The Department of Defense Kuwait Oil

Health Fire Risk Assessment (The "Persian

Gulf Veterans' Registry")

September 1994

OTA-BP-H-138

NTIS order #PB95-109716
TechnologyAssessment Board of the 103d Congress

EDWARD M. KENNEDY, Massachusetts, Chairman

DON SUNDQUIST, Tennessee, Vice Chairman

SENATE HOUSE

ERNEST F. HOLLINGS, South Carolina GEORGE E. BROWN, JR., California

CLAIBORNE PELL, Rhode Island JOHN D. DINGELL, Michigan

ORRIN G. HATCH, Utah JIM McDERMOTT, Washington

CHARLES E. GRASSLEY, Iowa AMO HOUGHTON, New York

DAVE DURENBERGER, Minnesota MICHAEL G. OXLEY, Ohio

ROGER C. HERDMAN

(Nonvoting)

Technology Assessment Advisory Council

NEIL E. HARL, Chairman

Charles F. Curtiss Distinguished Professor

Iowa State University

Ames, Iowa

JAMES C. HUNT, Vice Chairman

Distinguished Professor, Health Sciences Center

University of Tennessee

Memphis, Tennessee

CHARLES A. BOWSHER

Comptroller General of the United States

Washington, D.C.

MAX LENNON

President and CEO

Eastern Foods, Inc.

Atlanta, Georgia

THOMAS J. PERKINS

General Partner

Kleiner, Perkins, Caufield and Byers

San Francisco, California

L. DOUGLAS SMOOT

Dean, College of Engineering & Technology

Brigham Young University

Salt Lake City, Utah

LEWIS M. BRANSCOMB

Director, Science, Technology & Public DANIEL MULHOLLAN

Policy Program, Harvard University Director, Congressional Research

Cambridge, Massachusetts The Library of Congress

Washington, D.C.

HERBERT (TED) DOAN

President (Ret.), The Dow Chemical Company JOHN F.M. SIMS

Midland, Michigan Vice President, Marketing

Usibelli Coal Mine, Inc.

JOSHUA LEDERBERG Fairbanks, Alaska

Professor, Rockefeller University

New York, New York

Service

MARINA v.N. WHITMAN

Professor, Institute of Public Policy Studies

University of Michigan

Ann Arbor, Michigan

The Technology Assessment Board approves the release of this report. The views expressed in this report

are not necessarily those of the Board, OTA Advisory Council, or individual members thereof.
Clyde J. Behney

Assistant Director

Health, Education,

and Environment

Sean R. Tunis

Health Program Director

Project Staff

PRINCIPAL STAFF

Hellen Gelband

Project Director

Maria Hewitt

Senior Analyst

ONTRACTOR

ADMINISTRATIVE STAFF

Beckie Erickson

Health Program Office

Administrator

Daniel B. Carson

PC Specialist

Carolyn Martin

Word Processing Specialist

Stephen L. Brown

Risks of Radiation and Chemical

Compounds

Oakland, CA

Carolyn Swarm

PC Specialist
OTA Review

The Department of Defense Kuwait Oil Fire Health Risk Assessment

(The Persian Gulf Veterans’ Registry)

INTRODUCTION

Even before the end of Operation Desert Storm, the Department of Defense (DoD) began to

assess the likely health impacts of the conflict’s most visible icon--billowing smoke from 600 burning

Kuwaiti oil wells, ignited by retreating Iraqi troops. Then, just as the last fires were extinguished, the

Congress made its own specific demands for information about health risks to each smoke-exposed

military participant (in Public Law 102-190 and later expanded on in Public Law 102-585). DoD

responded with the Kuwait Oil Fire Health Risk Assessment, the heart of which is a computer-based

geographical information system (GIS). The completed part of the risk assessment is based on actual

measurements of contaminant levels taken while troops and smoke coexisted in the Persian Gulf. An

ongoing part will eventually produce estimates of health risks based on “modeled” contaminant levels

where and when no actual measurements were taken.

The Office of Technology Assessment was directed in Public Law 102-585 to assess whether

DoD’s project “meets the provisions of the law under which it was mandated,” to assess its “potential

utility . . . for scientific study and assessment of the intermediate and long-term health consequences of

military service in the Persian Gulf theater of operations during the Persian Gulf War, ” and to address

some other related questions. A requirement that OTA assess the Department of Veterans Affairs

Persian Gulf War Veterans’ Health Registry (which was mandated in the same public laws as the DoD

effort) was met by a report in October 1993.1

This Background Paper describes briefly the work on DoD’s Kuwait Oil Fire Health Risk

Assessment to date, including the results of a pilot study of health risks, and then answers the questions

addressed to OTA in PL 102-585. This review relies heavily on the work of a consultant expert in

chemical risk assessment who studied the DoD project for OTA (the consultant’s report is available from

OTA).2 His work is based on a variety of contacts with the U.S. Army Environmental Hygiene Agency

(EHA; recently renamed the U.S. Army Center for Health Promotion and Preventive Medicine, but

referred to in this report as EHA), which has major responsibility for this task within DoD, except for

determining troop locations. That latter task falls to the U.S. Army and Joint Services Environmental

Support Group (ESG), the Army’s experts on military records. OTA’s consultant (and OTA staff)

gathered information from ESG on their activities relevant to this review.

