Objective: High benzene exposure is related to acute nonlymphocytic leukemia. Recently, myelodysplastic syndrome has been observed at low benzene exposure levels.
Methods: We updated a mortality study of workers with benzene exposure examining acute nonlymphocytic leukemia and myelodysplastic syndrome. We calculated standardized mortality ratios with 95% confidence intervals and examined latency and trends for cumulative exposure levels.
Results: All leukemias (standardized mortality ratio = 1.21; 95% confidence interval = 0.74 to 1.97) and acute non-lymphocytic leukemia (standardized mortality ratio = 1.04; 95% confidence interval = 0.34 to 2.44) were at expected levels. We observed one death from myelodysplastic syndrome (standardized mortality ratio = 6.48; 95% confidence interval = 0.17 to 38.15). We observed no trend for cumulative exposure levels.
Conclusions: Our results for all leukemias are consistent with a small increase in risk observed in the lower-exposed subgroups of the Pliofilm study; however, our results are also consistent with no increased risk especially for acute nonlymphocytic leukemia.