Back to Top Skip to main content Skip to sub-navigation

Blood Lead Level Surveillance Among Pediatric Beneficiaries in the Military Health System, 2010–2017

U.S. Air Force Staff Sgt. Katie Duff, a medical technician with the 193rd Special Operations Wing's Medical Group, pricks the finger of brave 23-month old Kahia Inman, while his mother Malia Duvauchelle holds him during a free health screening. (U.S. Air Force photo by Tech. Sgt. Culeen Shaffer) U.S. Air Force Staff Sgt. Katie Duff, a medical technician with the 193rd Special Operations Wing's Medical Group, pricks the finger of brave 23-month old Kahia Inman, while his mother Malia Duvauchelle holds him during a free health screening. (U.S. Air Force photo by Tech. Sgt. Culeen Shaffer)

Recommended Content:

Medical Surveillance Monthly Report

ABSTRACT

The EpiData Center (EDC) has provided routine blood lead level (BLL) surveillance for Department of Defense (DoD) pediatric beneficiaries since 2011. Data for this study were collected and compiled from raw laboratory test records obtained from the Composite Health Care System Health Level 7 (HL7)-formatted chemistry data, allowing an overview of the number of tests performed and the number of elevated results. Between 2010 and 2017, there were 177,061 tests performed among 162,238 pediatric beneficiaries tested. Using only the highest test result per year for each individual, 169,917 tests were retained for analysis, of which 1,334 (0.79%) test results were considered elevated. The percentage of children with elevated BLLs generally decreased over the time period for children of every service affiliation. All tests throughout this time frame were evaluated using current standards and the protocol followed by the Centers for Disease Control and Prevention and the Department of the Navy (DON). The adoption of a standardized BLL surveillance methodology across the DoD supports a cohesive approach to an evolving public health surveillance topic.

WHAT ARE THE NEW FINDINGS?   

The EDC’s BLL surveillance program established a methodology for lead exposure surveillance among DoD pediatric beneficiaries, providing critical data and valuable historical context for the interpretation of findings. Between 2010 and 2017, the percentage of children with elevated BLLs generally remained below 1.2%, and by 2017, the overall percentage was 0.5% for all children tested.

WHAT IS THE IMPACT ON READINESS AND FORCE HEALTH PROTECTION?

Blood lead surveillance of DON pediatric beneficiaries is required under Bureau of Medicine and Surgery instruction 6200.14D. The EDC’s methodology for BLL surveillance may be leveraged for consistent BLL surveillance across the DoD.

BACKGROUND

Robust lead exposure surveillance is especially important in pediatric populations. There is no safe blood lead level (BLL) for children; even very low BLLs can increase the risk of harmful hematologic and neurologic effects.1 The U.S. Preventive Services Task Force concluded there is currently insufficient evidence to recommend BLL screening of asymptomatic children 5 years of age and younger.2 The Military Health System (MHS) does not require universal BLL screening for pediatric beneficiaries, but providers are directed to consider assessing the risk of lead exposure among children between 6 months and 6 years of age by parental questionnaire, in accordance with recommendations from the American Academy of Pediatrics.3 Children who screen positive on this questionnaire should have their BLLs tested. Additionally, clinical suspicion of lead exposure or poisoning should prompt a blood lead test. Providers should ensure the performance of follow-up care for any child with an elevated BLL, and retesting is recommended to confirm an initial elevated BLL and to monitor the decline in BLLs following treatment.4

Before 2012, a BLL of 10 µg/dL or greater was considered to be an elevated test result.In 2012, the Centers for Disease Control and Prevention (CDC) updated the guidelines for the blood lead reference value (BLRV) to 5 µg/dL or greater, based on National Health and Nutrition Examination Survey results showing declining BLLs in children.6 For an elevated BLL (5 µg/dL or greater) to be considered “confirmed,” CDC requires 1 elevated result from a venous blood test or 2 elevated results from capillary blood tests within 12 weeks.7 Traditional blood lead laboratory test results are the preferred test for Department of the Navy (DON) BLL surveillance. Rapid testing results, like finger-stick tests obtained by MHS providers at the point of care, were used for BLL surveillance purposes until 30 August 2017 when the Bureau of Medicine and Surgery (BUMED) released an instruction stating point-of-care blood testing devices were no longer authorized for compliance with the childhood lead poisoning prevention program in the DON.8

Since 2011, the EpiData Center (EDC) at the Navy and Marine Corps Public Health Center (NMCPHC) has conducted routine BLL surveillance among Department of Defense (DoD) pediatric beneficiaries on a quarterly basis. An annual report based on data at the military treatment facility (MTF) level is also prepared on DON pediatric beneficiaries at the request of the Occupational and Environmental Medicine Department of NMCPHC. All surveillance reports are available to qualified DoD personnel upon request. The EDC’s BLL surveillance program provides critical data and valuable historical context for evaluating lead exposure among DoD pediatric beneficiaries.

