| Objective To study the separate and synergic effects of dust exposure and smoking on mortality, and to compare their separate effects on mortality at the same time. These will provide scientific evidences for the establishing of modern occupational health policy and rule of law and for the related occupational work.Methods Based on the Guangzhou Occupational Health Surveillance Record System which was uniformly designed, organized, brought into effect and established in 1989-1992, workers, who were 30 years old or above, occupational dust exposure or non-dust exposure (controls), were included in a prospective cohort study. Personal Identification Number was applied for the tracing of survival status. Causes of death were coded according to International Code of Diseases (version 9). SPSS 10.0 was used to make the statistical analysis for the data. Cox proportional-hazards models was mainly applied for the calculation of all causes of deaths' Relative Risks (RRs) and their 95% Creditable Interval (95%CI).Results1. There were 80987 cases including male 49685 and female 31302 in this cohort. They averagely aged 43.5, 45.0 in male and 41.0 in female. Most of them were young, of secondary education and married. About two thirds were workers. There had been 1539 deaths for 8.0 (standard deviation,SD 1.4) years tracing, and there were 786, 357 and 90 cases who died of malignant neoplasm, cardio-cerebro-vascular diseases and respiratory system diseases respectively, which got the proportions of 51.1%, 23.2% and 5.8% of the total deaths respectively. Thirty five cases, which proportioned 0.04% of the total cases, were lost to follow-up. The mortality rates were 326.53/100000 in male (1294 deaths) and 97.99/100000 in female (245 deaths). They were increasing with age.2. The dust exposure rate was 16.3%, 18.4% in male and 12.9% in female. The mean duration of dust exposure was 14.9 (SD 9.1) years. The prevalence of smoking was 43.7%, 70.4% in male and 1.5% in female. The highest prevalences of smoking were 76.3% in male and 2.6% in female among those who exposed to in-organic dust. The average amount and duration of smoking were 17.7(SD 8.0) per day and 20.6(SD9.5) years respectively, and werealmost the same in male and in female.3. In male, who aged under 40, the abnormality rate of those who exposed to occupational hazards was almost the same as that of those who did not exposed to occupational hazards, but lower among those aged 40 to 49, and higher among those who aged 50 or above, especially among those who exposed to dust. In female, the abnormality rate of those exposed to occupational hazards was higher in all aged groups than that of those who did not exposed to occupational hazards. In male or female, the abnormality rate of workers was increased with the duration of dust exposure.4. The mortality rates for those who did not expose to dust and those who exposed to dust were 314.56/100000 and 380.14/100000 respectively in male and 98.33/100000 and 95.72/100000 respectively in female. To compare the death risk of those who exposed to dust with that of those who did not expose to dust, the adjusted death RRs(95%CI) of all causes, malignant neoplasm, and respiratory system diseases for those who exposed to dust were 1.24(1.09-1.41), 1.34(1.12-1.59) and 2.41(1.51-3.84) respectively, and 1.67(1.20-2.32), 1.81(1.05-3.13) and 1.6(0.80-3.20) respectively for lung cancer, nasopharynx cancer and stomach cancer in male. In male, the adjusted death RRs(95%CI) of malignant neoplasm for those exposed to dust of silica, coal and wood were 1.61(1.15-2.26), 1.52(0.97-2.38) and 1.51(0.83-2.75) respectively, and 1.78(1.00-3.16), 3.24(1.78-5.87) and 1.80(0.66-4.90) respectively for lung cancer. Also in male, the adjusted death RRs(95%CI) of respiratory system diseases in those exposed to dust of silica and of cardio-cerebro-vascular diseases in those exposed to dust of wood were 5.72(3.23-10.12) and 2.50(1.28-4.88) respectively. In male, the trend of death RRs of malignant neo...
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