Investigators collected and evaluated data from the following sources for use in the HRA:

• Survey. During 1999 RAND conducted a scientific survey of 2,005 Gulf War veterans randomly selected to statistically represent the entire Gulf War population on the ground in the Kuwait Theater of Operations (KTO).^[111]

• Preventive Medicine (PM) Interviews. Investigators conducted interviews of 252 preventive medicine personnel deployed on the ground in the KTO during the Gulf War who provided specific information on exposures to pesticides and related products. Investigators conducted interviews from February 1998 through November 1999. Tab C-4 contains additional information.

• Fly Bait Interviews. Investigators conducted interviews from December 1997 through February 1998 of 35 veterans who provided specific information on fly bait usage on the ground in the KTO during the Gulf War. Tab C-5 contains additional information.

• Delousing Interviews. Investigators conducted interviews from November 1998 through December 1999 of 60 personnel who participated in or witnessed delousing of enemy prisoners of war (EPWs). Investigators conducted 35 interviews expressly in connection with delousing, and conducted 25 interviews as part of the PM interviews. Tab C-6 contains additional information.

• Records Search. Investigators conducted a search of available contemporaneous deployment-derived information from sources such as the Defense Logistics Agency (DLA) and Armed Forces Pest Management Board (AFPMB). Tab C-7 contains additional information.

The main result of the data collection and evaluation step is the identification of those pesticide formulations to be retained for further evaluation in the HRA.

Many data used in the HRA drawn from the survey, interviews, and published sources are in the form of percentiles. A percentile is a value on a scale of 100 that indicates the percent of the distribution that is equal to or below it. For example, if the 5^th percentile value from the survey for exposure duration (ED) is 2 days/month, then we conclude that 5% of servicemembers were exposed 2 days or fewer per month. Likewise, if the 50^th percentile for ED is 20 days/month, then we conclude that 50% of servicemembers were exposed 20 or fewer days per month.

1.  Survey

In 1999, RAND scientifically surveyed 2,005 Gulf War veterans randomly selected to statistically represent all Gulf War KTO ground troops. RAND conducted the telephone survey from May to October 1999, drawing the sample from Army, Air Force, Marine Corps, and Navy servicemembers who served on the ground in the KTO between August 1, 1990 and July 31, 1991. RAND estimates that 469,047 servicemembers were actually on the ground in-theater during the period of interest. The report, "Pesticide Use During the Gulf War: A Survey of Gulf War Veterans," describes the survey in detail.^[112]

Table 7 briefly summarizes pesticide use by service according to the RAND findings. The two major categories of pesticides for survey purposes were "personal-use" pesticides and "field-use" pesticides. Personal-use pesticides are those deliberately applied to skin and/or clothing, while field-use pesticides cover all other types addressed by the survey. The most useful information for the HRA pertains to the two categories of pesticides listed in Table 7. Other types of pesticide products were those applied by certified applicators, and the lindane used for delousing EPWs. The most relevant information on these came from the preventive medicine (PM) interviews, fly bait interviews, and delousing interviews, all covered following this subsection.

Table 7. Survey, percentage of servicemembers estimated to have used pesticides from a given category, by service^[113]

Among other things, servicemembers were asked if they used various personal-use pesticides and if they used or saw others use various field-use pesticides. As can be seen in Table 7, 62% of servicemembers surveyed used personal-use pesticides, while 49% saw and/or used field-use pesticides.

Table 8 presents the most common pesticide products used and/or observed by servicemembers, as determined by the survey. The products are listed in descending order of prevalence within each category. Of the products listed, DEET was associated with the highest usage rate, while benzocaine and flea/tick collars were associated with the lowest. The Army used the highest levels of the pesticides listed, while the Air Force tended to use the lowest levels, although there are three exceptions. Six of the pesticide products listed in Table 8 are quantitatively evaluated later in the HRA, while benzocaine and flea/tick collars are not. The basis for excluding the latter is explained under "Screening of Pesticides for Risk Assessment."

Table 8. Survey, percentage of servicemembers estimated to have used the most common pesticides products, by service^[114]

Significant interpretation is necessary to extract the most accurate understanding of conditions in the Gulf based on the information in the survey. For example, Table 8 lists total permethrin usage at 44%. This is based on the survey usage rate for "personal-use spray" rather than the survey usage rate listed for "permethrin." The usage rate of 44% agrees fairly well with the usage rate of 40% for permethrin aerosol determined by the PM interviews. PM personnel are the most knowledgeable servicemembers regarding pesticides products. Permethrin would have been the most common personal-use aerosol spray. Although some DEET may have been present as a "personal-use spray," the best information available indicates that little if any DEET was issued in spray form from within the military supply system. While investigators conducted the interpretation of data carefully, it is possible that some bias was introduced here in extrapolating survey and interview data to the entire servicemember population deployed to the Gulf.

