Burn Pit Exposure Assessment to Support a Cohort Study of US Veterans of the Wars in Iraq and Afghanistan : Journal of Occupational and Environmental Medicine

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Burn Pit Exposure Assessment to Support a Cohort Study of US Veterans of the Wars in Iraq and Afghanistan

Woskie, Susan R. PhD; Bello, Anila ScD; Rennix, Christopher ScD; Jiang, Lan MS; Trivedi, Amal N. MD, MPH; Savitz, David A. PhD

Author Information
Journal of Occupational and Environmental Medicine 65(6):p 449-457, June 2023. | DOI: 10.1097/JOM.0000000000002788
  • Open
  • CME Test


For a cohort study of veterans' health conditions, we conducted an exposure assessment for 109 bases in Iraq and Afghanistan and 17 outside transit site bases.


The Department of Defense records were used to determine burn pit usage and waste disposal methods for each base in each year during the period of 2001 to 2014.


In the final cohort of 475,326 veterans, who had more than 80% of their deployment time characterized by our exposure matrix, only 14.5% were found to have no burn pit exposure. The 2009 Department of Defense regulations on burn pits did produce changes in waste segregation, as well as adding incineration and local disposal of waste.


Most Iraq and Afghanistan veterans were stationed on bases that had burn pits, although the contents disposed of in the burn pits changed over time.

CME Learning Objectives

After completing this enduring educational activity, the learner will be better able to:

  • Discuss the exposure assessment of veterans from Iraq and Afghanistan bases with burn pits
  • Review and clarify the 2009 DoD regulations on burn pits and the changes in waste segregation
  • Review the long-term health impact of exposure to burn pit emissions on veterans

Following the attacks of September 11, 2001, Operation Enduring Freedom (OEF) was initiated in Afghanistan in October of 2001 and Operation Iraqi Freedom (OIF) in Iraq in March 2003. The war in Iraq continued until December 2011, whereas in Afghanistan, the war concluded in September 2021. During these military actions, soldiers were housed in contingency (nonpermanent) bases that utilized open burn pits to dispose of waste materials.1 Burn pits exposed troops to a variable and poorly characterized mix of combustion materials.2–4 Many veterans have expressed a high level of concern regarding the long-term impact of exposure to burn pit emissions on their subsequent health.5,6 Given the established adverse health effects of particulate air pollution, the most plausible health consequences of open burn pit exposures would be development or exacerbation of chronic respiratory and cardiovascular diseases.

General studies of veterans deployed to Afghanistan and Iraq have shown an increased risk of respiratory impairments.7–10 However, these studies used any deployment to Iraq and/or Afghanistan as the predictor without further characterizing exposure to burn pits. Two studies that examined health outcomes for those deployed to bases known to have burn pits found inconsistent associations. In the Millennium Cohort Study, no associations between any of the potential burn pit exposure metrics and the prevalence of any self-reported indicators of respiratory health were identified.11,12 The Department of Veterans Affairs (VA) Airborne Hazard and Open Burn Pit Registry found that both self-reported hours of burn pit exposure during deployment and inferred exposure based on location were associated with increased rates of self-reported emphysema, chronic bronchitis, or chronic obstructive pulmonary disease, but not with asthma or coronary heart disease.13 However, no associations were found between exposure and diagnosed disease, as assessed through VA records.

To examine the health impacts experienced by veterans from potential burn pit exposures during the wars in Iraq and Afghanistan, we developed a method to characterize waste disposal methods over time, including the use of burn pits, on bases in Iraq and Afghanistan and to link that exposure matrix with veteran deployment records.

