Recommendations for a Military Health System Auditory Blast Injury Prevention Standard.

INTRODUCTION: Although existing auditory injury prevention standards benefit warfighters, the Department of Defense could do more to understand and address auditory injuries (e.g., hearing loss, tinnitus, and central processing deficits) among service members. The Blast Injury Prevention Standards Recommendation (BIPSR) Process is designed to address the needs of all the Military Services for biomedically valid Military Health System (MHS) Blast Injury Prevention Standards. MATERIALS AND METHODS: Through the BIPSR Process, stakeholders provided their intended uses and requested functionalities for an MHS Blast Injury Prevention Standard. The BIPSR Process established a broad-based, non-advocacy panel of auditory injury Subject Matter Expert (SME) Panel with members drawn from industry, academia, and government. The SME Panel selected evaluation factors, weighted priorities, and then evaluated the resulting candidate MHS Auditory Blast Injury Prevention Standards against the evaluation criteria. The SME Panel members provided rationales for their decisions, documented discussions, and used iterative rounds of feedback to promote consensus building among members. The BIPSR Process used multi-attribute utility theory to combine members' evaluations and compare the candidate standards. RESULTS: The SME Panel identified and collated information about existing auditory injury datasets to identify gaps and promote data sharing and comprehensive evaluations of standards for preventing auditory blast injury. The panel evaluated the candidate standards and developed recommendations for an MHS Blast Injury Prevention Standard. CONCLUSIONS: The BIPSR Process illuminated important characteristics, capabilities, and limitations of candidate standards and existing datasets (e.g., limited human exposure data to evaluate the validity of injury prediction) for auditory blast injury prevention. The evaluation resulted in the recommendation to use the 8-hour Equivalent Level (LAeq8hr) as the interim MHS Auditory Blast Injury Prevention Standard while the community performs additional research to fill critical knowledge gaps.

Noise exposures of rural adolescents.

PURPOSE: This project was conducted to characterize the noise exposure of adolescents living in rural and agricultural environments. METHODS: From May to October, 25 adolescents ages 13 through 17, living either on a farm or a rural nonfarm, were enrolled in the study. Subjects received training on the correct operation and use of personal noise dosimeters and the proper way to record their daily tasks on activity cards. Subjects completed 4 days of self-monitoring noise dosimetry, 2 days in the first round (May-July) and 2 days in the second round (August-October). In addition to dosimetry, subjects completed activity logs of their daily tasks. RESULTS: The mean daily noise exposures of adolescents living on farms and in nonfarm rural homes were between 55.4 dBA (A-weighted decibels) and 103.5 dBA, with 44% of the daily measurements greater than the National Institute of Occupational Safety and Health Recommended Exposure Level of 85 dBA. Task-based analysis of noise exposures found that activities involving mechanized equipment resulted in the highest exposures, while activities in the home resulted in the lowest exposure. No particular demographic group had a statistically higher noise exposure; therefore, specific factors apart from activities and noise sources could not be identified as risk factors for exposure to hazardous noise levels. CONCLUSIONS: The results of this project indicate that rural adolescents complete a variety of activities and are exposed to noise sources with a broad range of decibel levels. While the exposures may change from day to day, there are occasions when exposure to noise exceeds the recommended levels.

Hearing loss as a risk factor for agricultural injuries.

BACKGROUND: Previous studies suggested that hearing impairment based on self-report might increase the risk of agricultural injuries. However, self-reported hearing measures may be subject to inaccuracy and subjective perception. We assessed the association of agricultural injuries with hearing loss and other hearing characteristics using measured hearing. METHODS: Study subjects were 150 farmers who participated in the Iowa Certified Safe Farm study. Injury information was collected by telephone interviews at 2-5 month intervals from September 1999 to October 2002. Hearing levels were measured annually using the pure tone audiometry from 1998 to 2002. Adjusted rate ratios of injuries were calculated using the multivariate Poisson regression model. RESULTS: Hearing loss in the better ear (RR = 1.62), hearing asymmetry (RR = 1.67), and fair/poor self-reported hearing (RR = 1.96) were significantly associated with the risk of agricultural injuries. It is notable that self-reported hearing might be a stronger predictor of injuries than pure tone audiometry (PTA). Exposure to noise elevated the risk of injuries in those farmers with hearing loss or hearing asymmetry. The occasional use of hearing protection was significantly associated with agricultural injuries. CONCLUSIONS: This study adds substantial evidence that hearing loss acts as a risk for agricultural injuries. Prevention of hearing loss and noise exposure may be important in reducing the burden of agricultural injuries.

A comparison of self-reported hearing and pure tone threshold average in the Iowa Farm Family Health and Hazard Survey.

BACKGROUND: Self-reported hearing measures are useful for surveying hearing loss in a population because they are short, and easy to administer by either questionnaire or telephone. This study aims to assess the performance of several self-reported hearing measures to identify hearing loss in a group of Iowa farmers. METHODS: The study subjects were 98 male farmers who participated in the Iowa Farm Family Health and Hazard Survey. We tested three self-reported hearing measures; the hearing screening questions, the Rating Scale for Each Ear (RSEE), and the Health, Education and Welfare-Expanded Hearing Ability Scale (HEW-EHAS), which were originally developed and implemented in the National Health Interview Survey. The sensitivity and specificity of the self-reported hearing measures were assessed by comparing them with pure tone threshold averages. These sensitivity and specificity measures were compared between younger and older age groups. RESULTS: The sensitivities of the screening questions, RSEE, and HEW-EHAS were 73.0%, 66.7%, and 53.3%, respectively. The specificities of the self-reported hearing measures were similar, which ranged from 81.4% to 84.8%. The sensitivities of the self-reported hearing measures were higher in the younger age group while the specificities were higher in the older age group. CONCLUSIONS: The results of this study support the use of simple screening questions in identifying hearing loss among farmers.