A.6 lists the percentages of veterans reporting pesticide or solvent-related exposures of interest to the committee.

TABLE A.6 VA Study Percent Distribution of Self-Reported Exposures (n=11,441)

Self-Reported Exposures

Percentage

Personal pesticides, including creams, sprays and flea collars

48.4

Contact with prisoners of wara

32.8

Food contaminated with smoke, oil, or other chemicals

30.2

Other paint or solvent or petrochemicals substances

29.7

Chemical Agent Resistant Compound Paint

21.7

SOURCE: Kang et al., 2000

aLindane used as delousing agent (Cecchine et al., 2000)

Oregon and Washington Veterans

Veterans from Oregon or Washington were studied in a series of analyses by investigators of the Portland Environmental Hazards Research Center (McCauley et al., 1999). A questionnaire was sent to a random sample (n=2343) of 23,711 Gulf War veterans listing Oregon or Washington as their home state of record at the time of deployment. The response rate was 56%. The study found high rates (20–60%) of self-reported symptoms, including cognitive-psychologic symptoms, unexplained fatigue, musculoskeletal pain, gastrointestinal complaints, and rashes. However, among the first 225 participants who later came for a clinical examination, there were significant differences between their self-reported symptoms on questionnaires and their symptoms reported at clinical examination. Significantly fewer veterans reported symptoms at clinical examination.

Symptom clustering. Investigators studied clusters of unexplained symptoms by creating a new case definition for unexplained illness (Storzbach et al., 2000). Cases were identified through questionnaires as meeting a threshold number, combination, and duration of fatigue, cognitive/psychologic, and musculoskeletal symptoms. Veterans whose symptom clusters remained unexplained at clinical examination (after exclusion of established diagnoses) were defined as constituting cases. Controls were those who at the time of clinical examination had no history of case-defining symptoms during or after their service in the Gulf War. In an analysis of the 241 cases versus 113 controls, investigators found small but statistically significant deficits in cases on some neurobehavioral tests of memory, attention, and response speed. Cases also were significantly more likely to report increased distress and psychiatric symptoms (Storzbach et al., 2000). A later analysis focused on a subgroup of 30 (of the 241) cases whose performance was slowest on the Oregon Dual Task Procedure (ODTP), a relatively new test of digit recognition that assesses motivation, attention, and memory (Storzbach et al., 2001). In comparison with other cases, the “slow ODTP” group performed more poorly on other neurobehavioral tests of memory, attention, and reaction time but not on psychologic tests. Investigators plan more-extensive imaging and EEG tests on this subgroup of cases.

Exposure-symptom relationships. Another nested case-control analysis of the population-based cohort examined whether cases of unexplained illness were more common in any of the three periods of Gulf War deployment: precombat, combat, and postcombat (Spencer et al., 1998). Subjects were not asked about specific exposures, but their period of deployment was used as a proxy for different combinations of environmental exposures. Of 14 potential exposures likely to be differentially encountered during deployment periods, two were of special interest to the committee: “insect repellent” and “pesticides.” Those two



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