Background on Burn Pit Regulations

The US Central Command (CENTCOM) was the lead military organization for OIF in 2003 to 2014 and OEF in Afghanistan in 2002 to 2014. Prior to 2006, there was no specific guidance on waste disposal methods, and most waste was burned in open pits. In 2006, CENTCOM/Multinational Corps-Iraq (MNC-I) combined a series of fragmentary orders (FRAGO) on environmental policies by the MNC-I engineering staff into a document titled “MNC-I Environmental Standard Operating Procedure 2006” that discouraged the use of burn pits. However, it did not include any policies on operating/monitoring burn pits.14 There was also an Army Technical Bulletin on “Guidelines for Field Waste Management,” dated September 2006, which notes that troops should use open burning only in “emergency situations.”14

Starting in 2009, certain items were prohibited from disposal in burn pits, and their long-term use was discouraged. In Iraq, in 2009, an updated version of the “MNC-I Environmental Standard Operating Procedure” provided guidance on solid waste handling. It described burn pits as an expedient means to destroy solid waste during contingency operations but prohibits burn pits unless the base commander authorizes in writing. It recommends segregation of waste to facilitate reuse and recycling and provides guidelines on management of burn pits, including prohibiting hazardous waste, batteries, tires, electronics, and appliances from the burn pit and recommending that plastics be recycled.14

In Afghanistan, US Forces–Afghanistan (USFOR-A) issued a 2009 guidance on environmental practices including instructions that burn pits should be used only until more suitable methods can be put into place. Prohibited items included hazardous waste, oils, tires, batteries, electronics, pesticide containers, asphalt shingles, treated wood, and coated electrical wires, as well as plastics.14 This coincided with the arrival of the Joint Force Engineer Command in Afghanistan.

Also in 2009, CENTCOM issued Reg 200-2 for all contingency bases (virtually all bases in Iraq/Afghanistan). It provided detailed guidance on management of hazardous materials, regulated medical waste, and solid waste. Additional items were prohibited from burn pits compared with the USFOR-A and MNC-I guidance including hazardous and regulated medical waste; petroleum, oils, and lubricant products; rubber; tar paper; asphalt shingles; tires; treated wood; batteries of any type; unexploded ordnance; aerosol cans; compressed gas cylinders; plastic; paint; paint thinner and strippers; pesticides; pesticide containers; asbestos; appliances; and electrical equipment or wires.14

In 2010, Department of Defense (DoD) issued Directive-Type Memorandum 09-032 prohibiting the disposal of covered waste in open-air burn pits during contingency operations except when the relevant commander of a combatant command makes a formal determination that no alternative disposal method is feasible. This directive reduced the number of prohibited items from burn pits compared with CENTCOM 200-2.14


Iraq and Afghanistan Bases Selection

We received a list of all bases outside the United States and their populations per year (person-days) from 2001 to 2015 from the Defense Manpower Data Center (DMDC). The computerized recording of base deployments began with the Army, followed by the Air Force, with the Navy and Marines joining the DMDC electronic deployment system much later. The earliest date of any significant deployment population in the electronic DMDC records was 2004. Study population records show that many soldiers did not have a designated location throughout the period of 2001 to 2014 (unknown in the Service Personnel Accountability [SPA] software or empty [most likely a branch service not using the SPA software such as Navy/Marines]). The DMDC list we received included worldwide bases (approximately 1500 bases) and their population expressed in person-days. However, this list did not have country designated, so we merged it with a list of all bases in the Middle East received from the CENTCOM, which covered the area from Kazakhstan to Egypt, including Iraq and Afghanistan (approximately 978 bases). In addition, we received a second list from CENTCOM that comprised bases identified as ever having a burn pit (approximately 500 listings). After merger of these three lists, which required manual matching due to many alternate base names and spellings, we produced a working list of bases located in Iraq and Afghanistan where deployment of troops was recorded in the DMDC electronic records.

Then, starting with the bases with the largest populations, we reconstructed the timeline of burn pit presence, as well as the introduction of hazardous waste separation, medical waste incinerators, and general solid waste incinerators for each base. We focused on the largest bases in terms of maximum yearly and cumulative population census (person-days for the entire period from opening to closing of the base) for Iraq and Afghanistan. These 109 bases included those with 4000 to 363,000 maximum annual person-days based on DMDC records. The cumulative yearly person-days census of the top 109 bases was 16,802 to 2,116,470 person-days. We also included the top 17 bases in terms of population census outside Iraq and Afghanistan, which were used by soldiers deployed in OEF/OIF, most likely as a first stop on the way in and out of in-country deployments.

