144 for FVC and .151 for FEVi). DISCUSSION These results indicate that the previous estimates ofpulmonary loss in Vermont granite workers were probably in error, and we attribute the conflicting results to the fact that our spirometric measurements were techically rigorous, with careful attention to duration of expiration, calibration of the spirometer, and assuring maximum voluntary effort. Our analysis ofdust levels in the stone sheds suggest that no change has occurred in the industry since 1970-78. The mean dust concentration was 601 micrograms/cubic meter, which is quite similar to the results reported previously.8 Accepting die quartz levels at 10%, as stated by the previous workers,8 the average quartz exposure estimates are 60 micrograms/cubic meter, which is below the current OSHA limit, but above the recommended exposure limit of 50 micrograms/cubic meter proposed by NIOSH. We conclude that current pulmonary function losses are comparable to those seen in non-dust exposed working populations, and that cur rent dust exposures in the granite industry do not contribute to pulmonary function loss. Further, the observed annual losses are approximately halfthe values reported by previous studies in Vermont granite workers. 1979 426 1981 613 Table I Number of Workers With Data Available Years Tested 1983 1985 1987 3 or more 864 806 661 711 all 5 173 Table n Basic Mean Data of Workers With 3 or More Tests (All Subjects = 711) Age in 1983 Height Years in granite Mean FEV 1.0. , L. Mean FVC, L. Mean FEV 1.0/FVC 42.903 68.3 19.336 3.687 4.804 .766 871 Epidemiology--Silica < Asbestos Table m Mean Annual Longitudinal Losses in Pulmonary Function Parameters in 711 Workers Tested 3 or More Times Smokers N=316 Ex-smokers N=243 Non-smpkers N=152 All n = 711 FVC, L. FEV 1.0,L. FEV 1/FVC .032 .044 .437 .024 .033 .318 .014 .027 .314 x 100 No difference was found in annual losses of and FVC between office, quarry and stone shed workers in different smoking categories. .025 .036 .370 FEV 1.0 overall or REFERENCES 1. Theriault, G.P., Peters, J.M., Fine, LJ.: Pulmonary FunctioninGranite Shed Workers of Vermont. Arch. Environ. Health. 28:23-27 (1974). 2. Morgan, W.K.C.: The Walmus and the Carpenter ofthe Silca Criteria Standard. J. Occup. Med. 17:782-3 (1975). 3. Musk, A.W., Peter, J.M., Wegman, D.H., Fine, LJ.: Pulmonary Func tion in Granite Dust Exposure: a Four Year Follow-up. Am. Rev. Rap. Dis. 115:769-76 (1977). 4. Graham,W.G.B.,0'Gfady,R.V.,Dubuc,B.:PuliDoiiaryFunctiooLoss in the Vermont Granite Workers. Am. Rev. Resp. Dis. 123:25-28(1981). 5. Wegman, D.H., Eisen, E., Peters, J.M.: Letter to the Editor. Am. Rev. Resp. Dis. 128:776-777 (1983). 6. Eisen, E.E., Wegman, D.H., Louis, T.A.: Effects ofSelection in a Pro spective Study of Forced Expiratory Volume in Vermont Granite Workers. Am. Rev. Resp. Dis. 128:587-591 (1983). 7. Ferris, B.G.: Epidemiology Standardization Project. Am. Rev. Resp. Dis. 118:1-120 Part2 (1978). 8. Eisen, E.A., Smith, T.J., Wegman, D.H., Louis, T.S., Froines, J.: Estimation ofLong Term Dust Exposures in the Vermont Granite Sheds. Am. bid. Hyg. Assoc. J.: 45:89-94 (1984). Supported by National Institute for Occupational Safety and Health (5 ROl OH0135-04). 872 Prevention/Intervention ARBEITSMEDIZINISCHE VORSORGEUNTERSCICHUNGEN FUR QUARZFEINSTAUBGEFAHRDETE BESCHAFTIGTE IN DER BUNDESREPUBLIK DEUTSCHLAND SIEGFRIED KNOBLOCH, Dipl.-Ing. Steinbmchs--Berufisgenossenschaft, Hanover, Federal Republic of Germany In der Bundesrepublick Deutschland mussen alle Beschaftigten, die an ihrem Arbeitsplatz durch Quarzfeinstaub gefahrdet werden, vor Beginn ihrer Tatigkeit und danach in regelmia/ligen Abstanden arbeitsmedizinisch untersucht werden. Wann kann von einer Gefahrdung gesprochen werden? In der Bundesrepublik Deutschland ist fur Quarzfeinstaub in der Atemluft der Beschaftigten am Arbeitsplatz eine Schadstoffkonzentration von o, 15 mg/m3 zulassig. Dieser Wert setzt voraus, da/1 nur gesunde Personnen dieser Schadstoffkonzentration ausgesetzgt werden. Daraus folgt, da/1 Beschaftigte schon bei weitaus niedrigeren Schadstoffkonzentrationen arbeitsmedizinisch uberwacht werden mussen. In der Bundesrepublik Deutschland ist diese Ausloseschwelle auf die Halfte des oben genannten Grenzertes festgelegt worden. Die arbeitsmedizinischen Untersuchungen mussen vor Ausnahme der Tatigkeit (Erstuntersuchung) und danach in regelma/ligen Abstanden (Nachuntersuchimgen) wiederholt werden. Die Untersuchungen selbst durfen nur von besonderes erfahrenen und ermachtigten Arzten vorgenommen werden. Sofem diese keine kurzeren Zeitraume vor schlagben, erfolgen die Untersuchungen bei quarzfeinstaubgefahrdeten Beschaftigten in Abstanden von 3 Jahren. Nur wenn und solange der Arzt keine Bedenken erhebt, durfen die Beschaftigten dan ihrer Arbeit weiter nachgehen. Der Untemehmer hat die Untersuchungstermine zu uberwachen, die Untersuchungen zu veranlassen, zu bezahJen und auch fur jeden Beschaftigten eine Gesundheitskartei zu fuhren. In dieser Kartei sind neben den personlichen Daten festzuhalten: Tag der Einstellung und des Ausscheidens, Art der Gefahrdungsmoglichkeiten, Art der Tatigkeit mit Angabe des Zeitpunktes ihres Beginns und ihres Endes, Angaben von Zeiten uber fruhere Tatigkeiten, bei denen eine Gefahrdungsmoglichkeit bestand, Datum und Ergebnis der arbeitsmedizinischen Vorsorgeuntersuchungen. Die Steinbruchs-Berufsgenossenschaft, der Trager der gesetzlichen Unfallversichenmg auch fiir die Steinbrache, hat seit Jahrzehnten gleichsam als Serviceleistung--fiir ihre Mitglieder die Terminuverwachung dieser arztlichen Unter suchungen und die Aufbewahrung der Rontgenaufnahmen und sonstigen Unterlagen ubemommen. So sind fiir alle quarzfeinstaubgefahrdeten Beschaftigten luckenlos fur die Dauer ihrer Tatigkeit in einem Mitgliedsunternehmen Unterlagen vorhanden, die bei einer beginnenden oder festgestellten Erkrankung fiir die Beurteilung herangezogen werden konnen. Dies ist gerade im Hinblick auf die Vielzahl der ganz kleinen Steinbruche von sehr grower Bedeutung, da diese Betriebe selbst kaum in der Lage sind, die vorgeschriebenen Karteien zu fuhren und die Unterlagen aufeubewahren. Im Jahr 1986 hat die Steinbruchs-Berufsgenossenschaft begonnen, alle Daten EDV-ma/Jig zu erfassen. Seitdem erhalt jeder Betrieb, in dem Staubgefahrdete versichert sind, 2 Monate vor Ablauf der Untersuchungsfrist eine Benachrichtigung, da/1 eine weitere Untersuchung vorgenommen werden mup. Dieser Benachrichtigung werden nicht nur die notwendigen Formulare, sondem auch eine Liste der in der naheren Umgebung tatigen und von der Berufsgenossenschaft ermachtigten Arzte beigefiigt. Auf diese Weise hat der Beschaftigte die ffeie Arztwahl. Nach der Untersuchung werden die Rontgenaufnahmen und die arztliche Beurteilung der Berufsgenossenschaft zur Aufbewahrung ubergeben. Diese legt schlie/llich alle Unterlagen, die uber einen Beschaftigten vorhanden sind, einem besonders ausgebildeten und geiibten Arzt zur endgultigen Beurteilung vor. Diese Arzte besitzen nicht nur eine langjahrige Berufserfahrung als Lungenfacharzte, sondem haben sich durch die Vielzahl der Falle, die ihnen vorgelegt werden, ein besonders umfangreiches Wissen um die Silikose erworben. Jeder dieser Arzte begutachtet im Jahr etwa 2.000 Personen. Nicht selten kann ein Arzt lo bis 15 Rontgenaufnahmen desselben Beschaftigten zum Vergleich heranziehen. Dieser Arzt entscheidet auch, ob der Beschaftigte weiterhin seiner bisherigen Tatigkeit nachgehen kann, ob die ubliche Untersuchungsfrist von 3 Jahren verkiirzt werden mup und ob ein Beschafdgter gegebenen- falls seinen Arbeitsplatz wechseln m/3. Etwa 20.000 Beschaftigte, die staubgefahrlich tatig sind, werden auf diese Weiseuberwacht. Entscheidend fur den Grad der Gefahrdung eines 873 Preveruion/lntervention Beschaftigten ist neben seinezn Gesundheitszustand auch die Hobe der Schadstoffkonzentration in der Atemluft am Arbeitsplatz. Fur die Arbeitsmedizin