1 

u s Congress, office of Technology Assessment,

. . “The Department of Veterans Affairs Persian Gulf Veterans’

Health Registry, 1993.

2Risks of Radiation and Chemical compounds, “The DoD Persian Gulf Oil Fire GIS Modeling Project: A Review

and Evaluation, ” submitted to OTA September 1994.
2- The Department of Defense Kuwait Oil Fire Health Risk Assessment

SUMMARY OF OTA’S FINDINGS

DoD have designed a GIS capable of producing individual estimates of risk resulting from

exposure to oil fire smoke (and for smoke plus ambient background concentrations of toxic substances

using measurements of air samples over a nine-month period) for each person who served in the Persian

Gulf region, in response to the Congressional mandate. The system will be fully operational when the

exposure information is all placed into the GIS (some time in 1995) and daily location data for each unit

stationed in the region during the conflict are completely abstracted from original military records (some

time in 1996). The risk assessment framework adopted by DoD is a logical and well-executed response

to the mandate, based philosophically on the way the Environmental Protection Agency (EPA) conducts

risk assessments under various environmental health laws. This type of risk assessment, because of a

desire to protect public health, inherently overestimates risks to health.

In its Final Report: Kuwait Oil Fire Health Risk Assessment, EHA reported estimated health

risks that were extremely low: an estimated upper limit of lifetime cancer risk of two in a million

(possibly rising to three in a million when exposure is extended to the entire period during which the

fires burned, and possibly somewhat higher at some places where measurements were not taken), and a

low probability of noncancer health risks (not quantified in the same way as cancer risks). These risk

levels are similar to estimates for a person spending the same amount of time in a U.S. city, calculated in

the same way. Under existing risk assessment scenarios, these risk estimates would be considered so low

that, in most cases, they would be dismissed. Scientifically, there is no added value to actually

generating (or being able to generate) risks for individuals, all of which would be below these upper

limits (or slightly modified upper limits not expected to be much different from these) and would, in any

case, not be very accurate. Risk assessment methods have generally been designed to apply to groups of

people and not to estimate precise risks for any one individual. Since all estimated risks would be very

low, they could not be used to identify any particularly “high risk” cohorts that might benefit from

medical surveillance or other intervention.

The GIS may have uses other than generating oil fire health risk estimates. It is a versatile and

powerful analytic tool that might be put to use in epidemiologic studies of other exposures in the Persian

Gulf, but only if sufficient information on those other exposures were available and could be described

accurately in time and place. (OTA is unaware of efforts to systematically catalog exposures in this

way.) This type of use will depend on ESG completing its troop location inventory, independent of the

needs of the oil fire risk assessment.

The important conclusion that OTA draws from DoD’s report on oil fire health risk

assessment is that, using state-of-the-art risk assessment methods, the risks to health from

exposure to the smoke and the background air contaminants in the Persian Gulf are likely to be

extremely small. If aspects of the Persian Gulf experience are causing illness, they are likely to be other

than oil fire smoke, according to DoD’s risk assessment.

When completed, DoD’s GIS and its associated risk assessment system will meet the

Congressional mandate for individualized estimates of exposure from Persian Gulf oil fires. The

troop location and atmospheric data related to the smoke will be easily accessible indefinitely once they

are all entered into the system. The scientific value of the program, however, lies in what already has

been accomplished, which establishes that overall risks to health from oil fire smoke are very low.

Additional scientific value may come from its use in evaluating other exposures that are suspected of
The Department of Defense Kuwait Oil Fire Health Risk Assessment -3

causing health problems among Persian Gulf veterans, but this depends on having detailed information

about other potentially harmful exposures. Actually being able to generate individual exposure

estimates, which is required by the law, is of very low value as it relates to learning anything about

veterans’ health.

THE OIL FIRES IN KUWAIT

As Iraqi troops withdrew from Kuwait at the end of the Persian Gulf conflict, they destroyed

more than 700 oil wells in four major oil fields, and about 600 were burning at the end of February 1991.

Other wells were gushing oil and some of the resulting “oil lakes” also burned. When all the fires were

burning, perhaps 5 million barrels of oil were consumed each day. Before the last fire was extinguished

in early November 1991, 800 million barrels of oil may have burned.

The fires released copious smoke that rose to altitudes of one to four kilometers and moved

mostly to the south and west under the influence of prevailing winds. Some fires released predominantly

white smoke, indicating large quantities of water vapor; some released very black smoke, indicating high

soot content; and some released smoke intermediate in color. Plumes from the individual fires merged as

they moved downwind into a “super-plume” that could be tracked from satellite images of the Persian

Gulf region. The super-plume was dense enough to block out most sunlight when it was overhead.

The plumes contained both oil combustion products and unburned chemicals originating in the

oil, along with minerals associated with soil or water carried aloft by the fires. Significant quantities of

the more volatile chemicals in crude oil also were released to the atmosphere by evaporation from

gushing oil wells or crude oil pools.

Nearly 700,000 U.S. troops were deployed to the Persian Gulf region and many were in the

region while the fires were burning. When a plume was overhead in the vicinity of the troops, there was

a potential for exposure, although the densest part of the plume was generally well above the surface.

