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

El BATAWI MA. Work-related diseases: A new program of the World Health Organization. Scand J Work Environ Health 10 (1984) 341-346. "Work-related diseases" are multifactorial diseases in which the work environment plays a partial role in causation. They include chronic noncommunicable disease affecting working populations. There is evidence that such diseases as musculoskeletal disorders, hypertension, chronic bronchitis, and several psychosomatic disturbances affecting workers can be attributed to a variety of risk factors, including those in the workplace. Examples of investigations and the occurrence of various work-related diseases are cited from several countries. Occupational health is evolving to deal with multifactorial health problems from combined exposure to occupational and other environmental factors, life-style, and individual susceptibility. More attention should be given to psychosocial factors and ergonomics in the workplace, workers' participation and life-style, multifactorial occupational epidemiology, and new approaches to legislation. A list of research areas is given to cover the present gaps in knowledge. The World Health Organization has started a program of work in this field to identify the magnitude of these diseases in various parts of the world, to stimulate epidemiologic research, and to develop guidelines for control measures.

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