As of the end of February 2005, an estimated 827,277 servicemembers had been deployed in support of OIF. Deployed servicemembers, such as those in OIF, are potentially subject to occupational and environmental hazards that can include exposure to harmful levels of environmental contaminants such as industrial toxic chemicals, chemical and biological warfare agents, and radiological and nuclear contaminants. Harmful levels include high-level exposures that result in immediate health effects. Health hazards may also include low-level exposures that could result in delayed or long-term health effects. Occupational and environmental health hazards may include such things as contamination from the past use of a site, from battle damage, from stored stockpiles, from military use of hazardous materials, or from other sources. As a result of numerous investigations that found inadequate data on deployment occupational and environmental exposure to identify the potential causes of unexplained illnesses among veterans who served in the 1991 Persian Gulf War, the federal government increased efforts to identify potential occupational and environmental hazards during deployments. In 1997, a Presidential Review Directive called for a report by the National Science and Technology Council to establish an interagency plan to improve the federal response to the health needs of veterans and their families related to the adverse effects of deployment. The Council published a report that set a goal for the federal government to develop the capability to collect and assess data associated with anticipated exposure during deployments. Additionally, the report called for the maintenance of the capability to identify and link exposure and health data by Social Security number and unit identification code. Also in 1997, Public Law 105-85 included a provision recommending that DOD ensure the deployment of specialized units to theaters of operations to detect and monitor chemical, biological, and similar hazards. The Presidential Review Directive and the public law led to a number of DOD instructions, directives, and memoranda that have guided the collection and reporting of deployment OEHS data. DHSD makes recommendations for DOD-wide policies on OEHS data collection and reporting during deployments to the Office of the Assistant Secretary of Defense for Health Affairs. DHSD is assisted by the Joint Environmental Surveillance Working Group, established in 1997, which serves as a coordinating body to develop and make recommendations for DOD-wide OEHS policy. The working group includes representatives from the Army, Navy, and Air Force OEHS health surveillance centers, the Joint Staff, other DOD entities, and VA. Each service has a health surveillance center—the CHPPM, the Navy Environmental Health Center, and the Air Force Institute for Operational Health—that provides training, technical guidance and assistance, analytical support, and support for preventive medicine units in the theater in order to carry out deployment OEHS activities in accordance with DOD policy. In addition, these centers have developed and adapted military exposure guidelines for deployment using existing national standards for human health exposure limits and technical monitoring procedures (e.g., standards developed by the U.S. Environmental Protection Agency and the National Institute for Occupational Safety and Health) and have worked with other agencies to develop new guidelines when none existed. (See fig. 1.) DOD policies and military service guidelines require that the preventive medicine units of each military service be responsible for collecting and reporting deployment OEHS data. Deployment OEHS data are generally categorized into three types of reports: baseline, routine, or incident- driven. Baseline reports generally include site surveys and assessments of occupational and environmental hazards prior to deployment of servicemembers and initial environmental health site assessments once servicemembers are deployed. Routine reports record the results of regular monitoring of air, water, and soil, and of monitoring for known or possible hazards identified in the baseline assessment. Incident-driven reports document exposure or outbreak investigations. There are no DOD-wide requirements on the specific number or type of OEHS reports that must be created for each deployment location because reports generated for each location reflect the specific occupational and environmental circumstances unique to that location. CHPPM officials said that reports generally reflect deployment OEHS activities that are limited to established sites such as base camps or forward operating bases; an exception is an investigation during an incident outside these locations. Constraints to conducting OEHS outside of bases include risks to servicemembers encountered in combat and limits on the portability of OEHS equipment. In addition, DHSD officials said that preventive medicine units might not be aware of every potential health hazard and therefore might be unable to conduct appropriate OEHS activities. According to DOD policy, various entities must submit their completed OEHS reports to CHPPM during a deployment. The deployed military services have preventive medicine units that submit OEHS reports to their command surgeons, who review all reports and ensure that they are sent to a centralized archive that is maintained by CHPPM. Alternatively, preventive medicine units can be authorized to submit OEHS reports directly to CHPPM for archiving. (See