Table 9 and Table 10 present exposure factors of potential use in the HRA. Some of these data are more reliable than others, and investigators handled them accordingly, as the exposure assessment explains. Table 11 presents application rates for resin strips. These application rates are reliable data for risk assessment purposes, since servicemembers would likely have remembered seeing a common product they were probably familiar with. Table 12 provides selected exposure location data by service.

Table 9. Survey, exposure factors for personal-use products^[115]

Table 10. Survey, exposure factors for field-use products^[116]

Table 11. Survey, application rates for resin strips^[117]

Table 12. Survey, selected exposure location/facility data (percent)^[118]

2.  Preventive Medicine Interviews

Investigators conducted preventive medicine (PM) interviews from February 1998 through November 1999 (Tab C-4). PM personnel are the individuals most likely to have knowledge of pesticide products used in the Army, Navy, and Marines. The PM personnel interviewed included physicians, entomologists, environmental science officers, preventive medicine specialists, and field sanitation team members. In the Air Force, pest controllers are assigned to civil engineering units. Although not technically "preventive medicine" personnel, investigators covered interviews with Air Force pest controllers as part of the PM interviews, and as used below, "PM personnel" generally includes Air Force pest controllers. The PM personnel interviewed included those who were trained in pesticide application, conducted pesticide application, supervised, or witnessed pesticide application during the Gulf War.

Of the approximately 500 PM interviews conducted, investigators identified 252 of these as "exposure interviews." To be classified as an exposure interview, the interviewee had to demonstrate at least some knowledge of pesticide usage on the ground during the Gulf War. Interviews which did not demonstrate this knowledge were excluded. All information gleaned from the interviews is subjective, as it was based on the recollections of the veterans as interpreted and compiled by investigators.

During initial reviews of the PM interviews, it became obvious that, in addition to the mass of complete, correct, and unequivocal information, there was also some incomplete, incorrect, and ambiguous information. Thus, investigators made certain assumptions to interpret such problematic data, where possible, in order to make it useful for exposure assessment. These assumptions were based on the accumulated knowledge of pesticide product availability and usage during the Gulf War. Investigators developed the following set of directions to use when processing the interviews:

While we acknowledge that employment of the directions above potentially introduced some bias, we believe that it was necessary in order to use some data for exposure assessment which would otherwise have been incorrect or useless.

The discussion in this subsection centers on Table 13 through Table 15, which present a summary of exposure data from the exposure interviews. The data presented in Table 13 and Table 15 are primarily those which have a direct bearing on the HRA. In order to facilitate discussion of the data presented in Table 13, covering 14 of the 15 pesticides of potential concern (POPCs), the HRA will refer throughout to the "block" numbers listed in the left-hand column (see Section B.2.B,  Screening Pesticide Products for Risk Assessment, below for a description of how the POPCs were identified). Lindane (a POPC) is not covered in this section; rather, it is addressed under "Delousing Interviews." Each block is readily identifiable by the thick black line at the top, and the HRA refers to it below as "B#" (e.g., B1 for Block 1). The information presented in the summary tables is limited. The original responses contain much additional information which the tables do not reflect.

Table 13 summarizes formulation-specific exposure data. The table's approach is conservative because (1) all data and statistics are based exclusively on the 252 exposure interviews, and (2) investigators did not count negative responses or responses equal to zero. Although reliance on the 252 exposure interviews may bias the results high, it is necessary because very few of the other servicemembers were in a position to say that pesticide products were not used by their units or that they had not witnessed pesticide use; if anything, they were more likely to say that they just did not remember.

Table 13 presents various statistics, including the number of servicemembers providing a response, and the fraction of the total this represents. "Total" means the 252 exposure interviews, or all responses for a given formulation, as indicated in the table. Also listed, where appropriate, are the 10^th percentile, average, and 90^th percentile values calculated using Microsoft Excel^� based on the specific numerical responses provided by the interviewees. The percentile algorithm will calculate percentile values based on as few as two data points; however, the fewer the data points, the higher the uncertainty. In many cases, the 90^th percentile values are equal to the maximum values.