This article describes the EDC’s methodology for BLL surveillance in DoD pediatric beneficiaries. This methodology represents a potential model for the development of a shared, standardized BLL surveillance method because it could be tailored to meet the unique needs of each DoD service while also maximizing the comparison, replication, and utility of findings. DON blood lead surveillance is modified from the CDC’s standard blood lead surveillance definitions and classifications to best meet its needs using current capabilities. For every calendar year (CY), the EDC identifies elevated blood lead tests among DON pediatric beneficiaries and then verifies in the Armed Forces Health Longitudinal Technology Application (AHLTA) whether or not the provider followed up with the pediatric beneficiary. The EDC then provides a list of names of children that have not had follow-up testing to the Occupational and Environmental Medicine Department of NMCPHC.

METHODS

Laboratory test records with a sample collection date in CYs 2010–2017 (01 January 2010 through 31 December 2017) were obtained from the Composite Health Care System (CHCS) Health Level 7 (HL7)-formatted chemistry laboratory data. The EDC receives a feed of CHCS HL7-formatted chemistry laboratory data and demographic information daily from the Defense Health Agency. These data include all records from MTFs using the CHCS across the DoD. Records were excluded if the sample was not blood, if the unit of measure or the test result could not be determined, or if the results indicated a test was not performed. For example, before CDC updated its BLRV, 122 test results were recorded as “<10.” These results were removed from the final analysis, as it could not be determined if the results were less than the current BLRV of 5 µg/dL. Blood tests with the same sample collection date and date of certified results were excluded from the final sample, as these tests may have been unauthorized point of care tests8; moreover, it would have been highly unlikely for the laboratories to have been able to collect, analyze, and certify a sample on the same day. Zinc protoporphyrin (ZPP) tests, which measure the amount of ZPP in the blood (an indicator of chronic lead exposure) rather than BLL, were also excluded. If more than 1 BLL test result was identified for an individual in a single year, the highest BLL test result for that year was retained.

BLL tests administered to beneficiary children aged less than 18 years at the date and time of sample collection were included. Tests could either have been those completed within an MHS laboratory or those completed at an out-of-network laboratory, after which an MHS provider received and entered the results into AHLTA. Records were analyzed by sponsor service affiliation (Army, Air Force, Marine Corps, Navy, Other), age group (=6 years and 7–17 years), BLL value (<5 µg/dL, 5–9 µg/dL, 10–19 µg/dL, and =20 µg/dL), and geographic region (outside of the U.S., New England, Mid-Atlantic, Eastern North Central, Western North Central, South Atlantic, Eastern South Central, Western South Central, Mountain, Pacific). For sponsor service affiliation and geographic region, the percentage of elevated BLL tests per year was determined.

RESULTS

From 01 January 2010 through 31 December 2017, 169,917 BLL records were retained for analysis (Table 1). The Army tested more pediatric beneficiaries than any other service affiliation during the reporting period. The majority of testing occurred among pediatric beneficiaries aged 6 years or younger across all branches of service.
Overall, the percentage of elevated BLLs among pediatric beneficiaries decreased from 2010 to 2017 (Figure). Less than 1% of pediatric BLL tests in any service were elevated in 2016 and 2017, and no children in the “other” category had an elevated BLL test since 2014.