Base Waste Management Assessment

For the selected bases, we examined files received from the DoD Defense Occupational and Environmental Health Readiness System (DOEHRS) that consisted of a variety of records including air, soil, and ash sampling; public health site assessments; pest control records; site public health assessments; other reports collected by Preventive Medicine Medical Detachments, Public Health Officers, KBR, Inc (pest management); and reports by other countries participating in OEF and OIF. In addition, we examined records of initial environmental base surveys, environmental site closure surveys, and other environmental condition reports collected by CENTCOM Engineering. Because many of the CENTCOM files remain classified, we relied on contacts within CENTCOM and the Army Public Health Center to abstract these reports into data collection sheets we supplied.

We reviewed a total of 808 and 762 documents for Iraq and Afghanistan bases, respectively. After all inputs were assembled and examined, two industrial hygienists collaborated to determine a final timeline of burn pit presence (yes/no) for each year the base was populated by our cohort. In addition, we determined the timelines for introduction of medical and general solid waste incinerators or use of landfills or municipal waste processing facilities, as well as the segregation and storage of hazardous waste (yes/no).

The annual waste management coding consisted of one of the following categories:

Y = burn pit or simple burn box or burn barrel (presumably used for all waste)

Y-HW = burn pit or simple burn box/burn barrel for solid waste but evidence that hazardous waste segregated (usually sort and store), presumably medical waste disposed in burn pit.

Y-MW = burn pit or simple burn box/burn barrel for solid waste but evidence that medical waste segregated (usually sort and store) presumably hazardous waste disposed of in burn pit.

YSW = burn pit or simple burn box/burn barrel used only for solid waste, as medical waste AND hazardous waste segregated (either for sending out or incineration) OR see evidence that they segregate batteries, plastics, electronics, tires, and so on, from burn pit

YISW = burn pit or simple burn box/burn barrel used only for solid waste (segregate medical and hazardous waste) but starting to move to incinerators for solid waste as well

NIMW = no burn pit, only medical waste incinerated. Solid waste and hazardous waste landfilled or shipped out

NI = no burn pit, all waste incinerated onsite or solid waste incinerated onsite and other (medical and hazardous either shipped out or incinerated)

NOUT = no burn pit, all waste sent out to landfill or offsite or municipal waste treatment

For analyses focused on burn pit yes or no, all Y categories were considered a burn pit base, and all N categories were considered a nonburn pit base.

For years when we had no data inputs, we assumed the last category assigned stayed the same until a data source showed a change in waste treatment processes. In earlier years, we assumed that if there was a burn pit in later years, there was one in earlier years where we had no records. Unless data sources showed otherwise, we did not assume segregation of waste before 2009 when burn pit use came under more specific guidance through MNC-I 2009, USFOR-A 2009, and CENTCOM Reg 200-2 2009.

The cohort developed for the epidemiologic study was defined as those with OEF/OIF deployment in 2005 to 2011who had electronic deployment records in the DMDC, who enrolled for and obtained care at the Veterans Health Administration and were in the Army or Air Force. The goal of the assessment was to match this cohort with their DMDC base deployment records and then assign burn pit and waste disposal categories for each base in each deployment year. The DMDC deployment records contained many synonyms, misspellings, and four-letter GEOLOC codes for bases. A synonym crosswalk for base names was developed. Base names listed as unknown or were blank or null were considered as missing, as were bases not part of the exposure matrix. The start and end dates for base deployments had some overlaps and gaps. Nested or overlap deployment dates were counted toward the annual cumulative deployment days, and gaps in deployments were assumed to be out of OEF/OIF theater. In the final cohort, we excluded veterans who had greater than 20% of their cumulative deployment days at unknown or uncharacterized bases. For each veteran in each year of deployment, the cumulative days of deployment in each waste disposal category, as well as annual cumulative days of yes or no deployment at a burn pit base, were calculated. The population of deployed veterans in our cohort in each year was calculated based on the presence at any OEF/OIF base during that year.


