ORIGINAL ARTICLE An Investigation of Aircraft Worker Anemia: Medical Surveillance Interpretation in an Aging Workforce John Muller, MD, MPH, Karen Allstadt, MD, MPH, Christopher Rennix, ScD, MS, Lawrence Betts, MD, PhD, Patricia Krevonick, BS, and Mark Hammett, MD, MPH Objective: To identify exposures possibly contributing to anemia cases among hexavalent chromium medical surveillance program enrollees. Methods: An investigation encompassed metals surveillance programs, ex- tensive workplace sampling and remediation, consultation, evaluation of lab- oratory accuracy, and follow-up of anemic individuals. Results: Workers had underlying medical conditions that affected surveillance results. There was a systemic error in classification based on hematocrit value. The prevalence of anemia in a workforce averaging 52 years old was 16%. Conclusions: Anemia may be more prevalent in middle-aged workers than expected. Mod- ern laboratories generally report a calculated hematocrit value, and using hemoglobin for most classification purposes is preferred. Characteristics of a specific workforce, including age, health, hobbies, and diet, should be taken into account when interpreting medical surveillance program findings. The value of a team approach in addressing occupational health problems was demonstrated. M edical surveillance examinations on workers exposed to spe- cific toxicants in the workplace are mandated by federal regulation. 1 Navy occupational medical surveillance programs, in- cluding occupational medical surveillance programs for exposures to certain metals, are conducted in accordance with the Medical Ma- trix, a compilation of surveillance program requirements that meet or exceed federal regulations. 2 Occupational exposure to various met- als has been associated with alterations in hematological parameters: arsenic and lead (Pb) have been associated with anemia, and mer- cury (Hg) has been associated with increased red blood cell count and decreased red cell hemoglobin. 3–5 Chronic nonoccupational ex- posure to a form of chromium (Cr), Cr picolinate (in which Cr exists as Cr +3 ), has also been associated with anemia. 6 True anemia re- sults from blood loss or from decreased production or increased destruction of erythrocytes. 7 Medical Matrix requirements include a complete blood cell count (CBC ) in medical surveillance programs for the metals arsenic hexavalent Cr (Cr +6 ), Pb, and Hg. Changes in 2006 to the Occupational Safety and Health Act hexavalent chromium standards lowered the Cr +6 action level to 2.5 micrograms per cubic meter of air, calculated as an 8-hour time- weighted average, and a directive was issued to Occupational Safety and Health Act inspectors to examine more closely worksites with detectable surface levels in eating and drinking areas. 8,9 As a result of these changes, industrial hygienists at a Navy military aircraft From the Navy and Marine Corps Public Health Center (Drs Muller, Rennix, and Hammett and Ms Krevonick), Portsmouth, Va; Occupational Medicine Clinic (Dr Allstadt), Naval Hospital Jacksonville, Jacksonville, Fla; Eastern Virginia Medical School, Norfolk and US Navy. Poquoson, Va (Dr Betts). J.M., K.A., C.R., and P.K. are employed by the US Navy. M.H. is a US Navy service member. L.B. was a paid consultant to the US Navy during this investigation. The views expressed in this article are solely those of the authors and do not reflect the official policy or position of the US Navy, the Department of Defense, or the US Government. Address correspondence to: John Muller, MD, MPH, FACOEM, Navy and Marine Corps Public Health Center, 620 John Paul Jones Cir, Ste 1100, Portsmouth, VA 23708 (john.muller@med.navy.mil). Copyright C  2011 by American College of Occupational and Environmental Medicine DOI: 10.1097/JOM.0b013e318216d471. maintenance repair facility (MRF) recommended including workers from additional shops in the Cr +6 medical surveillance program. The recommendation was made because some chrome-related op- erations were being moved to different locations and, based on pre- vious sampling results, these shops were now going to meet the (now lowered) exposure criteria for medical surveillance program enrollment. Personnel at the MRF performed paint application and removal, welding, and machining operations involving products and processes containing metals. Some processes were unique to aircraft maintenance and repair. Workers were routinely examined under different programs because of potential exposure to numerous toxi- cants, including Cr +6 , aluminum (Al), cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), mercury (Hg), silver (Ag), strontium (Sr), and zinc (Zn). Biological monitoring was only per- formed as part of medical surveillance programs for Cd (blood and urine), Pb (blood), and Hg (urine). The MRF worker population was part of a coastal commu- nity in which many people participate in water-related recreation, especially fishing. In addition, the MRF encouraged workers to do- nate blood by offering time-off awards. Seafood was a major dietary component. Area groundwater had been found to contain arsenic, and some of the population’s drinking water came from local wells. In early 2009, the occupational and environmental medicine (OEM) physician performing routine surveillance examinations on workers recently enrolled in Cr +6 medical surveillance noticed that an unusually large number of hematocrit values were below the lab- oratory lower limit of normal; thus, those workers were classified as anemic. An extensive investigation was launched to determine the extent of abnormal laboratory findings among the workers and potential excessive occupational exposures to certain metals. Upon learning why they were undergoing further testing, workers became concerned about possible excessive exposure to Cr +6 , to the ex- tent that T-shirts were produced, worn by workers on Fridays, em- blazoned with skull and crossbones and proclaiming “I am being poisoned by chrome VI.” Requests for environmental differential (“hazardous duty”) pay were also made. Local consultative support was requested from industrial hygiene, hematology, and pathology. In addition, the Navy and Marine Corps Public Health Center and an independent OEM physician-toxicologist were brought in for sup- port in the investigation. This report details the salient findings of the occupational health investigation of the abnormal laboratory values and the industrial hygiene sampling. METHODS A workplace walk-through was completed, and industrial hy- gienists performed surface and air sampling within the involved shops. Personal breathing zone (PBZ) air sampling was performed on workers representative of various jobs being done. Semiquan- titative surface sampling was performed in 54 shop areas for 16 metals: those known to be present plus five others that are part of a panel (“Inductively Coupled Plasma Scan”) offered by the lab- oratory, including arsenic beryllium (Be), cobalt (Co), molybde- num (Mo), and vanadium (V). Sampled areas included floors, work- ing surfaces, workbenches, walls, windowpanes, desks, break room Copyright © 2011 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. 548 JOEM  Volume 53, Number 5, May 2011