For CYs 2010–2017, 96.2% of all BLL tests among pediatric beneficiaries were performed in the U.S. and 3.8% were performed elsewhere (Table 2). The percentages of elevated tests (0.8%) were equivalent for the 2 regions. Within the U.S., there were no tests performed in 9 states. Of all BLL tests in the U.S., 58.8% (n=96,089) were from the South Atlantic and Western South Central regions, which accounted for 54.8% (n=702) of all elevated BLLs. The New England region had the highest regional percentage of elevated BLLs (1.4%), but that percentage was based on just 22 elevated BLLs out of 1,561 tests, the lowest number of tests for any region. Among the states, Texas had the highest number of tests (n=29,340), followed by Virginia (n=25,852), but the percentages of tests with elevated BLLs were just 0.5% and 0.7%, respectively. The 5 states with the highest percentages of elevated BLLs (Connecticut, Rhode Island, Pennsylvania, New Hampshire, and Tennessee) accounted for just 22 elevated levels out of only 268 tests performed (Table 2). Among the remaining 37 states (including Washington, DC) that performed tests, the mean percentage positive was 0.9% and the values ranged from 0.3% (Arizona and Colorado) to 1.8% (Kansas and Mississippi).

EDITORIAL COMMENT

Across the DoD, there were 177,061 tests performed between 2010 and 2017 among 162,238 pediatric beneficiaries. Some children may have had multiple tests occurring within the same year or during the totality of the reporting time frame because they had a positive lead questionnaire screen during a doctor’s visit, exhibited clinical symptoms of lead poisoning per the provider’s discretion, or had a prior elevated BLL test. For surveillance purposes, the highest BLL result per year per pediatric beneficiary was kept for analysis, leading to a final observation count of 169,917 BLL tests.

While the percentage of elevated BLL tests varied by sponsor service affiliation, the overall percentage of elevated BLL tests decreased from 2010 to 2017. The number of BLL tests among pediatric beneficiaries varied by state because of the location of fixed MTFs; however, in general, the percentage of elevated BLL tests did not differ between regions inside and outside of the U.S. The number of children tested within each branch of service likely varied because of the difference in the size of the service populations. Percentages of children with elevated BLLs could potentially be affected by the number of children tested within a branch of service or geographic region, whether the children tested were at a lower or higher risk of lead exposure, and the screening recommendations of the MHS.

To adequately identify and address lead exposure risks in their active duty and beneficiary populations, the DON and other DoD services might consider the adoption of a single, standardized method for BLL surveillance. A shared methodology would facilitate comparisons and reduce duplicative effort across the services. Ideally, a shared methodology would also be flexible and responsive to accommodate the challenges related to BLL surveillance in the DoD.

HL7-formatted data are routinely generated within the CHCS at fixed MTFs. HL7-formatted data do not include records from BLL tests without certified results. This may include specimens collected at an MTF that were sent to an out-of-network laboratory for testing. Data from Purchased CareThe TRICARE Health Program is often referred to as purchased care. It is the services we “purchase” through the managed care support contracts.purchased care providers also were not included. Records from MHS GENESIS, a new electronic health record that launched in February 2017 at select MHS facilities, were unavailable. Therefore, records from the following MTFs throughout the Pacific Northwest region were not included in this analysis after the launch of MHS GENESIS at their facilities: Fairchild Air Force Base, Madigan Army Medical Center, Naval Health Clinic Oak Harbor, and Naval Hospital Bremerton. Changes in civilian and military testing policies, updates to exposure thresholds, population- or service-specific practices, and data limitations complicate comparisons over time and across services and limit the generalizability of findings.

The HL7-formatted chemistry database consists of nonculture laboratory test results (e.g., polymerase chain reaction and antigen testing). Providers may order a panel when patients present with nonspecific symptoms. If the test name or test results within a panel are not disease-specific, these results may not be captured in search terms used to query the chemistry data. Classifying chemistry tests involves extensive searching of free-text test result fields. It is possible that some test results were misclassified, though validation steps were included to reduce error. Venous and capillary BLL specimen samples are unable to be distinguished in the HL7-formatted chemistry data. Capillary specimen samples for lead testing are generally viewed as less reliable than venous samples because of the potential for lead contamination of specimens during collection that could result in false positives. For surveillance purposes, the EDC reports the highest BLL result per year per pediatric beneficiary and ensures that there is follow-up regarding that elevated test regardless of specimen sample type.

Universal BLL screening is not required in the MHS but is based on the discretion of healthcare practitioners. As a result, the proportion of pediatric beneficiaries with high BLLs may not be a true representation of the BLLs in the pediatric beneficiary population. However, the EDC’s pediatric BLL surveillance methods may provide a starting point for discussions on the value of developing a standardized blood lead surveillance program across all DoD services.