In Iraq, we characterized waste disposal relative to burn pits for 55 bases that also included 31 additional base name synonyms within the DMDC system. The cohort deployment records covered 2002 to 2014, although most of the start and end years for Iraq base deployments for our cohort in the DMDC records were 2004 to 2011.

In Afghanistan, we characterized waste disposal relative to burn pits for 54 bases that also included 61 DMDC system synonyms. The cohort deployment records covered 2001 to 2014, but most of the base deployment start years began in 2007/2008.

For bases outside of Iraq and Afghanistan, we focused on 17 bases in Bahrain, Djibouti, Egypt, Kuwait, Kyrgyzstan, Qatar, Germany, and the United Arab Emirates, as these bases had the largest populations of OEF/OIF soldiers transiting through. The cohort deployment records for these other bases covered the years 2001 to 2014, although all 17 were not open until 2006.

The original cohort that met our enrollment criteria consisted of 547,514 cohort members. Only 13% had less than 80% of their deployment time at bases not in our exposure matrix. Although our exposure matrix included 126 bases and their synonyms, the DMDC deployment records contained more than 625 Afghan and 270 Iraqi bases for which exposures were not classified, as well as more than 160 countries outside Iraq and Afghanistan that were part of the deployment records of the cohort. When the final cohort was limited to the 475,326 soldiers who had greater than 80% of their deployment time characterized by our exposure matrix, only 14.5% were found to have no burn pit exposure.

Waste Disposal History of Afghanistan Bases

In Afghanistan, the number of bases in our exposure matrix where our cohort was deployed increased from 3 to 5 bases in 2001 to 2004, to 14 to 36 in 2006 to 2008, and then up to 40 to 54 from 2009 onward. In the earlier years 2001 to 2003, there was an even split between bases with and without burn pits. However, starting in 2004, the percentage of burn pit bases increased, with 67% to 86% of bases having a burn pit in the period 2005 to 2012. In 2013 and 2014, the percent with burn pits dropped, with only 27% of bases having burn pits in 2014 (Fig. 1).

Percentage of Afghanistan bases with burn pits from 2001 to 2014. The percentage of bases with burn pits was reduced after the 2009 Department of Defense regulation on burn pits. The percentage is calculated based on the total number of Afghanistan bases in the exposure matrix per year (right axis).

The types of waste disposal and treatment also changed over time (Fig. 2). Unsegregated burn pit use (Y) increased from 2003 to a plateau in 2006 to 2008 (47% to 52%) and then decreased from 2009 onward. During that time, segregated burn pit use (YSW + Y-HW) increased to a peak in 2006 (79%) then declined in 2007/2008 at the height of unsegregated burn pit use. This was followed by an increase in segregated burn pit use 2009 to 2012 (44% to 54%). In addition, starting in 2006, incinerators were added at bases with segregated burn pits (YISW), increasing to a plateau of 23% to 24% in 2012/2013. There were some bases with only solid waste incinerators starting in 2011 and increasing to 20% in 2014 (NI). More common, however, was transporting out all waste for disposal offsite (NOUT). This reached a high in 2002 and 2003 (50%) and then declined to a low of 14% in 2006, followed by a gradual increase to 53% in 2014.

Percentage of the US bases in Afghanistan using various waste disposal methods each year from 2001 to 2014. Waste disposal methods are presented as follows: Y, unsegregated waste in burn pit; Y-HW + YSW, segregated waste in burn pit; YISW, segregated waste in burn pit plus incinerator; NI, solid waste incineration; NOUT, waste shipped out of base. Parenthesis number on time (x) axis is the number of bases in exposure matrix. The percentage is calculated based on the total number of Afghanistan bases in exposure matrix using each waste disposal method per year.