ist es sicherlich von sehr gro/?em Interesse, diese beiden Daten einander gegenuberzustelien bzw. zu verknupfen, um eine noch verla/?lichere Beurteilung der Grenzwerte zu eibalten. Die Steinbruchs-Berufsgenossenschaft ist diesem Ziel schon bereits ein gropes Stuck nahergekommen. Seit Jahrzehnten wird eine Zielzahl von Staubmessungen am Arbeitsplatz durchgeftihrt und ausgewertet. Im Jahr 1987 wurde nun mit der Zusammenfiihrung der medizinischen und me/?technischen Daten begonnen. Dabei wurde zunachst besonderer Wert auf eine moglicbst exakte Beschreibung des Arbeitsplatzes und Tadgkeit des einzelnen Beschaftigten gelegt. Bei Wechsel des Betriebes oder Aufnahme einer anderen Tadgkeit werden diese Daten aktualisiert. Auf diese Weise wissen wir schon heute nicht nur, ob ein Beschaftigter gesund ist, sondern seit wann er einer besdmmten Schadstoffkonzentration ausgesetzt ist. Wir beabsichdgen, dieses Verfahren forfzufuhren, so da/? wir schlie/?lich fur diese Beschaftigten uber ihr ganzes Arbeitsleben binweg die entsprecbenden Daten haben. Da nicht nur der Arbeitsplatz, sondern auch die Tadgkeit genau beschrieben und versehlusseit sind, wird es uns kunfdg auch moglich sein, einzelne Personengruppen daraufhin zu untersuchen, ob sie starker gefahrdet sind als andere. Der Vollstandigkeit halver mochte ich noch erwahnen, da/? die Steinbruchs-Berufsgenossenschaft auch einen Rontgenwagen besitzt, der in die Betriebe fahrt und dort an Ort und Stelle die Nachuntersuchungen durchfuhrt. Dadurch ist gewahrleisted, da/? diese Untersuchungen zum vorgeschriebenen Zeitpunkt nahezu luckenlos durchgefuhrt werden und andererseits den Betrieben betrachtliche Kosten fur die Arbeitsunterbrechung erspart bleiben. 874 PREVALENCE OF RADIOGRAPHIC SMALL LUNG OPACITIES AND PLEURAL ABNORMALITIES IN A REPRESENTATIVE SAMPLE OF ADULT FINNS A.J. ZITTING T. Kuusela O. Impivaara* J. Maatela* A. Aromaa* Institute of Occupational Health, Helsinki, Finland and Social Insurance Institution, Turku and Helsinki, Finland ABSTRACT This study is part of the Mini-Finland Health Survey which was carried out in a sample (n=8000) represen tative of die Finnish population aged 30 or over. The aim of the study was to investigate the prevalence or radiographic small lung opacities and pleural abnormalities in this population. Of the standard full size radiographs routinely taken, 7095 (89% of the sample) were acceptable for classification purposes. Two radiologists recorded the findings independently according to the ILO (1980) Classification of Radiographs of Pneumoconioses. The prevalences were calculated on die basis offindings agreed on by the two radiologists. The prevalences ofsmall lung opacities and pleural abnormalities all increased steeply with age and were much higher in men than in women. The prevalences (%, age-adjusted) of die most common findings are given in the table. Men Women Small opacities (at least category 1) Diffuse pleural thickening Pleural plaques Pleural calcification 16.5 10.0 13.8 3.2 10.2 6.6 2.6 2.3 The divergent prevalences in men and women are probably related to differences in working conditions and smoking habits which are currentiy subject to further analysis. These population based findings are likely to constitute a useful basis for various reference purposes. No Paper provided. 875 General Epidemiology OCCUPATIONAL ASTHMA IN MEAT WORKERS EXPOSED TO PROTEOLYTIC ENZYMES S.K. GALSON D.I. Bernstein* J.M. Boiano J.S. Gallagher* A.B. Smith National Institute for Occupational Safety and Health, Cincinnati, Ohio University of Cincinnati College of Medicine, Cincinnati, Ohio, USA ABSTRACT In January, 1987, work-related shortness ofbreath and wheezing among workers at a meat portioning facility prompted a request for a NIOSH health hazard evaluation. The facility sprays steaks with spice solutions con taining the enzymes papain, bromelain, and ficin. Occupational asthma related to enzyme exposure had not previously been reported in the meat industry. To identify individuals with symptoms compatible with occupational asthma, we administered a case-finding questionnaire to 376 of 400 current workers. Ninety-six workers with compatible symptoms, and an equal number of non-symptomatic workers, were invited to participate in a set of follow-up examinations, which included a more detailed questionnaire, pulmonary function testing, skin prick testing, and assays for specific IgE to papain. Ninety-six workers participated in the follow-up. Twenty-one (23%) of91 skin-tested workers reacted to at least one of die purified enzymes. Eight (11 %) of 73 participants completing peak-flow mea surements had evidence of symptomatic, work-related bronchial lability. Based on die medical studies, we diagnosed 29 workers with possible or definite tenderizer-related occupational asthma. This corresponds to aprevalence of 12% among workers exposed to tenderizers. This study demonstrated that IgE-mediated sen sitization to proteolytic enzymes, and tenderizer-related asthma can occur in the meat industry. No Paper provided. 876 General Epidemiology THE EFFECTS OF AGRICULTURAL DUSTS ON HUMAN HEALTH IN SHANGHAI AREA SHEW YI-E Ye Ting-Ting Dai Gou-Qiang Zhou Qun-Min Lu Pei-Lian Shanghai Medical University SUMMARY From 1985 through 1987, the surveys of several kinds of agricultural dusts, including rice, tea, hay and mushroom compost, on human health have been conducted in Shanghai. Totally, 1851 subjects were in vestigated. There were some disorders related to the exposure to the dusts, including stimulation symptoms on mucous membrane of airway (0.8-63.4% in diem), grain fever (5.1-17.5%), hypersensitivity pneumonitis (3.5-5.8%), chronic bronchitis (4.3-17.7%) and some changes of pulmonary function. Some potential etiological agents and mechanisms were studied in the survey. The findings show that these dusts have af fected human health. INTRODUCTION It is well known that agricultural dusts are harmful to human health.1 From 1985 through 1987, some field surveys were conducted in the Shanghai area in order to find out their ef fects on human health and to study some of the potential etiological agents and the mechanisms of the effects. METHODS AND MATERIALS Dust Concentrations in Air The total airborne dust concentrations in workplaces were determined by using the dust collectors of DK-60-2 type and conventional method. The Amount of Thermoactinomycetes In order to determine the amount of thermoactinomycetes in air, LWC-l centrifugal collectors ofairborne microorganisms were used to collect microoganisms in various workplaces of cultivating mushrooms. The samples were incubated at 52C and the colonies were counted every day through the fifth day. Finally, the thermoactinomycetes were identified morphologically. Subjects 1851 subjects were investigated, including 349 rice pro cessors, 259 tea workers, 746 rice farmers and 497 mushroom farmers. The controls were not exposed to dust in the same area. Questionnaire and Pulmonary Function Test The modified questionnaires were applied for interview to the subjects and controls.2 The pulmonary function tests were performed by using spirometer ofLR-80 type in most ofthem, but the tests were done by using Collin's spirometer in mushroom farmers and their controls. Immunological Test ELISA was applied to determine the level of IgE in serum from the tea workers and the precipitins in serum were tested in mushroom farmers and their controls.3'4 RESULTS The Environmental Study The geometric means of airborne dust concentration in dif ferent workplaces have been found to be from 13.2 to 76.9 mg per cubic meter in rice processing mills and from 2.3 to 36.4 mg per cubic meter in the tea mills. In addition, the geometric means ofthe amount ofthermoactinomycetes have been found to be from 1.07 x 104 to 4.39 X 105 CFU per gram of the compost of mushrooms and from 262 to 3276 CFU per cubic meter of air in the workplaces of cultivating mushrooms during the work except the duration of picking mushrooms, but only from 13 to 42 CFU per cubic meter of air in control places. Response to The Dusts The prevalence of stimulation symptoms on mucous mem brane was 63.4% in rice processors, 53.7% in tea workers, 29.8% in rice fanners and only 0.8% in mushroom formers. Meanwhile, the prevalence of grain fever was 17.5 % in rice processors and 5.1 % in rice farmers, being significantly dif ferent between them (P <0.05). However, die hypersensitivi ty pneumonitis (HP) was not found in rice processors. The prevalence of HP (former's lung) was 3.5% in rice farmers and the prevalence ofmushroom worker's lung, another kind of HP, was 5.8% in mushroom fanners, the latter being significantly higher than the former (P <0.05). 