The levels of uncertainty associated with the data presented in Table 13 vary from low to high, depending upon the specific datum in question, but probably tend to be high, in part, because the data are all based on the memories of events that occurred 7-9 years prior to the interviews. Some interviewees stated that they had been deployed to many different locations around the globe over the course of many years, and were unsure sometimes about which things had occurred in which locations. Higher quality data would be possible, for example, if more detailed records had been kept and real-time monitoring, with appropriate quality controls, had been conducted during operations. The level of certainty is also related to the question asked. For example, the interviewees were probably more accurate about the names of the pesticide products used than they were about estimating how many hours per day people were exposed. A detailed explanation of each section of Table 13 follows the table.

Table 13. PM interviews, summary of formulation-specific exposure data^a

Block Number/Descriptionb
B1. Pesticide Products Cited
Total Responses	78	46	102	19	68	108	16	62	39	42	14	14	27	33
Fraction of Exposure Interviews	31%	18%	40%	8%	27%	43%	6%	25%	15%	17%	6%	6%	11%	13%
B2. Final Concentration
Number of Responses								10	12	9	2	0	0	7
Fraction of Total Responses								16%	31%	21%	14%	--	--	21%
10th Percentile (%)								1	0.3	2	2	--	--	18
Average (%)								13	14	15	8	--	--	70
90th Percentile (%)								45	44	35	13	--	--	92
B3. Individuals Exposed
Number of Responses	31	18	43	7	20	50	3	30	17	24	6	6	15	13
Fraction of Total Responses	40%	39%	42%	37%	29%	46%	19%	48%	44%	57%	43%	43%	56%	39%
10th Percentile (%)	25	75	13	1	2	1	91	1	1	1	8	1	1	3
Average (%)	76	91	76	24	75	62	95	67	48	58	69	36	55	57
90th Percentile (%)	100	100	100	55	100	100	99	100	100	100	100	90	100	100
B4. Individuals Wearing PPEc
Number of Responses			14	5	15	37	2	27	21	27	8	12	21	20
Fraction of Total Responses			14%	26%	22%	34%	13%	44%	54%	64%	57%	86%	78%	61%
10th Percentile (%)			58	30	100	97	15	73	100	95	85	100	100	75
Average (%)			91	74	94	97	53	92	97	98	94	100	100	95
90th Percentile (%)			100	100	100	100	91	100	100	100	100	100	100	100
B5. Exposure Time
Responses	30	18	39	8	27	50	8	33	19	24	8	6	17	17
Fraction of Total Responses	38%	39%	38%	42%	40%	46%	50%	53%	49%	57%	57%	43%	63%	52%
10th Percentile (h/d)	2	2	1	1	1	1	3	1	1	1	1	1	1	1
Average (h/d)	14	15	15	3	7	6	11	5	4	3	2	1	2	3
90th Percentile (h/d)	24	24	24	9	20	16	22	12	11	6	3	3	4	7
B6. Exposure Frequency
Number of Responses	29	19	39	8	27	53	9	32	18	20	8	7	18	15
Fraction of Total Responses	37%	41%	38%	42%	40%	49%	56%	52%	46%	48%	57%	50%	67%	45%
10th Percentile (d/mo)	5	1	1	1	4	1	23	1	1	1	1	1	1	1
Average (d/mo)	22	23	20	11	22	18	27	13	11	10	4	6	8	10
90th Percentile (d/mo)	30	30	30	30	30	30	30	30	30	30	10	12	21	30
B7. Exposure Duration
Number of Responses	28	16	36	9	25	50	7	31	17	22	8	6	16	12
Fraction of Total Responses	36%	35%	35%	47%	36%	46%	44%	50%	44%	52%	57%	43%	59%	36%
10th Percentile (mo)	2	2	1	2	3	1	2	1	1	1	1	1	1	1
Average (mo)	4	5	4	4	5	4	4	4	4	5	3	4	4	5
90th Percentile (mo)	8	8	8	6	9	8	6	8	9	8	7	7	8	8
B8. Applied to Skin
Number of Responses	43	28	8	--
Fraction of Total Responses	55%	61%	8%	--
B9. Applied to Clothing
Number of Responses	2	3	60	2
Fraction of Total Responses	3%	7%	59%	11%
B10. Used Mainly Outdoors
Number of Responses			27	1	30	62	--	36	25	29	7	5	18	22
Fraction of Total Responses			26%	5%	44%	57%	--	58%	64%	69%	50%	36%	67%	67%
B11. Used Mainly Indoors
Number of Responses			9	15	13	14	9	5	5	7	5	7	3	1
Fraction of Total Responses			9%	79%	19%	13%	56%	8%	13%	17%	36%	50%	11%	3%
B12. Exposed Mainly Outdrs.
Number of Responses			19	1	28	61	--	32	23	28	6	6	16	23
Fraction of Total Responses			19%	5%	41%	56%	--	52%	59%	67%	43%	43%	59%	70%
B13. Exposed Mainly Indoors
Number of Responses			10	14	15	16	9	8	5	9	5	6	5	2
Fraction of Total Responses			10%	74%	22%	15%	56%	13%	13%	21%	36%	43%	19%	6%
B14. Body Parts Exposed
Hands, arms, face, headd	38	25	19	8	18	35	2	19	14	14	5	7	10	11
Entire body	5	3	21	2	--	--	--	4	1	4	--	--	1	1
Other parts	-	-	2	2	1	2	--	4	2	3	1	--	1	2