Author affiliations: EpiData Center, Navy and Marine Corps Public Health Center, Portsmouth, VA (Ms. Kotas, Ms. Madden, Ms. Luse, and Ms. Carroll).

Acknowledgments: The authors thank Ashleigh McCabe and Angela Schlein for their support of this analysis and manuscript.

Disclaimers: The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense, or the U.S. Government. The authors are employees of the U.S. Government. This work was prepared as part of their official duties. Title 17, U.S.C., §105 provides that copyright protection under this title is not available for any work of the U.S. Government. Title 17, U.S.C., §101 defines a U.S. Government work as a work prepared by a military service member or employee of the U.S. Government as part of that person’s official duties. This research was supported in part by an appointment to the Postgraduate Research Participation Program at the Navy and Marine Corps Public Health Center administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the U.S. Department of Energy and the Navy and Marine Corps Public Health Center.

REFERENCES

1. Centers for Disease Control and Prevention. Health effects of lead exposure. https://www.cdc.gov/nceh/lead/prevention/health-effects.htm. Accessed 05 March 2020.

2. U.S. Preventive Services Task Force. Elevated blood lead levels in children and pregnant women: screening. https://www.uspreventiveservicestaskforce.org/Page/Document/UpdateSummaryFinal/elevated-blood-lead-levels-in-childhood-and-pregnancy-screening. Accessed 05 March 2020.

3. American Academy of Pediatrics. Detection of lead poisoning. https://www.aap.org/en-us/advocacy-and-policy/aap-health-initiatives/lead-exposure/Pages/Detection-of-Lead-Poisoning.aspx. Accessed 05 March 2020.

4. Advisory Committee on Childhood Lead Poisoning Prevention, Centers for Disease Control and Prevention. Low level lead exposure harms children: a renewed call for primary prevention. https://www.cdc.gov/nceh/lead/ACCLPP/Final_Document_030712.pdf. Accessed 05 March 2020.

5. Centers for Disease Control and Prevention. Preventing lead poisoning in young children. https://wonder.cdc.gov/wonder/prevguid/p0000029/p0000029.asp. Accessed 05 March 2020.

6. Centers for Disease Control and Prevention. National Health and Nutrition Examination Survey (NHANES). https://www.cdc.gov/nceh/lead/data/nhanes.htm. Accessed 05 March 2020.

7. Centers for Disease Control and Prevention. Standard surveillance definitions and classifications. https://www.cdc.gov/nceh/lead/data/casedefinitions-classifications.htm. Accessed 05 March 2020.

8. Department of the Navy, Bureau of Medicine and Surgery. BUMED Instruction 6200.14D. Childhood Lead Poisoning Prevention. 30 August 2017.

Percentage of elevated (=5 µg/dL) pediatric BLL tests, by sponsor service affiliation, 2010–2017

Pediatric BLLs, by sponsor service affiliation and age group, 2010–2017

Number and percentage of elevated (=5 µg/dL) pediatric BLLs, by region and state, 2010–2017

You also may be interested in...

Skin and Soft Tissue Infections, Active Component, U.S. Armed Forces, January 2016–September 2020

Article
4/1/2021
Detailed view of elbow with carbuncle or furuncle. iStock.com/andriano_cz

Recommended Content:

Medical Surveillance Monthly Report

Update: Exertional Hyponatremia, Active Component, U.S. Armed Forces, 2005–2020

Article
4/1/2021
Marine Corps Recruit Depot, San Diego  Recruits with Bravo Company, 1st Recruit Training Battalion, hydrate after a physical training session at Marine Corps Recruit Depot San Diego, April 12, 2020. The recruits performed multiple exercises at different stations after completing a 400-meter dash. (U.S. Marine Corps photo by Cpl. Brooke C. Woods)

Recommended Content:

Medical Surveillance Monthly Report

Update: Heat Illness, Active Component, U.S. Armed Forces, 2020

Article
4/1/2021
Fort Jackson, SC. A trainee with 2nd Battalion, 60th Infantry Regiment puts his arms in an arm immersion cooling tank during training. The tanks allow Soldiers to rapidly cool by putting their forearms into a tank of ice water. (Photo by Saskia Gabriel)

Recommended Content:

Medical Surveillance Monthly Report

Disparities in COVID-19 Vaccine Initiation and Completion Among Active Component Service Members and Health Care Personnel, 11 December 2020–12 March 2021

Article
4/1/2021
Capt. Shamira Conerly, 149th Medical Group, gives Staff Sgt. Timmy Sanders, 149th Maintenance Squadron, his first does of COVID-19 vaccine on Joint Base San Antonio-Lackland, Texas, March 18, 2021. Members of the 149th Fighter Wing who have opted to receive their vaccine have been scheduled over the past two weeks by the 149th Medical Group. (US Air National Guard Photo by Senior Airman Ryan Mancuso)

Recommended Content:

Medical Surveillance Monthly Report

Update: Exertional Rhabdomyolysis, Active Component, U.S. Armed Forces, 2016–2020

Article
4/1/2021
Marine Corps Recruit Depot, San Diego  Recruits with Bravo Company, 1st Recruit Training Battalion, hydrate after a physical training session at Marine Corps Recruit Depot San Diego, April 12, 2020. The recruits performed multiple exercises at different stations after completing a 400-meter dash. (U.S. Marine Corps photo by Cpl. Brooke C. Woods)

Recommended Content:

Medical Surveillance Monthly Report

A Retrospective Cohort Study of Blood Lead Levels Among Special Operations Forces Soldiers Exposed to Lead at a Firing Range in Germany

Article
3/1/2021
A soldier assigned to the U. S. Army John F. Kennedy Special Warfare Center and School who is in the Special Forces Weapons Sergeant Course fires a pistol during small arms training at Fort Bragg, North Carolina November 4, 2019. The soldiers were trained to employ, maintain and engage targets with select U.S. and foreign pistols, rifles, shotguns, submachine and machine guns, grenade launchers and mortars and in the utilization of observed fire procedures. (U.S. Army photo illustration by K. Kassens)

Recommended Content:

Medical Surveillance Monthly Report

Influenza Outbreak During Exercise Talisman Sabre, Queensland, Australia, July 2019

Article
3/1/2021
Flight Lt. Michael Campion, an aviation medical officer from No. 3 Aeromedical Evacuation Squadron prepares a medical patient leaving Exercise Talisman Sabre to be transferred to a C-27J Spartan aircraft July 18, 2019 at Rockhampton Airport. No. 3 Aeromedical Evacuation Squadron is providing medical support to troops participating in Talisman Sabre 2019, a bilateral combined Australian and United States exercise designed to train respective military services in planning and conducting Combined and Joint Task Force operations, and improve the combat readiness and interoperability between Australian and US forces. (U.S. Army photo by Sgt. 1st Class John Etheridge)

Influenza Outbreak During Exercise Talisman Sabre, Queensland, Australia, July 2019

Recommended Content:

Medical Surveillance Monthly Report

Update: Sexually Transmitted Infections, Active Component, U.S. Armed Forces, 2012–2020

Article
3/1/2021
Under a magnification of 1150X, this photomicrograph of a Gram-stained urethral discharge specimen, demonstrated the presence of Gram-negative, intracellular diplococci, which is a finding indicative of the possible presence of Neisseria gonorrhoeae bacteria.  Credit: CDC/ Dr. Caldwell

Update: Sexually Transmitted Infections, Active Component, U.S. Armed Forces, 2012–2020

Recommended Content:

Medical Surveillance Monthly Report

Influenza Surveillance Trends and Influenza Vaccine Effectiveness Among Department of Defense Beneficiaries During the 2019–2020 Influenza Season

Article
3/1/2021
Captured in 2011, this transmission electron microscopic (TEM) image depicts some of the ultrastructural details displayed by H3N2 influenza virions, responsible for causing illness in Indiana and Pennsylvania in 2011. See PHIL 13469, for the diagrammatic representation of how this Swine Flu stain came to be, through the “reassortment” of two different Influenza viruses.  Credit: CDC/ Dr. Michael Shaw; Doug Jordan, M.A.