fig. 2.) According to DOD policy, baseline and routine reports should be submitted within 30 days of report completion. Initial incident-driven reports should be submitted within 7 days of an incident or outbreak. Interim and final reports for an incident should be submitted within 7 days of report completion. In addition, the preventive medicine units are required to provide quarterly lists of all completed deployment OEHS reports to the command surgeons. The command surgeons review these lists, merge them, and send CHPPM a quarterly consolidated list of all the deployment OEHS reports it should have received. To assess the completeness of its centralized OEHS archive, CHPPM develops a quarterly summary report that identifies the number of baseline, routine, and incident-driven reports that have been submitted for all bases in a command. This report also summarizes the status of OEHS report submissions by comparing the reports CHPPM receives with the quarterly consolidated lists from the command surgeons that list each of the OEHS reports that have been completed. For OIF, CHPPM is required to provide a quarterly summary report to the commander of U.S. Central Command on the deployed military services’ compliance with deployment OEHS reporting requirements. During deployments, military commanders can use deployment OEHS reports completed and maintained by preventive medicine units to identify occupational and environmental health hazards and to help guide their risk management decision making. Commanders use an operational risk management process to estimate health risks based on both the severity of the risks to servicemembers and the likelihood of encountering the specific hazard. Commanders balance the risk to servicemembers of encountering occupational and environmental health hazards while deployed, even following mitigation efforts, against the need to accomplish specific mission requirements. The operational risk management process, which varies slightly across the services, includes risk assessment, including hazard identification, to describe and measure the potential hazards at a location; risk control and mitigation activities intended to reduce potential exposures; and risk communication efforts to make servicemembers aware of possible exposures, any risks to health that they may pose, the countermeasures to be employed to mitigate exposure or disease outcome, and any necessary medical measures or follow-up required during or after the deployment. Along with health encounter and servicemember location data, archived deployment OEHS reports are needed by researchers to conduct epidemiologic studies on the long-term health issues of deployed servicemembers. These data are needed, for example, by VA, which in 2002 expanded the scope of its health research to include research on the potential long-term health effects on servicemembers in hazardous military deployments. In a letter to the Secretary of Defense in 2003, VA said it was important for DOD to collect adequate health and exposure data from deployed servicemembers to ensure VA’s ability to provide veterans’ health care and disability compensation. VA noted in the letter that much of the controversy over the health problems of veterans who fought in the 1991 Persian Gulf War could have been avoided had more extensive surveillance data been collected. VA asked in the letter that it be allowed access to any unclassified data collected during deployments on the possible exposure of servicemembers to environmental hazards of all kinds. The deployed military services generally have collected and reported OEHS data for OIF, as required by DOD policy. However, the deployed military services have used different OEHS data collection standards and practices, because each service has its own authority to implement broad DOD policies. To increase data collection uniformity, the Joint Environmental Surveillance Working Group has made some progress in devising cross-service standards and practices for some OEHS activities. In addition, the deployed military services have not submitted all of the OEHS reports they have completed for OIF to CHPPM’s centralized archive, as required by DOD policy. However, CHPPM officials said that they could not measure the magnitude of noncompliance because they have not received all of the required quarterly consolidated lists of OEHS reports that have been completed. To improve OEHS reporting compliance, DOD officials said they were revising an existing policy to add additional and more specific OEHS requirements. OEHS data collection standards and practices have varied among the military services because each service has its own authority to implement broad DOD policies, and the services have taken somewhat different approaches. For example, although one water monitoring standard has been adopted by all military services, the services have different standards for both air and soil monitoring. As a result, for similar OEHS events, preventive medicine units may collect and report different types of data. Each military service’s OEHS practices for implementing data collection standards also have differed because of varying levels of training and expertise among the service’s preventive medicine units. For example, CHPPM officials said that Air Force and Navy preventive medicine units had more specialized personnel with a narrower focus on specific OEHS activities than Army preventive medicine units, which included more generalist personnel who conducted a broader range of OEHS activities.