Paradigm Change in the Assessment of Myeloid and Lymphoid Neoplasms Associated with Occupational Benzene Exposure

Benzene-caused hematologic neoplasms may be recognized as an occupational disease (OD) according to the German ordinance on ODs. At present, the OD No. 1303 covers heterogeneous diseases and various chemical agents triggering these diseases. The members of the medical advisory board specia lizing in ODs within the Ministry of Employment and Social Affairs recently proposed excluding diseases of the blood, the hematopoietic and lymphatic system caused by benzene from OD No. 1303 and classifying them as a separate OD. Benzene is generally acknowledged as a cause of acute myeloid leukemia, proven by numerous epidemiologic studies. However, there is less epidemiologic evidence of its association with other hematologic neoplasms, notably non-Hodgkin's lymphoma (NHL). To clarify this issue, the experts evaluated international literature and concluded that all kinds of myeloid and lymphoid malignancies including their prestages can be caused by occupational benzene exposure. Hence, physicians should ask patients about occupational benzene exposure and report any kind of diagnosed hematologic neoplasms, including their prestages, as suspected OD. The advisory board considered that a dose range starting from 10 ppm-years (cumulative benzene exposure) is sufficient for a > 50% probability of causing leukemias according to the WHO classification, including chronic lymphatic leukemia, and the potential preleukemias aplastic anemia and myelodysplastic syndrome, but excluding chronic myeloid leukemia (CML). For NHL and myeloproliferative diseases (including CML) the present epidemiologic evidence is considered not to be sufficient to describe a precise dose-effect relationship.