877 General Epidemiology The prevalence ofchronic bronchitis in male and female rice processors was die highest (17.7 and 9.9%) of all male and female groups (P <0.01 and P <0.05). The prevalence (in male and female respectively) was 10.6 and 4.3% in rice farmers, 6.7 and 5.5% in mushroom farmers, 2.2 and 1.0% in controls. The prevalence in die tea workers of two mills was 5.6 and 6.0%, respectively. Pulmonary Function Test The ratio ofthe observed to the predicted (O/P) FEVj, V75, V30 and V25 declined in different groups. The values ofFVC, FEV1, V50 and V25 declined after shift compared with those before the shift in female tea workers significantly and the FEV) also declined in female rice processors, but not significandy. It was also shown that the values ofFEV1, FVC and FEF25-75% decreased significandy in the farmers after die season of cultivating mushrooms. Immunological Test The average levels oftotal IgE in serum from the tea workers in the two mills were significandy higher (490.83 and 539.63 IU per ml) than that (290.03 IU per ml) from the controls. Moreover, die prevalence of precipitin reaction against an tigens from T. Candidas 106 and T. vulgaris 941 was significandy higher (64.7 and 41.2%) in mushroom farmers than that (6.0 and 8.4%) in controls. DISCUSSION The Maximum Allowable Concentrations ofairborne rice and tea dusts in die workplace are 10 mg per cubic meter and 3 mg per cubic meter in China, respectively.5 In these surveys, most of the samples of airborne dusts had concentrations higher or much higher than die MACs. The rice processors and tea workers were exposed to the high concentration ofdust at work every day, which probably was the main cause ofdie high prevalence of stimulation symptoms on mucous mem branes. The rice farmers were only exposed to die rice dust outdoors in die harvest season, so their exposure might not be as serious as die processors and workers. Since the com post ofmushrooms was rather wet, there was not so much dust from it, but the aerosol containing microorganisms might generate from it. Therefore, die prevalence ofthe symptoms in the farmers was not as high as that in die processors and workers. The prevalence ofchronic bronchitis increased in pace with smoking and age.6 Although, there was no significant dif ference ofage and smoking habit between male rice processors and other subjects, the prevalence of chronic bronchitis was higher in diem than in others. There were almost no women smokers in Shanghai and die average age offemale rice pro cessors was younger than that of others, but die prevalence in diem was higher than that in others. In addition, the prevalence in every group ofsubjects was higher than that in controls. Therefore, the chronic bronchitis in the subjects might be related to their exposure to the agricultural dust. especially to die rice dust in the processing mills. The prevalence ofgrain fever in die rice processors was higher than that in rice fanners, which could be related to the fact that exposure to dust was more severe in the former than in die latter. But there was little mouldy rice in the rice process ing mills, so the HP was not found in the mills. However, since the rice farmers were not only exposed to the rice dust, but also to mouldy hay dust sometimes, the prevalence of HP (farmer's lung) was 3.5% in them. The mushroom farmers might be exposed to more amounts of thermoactinomycetes in die aerosol from the compost of mushrooms than the rice farmers, thus, the prevalence of HP in them was higher than that in the rice farmers. Many of the subjects exposed to the agricultural dusts have had some damage of pulmonary function. The changes were obvious in tea workers, which appeared to be obstructive in airway. FEVi and FVC decreased, but FEVi/FVC did not in some mushroom farmers after a cultivating season, which might be consistent with die change of HP.7 Mushroom fanners were mainly exposed to thermoac tinomycetes like T. vulgaris, but not to M. faeni, and the precipitins in serum from them were mainly against T. Can didas and T. vulgaris but not against M. faeni. So, die main antigens of HP might be from T. vulgaris and related taxa, winch is probably similar to the findings of die etiological study of farmer's lung in other districts of China.8 In addition, the level of IgE in serum was raised in some tea workers who had some respiratory symptoms related to ex posure to tea dust, which might imply that some symptoms were possibly related to the mechanism of allergy.9 It could be concluded that these agricultural dusts had affected human health in Shanghai. Some preventive measures should be taken such as supression ofdust and mould, personal pro tective measures, and so on.10 REFERENCES 1. Parkes, W.R.: Occupational Lung Disorder}, 2nd Ed., pp. 359-402. Bunerwoftfas, London (1982). 2. Lu Pei-lian et al.: Several Links in the Survey of Byssinosis. Chinese J. Industr. Hyg. Occup. Dis. 2:120-125 (1984). 3. Zhou Tong et al.: Level ofIgE in Human Serum Determined by ELISA. Chinese J. Microbiol. Immunol. 1:48-53 (1981). 4. Shen Yi-eetal.: A Primary Study ofCausative Agents ofFanner's Lung in Dafeng County. ChineseJ. Industr. Hyg. Occup. Dis. 5:377(1987). 5. Lu Pei-lian and Gu Xing-yuan: Preventive Medicine, 1st Ed., pp. 275-277. Shanghai Fust Medical College, Shanghai (1984). 6. Guo De-long: Smoking and Health. ChineseJ. TuberculosisRespir. Dis. 3:121-122 (1980). 7. Sben Yi-e and Lu Pei-lian: Some Views on the Diagnostic Criterion of Fanner's Lung. Chinese J. Industr. Hyg. Occup. Dis. 5:110 (1987). 8. Lu Yun-yu et al.: Studies on Pathogens of Farmer's Lung in Jiangsu-- Isolation ani Classification of Thermophilic Actinomycetes. Acta Microbiologica Sinica 25:351-355 (1985). 9. Zuskin, E. et al.: Immunological and Respiratory Changes in Tea Workers. Int. Arch. Occup. Environ. Health. 56:57-65 (1985). 10. Tao Bing-gen et al.: An Epidemiological Study on Farmer's Lung in Dafeng County, Jiangsu Province. ChineseJ. Industr. Hyg. Occup. Dis. 2:34-38 (1984). 878 General Epidemiology OCCUPATION INDUCED PULMONARY DISEASE IN A WAFER BOARD MANUFACTURING PLANT, COLORADO T.R. HALES P. J. Seligman B. J. Daniels National Institute for Occupational Safety and Health (NIOSH), Cincinnati, Ohio, USA ABSTRACT In December 1986 the Colorado Department of Health requested assistance from the National Institute for Occupational Safety and Health in evaluating a cluster of asthma cases among employees of a wafer board manufacturing plant. The plant reduces aspen logs to thin wafers, which are then pressed into rigid waferboards using MDI (4,4-diphenylmethane diisocyanate) as the binding agent. A cross-sectional survey of 97 current employees and directed review of 93 former employees identified 13 cases of disease for an overall attack rate of 6.7%. The attack rate among current employees was 3 %, while the attack rate among farmer employees was 11%. Personal air samples for MDI were within NIOSH 's standard <5 ppb), suggesting that our cases represent sensitized individuals. To identify risk factors associated with disease a case control study was undertaken. No association was found between family or personal history of asthma, eczema, hayfever, smoking, or job title. Given our inability to find any predictive pre-employment screening tests, nor identify any particular area orjob title with MDI exposure, surveillance of the current workforce for early MDI sen sitization is very important. Symptom questionnaires, peak expiratory flow readings, MDI-ELISA and RAST tests, could all be used. No Paper provided. 