B1. Pesticide Products Cited presents the number of "hits" for each of the 14 POPCs listed (the 15^th POPC, lindane, is addressed under "Delousing Interviews," later). A single hit means that the pesticide product was mentioned one or more times in the course of an interview. Thus, 68 hits for 1% azamethiphos means that 1% azamethiphos was mentioned at least once in each of 68 interviews. The fraction, represented as a percent, equals the number of hits divided by the number of exposure interviews (i.e., 252). The level of certainty associated with the data presented for B1 is high.

B2. Final Concentration presents data on the percent concentration of active ingredient (a.i.) reportedly applied; that is, the final concentration after dilution, if any. For example, the 90^th percentile final concentration for chlorpyrifos, 45% liquid (EC) is 45%. What this means is that at least 10% of personnel may have applied undiluted chlorpyrifos EC. This would be a violation of the label under any circumstances.

Investigators consider these values unreliable for the HRA. The actual concentrations applied were difficult for most people to recall, as partly evidenced by the low rates of response. The values listed are generally out of line with how trained applicators (pesticide workers) would most likely have used these formulations. However, there were a small number of apparently reliable reports, based on the level of detail provided, of extremely high application rates for some formulations.

B3. Individuals Exposed presents data on the number of individuals reportedly exposed to each formulation. There is moderate to high uncertainty associated with these data. Some respondents were referring only to applicators, while some were referring to all servicemembers within their units. Also, based on a review of the actual interview narratives, it appears that some interviewees excluded servicemembers wearing personal protective equipment (PPE), while others included those wearing PPE.

B4. Individuals Wearing PPE presents data on applicators wearing PPE. These data are associated with moderate uncertainty. One factor which lowers uncertainty is that respondents were referring only to applicators. However, there are several factors that tend to increase uncertainty. First, since "adequate PPE" was not defined in the interview, some personnel may be referring to applicators who were in fact inadequately protected (e.g., they had gloves, but not respirators when respirators were required). Second, there is a low response rate for most formulations. Finally, the data do not reflect many of the qualitative statements of veterans who did not answer this specific question that they frequently had little or no PPE.

B5 through B7. Data present the exposure times (hours/day), frequencies (days), and durations (months) for each pesticide product. These data are associated with moderate to high uncertainty. The response rates are low for some formulations. Some respondents were referring to applicators only, while some were referring to all members of their units. Recall was clearly a problem.

B8. Applied to Skin presents the numbers of respondents confirming that skin application occurred for DEET and permethrin. One can safely assume that most servicemembers who used 33% DEET deliberately applied it to their skin, while 61% of respondents identified skin application of 75% DEET. Eight percent stated that servicemembers applied permethrin to skin, which constitutes a misuse of the product.

B9. Applied to Clothing presents the numbers of respondents stating that pesticide products were applied to clothing. Permethrin was by far the most widely applied, as expected. It is noteworthy interviewees did not identify 75% DEET liquid as being used very much for clothing application, as military guidance issued following the Gulf War specified clothing application as the only appropriate use for 75% DEET.^[119] Chances are, troops applied much more DEET to clothing than is reflected here, since clothing application was an intended purpose of DEET, and such application would have enhanced protection against pests. It seems unlikely that much d-phenothrin was deliberately applied to clothing; only two respondents identified this use of d-phenothrin, and they may have been referring to incidental and/or infrequent application rather than intentional and/or frequent application. No further information on this issue was obtained.

