▼ The purpose of this study was to analyze the historical occurrence of documented cervical spine disease (CSD) and its surgical intervention among United States Air Force (USAF) ‘fighter aviators’. Fighter aviators are routinely exposed to supraphysiologic G-forces in the vertical plane (Gz) that can trigger cervical spine disease. Previous survey-based studies have shown a high incidence of neck pain or injury reported by fighter pilots. However, no cohort studies have evaluated the clinical occurrence of CSD in this population. In this study, the clinical occurrence of CSD and its surgical intervention were evaluated among three primary USAF officer populations: fighter aviators, non-fighter aviators, and non-flying officers. Furthermore, due to the unique seat position and additional neck flexion required to fly the F-16, CSD rates among F-16 pilots were compared to ‘Non F-16 fighter aviators.’ The USAF Clinical Informatics Branch (CIB) provided de-identified data sets containing all documented CSD and surgical interventions in these populations from 2001-2006. Poisson regression analysis was conducted on all documented CSD and surgical interventions among USAF officers (2001 to 2006) and was used to assess population heterogeneity and calculate risk ratios. Fighter aviators present to clinics for CSD at a significantly lower rate (RR: 0.90, CI: 0.85-0.95, p<0.0001), yet their overall rate of having a surgical intervention in their career is significantly higher (RR: 1.46, CI 1.07-1.99, p=0.016) than non-fighter aviators. Once diagnosed with CSD, fighter aviator surgical intervention rates are even higher compared to other officer populations (RR: 1.62, CI: 1.19-2.21, p=0.002 compared to non-fighters). Interestingly, F-16 pilots have the lowest CSD rate among all officer populations (RR: 0.73, CI: 0.67-0.80, p < 0.0001) compared to non F-16 fighter aviators). While they have a lower overall surgical rate compared to Non F-16 aviators, once diagnosed with CSD, they have the highest rate of surgical intervention of all populations (RR: 1.47, CI: 0.90-2.39, p= 0.12 compared to non F-16 aviators). In conclusion, supraphysiologic Gz exposure may not be associated with increased rates of CSD, but it may be associated with increased rates of cervical surgeries among USAF fighter aviators. The seat angle of the F-16 may provide a protective factor in reducing CSD diagnoses and overall surgical rates. However, once diagnosed with CSD, the increased neck flexion (due to a unique seat angle) required to fly the F-16 may have a direct contribution to the highest surgical rate among the study populations. Advisors/Committee Members: Rohs, Amy.

▼ Serum thyroxine (T4) was evaluated among 137 lead-exposed workers with a median blood lead level (BLL) of 39.0 μg/dL and 83 workers with no history of lead exposure (median BLL < 2 μg/dL). Free thyroxine (FT4) was evaluated among 83 of the lead-exposed workers and 47 of the non-exposed workers. Multiple linear regression and logistic regression results were adjusted for both age and race. There was no difference in mean T4 or FT4 concentrations between exposed and non-exposed workers. Neither the T4 concentration nor having a T4 concentration below the lower limit of normal was associated with BLL, zinc protoporphyrin (ZPP), duration of exposure, or estimated cumulative lead exposure. The concentration of FT4 was inversely associated with estimated cumulative lead exposure. The odds ratio for having a low FT4 level associated with an increase of 1 μg/dL of ZPP was 1.02. Advisors/Committee Members: Ross, Sue.

▼ Background: Urine thiocyanate(UTC) has been used as a marker of cyanide exposure. In 1996, 65 of 75(87%) workers in a TN plant had elevated UTC. After this, the testing laboratory(NMS) changed their testing method from spectrophotometry(SP) to ion chromatography(IC). Subsequently, only 1 of 13(8%) workers had elevated UTC. This prompted further investigation. Methods: 55 subjects without exposure to cyanide were tested for UTC by SP and IC. Known amounts of thiocyanate were added to a sample, and the resulting specimens were tested. A survey of laboratories was conducted. Results: The mean UTC level(µg/ml) by IC was 3.24 (σ = 3.75). The mean UTC level by SP was 16.84 (σ = 9.78). The RMS error was 8.06 for IC. The RMS error was 60.31 for SP. Three laboratories perform approximately 2400 UTC tests yearly in the US. Conclusions: The UTC testing by NMS in 1996 using the SP method overestimated levels. Advisors/Committee Members: Freeman, Andrew.