Waste Disposal History of Iraq Bases

In Iraq, the number of bases at which our cohort was deployed increased from 14 in 2003, to 42 to 55 in 2004 to 2011, and down to 10 to 22 in 2011 to 2014. The percent of bases with burn pits decreased from 100% down to 40% by 2014, with larger decreases starting in 2010 (Fig. 3). As unsegregated burn pit use (Y) declined starting in 2005, segregated waste burn pit use (YSW & Y-HW) increased to approximately 50% of bases from 2005 to 2009. At the same time, incineration was added to the segregated burn pits (YISW) starting in 2010, reaching a high of 27% of bases in 2012. Starting in 2008, there was an increase in the percent of bases that used only solid waste incineration (NI), although it remained of limited usage overall (never greater than 10% of bases). Starting in 2007, bases where either all waste or solid waste was transported out to landfills or municipal waste disposal sites steadily increased form 19% to a high of 50% by 2014 (NOUT) (Fig. 4).

Percentage of Iraq bases with burn pits from 2001 to 2014. The percentage of bases with burn pits was reduced after the 2009 Department of Defense regulations on burn pits. The percentage is calculated based on the total number of Iraq bases in exposure matrix per year (right axis).
Percentage of the US bases in Iraq using various waste disposal methods each year from 2001 to 2014. Waste disposal methods are presented as follows: Y, unsegregated waste in burn pit; Y-HW + YSW, segregated waste in burn pit; YISW, segregated waste in burn pit plus incinerator; NI, solid waste incineration; NOUT, waste shipped out of base. Parenthesis number on time (x) axis is the number of bases in exposure matrix. The percentage is calculated based on the total number of Iraq bases in the exposure matrix using each waste disposal method per year.

For the 17 non-Iraq and non-Afghanistan bases, only Lemonnier in Djibouti had a burn pit where medical and hazardous waste was segregated out from 2002 to 2010 (YSW). Then, solid waste incineration was added to the burn pit waste disposal method through 2014 (YISW). All other bases either transported all waste offsite or incinerated only medical waste onsite (NOUT).

Study Cohort Population Trends

Our cohort began recorded deployments in Afghanistan in 2002, but the deployed population was fewer than 11,300 until 2006 when it began to climb to the peak of 69,439 in 2010 followed by a decrease of 10,000 in 2011, with a continuing decline in subsequent years (Fig. 5). At the peak in 2010, the cohort comprised 82% of the DoD-reported boots on the ground (BOG) in Afghanistan.15,16 In 2008 and 2009, the cohort also comprised a high percentage of the DoD BOG, 75% and 83% respectively. In 2006 and earlier, the deployed cohort population made up less than 15% of the DoD BOG population, most likely because the computerization of DMDC deployment records was still being implemented. From 2012 to 2014, the cohort comprised 46% to 48% of the DoD BOG population.

Number of the US veterans in Afghanistan included in the cohort study compared with the boots on the ground (BOG) Department of Defense data*. *Boots on the BOG in Afghanistan (Congressional Research Service, 2009, 2019).

In Iraq, cohort deployments began in 2003, jumping up to 89,000 in 2005, then reaching a plateau of 128,000 to 139,000 in the years 2006 to 2009, and in subsequent years falling to fewer than 1000 in 2012 to 2014 (Fig. 6). At the plateau in 2006 to 2009, the cohort comprised 86% to 97% of the DoD BOG population.15,16 In 2003 to 2005, the DoD BOG population was much higher than the deployed cohort, most likely because the computerization of DMDC records was still being implemented. In 2010, the deployed cohort population exceeded the reports of DoD BOG, but in 2011, the cohort again comprised approximately 87% of the DoD BOG population.

Number of the US veterans in Iraq included in the cohort study compared with the boots on the ground (BOG) Department of Defense data*. *BOG in Iraq (Congressional Research Service, 2009, 2019).

