There were 60 cases of AML (241 controls) and 80 cases of
CLL (345 controls). Mean average intensity of benzene exposure
for AML cases and controls was 0.18 p.p.m. and 0.2 p.p.m.,
respectively, and for CLL cases and controls was 0.19 p.p.m. and
0.21 p.p.m., respectively.