Soon after the fires began, speculation arose that exposures might cause acute health effects in

some people. Measurements of pollutant concentrations and records of health complaints did not reveal

a widespread short-term problem, but the possibility remained that smoke exposures could cause

diseases, including cancer, later on.

THE CONGRESSIONAL MANDATE TO DOD

The first Congressional mandate came in the National Defense Authorization Act for Fiscal

Years 1992 and 1993 (Public Law 102-190, Section 734), passed in December 1991. The law calls for

the Secretary of Defense to:

establish and maintain a special record relating to members of the Armed Forces who, as

determined by the Secretary, were exposed to the fumes of burning oil in the Operation Desert

Storm theater of operations during the Persian Gulf conflict.
4- The Department of Defense Kuwait Oil Fire Health Risk Assessment

This “registry” was to include the name of each exposed individual and “a description of the

circumstances of each exposure of that member to the fumes of burning oil . . . including the length of

time of the exposure. ”

About a year later, in the Veterans Health Care Act of 1992 (Public Law 102-585, Section 704), the

Congressional mandate for information was expanded to all who served in the Persian Gulf during the

conflict, not just those known to be exposed to oil fire smoke. The new mandate called for information

(to the extent it is available) on the location and circumstances of each person’s service including

“atmospheric and other environmental circumstances in such locations. ” Public Law 102-585 also

directs OTA to assess the mandated DoD “registry,” as described in the law.

THE KUWAIT OIL FIRE GIS MODELING PROJECT

Status of the Project

As of September 1994, a preliminary version of the GIS had been completed and tested in a pilot

project, described in EHA’s Final Report: Kuwait Oil Fire Health Risk Assessment. EHA’s report was

made available to OTA in August by the Office of the Assistant Secretary of Defense for Health Affairs

for the purpose of completing this Background Paper, but otherwise has not been released by them.

EHA are still working on completing the GIS database, but the basic structure of the system is in

place. The main tasks remaining are to define the smoke plume boundary for each day, which is a welldefined activity but one that requires intensive work, and to determine “emission” rates for each toxic

substance in the smoke (discussed later). Once this is complete, in early 1995, the system will be ready

to generate health risk estimates for each individual who served during the period of the oil fires.

ESG have made considerable progress in computerizing the daily troop locations, but project that

it will be another two years before the task is complete. Locations are abstracted on a unit-by-unit basis,

so ESG already are able to provide EHA with daily locations for some units and will be able to add units

as they progress. In addition, they have once-per-month locations for most of the Army units that served

in the Persian Gulf (most units did not move around very much, so these locations probably represent

relatively well the dispersion of troops).

Description of the Project

The GIS is a computer-based system designed to capture, maintain, and analyze information

about troop exposures to the oil fire smoke and any risks to their health that might result. The

information needed for an ideal assessment includes:

● the location of each service person on each day of service in the Desert Shield/Storm theater of

operations,

● the location of every smoke plume on each day smoke was in the air,

● the inventory of toxic substances entering each plume,
The Department of Defense Kuwait Oil Fire Health Risk Assessment -5

● the concentrations of those toxic substances at the location of each service person on each day,

● the conditions of each person’s exposure (e.g., the rate at which each person is inhaling air), and

● the inherent toxicity (including all diseases) of each substance to which each person is exposed.

In spite of its relatively straightforward purpose, the Kuwait Oil Fire GIS is a complex and

resource-intensive undertaking. It requires a great many assumptions and procedures that are not

demonstrably correct or incorrect. The GIS shares with most other risk assessment systems the need to

deal with substantial uncertainties about both toxicity and exposure. As with many such assessments, the

GIS copes with uncertainty by using assumptions that overestimate rather than underestimate risk; in the

jargon of risk assessment, they are “conservative” assumptions. Both the values for toxicity and the

exposure scenario parameters (such as the duration and intensity of exposure) are chosen to minimize the

possibility that risks will be underestimated. EHA have generally followed the lead of the EPA in these

areas.

For each person, two risk numbers may be produced: the risk of cancer (all cancers combined),

which is expressed as a fraction (e.g., one in one million) and the risk of all other chronic diseases (the

nature of which are not specified), given as a “hazard index, ” expressed as a multiple of one, which is set

at a level at which no toxicity is likely to occur even after years of exposure (discussed in more detail

below).

Information on the toxicity of chemicals found in the smoke comes from various EPA sources

and is “generic” (i.e., the same toxicity relationships are applied regardless of the source of the chemical,

so the ones used are not specific to these chemicals as constituents of smoke). Information on the levels

of those constituents to which troops were exposed is specific to the Persian Gulf experience and comes

from a variety of data sources on the oil fires. Troop location data come mainly from written military

records. Each component of the system is discussed below.

Troop Identification and Location

The identity of nearly all the 696,000 individuals who served in the Desert Shield/Storm theater

of operations during the Persian Gulf conflict have been available since the early development of the

GIS. The Defense Manpower Data Center has supplied this information to ESG (including 64 data

elements for each person). It is a simple matter to pinpoint the dates of service in the Persian Gulf and

the unit with which each person served; these two pieces of information are all that is needed to enter the

GIS on an individual basis.