Potential Burn Pit Exposures Among the Cohort Participants

For each cohort member, we calculated the cumulative deployment days at bases with a burn pit, as well as the cumulative deployment days at bases without a burn pit, using their OEF/OIF deployment history from 2001 to 2014. For cohort members who were deployed at a base with a burn pit, the mean deployment days on burn pit bases was 470, median of 370 days, 5th to 95th percentile of 162 to 1014 days, and 25th to 75th percentile of 288 to 608 days (Fig. 7). For cohort members who were deployed to a base without a burn pit, the mean deployment days on nonburn pit bases was 306 days, median of 290 days, 5th to 95th percentile of 61 to 618 days, and 25th to 75th percentile of 207 to 357 days (Fig. 8).

Cumulative days of deployment on bases with burn pits for cohort.
Cumulative days of deployment to bases with no burn pit for cohort.


To date, two studies of veterans' health have incorporated burn pit exposures as a risk factor. The Millennium Cohort Study focused on those deployed at three large bases at which open burn pits were used in Iraq (Joint Base Balad, Camp Taji, and Camp Speicher). The authors used several metrics of exposure status including deployment within a 2-, 3-, or 5-mile radius of a documented open burn pit between 2003 and 2008, compared with deployment at bases more than 2 to 3 miles away from a base with burn pits, or in some cases, they used soldiers deployed to Kuwait Camp Arifjan as the control group. Cumulative days deployed to any bases with a burn pit were calculated, and also exposure days by camp were determined.11,12 The authors stated that “data to assess possible burn pit exposure over the entire Theater of Operation was not available.”11

Liu et al13 analyzed data from the VA Airborne Hazard and Open Burn Pit Registry, a data collection system in which volunteers enrolled and provided information on health and exposure. These researchers relied on self-reported hours of burn pit exposure during deployment and exposure based on location (deployment time within 2 miles of Joint Base Balad and Camp Taji in Iraq). However, the authors point out that the use of self-reported hours of burn pit smoke exposure assumes no recall bias or errors, that the self-reported smoke exposure was from the burn pit, and that all self-reported hours represent equivalent exposure.

In 1998, President Clinton's National Science and Technology Council released Directive 5, “A National Obligation for Planning for Health Preparedness for and Readjustment of the Military, Veterans, and Their Families After Future Deployments.”17 With this document and the 1999 Institute of Medicine report on “Strategies to Protect the Health of Deployed US Forces: Medical Surveillance, Record Keeping, and Risk Reduction,” a joint VA and DoD effort was begun to develop the systems that would in part meet the requirements of Presidential Review Directive 5 by creating individual longitudinal exposure records (ILERs). The ILER system is well underway but has not yet been able to be used for research purposes. The ILER system is designed to look at a wide array of risks including nerve agents, fuels, agent orange, solvents, antimalarials, pesticides, radiation, depleted uranium, vaccines, oil well fires, dust and sand, and so on.18 The assessment conducted here for the potential for burn pit exposures among deployed military personnel was based on records of base waste disposal methods found through some of the inputs to the ILER system: DOEHRS reports, records of air, soil, ash sampling, public health site assessments, and pest control records. In addition, we were able to access CENTCOM Engineering reports, which are not part of the ILER system.

The changes we recorded in waste disposal methods seem to reflect the release of burn pit guidance in 2009 through the MNC-I SOP, USFOR-A Guidance, and CENTCOM Reg 200-2. These regulations did produce changes in waste management on the bases, increasing the segregation of waste. Addition of incinerators as supplements to burn pits began in 2006 in Iraq and Afghanistan, reaching a high in 2012 of 24% and 27% of our cohort bases in Afghanistan and Iraq, respectively.