879 General Epidemiology BYSSINOSIS: RESPIRATORY PROBLEMS AMONG COTTON TEXTILE MILL WORKERS IN ETHIOPIA WOLDE YOHANNES MENTESINOT,* M.D., MSc Yves Bergevin.t MDCM, MSc Amani Yacob Mgeni,* M.D., DPH, MSc Department of Community Health, Faculty of Medicine, Addis Ababa University and Ministry of Health, Addis Ababa, People's Democratic Republic of Ethiopia tDepartment of Epidemiology and Biostatistics, McGill University, Montreal, Canada and McGill-Ethiopia Community Health Project, Addis Ababa, People's Democratic Republic of Ethiopia tRepresentative Office, World Health Organization, Addis Ababa, People's Democratic Republic ofEthiopia INTRODUCTION Although occupational lung disorder caused by inhalation of cotton dust is a continuing problem and byssinosis is now known to occur worldwide, cotton production and consump tion has expanded rapidly in developing countries. The Peo ple's Democratic Republic of Ethiopia being one of the cot ton producers and consumers countries in Africa, started ex panding its textile industries since die last decade and the number ofits workers in cotton processing continues to grow annually. Lots of studies in cotton mills were done and reported from many developed nations and also few reports regarding respiratory problems have been documented from develop ing countries like Egypt,1 Sudan,2 Tanzania,3 and Hong Kong,4 but there is no article published concerning die prob lems caused by cotton dust in Ethiopia. Thus, this paper represents the first epidemiological study ofthe textile industry in Ethiopia using diagnostic criterion similar to those which are applied in developed countries, such as die United States of America and Great Britain. A few studies of cotton textile workers have looked into the prevalence ofrespiratory symptoms and lung function com pared with those of control subjects.5'6,7,8 There is also a limited number of studies that have reviewed lung function in cotton textile workers with and without byssinosis or bron chitis.91011 This study investigated the prevalence of byssinosis and other respiratory problems among workers ex posed to cotton dust in a textile mill in Ethiopia and also at tempted to explore determinants by considering workers ex posed to cotton dust in the textile mill with respiratory tract diseases as case study group and without respiratory tract disease as control group. Ibis cotton textile mill was established in the early 1960s and a daily eight hourly system is operating continously for the whole week, while intermittently providing a "day-off" for each worker to rest. In spite oftoe attempt to retrofit current ventilation systems in toe early 1980s, plant officials stated that toe dusty environment remained unchanged since the early 1960s.12 880 MATERIAL AND METHODS Population This study included a group ofrandomly selected 595 workers (322 male and 273 female) representing 40.5% of workers involved in dusty operations in the blowing, carding, draw ing, simplex, ringframe, preparatory and weaving sections of a cotton textile mill in Bahir Dar, Ethiopia. Environmental Assessment The concentration ofairborne dust in toe breathing zone was determined with toe casella personal dust sampler and toe sampling rate was set to 0.2 1/min. The concentration ofair borne dust in toe general environment was concurrently monitored with an Anderson dust sampler fitted with a ver tical elutriator (General Metal Works Inc.) that was set up at a height of 1.5m at selected positions and samples were drawn at a rate of 7.41/min. Multiple area samples were taken and toe duration of sampling ranged between 8-10 hours (mean 8.7 hours). All samples were collected on What man glass fibre GF/A with 3.7 cm diameter and weighing was done on a calibrated analytical balance before and after sample col lection after equilibrating filters in the laboratory for 24 hours. Interviews and Physical Examination A modified version oftoe British Medical Research Council Questionnaire was filled out and each worker was fully ex amined with emphasis being laid on signs and symptoms sug gestive of respiratory diseases. All workers were blindly in terviewed and examined by one trained physician. The stages ofbyssinosis were defined according to the clinical grades sug gested by Schilling et al.13 Subjects were also diagnosed as having other respiratory diseases based on previously stated criteria.14,1516 Subjects who gave confirmed past history of respiratory diseases were also considered in this study. Pulmonary Function Test Subjects' forced vital capacity (FVQ and forced expiratory volume in one second (FEVj) were measured under the direction of a technician using a multipurpose spirometer. Function testings were carried out on each worker on the first day of the shift after at least one day absence from work and repeated at the end of the same shift. Five expiratory efforts were recorded and the mean ofthe two highest values was used to estimate the FEV i and FVC. All volumes were adjusted to body temperature and pressure saturated with water vapour (BTPS). The preshift FEVi values were compared with the expected normal values of Chemiack and Rater.17 For all statistical tests, P less than 0.05 was considered significant. RESULTS Population All the 595 workers in die study voluntarily underwent inter view, physical examination and pulmonary function testing. Non-reproducible function tests of 32 subjects were exclud ed only from pulmonary function test analysis. There were only 14 smokers and 4 ex-smokers, all male. Over 95% of die cotton workers had not changedjobs or their sections dur ing the course of their employment. Environmental Assessment The concetrations ofairborne cotton dust are shown in Table I. Hie highest concentration of cotton dust was recorded in the blowing and carding sections, whereas the lowest was recorded in the weaving and preparatory sections. The amount of dust generated in the blowing and carding operations was high and more than two fold compared to other operations (P<0.005). The mean dust concentration and the mean timeweighted dust concentration were much higher (P< 0.001) in the case study group than in die control group. Respiratory Conditions The prevalence of byssinosis and other respiratory tract diseases is summarized in Table n and Figure 1. The prevalences of byssinosis, chronic bronchitis and bronchial asthma were very high (P<0.001) among blowers and carders in comparison to those in other sections. The overall prevalence of hay fever (28.3%) was the highest of all the respiratory problems in die textile mill. Generally, die prevalence of byssinosis, chronic bronchitis and bronchial asthma showed a significant increase with the duration ofex posure to cotton dust in die textile mill (Table HI). No signifi cant difference was observed in die prevalence ofbyssinosis between smoking and non-smoking workers, otherwise, die effect ofsmoking on die prevalence ofchronic bronchitis was significant (Table IV). In general, 48.1 % ofdie study popula tion had one or more respiratory tract problems while die re maining 51.9% had neither symptoms and signs nor gave past histories of respiratory tract diseases. We regrouped die study population in two strata based on die frequency distribution of die time-weighted elutriated dust concentration as those with a high and low cumulative dust exposure and cross tabulated, assuming the present dust levels were more or less similar to the past ones. The