The extent to which military personnel were exposed obviously depends on where people were

in relation to the smoke. The whereabouts of each service member at each moment he or she was in the

Persian Gulf cannot be known precisely, of course, but accepting a few basic assumptions, locations that

in most cases will be reasonably close can be assigned. This aspect of the GIS involves fewer

assumptions and less estimating than do others.

For the purposes of the GIS, a location for each company-level unit (most representing about 150

people) will be determined for each day of the Persian Gulf era (not just the period of burning oil fires,

following the expanded mandate of PL 102-585). This information for each such unit was recorded on
6- The Department of Defense Kuwait Oil Fire Health Risk Assessment

paper in their daily records. Abstracting these data points requires actually reading through the records

for each of these approximately 13,000 units and transcribing each point (by latitude and longitude). The

points captured in the records came from automated locators that use satellite contact to calculate

position. To the extent the record keeper read the instrument and entered the numbers correctly, the

locations should be quite exact.

The most important assumption about the location coordinates is that all members of the unit are

assumed to have been at the same place. This clearly is not true. In general, however, it is probably true

that troops were relatively near their unit location most of the time. As it turns out, the resolution of

other parts of the GIS is not so great as to make locations that might be off by even 15 kilometers a big

problem. In addition, it appears that the smoke plumes did not vary a great deal over short distances, so

all in all, the troop location data will be sufficiently precise for nearly all individuals. There undoubtedly

were times when people were distant from their unit for particular reasons. One can conceive of

scenarios in which location away from an individual’s unit might be important, but it is unlikely to be a

major problem.

Smoke Measurements

The level of risk associated with the oil fire smoke depends on what the various compounds are

that made up the smoke and on the levels of each one when and where troops were exposed. One could

imagine a map of the smoky region blanketed with numbers that describe the concentrations of each

relevant smoke constituent for each day the fires burned (assuming that conditions did not change

appreciably over the course of a day). It might then seem a simple matter to describe the level of

exposure to each person on the ground in contact with all the various substances. EHA’s task in this area

is to develop the blanket of numbers from data that are rather limited, in both place and time. They are

going about this using two independent methods: first, using measurements from air monitoring in the

Gulf while the fires were alight; and second, mathematical modeling of smoke dispersion using

meteorological data and information on smoke emissions from the fires. These approaches, which give

rise to quite different estimates, are described in the following paragraphs.

EHA sampled air in the Gulf area from early May through December 1991, which includes about

a month of sampling after the last fire was extinguished. Using methods recommended by EPA, about

4,000 samples from eight sites (four in Kuwait and four in Saudi Arabia) were taken and analyzed, The

sample locations were chosen primarily on the basis of major troop concentrations, and included areas

where the smoke was considered heaviest . Samples were analyzed for all toxic substances reasonably

anticipated to be in smoke from an oil well fire involving Kuwait crude oil, as well as for other

potentially toxic substances. Airborne concentrations can result from the vapors of volatile organic

compounds or from less volatile compounds attached to fine particles of smoke or dust. These

measurements represent the combined concentration of substances in the smoke and background levels

of those substances.

Using the air monitoring data, individuals are assumed to be exposed to the concentrations at the

monitoring site closest to their company’s location on each day. Estimates will also be made using the

HY-SPLIT model (see below) for those locations during the early period of burning oil wells, before

monitoring began, from February to April 1991. (These estimates will differ from the monitored levels

because they will not include background concentrations.)
The Department of Defense Kuwait Oil Fire Health Risk Assessment -7

In the second approach, the National Oceanographic and Atmospheric Administration (NOAA)

used a mathematical model, “HY-SPLIT,” to estimate for each “grid point” the average daily

concentrations that would be caused by burning oil wells. HY-SPLIT is a state-of-the-art “trajectory”

model that uses information on wind speed and direction along with particle settling and diffusion rates

to simulate the movement of “packets” of particles over time. The model was calibrated using

measurements from air samples taken in “flythroughs” of the super-plume by the National Center for

Atmospheric Research, the National Aeronautic and Space Administration, university groups, and EHA’s

ground measurements. A third piece of information on smoke concentrations--satellite imagery of the

plumes--is being used as well. By combining this visual “truth” with the boundaries of the HY-SPLIT

model plumes, even better location of the smoke with time is possible.

The GIS modeled data from the period when some measurements were available (which has the

advantage of calibration with the data from air monitoring) will be used to predict smoke-related

concentrations for locations and days when there were no measurements, especially the period before

field measurements began. For all periods, the modeled concentrations estimate only the contribution

from the smoke itself, and therefore will be lower than the estimates from the ground measurements

(which include other sources of pollutants, such as auto emissions). Exposures are assigned based on the

nearest grid point to an individual’s company location. Because the spacing of the grid points is

relatively fine in comparison to the plume dimensions, these modeled exposures are not likely to be

misestimated substantially even if a person was not near the grid point all day, as long he or she was

closer to that grid point than to any other.

