Hearing Loss in Israeli Air Force Aviators: Natural History and Risk Factors.

OBJECTIVE: To investigate the natural history of hearing loss (HL) in Israeli military aviators and its risk factors. METHODS: Audiometric results of aviators with available audiometry at ages 30 and 40 years, and up to their last available audiometry were retrieved. HL DEFINITION: pure-tone threshold (PTT) of 30 dB or higher in at least one frequency in at least one ear, moderate-to-severe (M-S) HL as PTT of 45 dB or higher, and suspected noise-induced HL (NIHL) as HL at 3 to 6 kHz. Potential risk factors for HL were assessed by the χ(2) test and logistic regression models. RESULTS: 298 aviators were included. Rates of HL increased with age, up to 57.5% at age 50. All M-S HL at age 50 years had clues on previous examinations, but new HL was observed in all ages. Age was found as a statistically significant risk factor, but aircraft type was not. Total flying hours were found to be an independent risk factor for suspected NIHL only. Self-reported earplug use was not found to protect from HL, with methodological limitations. CONCLUSIONS: HL is prevalent in aviators. Age and total flying hours are risk factors, the latter probably only for NIHL, whereas aircraft type is not.

Detection of occult lung impairment in welders by induced sputum particles and breath oxidation.

BACKGROUND: We evaluated particulate matter in combined induced sputum (IS) and oxidation in exhaled breath condensate (EBC) to test whether underlying inflammatory changes are present in asymptomatic welders. METHODS: Thirty welders from the Israel Defense Forces exposed to aluminum/iron (Group 1) or to cadmium/chromium/iron/lead/nickel (Group 2, N = 16) and 27 non-exposed administrators were studied. IS was recovered, particle size distribution, hydrogen peroxide and pH were measured, and exhaled breath condensate was collected. RESULTS: Group 2 had a higher % neutrophils than all other participants (P = 0.0001) and a higher % particles >2 microm in diameter (P = 0.0017). Percent particles and years of exposure highly correlated (P = 0.051). All welders EBC samples had higher concentrations of hydrogen peroxide than controls (P = 0.0001). pH was lower only for Group 2 (P = 0.0001). CONCLUSIONS: Combined IS and EBC measurements detect underlying inflammation in airways of asymptomatic welders. It emerged that airway inflammation is present in asymptomatic welders, and that the particle burden, inflammatory cells, and level of oxidative stress are a function of the type and the duration of welding. Am. J. Ind. Med. 51:503-511, 2008.

Asymmetry in noise-induced hearing loss: relevance of acoustic reflex and left or right handedness.

OBJECTIVE: Noise-induced hearing loss (NIHL) is more severe in the left ear than the right ear. The aim of this study was to examine the possible association of handedness and acoustic reflex parameters on right or left NIHL predominance. STUDY DESIGN: Retrospective case review and prospective series. SETTING: Tertiary center. PATIENTS: Three samples were studied: 1) the files of 4,277 army personnel with NIHL were reviewed to analyze the relation between the side affected and age, sex, duration of noise exposure, and acoustic damage; 2) an additional 119 army personnel with NIHL were evaluated for the possible association of handedness and NIHL asymmetry; and 3) fifty-one normal-hearing subjects were tested for threshold and latency of acoustic reflex by handedness. INTERVENTION: None. MAIN OUTCOME MEASURE: Differences in NIHL asymmetry by background and noise-related variables and handedness. RESULTS: NIHL was more pronounced in the left ear, regardless of demographic characteristics, noise exposure parameters, acoustic reflex measures, or handedness. CONCLUSION: The asymmetry in hearing loss severity may be attributed to the cortical pathways, specifically to the more pronounced efferent auditory system on the right side, which reduces the susceptibility of the right ear to cochlear insult.

Heat stress and carbon monoxide exposure during C-130 vehicle transportation.

INTRODUCTION: Running gasoline engines in a confined space causes heat stress and carbon monoxide (CO) buildup. Loading the C-130 aircraft by driving the vehicles onto the platform may expose the C-130 cabin crew to these environmental hazards. This study was aimed at investigating heat stress and CO exposure in the C-130 cabin during vehicle airlift. METHODS: There were four summer flights (two two-vehicle, two three-vehicle; 2 d, 2 nights) studied. The cabin heat stress index (wet bulb globe temperature, WBGT) and CO levels before vehicle loading (control) were compared with those after vehicle loading. Furthermore, two- and three-vehicle transportations, as well as day and night transportations, were compared. RESULTS: Ground temperature ranged from 18.2 to 33.4 degrees C. Mean heat stress index was higher in vehicle transportation than control flights, the greatest difference being 5.9 degrees C (p < 0.001). The WBGT levels exceeded the recommended exposure limit in 28 of 38 measurements during day flights. The cabin heat stress increased sharply with vehicle loading, and continued to increase for a range of 60-140 min after loading. Elevated cabin CO levels were found in three-vehicle flights as compared with two, and in night flights as compared with day. CONCLUSIONS: In hot climates, C-130 vehicle transportation may exacerbate heat stress. The in-flight heat stress can be predicted by the ambient temperature, duration of the vehicle transportation, and number of transported vehicles. The cabin CO level is related to the number of transported vehicles. We recommend the use of effective environmental control systems during C-130 vehicle transportation in hot climates.