Reference

Study Population

Exposed Cases

Estimated Relative Risk (95% CI)

 

Printers, white males

 

 

15–44 years

2

8.50

 

45–64 years

4

1.40

 

65–48 years

11

1.00

NOTE: NA=not available.

a95% CI were calculated by the committee with standard methods from the observed and expected numbers presented in the original papers.

bEstimated risks and 95% CI were calculated by the committee with standard methods from the observed and expected numbers presented in the original papers.

Epidemiologic Studies of Exposure to Organic Solvents and Acute Leukemia

Virtually all studies of exposure to benzene and acute leukemia (specifically AML or acute nonlymphocytic leukemia [ANLL], and ALL) showed positive associations (Albin et al., 2000; Ciccone et al., 1993; Crump, 1994; Ireland et al., 1997; Richardson et al., 1992; Rushton and Romaniuk, 1996; Wong, 1995; Yin et al., 1996a,b). In several cohort and case-control studies, the risks of acute leukemia were found to increase as the level or duration of exposure to benzene increased (Ireland et al., 1997; Richardson et al., 1992; Rushton and Romaniuk, 1996; Wong, 1995).

Increases in incidence of and mortality from AML were reported in the cohort studies of Chinese factory workers (SMR=3.1, 95% CI=1.2–10.7) (Yin et al., 1996a,b) and Pliofilm workers in Ohio (SMR=5.03, 95% CI=1.84–10.97) (Wong, 1995) respectively. Increased risks of AML were also reported in the cohort of petroleum-distribution workers in the UK (Rushton and Romaniuk (1996) and in a case-control study in Sweden by Albin and colleagues (2000) (OR=1.5, 95% CI=0.89–2.6 for all exposure levels). In a case-control study in France, Richardson and colleagues (1992) found an increased odds ratio among those with “medium/high” exposure to benzene (OR=2.8, 95% CI=1.3–5.9) when other occupational exposures were adjusted for. Increased risk of ANLL (RR=1.4, 95% CI=0.4–3.42) was reported from the cohort study of Monsanto chemical workers (Ireland et al., 1997). Yin and colleagues (1996a,b) found increased ALL risk among benzene-exposed workers, although the CIs were quite broad (SIR=2.8, 95% CI=0.5–54.5). Weak positive associations were observed in a low-powered case-control study in which exposure to solvents was assessed by industrial hygienists (Ciccone et al., 1993).

A number of case-control studies showed mostly positive associations between acute leukemia and exposure to unspecified mixtures of organic solvents (Albin et al., 2000; Flodin et al., 1981; Lazarov et al., 2000; Mele et al., 1994; Richardson et al., 1992). To increase the accuracy of exposure and to reduce recall bias, industrial hygienists, unaware of the case status of subjects, attributed exposure on the basis of job descriptions (Albin et al., 2000; Lazarov et al., 2000; and Richardson et al., 1992). In a case-control study by Albin and colleagues (2000), the OR for AML for all levels of exposure to organic solvents was 1.6 (95% CI=1.1–2.4) and 2.3 (95% CI=1.0–5.0) for moderate to high levels of exposure. For exposure to solvents in general, Lazarov and colleagues (2000) also showed an increased risk of AML (OR=2.52, 95% CI=1.45–4.39); the risk increased to 3.86 (95% CI=1.83–8.14) for “probable exposure” to solvents. In the case-control study by Flodin and colleagues (1981), the risk of AML increased to 6.3 (95% CI=2.6–15.3). A study of people ever employed as painters or shoemakers showed increased relative risks of both AML and ALL: for painters, the OR was 3.2 (95% CI=0.5–20.8)



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