Review of epidemiologic evidence on benzene and lymphatic and hematopoietic cancers.

Exposure to benzene is generally accepted as a cause of acute myeloid leukemia (AML), but the association with other cell types of leukemia and other lymphatic and hematopoietic cancers is controversial. We compiled epidemiologic research on benzene and lymphatic and hematopoietic cancers in order to assess the pattern of associations. Eighteen relevant community-based and 16 industry-based studies were located. Four of seven studies of lymphatic and hematopoietic cancer in the aggregate identified relative risks of 1.8 or more, and eight of 14 total leukemia studies yielded relative risks in that range. The few available studies of specific histologic types of leukemia do not indicate larger or more consistent elevations in risk for AML compared to other leukemia cell types. Sporadic reports have linked benzene to non-Hodgkin's lymphoma and multiple myeloma, but most studies do not indicate a positive association. Limitations in study quality, particularly exposure assessment, pervade all of the studies reviewed, and the distinction between studies addressing benzene and those addressing jobs in industries that use benzene is somewhat arbitrary. Nonetheless, the epidemiologic evidence linking benzene to leukemia in the aggregate, as well as for subtypes other than AML, is no less persuasive than that for AML alone.