▼ On first blush it may seem odd that a thesis discussing alternative medicine would be presented to the department of Occupational and Environmental Medicine. however, it is quite logical to place alternative medicine in the context of occupational medicine, because it is a useful tool in getting people back to work, and staying at work, at a reasonable cost. Furthermore, people who through alternative or traditional medicine, become partners in improving their own health, will also take care of themselves at work, an at home avoiding injuries, and illnesses. This thesis does not negate the value of traditional medicine, which is excellent at treating acute illness and injuries. Rather, this thesis attempts to create a new paradigm for wellness: the Healing Arts, which blends both traditional and Complementary Alternative Medicine (CAM). This new paradigm includes occupational and preventative medicine, by working with the whole patient using various methods to improve that patient’s well being. The end result is a patient that is healthier, more able to work, more aware of his or her health, and less in need of the radical, invasive, and expensive treatment that is traditional medicine’s strength. In turn, this healthier patient is a worker who is able to work more productively, is more involved in his or her own well being, and therefore less prone to accidents. For businesses this means financial savings in healthcare costs, overall costs, as well as expenses for injury, surgeries, and missed workdays. It means improved earnings from a more aware and a more able workforce. Clearly, CAM is an integral part of the Healing Arts as is Occupational and Preventative Medicine. This thesis will examine this new paradigm for healing and well-being, and will offer various methods for improving the health of all patients, just as Occupational and Preventative medicine can be applied to the health and level of function of all patients. Advisors/Committee Members: Shukla, Dr. Rakesh.

▼ Background: The origin of the hesitating start criterion was not established from a peer reviewed scientific study, but was based upon clinical opinion from expert users. The primary purpose of the current study is to investigate alternative hesitating start criteria for shorter forced expiratory times with a high degree of correlation to the currently accepted method. Methods: A total of 1,719 workers met eligibility criteria for this study and contributed 24,945 trials. The primary purpose was to find the slope of the regression of EV/FVC on EV/FEV1, EV/FEV3, and EV/FEV6. Results: From regression analyses, the values for EV/FEV1, EV/FEV3, and EV/FEV6 corresponding to the five percent EV/FVC value were determined to be 6.62%, 5.59%, and 5.25%, respectively. Application of the newly developed EV/FEV6 hesitating start criteria to trials truncated at six seconds resulted in 125 (0.96%) fewer trials being rejected when compared to the conventional hesitating start criteria of EV/FVC of 5%. Conclusions: A newly derived hesitating start criterion using EV/FEV6 of 5.25% was determined. This new criterion is recommended for tracings that do not achieve a plateau, such as when a six second expiration (FEV6) is performed. Application of this new hesitating start criterion was shown to reduce the number of maneuvers falsely rejected when a plateau is not achieved. Advisors/Committee Members: McKay, Roy.

▼ Spinal Cord Stimulation (SCS) is used to treat certain types of chronic pain. It involves an electrical generator delivering pulses to a targeted spinal cord area. Leads are implanted by laminectomy, subcutaneously or percutaneously, and power is supplied by implanted battery or external transmitter. One possible mechanism of SCS is Melzack and Wall's "Gate Control Theory" describing how stimulation of large fibers closes the gate to stimuli reception by small pain fibers. Complications are relatively common after stimulator placement and most commonly include technical failures (battery failure, device failure, electrode failure, electrode slip, generator failure, and hardware malfunction). Biological complications include infection, spinal fluid leakage, headaches, bladder problems, and psychological intolerance. Rarely, allergic response to the implant occurs. A few studies have investigated complication types and predictors, but none involved a workers' compensation claimant cohort. This analysis was undertaken to determine the complication rates and predictors using such a cohort. Advisors/Committee Members: Ross, Clara Sue.

▼ The current study uses the cross-sectional design of a NIOSH health hazard evaluation of health complaints in a moldy water damaged building and evaluates both symptom prevalence and the use of a fungal-specific hemolysin, Stachylysin™, as a possible serum biomarker of internal fungal exposure. Results revealed that employees of two different employers occupying different parts of the fungal contaminated building reported higher rates of respiratory complaints than that of an off-site comparison group. In addition, one group of exposed workers had a much greater prevalence of symptoms than the other exposed group despite sharing different parts of the same workplace, possibly reflecting differences in exposure (differences in HVAC systems and building condition). Poor reproducibility of the Stachylysin™ assay, and poor correlation with environmental sampling measurements of exposure, suggest that measurement of serum Stachylysin™ in its present form may not be useful in investigations of Stachybotrys chartarum exposure. Advisors/Committee Members: Ross, Dr. Sue.