NEW YORK (Reuters Health) - Research from Italy provides new evidence that exposure to the industrial solvent benzene increases a person's risk of developing multiple myeloma.
Dr. Adele Seniori Constantini of the Center for Study and Prevention of Cancer and her colleagues also found an increased risk of chronic lymphoid leukemia with benzene exposure. Two other oil-derived industrial chemicals, xylene and toluene, were also tied to greater chronic lymphoid leukemia risk.
Benzene, a known carcinogen, is used in the manufacturing of plastic, synthetic rubber, dyes and drugs. It is understood to cause acute myeloid leukemia, but its association with multiple myeloma and chronic lymphoid leukemia risk "are still under debate," Constantini and her team explain in the American Journal of Industrial Medicine.
To investigate, they identified all cases of blood and lymphatic cancers diagnosed in people 20 to 74 years old between 1991 and 1993 in 11 regions in Italy, including a total of 2,737 malignancies. In the current study, they looked at 586 cases of leukemia found in seven of the regions, comparing chemical exposures for the ill individuals to those for 1,278 controls based on occupation.
There was no association between acute myeloid leukemia and benzene, probably, the researchers say, because the disease develops within a relatively short time after exposure, and the cases were diagnosed about 30 years after benzene was "effectively banned" by a 1963 law limiting the amount used in industrial materials to 2 percent.
The researchers did find a link between multiple myeloma and chronic lymphoid leukemia and benzene exposure.
Overall, medium to high levels of benzene exposure nearly doubled the risk of these two blood cancers. The more intense exposure was and the longer it lasted, the greater the risk.
Being exposed to medium to high levels of benzene for more than 15 years increased a person's chronic lymphoid leukemia risk 4.7-fold, while the same degree of exposure to xylene more than tripled risk. Similar exposure to toluene boosted chronic lymphoid leukemia risk 4.4-fold. However, the increased risk for multiple myeloma was only seen with benzene, not with exposure to the other two chemicals.
"Our results," the team concludes, "even if based on small numbers, are in agreement with the hypothesis that acute myeloid leukemia risk following benzene exposure declines in time while chronic lymphoid leukemia and multiple myeloma risks are not seen until a longer latency period has passed."
SOURCE: American Journal of Industrial Medicine