Gulf War and Health: Volume 2. Insecticides and Solvents

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	—

Table of Contents

Front Matter R1-R16

Executive Summary 1-9

1. Introduction 10-16

2. Identifying and Evaluating the Literature 17-38

3. Insecticide Toxicology 39-81

4. Solvent Toxicology 82-97

5. Cancer and Exposure to Insecticides 98-155

6. Cancer and Exposure to Solvents 156-349

7. Neurologic Effects 350-449

8. Reproductive and Developmental Effects 450-483

9. Additional Health Effects 484-530

Appendix A: Overview of Illnesses in Gulf War Veterens 531-561

Appendix B: Conclusions and Recommendations: Gulf War and Health, Volume 1 562-564

Appendix C: Identifying the Literature 565-568

Appendix D: Insecticides and Solvents Sent to the Gulf War 569-569

Appendix E: Relative Risks for Lung Cancer 570-573

Appendix F: Neurologic Examination 574-579

Appendix G: Consensus Conclusions Arranged by Health Outcome 580-583

Index 584-600

Summary and Conclusion