A weak link of the HY-SPLIT procedure is currently in the estimation of “emissions” for each

constituent of the oil smoke. Only emissions of sulfur dioxide (S02

) and soot are known with any

certainty because the sulfur and carbon content of the oil can be estimated and because some crosscalibration was possible with measured concentrations in the plumes. For other substances, the estimates

are less firm. Even for the metals, which are neither created nor destroyed by the fire, estimates are

difficult because of the range of metal content in the crude oil from different wells and uncertainties

about the fraction of each metal that reached the plume. Some of the metals would remain in oil pools

and never enter the atmosphere, while another portion would attach to large-diameter particles falling out

of the smoke early and not reaching the main plume altitude used in the modeling. For volatile and

semivolatile organic compounds present in the oil, emission rates are even more speculative.

Conversely, the rate of formation of hazardous substances during combustion is very uncertain. EHA are

in the process of collecting information on the chemical composition of oil from each oil well field and

on the total amount of oil released, to aid in determining appropriate emission rates.

The two types of concentration estimates generated by EHA have one fundamental difference:

the measured concentrations provide a way to estimate total exposure for troops located at or near one of

the eight sampling sites for any day during which measurements were taken. Themodeled

concentrations provide a way to estimate Smoke-related exposures at any gridded location on any day the

fires were burning, but provide no information on the contribution to total exposure from local, non-fire

sources (e.g., auto emissions, airborne soil).
8- The Department of Defense Kuwait Oil Fire Health Risk Assessment

Personal Exposures

The juxtaposition of people with smoke makes for exposure. EHA included three routes of

exposure in their risk analysis: direct inhalation of smoke, incidental ingestion of soil particles with

smoke constituents attached to them, and dermal absorption of smoke constituents from soil adhering to

the skin.

Inhalation is by far the most important exposure route (accounting for more than 90 percent of

the total risk). The airborne concentration estimates described above form the basis for inhaled

exposures. To determine how much exposure took place, EHA assumed a breathing rate based on 20

hours of relatively strenuous activity every day and four hours of sleep. Multiplying the total volume of

air inhaled daily and the average daily concentration gives an estimate of the total amount of substance

inhaled on that day. Dividing by body weight provides an estimate of the inhaled “dose” (milligrams of

substance inhaled per unit body weight per day).

Soil is ingested when it sticks to food or fingers and is then eaten. Soil ingestion occurs under

very ordinary conditions, and probably occurred to a substantial degree in the dusty Persian Gulf where

hand-washing was not always feasible. EHA have assumed that each person ingested 300 mg of soil

each day (a relatively high estimate). Soil concentrations have been determined from measurements at

each of the same eight sampling sites as for the air concentrations.

Absorption through the skin depends on how much soil adheres to the skin, how much skin is

exposed, and the fraction of each constituent that migrates out of the soil and through the skin over a day

of exposure (which varies from chemical to chemical). EHA have assumed that one milligram of soil

adhered to each square centimeter of exposed skin each day, that on average 4,270 square centimeters of

skin were exposed (about 20 to 25 percent of total skin area), and that from 1 to 5 percent of each

compound was absorbed.

The exposure assessment, consistent with other aspects of the model, has been deliberately

“high-sided,” so the exposure numbers coming from these calculations should represent the uppermost

plausible level of exposure.

Estimating Risk

Estimates of health risk are calculated by applying generic information about the risks of each

toxic substance (toxicity values) to individual quantitative estimates of exposure (discussed above) using

some standard formulas. EHA used toxicity values from EPA’s Integrated Risk Information System

(IRIS), considered to be that agency’s most thoroughly reviewed source of toxicity information. Because

IRIS has not released toxicity summaries for all the substances of possible interest in the smoke from the

Persian Gulf oil fires, other sources of information (mainly from other EPA programs) were used when

necessary. Nearly all the toxicity values are based on data from animal experiments. Information on the

toxicity of only some metals and a few other compounds is known directly for human beings.
The Department of Defense Kuwait Oil Fire Health Risk Assessment -9

Once toxicity values have been decided on, risk calculations are quite straightforward in the

approach taken by EHA. For these calculations, exposures were expressed as average daily doses over

the period of exposure.

For noncarcinogens a “hazard quotient” (HQ) is calculated by taking the ratio of the estimated

average daily dose to a “reference dose” (RfD). An RfD is a daily dose that is unlikely to cause any

health effect in most people even if they are exposed at that level indefinitely. If the estimated daily dose

is less than or equal to the RfD (i.e., the HQ is less than or equal to 1.0), no health effects of any kind

would be expected. If the estimated daily dose is higher than the RfD (i.e., the HQ is greater than 1.0),

then there is some possibility of a health effect; the probability, the severity, or both increase as the HQ

rises further above 1.0. However, neither the probability nor severity is quantified and doses slightly

exceeding the RfD may be inconsequential. On a more practical level for the exposed individual, the HQ

does not refer to any specific disease, but to health effects in general.

To take account of possible additive effects among chemicals that affect the same organ systems,

a “hazard index” (HI) is computed by adding together the HQs for every chemical affecting that system.

If the HI is above 1.0, some health effects are possible.