Influenza Surveillance Trends and Influenza Vaccine Effectiveness Among Department of Defense Beneficiaries During the 2019–2020 Influenza Season

Recommended Content:

Medical Surveillance Monthly Report

Surveillance for Vector-borne Diseases Among Active and Reserve Component Service Members, U.S. Armed Forces, 2016–2020

Article
2/1/2021
This image depicts a dorsal view of a female lone star tick, Amblyomma americanum, and is found in the Southeastern, and Mid-Atlantic United States. Females exhibit the star-like spot on their distal scutum. This tick is a vector of several zoonotic diseases, including human monocytic ehrlichiosis, and Rocky Mountain spotted fever (RMSF).  CDC/Michael L. Levin, PhD

Recommended Content:

Medical Surveillance Monthly Report

Historical Perspective: The Evolution of Post-exposure Prophylaxis for Vivax Malaria Since the Korean War

Article
2/1/2021
An Aedes aegypti mosquito can transmit the viruses that cause dengue fever.  CDC/Prof. Frank Hadley Collins, Cntr. for Global Health and Infectious Diseases, Univ. of Notre Dame

Recommended Content:

Medical Surveillance Monthly Report

Update: Malaria, U.S. Armed Forces, 2020

Article
2/1/2021
Spc. Joshua Jones, left, and Pfc. Richard Bower, both preventive medicine specialists, 227th Preventive Medicine Detachment, 62nd Medical Brigade, check an insect trap during a field training exercise on Joint Base Lewis-McChord, June 20. The 227th PMD notionally deployed to Guiria, Venezuela, where a tropical storm caused floods and presented a real world concern for mosquitos, which are known to spawn in stagnant water and cause widespread vector borne illnesses such as malaria, yellow fever and dengue fever.  Photo by Sgt. Sarah Enos 5th Mobile Public Affairs Detachment

Recommended Content:

Medical Surveillance Monthly Report

Attrition Rates and Incidence of Mental Health Disorders in an Attention-Deficit/Hyperactivity Disorder (ADHD) Cohort, Active Component, U.S. Armed Forces, 2014–2018

Article
1/1/2021
Capt. Michelle Tsai, the behavioral health officer for the 4th Brigade, 2nd Infantry Division, reviews medical information in her office at the Joint Readiness Training Center June 17. Tsai, an Alexandria, Va., native, is here with the Raider Brigade in support of training operations for the unit's upcoming deployment to Iraq. (Photo by Pfc. Luke Rollins)

Recommended Content:

Medical Surveillance Monthly Report

Exertional Rhabdomyolysis and Sickle Cell Trait Status in the U.S. Air Force, January 2009–December 2018

Article
1/1/2021
JOINT BASE SAN ANTONIO, Texas - Master Sgt. Daniel Bedford, Air Force Recruiting Service National Events program manager, prepares to pump up a gold medal lift in the bench press during the USPA (United State Powerlifting Association) 2020 Texas State Bench Press Championship. Senior Master Sgt. Michael Lear, AFRS Strategic Marketing Division superintendent, prepares to spot Bedford. Lear and Bedford are Total Force recruiting partners who train together and motivate one another at work and in the gym. (Courtesy photo) (Photo By: babin.)

Recommended Content:

Medical Surveillance Monthly Report

The Prevalence of Attention-Deficit/Hyperactivity Disorder (ADHD) and ADHD Medication Treatment in Active Component Service Members, U.S. Armed Forces, 2014–2018

Article
1/1/2021
New Recruits with Golf Company, 2nd Recruit Training Battalion, are screened after arriving at Marine Corps Recruit Depot, San Diego, Dec. 28, 2020. As recruits arrive to the depot in the future, they will enter a staging period of 14 days during which they will be medically screened, monitored, and provided classes to prepare and orient them to begin recruit training. All of this will occur before they step onto our iconic yellow footprints and make that memorable move toward earning the title Marine. Current planning and execution remain fluid as the situation continues to evolve. The health and well-being of our recruits, recruiting and training personnel, and their families remain our primary concerns. All recruits will be screened and tested for COVID-19 prior to beginning recruit training. (U.S. Marine Corps photo by Lance Cpl. Grace J. Kindred)

Recommended Content:

Medical Surveillance Monthly Report
<< < 1 2 3 4 5  ... > >> 
Showing results 1 - 15 Page 1 of 13

DHA Address: 7700 Arlington Boulevard | Suite 5101 | Falls Church, VA | 22042-5101

Some documents are presented in Portable Document Format (PDF). A PDF reader is required for viewing. Download a PDF Reader or learn more about PDFs.