estimated relative risks ofdeveloping byssinosis and other General Epidemiology respiratory problems in high cumulative cotton dust exposure were statistically significant when compared to low cumulative cotton dust exposure (Table V). Also the estimated relative risk ofmanifesting symptoms of respiratory impairment was significant in those exposed to high cumulative cotton dust and developed respiratory tract problems when compared with those exposed to low cumulative cotton dust (Table VI). Pulmonary Function Test Analysis A statistically significant (P<0.001) across-shift decrements in FEVj and FVC and also a decrease in the percentage predicted FEVi were noted in the case study group when compared with the control group. There was a significant reduction in FEVj (P<0.001) at the end of the shift, more than 10% and/or 20% among byssinotics when compared with the controls (Figure 2). Also a significant increase in percen tage reduction in FEVj was noted with an increase in byssinoiss grade. The chronic changes in FEVj among ex posed workers were further analysed according to Bouhuys et al.18 While 24% of byssinotics developed FEVj moderate to severe chronic changes (P< 0.001), only 1% of the nonrespiratory tract disease group (controls) showed similar changes (Table VII). Generally, die regression analysis results shown in Tables vm and DC indicate statistically signficant dose-response relation ship between respiratory problems and pulmonary function test results at one hand and current, cumulative and length of exposure to cotton dust at the other. DISCCISSION The results of our study showed that the concentrations of air borne cotton dust in the different sections ofthe surveyed tex tile mill were very high, with concentrations greatly in excess (nearly 4 to 17 tons) of 0.2 mg/m3 of dust.19 This was in ac cordance with reports on other cotton mills.2'6'20 Also the dust collected at die early stage ofyam production was very high and this was similar to those reported by others.2'21*22 The high prevalence ofbyssinosis in die blowing and carding processes is similar to those reported by other in vestigators.2'23'24 The high prevalence of byssinosis in draw ing, simplex and ringffame spinners may be due to the fact that the level of cotton dust was still high in these sections. Inspite of the controversy surrounding the relationship be tween the prevalence of byssinosis and the duration of ex posure, our study showed a significant increase in the prevalence ofbyssinosis with duration of exposure. The same relationship had also been observed in Sudan and Egypt.2*20'21 The progression in the stages of byssinosis in relation to the duration of exposure observed in our finding support previously reported conclusions that the different grades of byssinosis succeed each other in diseased sub jects.2,20'21 Our results also showed that there was a signifi cant association between the prevalence of byssinosis and time-weighted dust concentration. This is in agreement with Fox et al.25 Our results showed that smoking had no signifi cant relationship with the prevalence ofbyssinosis, probably because of the small number of smokers in our study. Hence due to this small number, there may be a risk of a type n error. 881 General Epidemiology Figure 1. Prevalence of respiratory tract diseases among exposed workers. 882 Section Table I The Concentration of Airborne Cotton Dust in Study Sections by Area Sampling and Personal Sampling (MeanSD) General Epidemiology Number of Samples Area Sampling "lnhatableZ Dust mg/mJ Personal Sampling "Respirable" Dust mgfar Blowing (1) Carding (2) Drawing (3) Simplex (4) Ringframe (5) Preparatory (6) Weaving (7) n 18 ii ii 21 12 25 3.52 t 0.98 3.21 1.09 1.62 t 0.44 1.29 0.32 1.19 0.49 0.92 0.23 0.86 0.35 3.83 1.06 3.58 1.07 1.93 0.23 1.72 0.26 1.57 0.55 1.21 0.33 1.03 0.37 Level of Significance (Bahir Dar, 1988) IVs2 P>0.05 IV$2 P>0.05 IVs3 - 7P<0.0005 iVs3 - 7PK0.0005 2Vs3 - 7PK0.005 2Vs 3 - 7PK0.0005 $83 General Epidemiology 40- -40- VI tuoc - * 30 oc _Oa____ 1-O-----------"cr .c *--?0- (AIL GRADESL JiCL. _. ____ (CONTROL CROUPE : fj KK; > 7(7% < 20% .{P Cjuxni- FEVj > 20% ^P-<Uf*40h * Lung-function .fap~4t Byssinotics^wos--not recorded CBahirDar-i1988 J Figure 2. Percent reduction in FEVj in examined workers during the first working day after absence from work.* 884 Table U The Prevalence of Respiratory Diseases Among Exposed Workers Mean Age and Duration of Exposure General Epidemiology SECTION Number Examined Age (Years) Mean * SO Duration of Exposure (Months) MEAN * SD Gi BYSSINOSIS NO. (%) Cl Gil Total . Chronic Bronchitis No. (%) Bronchial Asthma No. (%) Blowingfl) 44 Carding (2) 40 Drawing (3) 25 Simplex (4) 42 Ringfrome(5) 174 Preparatory (6) 128 Weaving (7) 142 TOTAL 595 +1 rn 41.3 7.3 201.9 87.2 3(7) 7(15.9) 9(20.5) 19(43. 2)* 41.5 * 6.9 200.7 * 74.8 - 2(5) 13(32.5) 15(37.5)* 21(47. 7)* 9(20. S)* 18(45)* 5(12.5) 39.9 *6.6 239.6 * 68.5 3(12) 1(4) 2(8} 6(24) 8(32) 3(12) 40 * 6.8 235.3 * 69.4 3(7) 3(7.1) 4(9.5) 10(23.8) 10(23.8) 3(7.1) 37.5 *6.5 233.1 *73.2 12(6.9) 9(5.2) 9(5.2) 30(17.2) 32(20.7) 17(9.8) 37.1 * 5.8 222.9 *71.5 10(8) - 4(3.1) 14(10.9) 23(18.0) 15(11.7) 4.6 238.7 * 67 3(2.1) 2(1.4) 1(0.7) 6(4.2) 25(17.6) 12(8.5) 38 * 6.9 218.3 * 79.5 34(5.7) 24(4) 42(7.1) 100(16.8) 137(23) 65(10.8) * P< 0.001 (Bahir Dar, 1988 Duration of Exposure (Years) Table m Duration of Exposure and the Prevalence of Respiratory Diseases Number Examined G) BYSSINOSIS NO (V Cl Gil TOTAL Chronci Bronchitis No. (%) Bronchial Asthma No. (%) < 10 Years 10-20 Years 105 208 20 Years 282 TOTAL 595 2 (1.9) 11 (5.3) 21(7.4) 34(5.7) 4(3.8 ) 6(2.9) 14 (5) 8 (3.8) 34(12.1 ) 24(4) 42(7.1) 6(5.7) 25(12) 69(24.5) 100( 16.8) P<0.001 17(16.2) 43(20.7) 77(27.3) 2 (1.9 ) 12 (5.8 ) 50(17.7 ) 137 (23 ) 64( 10.8) P< 0.05 P< 0.001 885 General Epidemiology Table IV The Effect of Smoking on the Prevalence of Byssinosis GROUP NUMBER EXAMINED DURATION EXPOSURE (YEARS) (MEAN * SD )* BYSSINOSIS NO. (\ CHRONIC BRONCHIAL Ci Cl BRONCHITIS ASTHMA Cll TOTAL No no. (%) Smokers Non or Ex smokers 14 581 17.1*8.2 18.2 * 6.6 1(7.1) 1(7.1) 1(7.1) 3(21.4)* 9(64.3)** 33(5.7) 23 (4 h 41 (7) 97(16.7) 128 (22) 64 (11) (Bobir Dor, 1988) *N.S.(P> 0.05) * N.S. ** P<0.001 Table V Comparison of Cases (Byssinosis and Other Respiratory Tract Diseases Groups) with Control (No Respiratory Tract Disease Group) Using Time Weighted Dust Concentration High Time Weighted Low Time Weighted 2 95^ , Dust Concentration Dust Concentration * (Id.f.) P-Value Odds Confidence (366.72-1182.72) (mg months/m ) (183.36 -206.4J (mg months/m*) Ratio Interval (C.l.) NO. % NO. % Control . No R.T.D 78 (38.8) Cases . All R.T.D 122 (63.2) . Byssinosis 69 (93.2) . Chronic Bronchitis 67 (69.8) . Bronchial Asthma 29 (78.4) . Plumonary 12 (75) Tuberculosis . Pneumonia 32 (61.5) . Hay Fever 67 (61.5) 123 71 S 29 8 4 20 42 (61.2) (36.8) ( 6.8) (30.2) (21.6) (25) (38.5) (38.5) 23.46 64.41 24.96 19.79 7.99 8.68 14.59 PK0.001 PK0.001 P<0.001 PK0.001 P<0.0l 2.71 21.76 3.64 5.72 4. 