RfDs (and the HQs and HIs based on them) represent the best estimate of health risk after longterm exposure to a substance (long enough for the concentrations of the substance inside the body to

have stabilized even with continuing exposure). Generally, shorter periods of exposure, like those in the

Persian Gulf, will be associated with lower risks, but except in those few cases where a “subchronic”

RfD has been defined, the RfD cannot be “adjusted” to account for that lesser risk. Therefore, troops

who remained in the Persian Gulf for only a few weeks or months are probably not at as high a risk as

would be predicted by their HI, but a quantitative adjustment cannot be made. HQs and HIs are, in the

end, rather crude measures.

With carcinogens, the approach is different. Any exposure is assumed to carry some risk of

cancer, and the risk is assumed to increase linearly with total exposure. The proportional linear increase

of risk with exposure is called the “cancer potency slope factor” which, when multiplied by an average

daily dose, gives an estimate of the lifetime probability of developing cancer because of that substance

assuming a lifetime of exposure at that dose. If exposure does not continue for a lifetime, as in the case

of the Persian Gulf troops, an adjustment is made to scale back the risk proportionate to the length of

exposure. The probabilities are usually expressed in some natural unit, such as three chances in a

million. The resulting estimate must then be held up to a standard of “acceptable risk. ” The notion of

what is acceptable derives from a combination of science and policy and depends on the context of the

risk estimate.

The cancer slope factors and the exposure estimates are calculated with “conservative”

assumptions, so the resulting risk estimate is usually described as a plausible upper limit on the

probability of developing cancer. The estimate is “plausible” in the sense that none of the individual

assumptions is so conservative as to be beyond belief. In the vast majority of cases assessed in this way,

the estimated risks will be greater than the true risks, sometimes by large margins. In a few cases, the

estimated risks will be approximately correct, and in a very few cases, they will be too low.
10- The Department of Defense Kuwait Oil Fire Health Risk Assessment

Predicted Health Risks from the Oil Fires

EHA used the measurements at the eight ground monitoring sites to estimate the risk to

hypothetical individuals assumed to have been present at those sites from May 5 through December 3,

1991, which was the monitoring period. (These risks, therefore, exclude the risk from exposures before

monitoring took place, from February through early May.) The eight sites include both areas very near

the fires, including one (Al Ahmadi Hospital) that was only about a mile from a burning oil field, and

areas more or less unaffected by them.

The predicted excess cancer risk during the seven-month monitoring period ranged from a low of

four in ten million to a high of two in a million, including all routes of exposure. Benzene, one of

commonest air contaminants everywhere, mainly from the combustion of gasoline, is the main “driver”

of cancer risk in these estimates. The risk levels differed little among the smokier monitoring sites in

Kuwait and the “cleaner” ones in Saudi Arabia. The total predicted risk of all noncancer chronic

conditions ranged from an HI of 0.5 to an HI of 5,0. The HIs were higher than 1.0 (i.e., some potential

for chronic disease) at all but one site. Inhalation of volatile organic compounds, particularly benzene,

accounted for more than 99 percent of the noncancer risk.

Generating Individual Health Risk Estimates With the GIS

The Kuwait Oil Fire GIS was designed to respond to the Congressional mandate for

individualized information on health risks from oil fire smoke for each person who served in the military

during the Persian Gulf conflict. As currently conceived, EHA would provide a complete database of

daily contaminant levels over the region to ESG. When a request is received to estimate an individual’s

risk, ESG (using similar GIS software) would enter the appropriate identifying information and the

program would link an individual to his or her unit, and then calculate an aggregate exposure and risk

over the time the veteran was in the Persian Gulf. ESG would then communicate risk levels to the

veterans who have asked for their exposure information. The format for that communication has not yet

been worked out, though this issue has been discussed among various parts of DoD.

Two questions arise in evaluating the utility of individual risk estimates: how accurate will the

information be and how should it be presented to maximize its usefulness to the veteran? As to

accuracy, it is clear that the risk estimates will not be very accurate for an individual. The preference for

conservative assumptions will mean a consistent bias toward overestimation of risk, while uncertainties

about an individual’s location with respect to his or her unit will mean an additional random uncertainty.

The raw estimates of risk that will be generated by the GIS are not easy to understand in relation

to an individual’s health. What does a cancer risk of one in a million mean? Will use of the words

“cancer” and “chronic toxicity” themselves induce fears? Alternatives to reporting these raw estimates

would be to describe a gradation of exposures (low, medium, high) or to use the average risk as a

reference and report an individual’s risk in relation to it, though the interpretation of these relative terms

may also mislead. These issues have not yet been taken up by DoD, but presumably they will require

attention if the system proceeds as planned.
The Department of Defense Kuwait Oil Fire Health Risk Assessment -11

OTA EVALUATION

The GIS

The estimation of troop exposures to oil fire smoke might have been handled by any number of

computer-based systems, including relational databases or spreadsheet programs. But these types of

systems are severely limited in both their analytic and display capabilities. The decision to use a GIS

was based on its ability to capture, manage, manipulate, analyze, model, and display spatial data. The

key to a GIS, setting it apart from other software (such as computer-aided mapping) is the “topology”

that allows the user to query, analyze, and display the data with respect to the connectedness of elements

with spatial features (e.g., grid points, lines, or polygons).

