Respiratory function was studied in three groups of workers employed in processing coffee. The prevalence of almost all chronic respiratory symptoms was significantly higher in coffee processors than in control workers. In each group during the Monday work shift there was a significant mean acute decrease in the maximum expiratory flow rate at 50 % vital capacity (VC), ranging from 4-0 % to ,, and at 25 % VC, ranging from 60 '/ to 18-5 %. Acute reductions in FEV1.0 were considerably lower, ranging from 1-3 % to 2-8 %. On (Figley and Rawling, 1950;Bruun, 1957;Kaye and Freedman, 1961;Layton et al., 1965;Turula et al., 1966; Van Toom, 1970; Somazzi and Wiutrich, 1975). However, there have been no epidemiological studies of lung function in a population occupationally exposed to coffee. We have studied two groups of workers employed in the processing of (a) roasted and (b) green coffee, with particular reference to acute and chronic changes of lung function. Subjects and methods THE PROCESSGreen coffee This involves manual unloading of bags of green coffee, manual emptying of bags into a pneumatic transport system, and packing of green coffee.Roasted coffee Workers are involved in the roasting of coffee, grinding of roasted coffee, and in manual and mechanical packing. Received for publication 18 November 1977 Accepted for publication 10 November 1978 SUBJECTSThe study groups included 72 processors of roasted coffee (51 women and 21 men) and 31 processors of green coffee (women only) representing 94% of all the workers employed. Female workers were nonsmokers. Male workers were all smokers (average 20 cigarettes daily). In addition, 103 workers employed in the production of soft drinks, matching coffee workers in age, height, and smoking habits, were studied as controls (82 women and 21 men). The mean age and duration of employment of subjects in processing of coffee are shown in Table 1. DEFINITIONSThe British Medical Research Council Committee Questionnaire (Medical Research Council, 1960) was used to assess the prevalence of chronic respiratory symptoms. Chronic cough and/or phlegm were defined as cough and/or phlegm production on most days for at least three months per year. Chronic bronchitis described cough and phlegm for a minimum of three months in the year and for not less than two successive years. Dyspnoea was graded as follows: 3 = shortness of breath when walking with other people at an ordinary pace on the level; 4 = shortness of breath when walking at own pace on the level.

A study in Egypt of 99 male cotton workers in a cotton ginnery and spinning mill, and of a control group of 12 power station workers, showed that the groups exposed to cotton dust had significantly greater falls in indirect maximum breathing capacity (I.M.B.C.) during the shift than groups not exposed to dust. Long-term effects of exposure to cotton dust were studied by examining the I.M.B.C.s measured at the beginning of the shift after adjustment to allow for differences in age and sitting height. The adjusted mean value for those with byssinosis was 10-1 litres/min. lower than for normal cotton workers and 19-6 litres/min. lower than for the power station workers. Four men were judged by their breathlessness on slight exertion and low ventilatory capacities to be seriously disabled with byssinosis.In four other mills, all spinning similar types of cotton, changes in I.M.B.C. during the shift correlated highly with dust concentrations and indicated a safe level of dustiness of 1 mg./m.3 (total dust) at which the effects on ventilatory capacity were minimal. An epidemiological survey by Batawi (1962) provides the first published evidence of the occurrence of byssinosis in the Egyptian cotton industry. Batawi examined more than 600 workers and found that the prevalence of byssinosis was 38% in the ginneries where the cotton seeds are removed, 53 % in the bale pressing plants, and 27°' in the card rooms of spinning mills. Byssinosis was diagnosed on the characteristic history of tightness in the chest on the first working day of the week, which is Saturday in Arab countries. On this evidence it seemed to be a major problem demanding further investigation.Exposure to cotton dust has been found to be associated with a fall in ventilatory capacity during the work shift (McKerrow, McDermott, Gilson, and Schilling, 1958). This fall is particularly marked in workers suffering from byssinosis and provides additional and more objective evidence of the hazard of byssinosis to support that based on the characteristic history of chest tightness. It has been us.d in several recent field and laboratory investigations of persons exposed to vegetable dusts

The prevalence of respiratory symptoms and acute and chronic changes in ventilatory function were studied in three groups of textile workers: 68 workers with exposure to synthetic fibers only, 30 with previous exposure to cotton, and 77 with previous exposure to hemp. The prevalence of dyspnea, grade 3 to 4, was significantly lower (P less than .01) in workers with a history of exposure to synthetic fibers only than in those previously exposed to hemp or cotton. No case of byssinosis was found in any of the workers studied. Values in ventilatory-function tests (FEV 1.0, FVC and MEF 50%) were significantly reduced during the work shift on Monday and Thursday. The Monday MEF 50% preshift values were significantly lower than expected in all three groups of workers. A comparison of the 1963-1973 data on the 77 workers previously exposed to hemp showed a lower prevalence of most chronic respiratory symptoms and smaller acute FEV1.0 and FVC reductions when they worked with synthetic fibers (1973) than when they were exposed to hemp (1963).