[An analysis of the main causes of death in different industrial systems in Guangzhou]

To study the main causes of death in workers from different industries in Guangzhou.

The industrial systems in Guangzhou were classified into six categories according to the Chinese Public Health Inspection Statistical Report. Baseline data on 79,547 workers, age > or = 35, were retrieved from individual health records under the Guangzhou Occupational Health Surveillance Record System established in 1989-1992. In this prospective cohort study, the workers' vital status and causes of death were followed up until 31 December 1998. Using SPSS 10.0, crude death rates were calculated and relative risks(RR) (95% CI) were estimated using Cox proportional-hazard models.

(1) Among 79,547 workers were 49,355 men and 30,192 women, with mean age of (43.8 +/- 6.5) years, and 64% were aged 35-44. The mean age difference of workers in different industries was +/- 1 year. At baseline, 41% had been exposed to occupational hazards. Exposure was most prevalent in petroleum chemical industry(53.9%), followed by metallurgical industry, and the lowest exposure was in mechanical industry (30.2%). (2) The mean follow-up period was (8.0 +/- 1.3) years with 633,510 person-years. 1,577 workers had died with a total death rate of 248.9 per 100,000 person-years. The death rate in rubber industry was the highest, followed by metallurgical and petroleum chemical industries. Malignant neoplasms, vascular and respiratory diseases were most common, constituting 80.3% of all causes of death. (3) For all causes of death and the three main categories, the top three crude death rates were observed in rubber and petroleum chemical industries, and in the metallurgical industry except for vascular causes. The rubber industry had the highest crude death rate for all and vascular causes, and the metallurgical industry for malignant neoplasms and respiratory causes. (4) With the light industry as a reference (RR = 1.0), the metallurgical industry had the highest adjusted relative risks (RR) (95% CI) of 1.62(1.20-2.18) and 7.42(3.38-16.31) for malignant neoplasms and respiratory causes, respectively. The rubber industry had the highest RR of 1.69(1.40-2.04) for all causes. A significant RR of 2.03(1.43-2.88) for vascular causes was observed only in the rubber industry.

The main causes of death varied from industry. Malignant neoplasms and respiratory diseases were the leading causes in metallurgical and petroleum chemical industries. In rubber industry, vascular and respiratory causes were most common. Preventive measures for disease control should be tailor-made for each industry.