73 (2.48, 2.94) (8.41, 56.261 (2.16, 6.11) (2.48, 13.07) (1.46, 15.18) PK0.01 P<0.001 2.52 2.52 (1.34, 4.71) (1.55, 4.06) (Bobir Dar, 1988) 886 Although previous investigators7*25 found that the prevalence ofchronic bronchitis is not related to dust concentrations, the significant relationship observed in our study is in agreement with those of El Karim2 and Merchant et al.26 Although cigarette smoking is the single most important etiologic fac tor of chronic bronchitis, occupational and environmental ex posures are now receiving more attention as also supported by our finding. Our finding also showed that bronchial asthma was high among die blowers and had a significant relationship with the cumulative cotton dust exposure. A majority ofthe asthmatics developed the problem after they had worked for several years in this textile mill. Even though a majority of the asthmatics gave negative family histories of allergy, 34.4% had had in termittent symptoms of rhinitis which was mostly seasonal. Our finding showed that there was no significant relationship between hay fever and current dust exposure but the relation ship with longevity in the cotton textile mill and cumulative cotton dust exposure was significant. This finding probably might be due to the reason that an allergic reaction does not occur on first exposure. The latent interval during which sen sitization occurs varies from a few weeks to many years. When hay fever, for that matter even asthma, first develops some years after an employee entered an industry, it is easy to understand that an occupational origin may be completely overlooked. In our study a majority of hay fever cases developed die symptom complex after many years oflongevity in the textile mill. Even though there is some evidence that byssinosis is not more General Epidemiology prevalent among atopic than non-atopic workers,27 our find ing revealed that the majority ofbyssinotics (55%) had clearcut characteristic symptom complex of hay fever (allergic rhinitis). Added to this, the prevalence ofhay fever was very high in our study population. In agreement to this and as described by Jones et al,28 atopy might be an important risk factor in the development ofbyssinosis and indicates the im portance of identifying atopic workers. Our study demonstrated that byssinotics had significantly greater acute decrements in FEV\ throughout a workshift than those without respiratory tract diseases, supporting the find ings of earlier investigators.9*29'30 The cotton exposed workers with byssinosis had also a significantly lower percentpredicted FEVi than those in the group without respiratory tract desease (control), being in agreement with previous investigators.2*8'9'31'32'33 In conclusion, our findings suggest that there may be high estimated risk ofdeveloping respiratory diseases and impair ment as well as leading workers to absence from work due to illness in high time-weighted dust concentration than in low time-weighted dust concentration signifying the extent ofthe occupational health hazard that calls for due consideration by all those concerned. Also an immunological dysfunction such as atopy, may be a risk factor in the development of cotton dust induced respiratory disease. Thus keeping in mind cot ton dust has diverse content as described by many investiga tors, the extent of association between exposure to cotton dust and hay fever and also die extent ofdevelopment ofbyssinosis and other respiratory problems among atopic and non-atopic workers should be investigated and analysed in depth. Table VI Comparison of Symptoms of Respiratory Impairment and Period of Absence from Work Due to Sickness in Those Cases with High and Low Time Weighted Dust Concentration with "No Respiratory Tract Disease" Group as Control GROUP Control 4- No R. T.D Cases . Sob Hill* . Sob Level ** . Sob Pace *** . Sick Week . More Illness High Time Weighted Dust Concentration (366.72 - 1182.72) (mg months./ m2) Low Time Weighted Dust Concentration (183.36 - 206.4) (mg months/m*) No. (%) No. (%) X2(1 d.f.) ODDS P-Value Rati o 95% Confidence Interval (C.l.) 78 (38.8) 123 112 (70) 48 81 (80.2) 20 29 (87.9) 4 64 (71.9) 25 32 (69.6) 14 (61.2) (30) (19.8) (12.1) (28. 1) (30.4) 34.77 46.18 27. 5 27.05 13.77 p<0.001 p<0.001 p<0.001 p<0.001 p<0.001 3.68 6.39 11.43 4.04 3. 6 (2.36, 5.7) (3.6, 11.25) (6.62, 19.89) (2.36, 6.96) (1.8, 7.17) (bahir Dor, 1988) * Shortness of breath while walking up a slight hill ** Shortness of breath while walking on a level ground with persons of the some age *** Shortness of breath even when walking at own pace. 887 General Epidemiology Table VH Chronic Changes in FEVj among Exposed Workers Byssinosis Number Examined FEVj CHRONIC CHANCES * No. Change Moderate > 80% of Pre- 60-80% of dieted Value Predited Value Severe " 4(50% of Predicted Value. No. % No. % No. % No. R.T.D Controls 309(51.93) 210 67.96 96 31.07 Byssinosis Grade } 34(5.71) 20 58.82 13 38.24 Grade 1 24(4.03) 11 45.83 8 33.33 Grade II 42(7.06) 9 21.43 15 35.71 All Grades 100(16.81) 40 40 36 36 Total 595(100) 376 63.19 191 32.1 3 .97 1 2.94 5 20.83 18 42.86 24 24** 28 4.71 Lung function was not recorded for 32 subjects. * Graded according to Bouhuys et al. (1970) ** P< 0.001 (Bahir Dar, 1988) S\ 888 Table VIE Regression Coefficients for Time Weighted Cotton Dust Concentration, Age, Height and Weight in Byssinosis and Pulmonary Function Models General Epidemiology VARIABLE MALE (N = 323) FEMALE (n= 272) ALL WORKERS (N = 597) Byssinosis* Total Dust Age Weight Height o.oor 0.059 -0.012+ -0.01 FEV ** Total Dust Age Weight Height 0. 221~ 0.095 -0.07 -0.018 o.oor 0. 104* -0.109* 0.002 + 0.1670.009 -0.017 -0.044 o.oor 0.079 - 0.01+ 0.033 + 0.207 0.06 - 0.045 - 0.011 FVC*** Total Dust Age Weight Height + 0.085~ 0.115 -1.029+ 0.039 0.0440.015 0.033 0.072 + 0.0611.088+ - 0.019 0.048 Lung function was not recorded for 32 subjects. + p< 0.001 + p< 0.05 N.B. For differences between sexes, after allowance for age, height and weight. *MALE F (1 and 320 d.f.) = 98.96 *FEMALE F(1 and 271 d.f.) =44.96 ** MALE F (1 and 302 d.f.) =52.53 ** FEMALE F (1 and 257 d.f) =17.2 *** MALE F (1 and 302 d.f.) =22.14 *** FEMALE F(1 and 257 d.f.) = 4.05 P<0.000 and R2 =0.23621 P<0.000 and R\ =0.14229 P<0.000 and R-=0.14100 P<0.0000 and R=0.05967 P<0.000 and R 7=0.06471 P<0.0452 and R =0.01472 (Bahir Dar, 1988) 889 General Epidemiology Table IX Regression Coefficients for Period of Exposure, Current Cotton Dust Exposure and Cumulative Cotton Dust Exposure in Byssinosis, Chronic Bronchitis, Bronchial Asthma, Pulmonary Tuberculosis, Pneumonia, Hay Fever and Pulmonary Function Models Symptom Period of Exposure (Months) Current Exposure Cotton Dust Concentration (mg!mi ) Cumulative Exposure Cotton Dust Concentration (mg months/mJ) Byssinosis 0.002* Chronic Bronchitis 0.042** Bronchial Asthma 0.066* Pulmonary Tuberculosis 8.65 E-04 Pneumonia 0.046 Hay Fever 7.14 E-04+ FEV7 0.427 FVC 0.005 0.308# 0.065 0.117 0.011 0.055 0.066 0.054 0.006 0.001* 3.76 E-04* 0.075** 7.26 E-05* 1.84 E-04+ 0.077** 0.154** 0.06* # P< 0.00 7 + P< 0.01 * P< 0.05 ** P< 0.05 in one tail test (this is considered since the hypothesis from the outset was unindirectional ) N.B. General Models: Symptom = + p7 (age) + + fiy (weight) + (Sex) + (height) (exposure) x (Bahir Dar 1988) 890 REFERENCES 1. El. Batawi, M.A.: Byssinosis in the Cotton Industry in Egypt. Br. J. Ind. Med, 19:126-130(1962). 2. Awad El Karim, M.A., Osman, Y., El Haimi, Y.A.: Byssinosis: En vironmental and Respiratory Symptoms Among Textile Workers in Sudan. Ira. Arch, Occup: Environ. Health. 57:101-108 (1986). 3. Mustafa, K.Y.: Byssinosis in Tanzanian Textile Workers, lung 159:39-44 (1969). 4. Morgan,P.G.M.,Ong,S.G.:FirstReportofByssinosisinHongKoog. Br. J. Ind. Med. 38:290-292 (1981). 5. Schilling,R.S.F.:ByssinosisinCotton&otherTextileworkers.nnf. 2:261-265 (1956). 6. Molyneux, M.K.B., Tombleson, J.B.L.: An Epidemiological Study of Respiratory Symptoms in Lancashire Mills, 1963-1966. Br. J. bid. Med. 27:225-234 (1970). 7. Berry, G., Molyneux, M.K.B., Tombleson, J.B.L.: Relationship be tween Dust Level & Byssinosis & Bronchitis in Lancashire Cotton Mills. Br. J. Ind. Med. 31:18-27 (1974). 8. Schilling, R.S.F.: Epidemiological Studies of Chronic Respiratory Diseases Among Cotton Operatives. J. BioL Med. 37:55-74 (1964). 9. Berry, G., McKerrow, C.B., Rossiter, C.E., Tombleson, J.B.L.: A study of Acute and Chronic Changes in Ventilatory Capacity inWorkers in Lancashire Cotton Mills. Br. J. Ind. Med. 30:25-36 (1973). 10. Bouhuys, A., Schoenberg, J.B., Beck, G.J., Schilling, R.S.F.: Epidemiology of Chronic Lung Disease in a Cotton Mill Community. Lung. 154:167-186(1977). 11. Mair, A., Smith, D.A., Wilson, W.A., Lockhart, W.: Dust Diseases in the Dundee Textile Workers. Br. J. Ind. Med. 17:272-278 (1960). 