BYSSINOSIS IN GUANGZHOU, CHINA

Objectives-To study the prevalence of byssinosis and other respiratory abnormalities in workers exposed to cotton dust in Guangzhou in two f actories that processed purely cotton. Methods-All the 1320 workers ex posed were included. The controls were 1306 workers with no history of occupational dust exposure. Total dust and inhalable dust were measur ed by Chinese total dust sampler and American vertical elutriator resp ectively. A World Health Organisation questionnaire was used. Forced v ital capacity (FVC) and forced expiratory volume in one second (FEV(1) ) were measured by a Vitalograph spirometer. Results-The median inhala ble dust concentrations ranged from 0.41 to 1.51 mg/m(3) and median to tal dust concentrations from 3.04 to 12.32 mg/m.(3) The prevalence of respiratory abnormalities in the cotton workers were (a) typical Monda y symptoms 9.0%; (6) FEV(1) fall by greater than or equal to 5% after a shift 16.8%; (c) FEV(1) fall by greater than or equal to 10% after a shift 4.2%; (d) FEV(1) < 80% predicted 6.1%; (e) FEV(1)/FVC < 75% 4.0 %; (f) cough or phlegm 18.2%; (g) chronic bronchitis 10.9%; and (h) by ssinosis, defined by (a) plus (b) 1.7%. With the exception of (d), mos t of the prevalences increased with increasing age, duration of exposu re, and cumulative inhalable dust exposure. No increasing trends of re spiratory abnormalities were found for current total dust, inhalable d ust, and cumulative total dust concentrations. Compared with controls, after adjustment for sex and smoking, with the exception of (d), all the pooled relative risks of respiratory abnormalities were raised for cotton exposure. Conclusions-It is concluded that cumulative inhalabl e cotton is likely to be the cause of byssinotic symptoms, acute lung function decrements, cough, or phlegm, and chronic bronchitis.