B10 and B11. Data describe the predominant location of pesticide product use as either outdoors or indoors; that is, outside or inside any enclosed structure, including a tent. Low response rates for some of the formulations limit data usability for the HRA, and the actual differences for some formulations are highly uncertain. For example, 26% said permethrin was used mainly outdoors, while 9% said it was used mainly indoors. It would be useful to know where the other 65% recalled seeing it used. On the other hand, some of the responses confirm what would be expected. For example, 91% malathion was reportedly used outdoors the majority of the time. Despite the shortcomings of the data, it is safe to conclude that most pesticide products were used more outdoors than indoors, with the exception of dichlorvos, d-phenothrin, and bendiocarb. Consideration of outdoor versus indoor use is irrelevant for DEET, since an individual is in continuous contact with it once applied.

B12 and B13. Data describe the predominant exposure point to the pesticide product as either outdoors or indoors. There is a high level of agreement between B10 and B12, and B11 and B13, indicating respondents answered conscientiously. This fact may be viewed as increasing the reliability of these answers, although the low response rate for some formulations has the opposite effect.

B14. Body Parts Exposed presents the numbers of veterans reporting that various body parts were predominantly exposed to pesticide products. As expected, the greatest dermal exposure for most of the pesticide products used was to hands, arms, face, head, and/or neck. The only exception is permethrin, where about half of those providing an answer to this question indicated predominant exposure was whole body. Few PM personnel indicated that other parts were exposed.

All the pesticides and related products identified in the PM exposure interviews were ranked in Table 14 based on the "hit" rate. Each interview mentioning a given pesticide product at least once counts as a hit. The level of certainty associated with the data presented for Table 14 is high.

Table 14. PM interviews,   pesticide product rankings

Table 15 presents a brief summary of other exposure data collected during the PM interviews. When asked about exposure route, most interviewees felt that the dermal route was the main one, with inhalation a close second. Only about 2% felt that the oral route was of concern. Most servicemembers were quartered in GP-medium tents, and most respondents reported that their quarters were very dusty. Almost half reported that the wind commonly penetrated quarters. Pesticide-contaminated dust may have been an issue for some servicemembers. On the other hand, wind penetrating quarters would dilute potential inhalation exposures.

Table 15 indicates a few other points worth noting. At least 12% of interviewees believed specific documentation may have existed regarding pesticide product use and/or exposures. At least 17% of interviewees provided information on pesticide product disposal practices. Seven percent of interviewees could describe specific incidents of overexposure to pesticide products that caused an immediate reaction or symptoms. Fifteen percent of interviewees witnessed host nation preparation and application of pesticide products.

The survey and the PM interview results are not directly comparable, as investigators undertook each component for a different purpose, employing radically different methods. Despite this, there is reasonable agreement regarding reported usage rates for DEET, permethrin, and dichlorvos. There appear to be significant discrepancies for fly baits and d-phenothrin. The survey indicates that there was a 12% usage rate for fly baits, while the PM interviews indicate a rate of at least 43%. For d-phenothrin, apparent usage rates were 28% versus 8% from the survey and PM interviews, respectively. The survey usage rates for fly baits and d-phenothrin are likely overestimates.

Table 15. PM interviews, summary of other exposure data

3.   Fly Bait Interviews

Early in the pesticides exposure investigation it became apparent that troops used fly baits widely during the Gulf War. Consequently, investigators completed 35 interviews, addressing mainly fly baits, from December 1997 through February 1998 (Tab C-5). The RAND survey confirmed the prevalence of fly baits, as did the PM interviews. Table 16 summarizes the qualitative and quantitative exposure information from the fly bait interviews.

Table 16. Fly bait interviews, summary of exposure data^a

4.  Delousing Interviews

Investigators used a total of 60 interviews to evaluate exposure to lindane dust. Delousing of thousands of enemy prisoners of war (EPWs) was a specialized function carried out exclusively or almost exclusively by military police (MPs). The best information available indicates that lindane, 1% powder was virtually the only formulation used by US servicemembers for delousing EPWs. UK troops reportedly used a malathion formulation. Twenty-five of the preventive medicine interviews provided information about delousing. To better capture the details of the process, investigators completed 35 additional interviews of servicemembers likely to be knowledgeable about delousing, from November 1998 through December 1999 (Tab C-6). Table 17 summarizes exposure data from all 60 delousing interviews.

Table 17. Delousing interviews, summary of exposure data^a