Summary and Conclusion

All but one (Goldberg et al., 1990) of the studies reviewed by the committee and identified below in Table 6.46 found consistently positive odds ratios for the association between MDS and exposure to unspecified mixtures of organic solvents. Given that all the studies reviewed are case-control studies, almost all relied exclusively on self-reported exposures, which may be subject to recall bias. The difficulty in classifying MDS accurately and consistently is another limitation that the committee considered in evaluating the literature.

The committee concludes, from its assessment of the epidemiologic literature, that there is limited/suggestive evidence of an association between chronic exposure to unspecified mixtures of organic solvents and myelodysplastic syndromes.

For exposure to specific solvents, such as benzene, the rarity of the disease and the difficulty in classifying MDS as a separate entity have limited the evaluation of associations in most studies. Additional studies are needed to elucidate and support the association between exposure to benzene and MDS. They should also attempt to separate MDS from other cancers, such as ANLL, so that the relationship between exposure to benzene and MDS can be further understood. Table 6.46 identifies the studies related to MDS and solvent exposure. Unless indicated in the table, the study populations include both men and women.

The committee concludes, from its assessment of the epidemiologic literature, that there is inadequate/insufficient evidence to determine whether an association exists between chronic exposure to benzene and myelodysplastic syndromes.

TABLE 6.46 Selected Epidemiologic Studies—Myelodysplastic Syndromes and Exposure to Organic Solvents

Reference

Study description

Exposed Cases

Estimated Relative Risk (95% CI)

Benzene

Cohort Study—Incidence

Hayes et al., 1997

Chinese factory workers

 

 

ANLL or MDS

 

 

All unexposed

4

1.0

 

All exposed

28

4.1 (1.4–11.6)

 

Rubber workers

2

6.1

 

Chemical workers

4

4.5

 

Constant exposure, ANLL or MDS

 

 

<10 ppm

10

3.2 (1.0–10.3)

 

10–24 ppm

4

5.1 (1.3–20.6)

 

≥25 ppm

8

7.1 (2.1–23.7)

 

p-trend=0.0003

Unspecified Mixtures of Organic Solvents

Case-Control Studies

Nisse et al., 2001

Residents of northern France

 

 

Solvents, ever exposed

43

2.6 (1.6–5.4)

 

Glue adhesives, ever exposed

11

2.8 (0.8–11.8)

West et al., 2000

Residents of the UK

 

 

Organic chemicals, >50 hours of exposure at moderate intensity

75

1.8 (0.6–6.0)



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