12. Wolde, Yohannes M.: Health Profile & Plan ofActionfor Bahir Dor Awraja. Ministry ofHealth, Educational Health Service Report. Addis Ababa (1987). 13. Schilling, R.S.F., Vigliani, E.C., Lammers, B., Valic, F., Gilson, J.C.: A Report on a Conference on Byssinosis. (14th International Conference on Occupational Health, Madrid, 1963). Excrepta. Media. 2:137-145 (1964). 14. Fletcher, C.M.: Chronic Bronchitis. Am Rev. Respir. Dis. 80:483-484 (1959). 15. Hinshaw, H-D., Garland, L.H.: "Diseases ofthe Chest. 2ndEd. pp 299. W.B. Saunders Co., Philadelphia (1963). 16. Isselbacber, K.J., Adams, R.D., Braunwald, E., Petersdorf, R.G., Welson, J.D.: Harrison's Principles ofInternal Medicine. 11th Ed. pp 1412-1414. McGraw-Hill Inc. Hamburg (1987). 17. Cheraiack,R.M.,Rater,M.B.:NormalStandardsfbrVeotilationFunction Using an Automated Wedge Spirometer. Am. Rev. Respir. Dis. 106:38-46 (1972). 18. Bouhuys, A., Gilson, J.C., Schilling, R.S.F.: Byssinosis intbe Textile Industry. Arch. Environ. Health. 21:475-478 (1970). 19. American Conference ofGovernment Industrial Hygienists. Threshold Limit Values, AGGIH, Cincinnati, Ohio (1983). General Epidemiology 20. Awad El Karim, M.A., El Hag, A.A.: Byssinosis and Tuberculosis in Cotton Industry in Sudan. East. Afr. Med. J. 62:491-500 (1985). 21. Noweir, M.H., Noweir, K.H., Osstnan, H.A., Moseillin, M.: An En vironmental & Medical Study ofByssinosis and other Respiratory con ditions in the Cotton Textile Industry in Egypt. Am J. Ind. Med. 6:173-183 (1984). 22. Holness, D.L., Taraschuk, L.G., Pelmear, P.L.: Effect of Dust Ex posure in Ontario Cotton Textile Mills. J. Occup-Med. 25:26-69 (1983). 23. Oog, S.G.,Jam, T.H.,Wong, C.M., Ma, P.L., Lam, S.K., O'Kelly, E.J.: Byssinosis in Hong Kong. Br. J. Ind. Med. 42:499-52 (1985). 24. Parikh,J.R.,Cbattei}ee,B.B.,Rao,N.MMBahgia,L.J.: The Clinical Manifestations ofByssinosis in Indian Textile Workers. NIOH (National Institute of Occupational Health.) pp. 24-28. Ahmedabad, India. 25. Fox, A.J., Tombleson, J.B.L., Watt, A., Wilkie, A.G.: A Survey of Respiratory Disease in Cotton Operatives. Part D Symptoms, Dust Estimations & the Effect ofSmoking Habit. Br. J. Ind. Med. 30:48-53 (1973). 26. Merchant, J.A., Lumsden, J.C., Kilburo, K.H., O'FaDoo, W.M., Ujda, J.R., Germino, V.H., Hamilton, J.D.: An Industrial Study of the Biological Effects ofCotton Dust & Cigarette Smoke Exposure. J. Oc cup. Med. 15:212-221 (1973). 27. Bouhuys, A.: Asthma & Byssinosis. Rev. Allergy. 22:473-476(1966). 28. Jones,R.N.,Butcher, B.T., Hammand, Y.Y., Diem, J.E., Glindmeyer, H.W. m, Jehrer, S.B., Hughes, J.M., Wall, H.: Interaction ofAtopy & Exposure to Cotton Dust in the Bronchoconstrictor Response. Br. J. Ind. Med. 37:141-146 (1980). 29. McKerron, C.B., McDermoth, M., Gelson, J.C., Schilling, R.S.F.: Respiratory Function During the Day in Cotton Workers: A Study in Byssinosis. Br. J. Ind. Med. 15:75-83 (1958). 30. Bock,M. .Bouhuys, A.: A Purified Extract from CottonBracts Induces Airway Constriction in Humans. Chest. 79:43-49 (1981). 31. Beck, G.J., Schachter, E.N.: The Evidence for Chronic Lung Disease in Cotton Textile Workers. Am Stat. 37:404-412 (1983). 32. Schachter, E.N., Maunder, L.R., Beck, GJ.: The Pattern ofLung Func tion Abnormalities in Cotton Tactile Workers. Am Rev. Respir. Dis. 124:523-527 (1984). 33. Beck, G.J., Schachter, E.N., Maunder, L., Schilling. R.S.F.: AProspective Study of Chronic Lung Disease in Cotton Textile Workers. Am ha. Med. 97:645-651 (1982). ACKNOWLEDGEMENTS: We acknowledge with many thanks the cooperation of Drs. Getacbew Tadesse, Zein Ahmed Zein, Gebreselassie Okubagzi, Yemane Asgedom and all ofthe colleagues who have contributed much to the successful completion ofthis study. We are greatly indebted to to the International Development and Research Centre (IDRC) forgenerously funding this project. Thanks are alsogiven to Drs. Charles Larson and Francis Larson for their kind advice. 891 General Epidemiology RESPIRATORY SYMPTOMS AND DUST EXPOSURE IN THE WOOL TEXTILE INDUSTRY R.G. LOVE, Ph.D. C.O. Jones, MSc D. Gunr CA. Soutar, M.D. A. Seaton, M.D. Institute of Occupational Medicine, Edinburgh U.K. Previous studies have indicated that respiratory symptoms are more prevalent in workers exposed to wool mill dust than in those who are not1'2*4*5*7'9 but only one study of respiratory symptoms in wool textile workers in the United Kingdom has been reported.1 Moll6 first identified cases of occupational asthma among workers exposed to wool in 1933 but more recent studies have reported non-specific symptoms of chronic bronchitis and shortness of breath as die main respiratory condition ex perienced by between 5% and 50% ofthe workforce depend ing on age and length ofexposure.2*4*3 Other studies of wool textile workers have also indicated a fall oflung function dur ing a work shift9 or on the first day back at work.7 Bacterial endotoxin has been implicated as die aetiological agent in the most recent study.7 We have undertaken an epidemiological survey of over two thousand workers in the woollen, worsted and carpet yam sec tors of die industry and have compared the frequencies of respiratory symptoms reported by these workers with measured concentrations ofinspirable wool mill dust in their immediate vicinity by means of personal dust sampling. METHODS Fifteen wool textile mills employing 2783 workers in and around Bradford, Dewsbury and Hudderfield in West Yorkshire were selected to participate in the study. They represented all die main processes which are carried out in the industry, and ranged in size from 4 to nearly 400 employees. We designed a respiratory symptoms question naire intended to establish a broad range ofsymptoms and their possible temporal and locational relationships to occupation and current dust exposure. Questions about cough, phlegm, wheezing, chest tightness, breathlessness and its variability, rhinitis, conjunctivitis, nosebleeds, chills and chest illnesses were included, some ofthese qualified by additional questions identifying exacerbation or improvement ofsymptoms at dif ferent times ofday, days ofthe week, seasons and in particular places. Detailed smoking histories and occupational histories including details of shifts and part-time work were also ob tained from which jobs could be allocated to occupational groups. These questionnaires were translated into Urdu for use on Asian workers who did not speak fluent English. Concentrations of inspirable dust were measured using In stitute of Occupational Medicine personal inspirable dust samplers, which were worn for part or all of a shift by 892 representative workers in eachjob or process, a larger number of samples being collected in the dustier jobs. Average in spirable dust concentrations were assigned to each of 16 oc cupational groups, based on the measurements made at the mill concerned or estimates derived from log-linear models from the measurements made elsewhere. Endotoxin levels in dust were also measured in a limited number of static samples at six mills by the Limulus method.8 These measurements were performed under die direction of Dr. M.D. Topping, Occupational Medicine and Hygiene Laboratory, Health and Safety Executive). Logistic regression analyses were used to assess die contribu tion ofindependent variables such as dust concentration to ex plain die variation in each of the symptoms separately. RESULTS Inspirable dust concentrations based on 630 personal samples ranged from zero in non-process work to over 100 mg/m3 in some very dusty processes, such as work with wool waste. Over 9 % ofthe workforce were exposed to shift average dust levels greater than 10 mg/m3, the nuisance dust standard cur rently applied to the industry. Wool opening, blending, worsted carding and carpet yam backwinding were particular ly dusty jobs, average levels being as high as 14.8, 180.5, 39.1, and 46.7 mg/m3 respectively in some mills. Endotox in was found in measurable quantities (up to 650 ng/mg