Despite the 2010 DoD Directive-Type Memorandum 09-032 directive prohibiting burn pits without a formal determination by the base commander that no other method is feasible, greater than 54% to 67% of the bases in Iraq had burn pits from 2011 to 2013. Similarly in Afghanistan, 59% to 71% of the bases had burn pits from 2011 to 2013. The DoD regulation has very strict requirements for reporting such that the commander must forward their determination in writing to the Under Secretary of Defense for Acquisition, Technology, and Logistics within 15 calendar days. Then the Under Secretary must submit the determination to the Senate and House Armed Services Committees within 30 days. If the use of the burn pit is to continue, the commander must provide a written justification to the Under Secretary every 180 days, and the Under Secretary must also forward these justifications to the Senate and House Armed Services Committees.14

The utilization of incinerators was one step the DoD took to reduce potentially toxic emissions from solid waste disposal. There were no hazardous waste incinerators in Iraq or Afghanistan. The data on the numbers and types of general solid waste and medical waste incinerators were sparse and often lacking in detail. Incinerators were sometimes ordered, but receipt was delayed, installations were sometimes delayed, and finally, incinerators were sometimes not used regularly or properly because of lack of trained personnel. We were unable to quantify changes in emissions over time because of the introduction of incinerators, as even in controlled situations other factors can complicate the interpretation of any ambient measurements taken (weather, distance of sampler from source, other sources, etc).

Aurell et al19 reported that running an air curtain burner/burn box in a continuous batch feed mode produced lower emissions than burning waste in a pile for all compounds studied (polychlorinated dibenzo-p-dioxins [PCDDs], polychlorinated dibenzofurans [PCDFs], polycyclic aromatic hydrocarbons [PAHs] CO2, PM2.5, and volatile organic compounds). However, running both methods under smoldering conditions produced similar emissions. Masiol et al20 reported that there was no significant difference in ambient levels of gas and particulate phase organics (PCDDs, PCDFs, PAHs) after two incinerators, in addition to the burn pit, were operating at Joint Base Balad. Although the introduction of the two incinerators reduced the waste burned in the burn pit by half, the lack of difference in ambient levels was attributed to uncertainty about the types of incinerators (two-stage vs air curtain), differences in weather conditions during sampling, and the presence of other sources of PAHs (diesel engines in vehicles, generators, aircraft and space heaters). Because of the large volume of plastics burned in medical waste incinerators, they are also considered to be emission sources for PCDDs/PCDFs and PAHs.21

In a 2014 Report to Congress,22 a DoD Instruction (DoDI) 4715.19, “Use of Open-Air Burn Pits in Contingency Operations Feb 2013,” defined an open-air burn pit as “an area designated for the purpose of disposing of solid waste by burning in the outdoor air at a location with more than 100 attached or assigned personnel and that is in place longer than 90 days.” The report stated that there was only one base in Afghanistan using open-air burning, and it was expected to close in April 2014. However, our data indicated that there were 40 bases in Afghanistan according to our cohort deployment records, and we believe 26% (n = 10) had open burn pits in 2014. However, it may be that these bases were considered to have populations fewer than 100 by that time.

In Afghanistan, bases where only incinerators were used for solid waste did not show up until 2011 (one base) and rose slowly until 2014 (20%, n = 8). However, in Iraq, in 2008, 2% of bases (n = 1) used only incinerators for solid waste. Although starting earlier, fewer bases in Iraq used only incineration for solid waste (8% to 10% in 2011 to 2014). In both Iraq and Afghanistan, when burn pits were not in use, the most common waste disposal method was to transport waste offsite to landfills or other municipal waste disposal sites, which could have included open burning or incineration as well.

It was not until 2016 that the DoDI 4715.23, “Integrated Recycling and Solid Waste Management,” described an integrated solid waste management approach to manage solid waste generation to minimize waste disposal through diversion. The DoD adopted and implemented the environmental waste management hierarchy of source reduction, sustainable procurement, reuse, donation, recycling, composting, and waste-to-energy before incineration or landfilling. These approaches along with the DoDI 4715.19 on Burn Pits reduced toxic inputs into the solid waste stream.