The GIS is an essential tool to achieve the objectives of the risk assessment project, cast

narrowly to estimate exposures and risks to troops operating in the Persian Gulf. However, the purposes

of the project beyond this have not been stated clearly. Neither the types of reports that will be generated

for individual veterans nor their formats are well described. It is clear that ESG will use the system to

respond to veterans’ requests, but no other particular uses (i.e., for research) have been specified. If

multiple users are contemplated, there should be more coordination in designing the system to meet their

needs.

In principle, the GIS could be used to investigate exposures and risks from any other events or

activities involving hazardous substances that could be located by geographic coordinates and date.

Some exposures that have been mentioned are spraying of pesticides, use of diesel-fueled heaters in

tents, chemical or biological agents deployed by Scud missiles, and depleted uranium used in projectiles

and tank walls. OTA learned of no attempts to develop a database for any such exposures. Although it

seems feasible to develop a database of location and time for some of these exposures and therefore to

identify troops that were nearby, developing quantitative “exposure” estimates would be difficult or

impossible. Given the extremely low estimates of risk from the oil smoke itself, using the GIS to aid in

investigating other exposures might give added value to the investment that already has been made.

Information on Oil Fire Constituent Levels

EHA has made efficient use of the ground measurements of air during the period that monitoring

took place. But there are limits to those data, which will affect EHA’s ability to predict health risks over

the entire area occupied by troops and over the entire time during which smoke was in the air. The

principal limitations of the measured values are:

. The restriction to eight sampling locations that may not be representative of the distribution of

troops.--Four of the locations are clustered tightly around Kuwait City and the four in Saudi Arabia

represent only a portion of the area that was affected by the oil fire plume. Because monitoring sites

were chosen on the basis of troop concentration, however, this is probably of little importance.

. The restriction to the period May through November (and to shorter periods for most of the

stations) .--Concentrations of smoke-related substances could have been higher during the period

February through April when more fires were burning.
12- The Department of Defense Kuwait Oil Fire Health Risk Assessment

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The inability to separate smoke-related contributions from those related to natural

background or other non-smoke sources.--The dominant source of both cancer and noncancer risk

is benzene and it is not clear whether or not this is mainly smoke-related. The variation of chemical

concentrations with distance from the fires is often inconsistent with a smoke source; for example,

neither chromium nor benzene concentrations were significantly different between the Kuwait and

Saudi Arabia stations (although this may bean effect of the super-plume). The degree of

overestimation of smoke risk is difficult to evaluate but is probably substantial.

The use of one-half the detection limit for the concentration of every chemical reported as

below the detection limit. --Although the inability to detect a chemical in a sample is no assurance

that it is not present, it may not be present or may be present a level well below one-half the

detection limit. Using one-half the detection limit is appropriate where good reasons exist for

assuming the chemical is present, but is questionable when few samples show detectable levels.

EHA has followed EPA policy on this point, however.

Disposition of “non-target analytes.” --At every sampling location, the total concentration of “nontarget analytes” (everything not specifically measured) among the volatile organic compounds was

much greater than the total concentration of the target analytes. Some description is needed of the

composition of the “non-target analyte” fraction and an explanation of why the detected substances

were not target analytes.

Lack of consideration of particulate matter---Although it includes a section discussing generally

the health effects of inhaled particulate, EHA did not formally assess the potential toxicity of

particulate (other than “soot,” or carbonaceous particles) independent of the chemicals associated

with the particles. Respirable particulate matter, which apparently came not from the smoke but

mainly from background dust, is considered a health hazard at concentrations lower than some of

those measured by EHA.

Exposure estimates based on the HY-SPLIT model are not yet possible because EHA has not

fixed on a procedure for estimating emissions of each substance from the various burning wells. Without

these emission rates, no modeled exposures can be calculated (but by design, they must be lower than the

measured values, which include ambient substances).

Toxicity Information

EPA is widely perceived as the most authoritative source of information on environmental health

hazards, so EHA’s decision to use EPA toxicity information is well justified. EPA’s mandate to protect

human health from environmental hazards means, however, that its estimates of the toxic potencies of

chemicals are conservative, i.e., tend to err on the side of overestimating risk when the true values are

uncertain. This conservatism may or may not be appropriate, depending on how the estimates are to be

used.

EHA’s use of the RfD to evaluate noncancer risks (in calculating HIs and HQs) may have been

unavoidable (no other set of risk relationships is available for a wide range of substances) but it presents

significant problems in interpretation. The RfD is intended as an exposure level that is without any risk

of toxic effect, even if the exposure continues indefinitely, but somewhat higher doses are not necessarily
The Department of Defense Kuwait Oil Fire Health Risk Assessment -13

risky either. Most RfDs embody uncertainty factors of between 100 and 1,000, so they represent values

far above those for which toxic effects may ever have been observed. For nearly all compounds, a true

“threshold” for toxic effects in humans is unknown. This great uncertainty even under conditions of

continued exposure is compounded by the fact the RfDs cannot be adjusted for assessing the shorter

exposures experienced in the Persian Gulf. In order to understand the potential for noncancer effects, the

nature of the health conditions that make up the risk should be examined for each substance so that

judgments can made about their plausibility.

Interpretation of the Health Risk Assessments

The levels of cancer risk reported by EHA are considered to be below the level of concern under

virtually every environmental or occupational regulatory proceeding. If the missing three months of

exposure were considered, the highest risk might rise to about three in a million. A risk of one in a

million has been considered unacceptable in some risk management decisions, but usually only when

large populations are exposed.

