Only one study investigated ANLL in conjunction with preconception solvent exposure (Buckley et al., 1989). On the basis of self-reported exposure, a positive association between ANLL and paternal solvent exposure before pregnancy (OR=2.2, p<0.05) was found. No estimates of relative risk for maternal exposure to solvents were presented.

Summary and Conclusion

The studies on childhood leukemia and exposure to organic solvents generally followed similar procedures for ascertaining cases, matching controls, and interviewing parents to obtain relevant information. Studies generally controlled for known confounders, but in most cases risk factors are not well understood. Studies that examined parental occupational exposure often did not differentiate whether the exposure occurred before, during, or after pregnancy. Little information was available on preconception exposure for each cancer type. Exposure measures were based largely on interviews and, thus, were subject to recall bias or random misclassification of exposures; the former tends to artificially increase the odds ratio, and the latter attenuates toward the null value. Many of the studies presented the additional concern that mothers who reported on their husbands’ work exposure further increased the likelihood of misclassification of the fathers’ exposure.

For childhood leukemias combined, several studies showed positive associations with exposure to solvents. Several studies were limited by misclassification bias related to self-reporting of exposure and by the fact that some looked at all childhood leukemias and others focused on specific cell types, such as ALL and ANLL. Given the combination of the limitations of this body of evidence and the consistently positive findings, the committee was unable to reach a consensus conclusion. Some committee members believed that the evidence fulfilled the category of inadequate/insufficient, while others believed it was limited/suggestive of an association. Future studies that address some of the limitations identified above are needed to understand the association between childhood leukemia and exposure to solvents. Table 6.48 identifies all the studies evaluated by the committee.

TABLE 6.48 Selected Epidemiologic Studies—Childhood Leukemia and Exposure to Organic Solvents

Reference

Study Population

Exposed Cases

Estimated Relative Risk (95% CI)

Leukemia (all types)

Cohort Study—Incidence

Feychting et al., 2001

Children in Sweden

 

 

Paternal preconception exposure

 

 

Solvents

23

1.25 (0.80–1.95)

 

Benzene

3

1.23 (0.39–3.85)

Case-Control Studies

Smulevich et al., 1999

Children in Moscow

 

 

Occupational exposure before conception

 

 

Maternal exposure to solvents

20

3.1 (1.5–6.3)

 

Paternal exposure to solvents

70

1.4 (0.95–2.1)

Lowengart et al., 1987

Children in Los Angeles County

 

 

Paternal preconception exposure

 

 

Chlorinated solvents

9

2.2 (p=0.09)

 

Trichloroethylene

6

2.0 (p=0.16)

 

Methyl ethyl ketone

5

1.7 (p=0.24)



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