Summary and Conclusion

Overall, the studies reviewed by the committee did not show any persuasive evidence of associations between HD and exposure to specific solvents or solvent mixtures. Although many of the studies of exposure to mixtures of solvents yielded increased risk estimates, there was considerable statistical variability in them. The incidence of HD is low, and most studies had small numbers of exposed cases to evaluate. Having such small numbers may lead to spuriously increased relative risks when the null hypothesis of no association is true. That limitation is reflected in the wide CIs observed in most of the studies. The lack of specific or validated exposure-assessment information and the impact of bias are other limitations that the committee considered in drawing its conclusion. Table 6.36 identifies the key studies reviewed for each exposure and the data points evaluated by the committee. Unless indicated in the tables, 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 solvents under review and Hodgkin’s disease.

TABLE 6.36 Selected Epidemiologic Studies—Hodgkin’s Disease and Exposure to Organic Solvents

Reference

Study Population

Exposed Cases

Estimated Relative Risk (95% CI)

Trichloroethylene

Cohort Study—Incidence

Anttila et al., 1995

Biologically monitored workers in Finland

3

1.70 (0.35–4.96)

 

<100 µmol/L

2

2.00 (0.24–7.22)

 

≥100 µmol/L

1

1.83 (0.05–10.2)

Cohort Studies—Mortality

Boice et al., 1999

Aircraft-manufacturing workers in California, potential routine exposure

4

2.77 (0.76–7.10)

Blair et al., 1998

Aircraft-maintenance workers in Utah, employed >1 year

5

1.4 (0.2–12.0)

Morgan et al., 1998

Aerospace workers in Arizona

 

 

All exposed

1

0.60 (0.02–3.35)

 

Low exposure

1

1.55 (0.04–8.64)

 

High exposure

0

Axelson et al., 1994

Biologically monitored male workers in Sweden

1

1.07 (0.03–5.95)

Case-Control Study

Persson et al., 1989

Residents of Sweden, exposed >1 year

7

2.8 (0.96–7.86)a

Benzene

Cohort Study—Mortality

Wong, 1987a,b

US male chemical-plant workers

3

0.81 (0.16–2.36)

 

Benzene, continuously exposed

2

1.12 (0.14–4.05)

 

Not exposed to benzene

1

0.75 (0.19–4.15)

 

Duration of exposure, continuously exposed to benzene:

 

 

<5 years

1

0.88

 

5–14 years

1

2.37

 

≥15 years

0



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