The highest noncancer risks suggest that some chronic health effects from these exposures are

possible. EHA have pointed out that the estimates contain so many conservative assumptions about both

exposure and toxicity that they are likely to be substantial overestimates and may not imply any health

risk at all, The addition of the three unmonitored months of exposure might increase the HIs somewhat

because more fires were burning then, and the average daily exposure might have been higher. Because

calculation of the HIs assumes exposures continuing indefinitely, the extra time itself would not affect

the HIs.

The risks reported by EHA were from measurements of the air at ground level, so they represent

background plus smoke-related contributions. No risk estimates were reported for modeled

concentrations, which would, of course, be lower, because the background would be eliminated. If this

risk of total exposure in the Persian Gulf is seen as an appropriate measure of impact on service

personnel, then one might also ask what the risk would have been had the person spent eight months in

the United States. The lifetime cancer risk of spending that time in the San Francisco Bay area,

calculated in the same way as the risks for the Persian Gulf, is in the vicinity of 5 in a million--about

twice the calculated risk in the Persian Gulf.

Comparisons such as these maybe criticized as trivializing the Persian Gulf experience, and it

may be difficult for the troops who were in the Persian Gulf, as well as the public who daily witnessed

massive, billowing smoke plumes blocking the sun in Kuwait, to accept the results. But stating them is

important to place the risk in some context. It should also be understood that, like the risks predicted

from exposure to Persian Gulf oil smoke, risks predicted from monitoring in the United States are

overestimates based on conservative assessment methods and are still far too low to be confirmed or

disproved by epidemiologic observations in the exposed populations.

Uses of the GIS and Related Information

DoD’s mandate from Congress was to describe each individual’s exposure to oil fire smoke in the

Persian Gulf. EHA has taken this a step further by creating a capability to translate exposures into
14- The Department of Defense Kuwait Oil Fire Health Risk Assessment

health risk estimates. EHA’s system, relying on the GIS, should be fully functional once the system

contains all the relevant atmospheric data (sometime in 1995) and the daily locations for each unit have

been entered (sometime in 1996 or possibly sooner). Depending on whether the measured values of

substances (from ground monitoring) are used or the modeled concentrations (from HY-SPLIT) are used,

the risk will represent either total risk (in the former case) or the incremental risk of exposure to oil fire

smoke. Which is preferred is a question of policy rather than science.

Whichever source of risk is chosen, the actual predicted levels will be very low. The figures

reported by EHA in their report, which represent risks from both background and smoke (from ground

monitoring measurements) ranged only as high as two in a million for lifetime cancer risk. Because of

the highly conservative assumptions embodied in the RfDs and their unsuitability for predicting effects

of short-term exposure, the highest HI (5.0) is probably of little health consequence. While it is not clear

that these estimates represent the absolute worst case, it would be surprising to find exposures much

higher anywhere in the Persian Gulf theater of operations. EHA might consider carrying out a

“plausible” worse case risk estimate based on existing knowledge of where troops were and the known

contaminant levels. Although complete troop location data will not be available for perhaps two years,

ESG already has monthly location data for a large number of Army units that served in the Persian Gulf.

Using this information now could provide a reasonable estimate of troop dispersion and perhaps identify

a confluence of troops and relatively heavy smoke for purposes of estimating the highest of risks.

The question that can’t be ignored is whether it is worthwhile to go ahead with a system that will

generate extremely low risk numbers for everyone---numbers that are virtually uninterpretable (and not

very accurate on an individual basis) in terms of one’s health. The numbers generated will undoubtedly

change over the years as the best information on risk changes (some upward, some downward), but it

would be almost unthinkable that the risks would change by, say, a factor of 10.

Are there other uses for this system? As mentioned earlier, any risk that can be located in place

and time is amenable to inclusion in the GIS. Complete information on suspicious exposures of virtually

any kind are going to be hard, but not impossible, to come by. Once mapped, they could be matched up

with the troops near them spatially and temporally, perhaps as the basis of choosing cohorts for an

epidemiologic study. Such studies would require careful planning and cooperation and coordination

between the researchers and EHA. (It should be noted that the exposures and resulting risks from the oil

fire smoke are, as currently estimated, too low and too small in range to support epidemiologic studies.)

If it is decided that the GIS should be available to assist in some of these studies, it would be important

to complete the troop location component of the project, and to maintain the GIS as an analytic tool.

If the Congressional mandate to produce individual exposure estimates remains intact, DoD

would be compelled to complete the GIS as it is doing, and eventually, the individual information would

be available to veterans, whether or not it signifies anything about their future health (or more than

would be signified by telling them that no one’s risk is above a certain level). Scientifically, this exercise

appears to have limited value in terms of the veterans’ health if the reported risk numbers are confirmed

and it is accepted that the risks from oil fire smoke are negligible. In terms of the veterans themselves,

they may want these estimates. According to the Director of ESG, providing individual exposure

assessments (along with an explanation of what they mean) may help allay the fears of Persian Gulf

veterans concerning their exposures, and there may be value (other than scientific) in that.