Mortality of iron and steel workers in Korea

BACKGROUND: The mortality experience of iron and steel workers from modern plants in developing countries has not been extensively described. METHODS: Mortality at two Korean iron and steel manufacturing complexes was analyzed using Poisson regression methods with both direct and indirect standardization. Work histories were linked with a national mortality registry. Workers (44,974) hired beginning in 1968 were followed from 1992 to 2001. RESULTS: The 806 deaths observed during 10 years of follow-up comprised 2% of the population at risk and represented a large healthy worker effect (HWE) for all causes (SMR = 0.59, 95% CI = 0.55-0.63) and for cancer (SMR = 0.79, 95% CI = 0.70-0.90). Mortality at subsidiaries was considerably higher than at the parent plants (SRR = 1.71, 95% CI = 1.47-1.99). Relative mortality rates declined with employment duration: > 20 years had significantly reduced mortality (SRR = 0.59, 95% CI = 0.43-0.82) compared to duration < 1 year (test for trend: P = 0.0006). Fatal injury deaths in the first year were highly elevated (SMR = 3.10, 95% CI = 2.17-4.26) declining to less than that expected after 5 years. Cancer mortality was elevated in stainless steel production (SRR = 3.26, 95% CI = 1.37-6.49) and overall mortality was elevated for work in plant maintenance departments (SRR = 1.17, 95% CI = 1.00-1.37), particularly for fatal injuries (SRR = 1.67, 95% CI = 1.29-2.14). All-cause mortality increased with employment duration in the steel-production departments, as did fatal injuries in material handling/construction. CONCLUSIONS: This steelworker cohort exhibits excess mortality in some process areas. More detailed retrospective exposure assessment and future follow-up of this cohort will better define health risks in the modern iron and steel manufacturing.