dust) in several samples throughout the process. Complete questionnaire data were available for 2151 workers, which represents 85% of die available workforce. Of these workers 77% were male, 69% European, 28% Asian and 3% West Indian in origin. Just under halfwere current smokers. Eighteen percent opted to be interviewed in Urdu. Symptom prevalences in the population overall were as follows: Chronic bronchitis (persistent cough and phlegm), 9%; wheeze (at any time), 31%; breathlessness grade 3 (walk ing with others on level ground), 10%;persistent rhinitis, con junctivitis and chills, 18%, 10% and2% respectively and 10 or more nosebleeds in the past year, 2%. The first five ofthese symptoms were significandy related to current dust concen tration once age, sex, smoking habit and ethnic group had been allowed for. Table I shows the prevalence ofthese symptoms at increasing inspirable dust levels. The results ofthe logistic regression analysis predicted a rapid rise in symptom prevalences over the dust concentration range 0-5 mg/m3 and a slower increase at higher concentrations up to 20 mg/m3 and above (Table II). The highest relative risks in non-smokers for some of the more important symptoms were found among European women and were, in relation to non-dust exposed, non-smoking women aged 40, 2.47 for rhinitis, 2.77 for chronic bronchitis, 3.56 for conjunctivitis and 6.20 for grade 3 breathlessness at concentrations of 10 mg/m3. In addition, the risk oftaking time off work because of chest illnesses increased significantly with increasing dust exposure, and dyers and scourers had a four-fold higher risk despite low dust exposures. General Epidemiology DISCUSSION This study was designed to include the full range of working conditions to be found in the British wool textile industry. The entire workforce of 15 mills was encouraged to participate and the overall response rate of 85 % gives confidence that the results are reasonably representative of the whole current workforce. The specially designed questionnaire was intended to identify all the common respiratory symptoms, in order to assess die syndromes related to wool dust exposure. Inclusion of material from other tried and tested questionnaires; thorough testing for comprehensibility and ease of use; and the similar relations of symptoms and smoking habit among Table I Symptom Prevalences in Groups Exposed to Different Dust Levels Symptom Grade Cough and Phlegm Wheeze Breathlessness Rhinitis Conjunctivitis Occasional Persistent Present 2 and 3 4 and 5 Occasional Persistent Occasional Persistent Dust concentration (mg/m3) <0.1 (4)* 0.1-1 (1206) 1-10 (740) 10-100 (187) 25 19.6 25.2 37.4 0 5.8 10.8 19.8 50 24.6 35.3 55.1 25 39.3 40.8 60.4 0 1.8 3.0 1.6 25 15.7 19.7 29.4 0 14.9 19.3 36.9 25 11.3 12.6 23.0 0 8.0 10.0 23.0 >100 (6) 50 33.3 66.7 50 0 0 16.7 33.3 50 * Ntanber of individuals in group Table n Estimated Frequencies* of Symptoms, Predicted for Different Inspirable Dust Concentrations in Current Job Estimated symptom frequency (%) Persistent cough and phlegm Breathlessness, grade 3 or more Persistent rhinitis Persistent conjunctivitis Dust concentration (mg/m3) 0 2.5 5 59 11 6 10.5 13 12 18 20 6 10 11.5 10 12.5 14 22 13.5 20 14.5 14.5 23 16.5 * weighted averages of estimated frequencies for non-smokers and current smokers aged 40, assigning a population including proportions of smokers, non-smokers, men, women, ages and ethnic groups similar to the population under study. 893 General Epidemiology different ethnic groups and Urdu speakers also encourages us to have confidence in the results of this questionnaire. Fur thermore the consistency ofthe results across all factories and other subgroups of die workforce, and consistency between symptom complexes, is strong evidence that die associations between symptoms and inspirable dust concentrations are real. We selected die inspirable fraction, which includes die respirable fraction, because ofour concern with health effects on the nose as well as die lungs. Our results confirm previous reports ofrespiratory symptoms related to exposure to dust or length of time spent working in wool textile mills.1*2*4'5-7-9 We also identified the presence of endotoxin in a limited series ofmeasurements and further studies are currently being undertaken to investigate the possi ble role of endotoxin in the causation of respiratory disease among wool textile workers. Indeed a recent study has im plicated bacterial endotoxin in die aetiology of a byssinoticlike condition among Turkish carpet weavers.7 The questionnaire responses indicate dust related disease at all levels of the respiratory tract, although it is not clear whether die pathogenesis of this response includes phar macological, toxic or allergic mechanisms, or is merely a response to die physical dust load. Evidence (not presented here) from exploratory questions on the variability ofbreathlessness suggests that, although related to dust exposure, such symptoms are relatively infrequent, about 3% overall. Therefore these symptoms are in most cases not very like asthma but require further investigation as does the observation ofincreased risk oftime offworkbecause of chest illnesses amongst workers involved in the scouring (hot, usually alkaline, washing) and dyeing ofwool. The latter pro cess has been shown to be associated with increased respiratory and nasal symptoms of either an irritant or a specific allergic nature.3 Positive responses to questions about chills (shivering or feverishness), an attempt to iden tify symptoms of humidifier fever, were unduly frequent in some occupational groups but did not, as expected, show any relation with exposure to dust. The functional and prognostic implications of wool dust related symptoms are not yet known. However, recent studies undertaken by us suggest that dust related functional impair ment does occur, slight but significant reductions ofFEVi and FVC being observed among Asian men and reduced FEVi/FVC ratio among European women. An additional loss of FEVi among dyers and scourers (unrelated to dust ex posure) is consistent with the observations on respiratory ill nesses made by ourselves and others.3 Other investigations currently being pursued suggest that inflammatory and non specific immunological responses can be caused in rodent models by inspirable wool mill dust and we intend to report on these shortly. Meanwhile, we can conclude that exposure to wool mill dust appears to be related to symptoms, when exposure is within ``nuisance dust" limits of 10 mg/m3. At this concentration toe overall estimated risks of symptoms relative to unexposed workers are: chronic bronchitis, 1.37; wheeze, 1.40; breathlessness grade 3 or more, 1.48; persistent rhinitis, 1.24; and persistent conjunctivitis, 1.70. The relative risk ofthese symptoms increases rapidly up to 5mg/m3 and more slowly thereafter. The results ofthese studies and further investiga tions into the functional and other characteristics ofrespiratory conditions among wool textile workers, should be helpful in making decisions on an airborne dust standard for toe wool textile industry. REFERENCES 1. AHardice, J.T., Clarke, E.C., Jones, R.D.: A study ofthe prevalence of epistaxis and respiratory symptoms in carpet backwinders. J. Soc. Occap. Med 33:36-41 (1983). 2. Brysiewicz, K., Buluk, H., Cesar-Fronczyk, M., Korkecha, J., Leszczynsld, B., Lukian, K., Sadokierska, H.: The effect of work in dusty surroundings on the prevalence ofchronic bronchitis among the workmen ofSierzon's establishments ofthe wool industry at Bialystok. Gruziica 38:637-661 (1970). 3. Docker, A., Wattie,J.M., Topping, M.D.,Luczynka, C.M.,NewmanTaylor, AJ., Pickering, C.A.C., Thomas, P., GompertzD.: Clinical and immunological investigations ofrespiratory disease in workers us ing reactive dyes. Br. J. buL Med 44:534-541 (1987). 4. 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