In this cohort of 475,326, 85.5% of the Army and Air Force personnel deployed in OEF/OIF were deployed to bases with burn pits. For these 406,191 soldiers with burn pit exposure, the median number of days deployed at bases with burn pits was more than a year (370 days). However, the range was quite wide (5th to 95th percentile, 162 to 1014 days). Some of the cumulative deployment lengths in the DMDC records were quite long, with a maximum of 3565 days (9.8 years) for burn pit bases and 3608 days (9.9 years) for nonburn pit bases. These outliers may represent errors in the SPA software where gaps between reenlistments and redeployments were not accurately recorded; however, they represent approximately only 1% of the cohort cumulative deployment records.

Limitations of this study include the following: Although there are years where our cohort comprises a large percentage of the DoD BOG population, there are also years where there were many more soldiers in-country that are not part of our cohort. This is in part because the cohort includes only those enrolled for care with the Veterans Health Administration, but also because we found that computerized deployment records did not become common until 2004 to 2005 at the earliest and that base names were not entered systematically with many synonyms for the same base. Other limitations include spotty records on waste disposal methods at the bases. We found that environmental reports were infrequent before 2007 in Afghanistan and 2005 in Iraq. As a result, we extrapolated waste disposal methods before and between reports showing waste disposal method changes.

We acknowledge that distance and prevailing weather conditions, as well as job duties, can impact the likelihood and intensity of potential burn pit emission exposures. However, we were unable to identify volumes of waste disposed of at the bases, nor were we able to identify specific personnel that worked at the burn pits based on military rank or job title. There were very limited data on burn pit location, distance of the troop housing, base-specific waste materials, and volume or frequency of waste materials burned. The segregation of particular types of waste in the burn pits and the use of solid waste and medical incinerators may reduce the toxicity or intensity of waste disposal emissions. However, we lacked data from ambient air sampling to test this assumption. Finally, no validation of our burn pit or waste disposal categories has been conducted using self-reports of veterans on site at our target bases during the time frame of the study.

There are many researchers interested in investigating veterans' health outcomes related to deployment exposures. The exposure assessment developed for this VA cohort would not have been possible without the declassification of the DMDC deployment records that provided base listings, population data, and direct linkage with the VA cohort. Establishing the privacy protocols and receiving the approvals for this linkage were time consuming and required the cooperation of numerous offices within the VA and DoD. We utilized a range of data inputs based on field reports, some of which remain classified and some of which have only recently become available through the DOEHRS and ILER systems. To access these records required the cooperation and the time commitment of contacts within DoD, including the Army Public Health Center and CENTCOM. The development of a synonym list for base names in the DMDC records highlighted how much cleanup is needed to make these records more useful. Future researchers wishing to develop exposure assessments for other risk factors will need to work with a variety of DoD personnel, all of whom have many other job demands, to access the deployment records, environmental reports, and data they need.


Most US veterans from the Iraq and Afghanistan wars were deployed on bases that had burn pits. This exposure assessment of 109 Iraq and Afghanistan bases found 85.5% of the 475,326 veterans had been deployed to bases with burn pits. However, the DoD regulations of 2009 resulted in changes in waste disposal methods, requiring segregation of hazardous and medical waste and limiting contents for the burn pits. In Afghanistan in 2011, only 2% of bases had burn pits with unsegregated waste in use, but even in 2014, 27% of bases still had waste segregated burn pits in use. In Iraq, by 2012, only 5% of bases had burn pits with unsegregated waste in use, but even in 2014, 40% of the bases still had waste segregated burn pits in use. Other changes included increasing use of waste incineration and local disposal of waste offsite.


The authors thank Steve Jones, Assistant Under Secretary of Defense, Health Affairs; Mike Wolford, Central Command; Tony Pitrat, Army Public Health Center; John E. Kolivosky, Army Public Health Center; Andrew Ricci, DMDC; Thomas Sherbert, Central Command; Larry Vandergrift, Contractor in support of Defense Health Agency; and Brad Hutchens, Army Public Health Center.


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Afghanistan; burn pit; exposure assessment; Iraq; veterans

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