Risk factors for acute myeloid leukemia and multiple myeloma: a combination of GIS and case-control studies

Risk factors for acute myeloid leukemia (AML) and multiple myeloma (MM) include exposure to toxic chemicals present in tobacco smoke, as well as to emissions from industrial operations and petroleum refinery waste dumps. The study reported here identified these risk factors among case patients and control patients in Orange County, California, from 1984 to 1993 and determined the significance of the risk factors in the study population. A case-control study was performed for 604 cases of AML and 643 cases of MM; there were 7,112 control subjects who had colon cancer. The model included the variables smoking history, occupational history, and residence in a census tract with a petroleum refinery waste dump. A geographic information system (GIS) analysis also was performed to correlate the incidence of AML and MM with proximity to the six dump sites that received large amounts of petroleum refinery waste. Current smokers were found to be at an increased risk of AML with an odds ratio of 2.0. Laborer/equipment cleaners and transportation workers/movers were at risk of AML with odds ratios of 3.5 and 2.4, respectively. Construction/resource extraction workers were at risk of MM with an odds ratio of 2.8. GIS analysis determined that the risk for MM was 1.6 cases per mile for 10 or more years of residence near a large chemical dump. The authors were able to identify census tracts with a high incidence of AML and MM, and to perform distance analysis using a statistical measure of spatial randomness. The case-control study identified occupational and lifestyle risk factors for AML and MM that were not apparent from census-tract-level data.