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Introduction Illnesses among Navy divers degrade readiness, decrease manpower levels, and increase costs for medical care. Prior research has shown that Navy divers have high rates of the types of illnesses that might be because of diving in contaminated water. The objectives of this study were to examine medical records of U.S. Navy Sailors from 2016 to 2022 and determine if divers have higher incidence rates of health conditions that might be associated with contaminated water diving compared to non-divers. Materials and Methods For this retrospective cohort study, we used data from the Defense Medical Epidemiology Database (DMED). The DMED is operated by the Armed Forces Health Surveillance Division and uses data from the Defense Manpower Data Center to classify occupations. The DMED provides free online access to a de-identified subset of data contained within the Defense Medical Surveillance System. The population was U.S. Navy enlisted males, aged 25 to 29 years. Divers were compared to non-divers using 8 selected diagnoses that may reasonably be associated with diving in contaminated water. Results During the study period, the database contained a total of 5,474 diver and 827,406 non-diver person-years. Of the 8 diagnoses, the ones with the largest number of cases for divers were upper respiratory infections with 128 and ear disorders with 62. The relative risks (RRs) for divers compared to non-divers were higher for otitis externa (RR = 1.44; confidence interval = 1.03, 2.01) and for ear disorders (RR = 1.15; confidence interval = 0.89, 1.47); for the other 6 diagnoses, the divers had lower rates than the non-divers. Conclusions The high RRs found for otitis externa and ear disorders support the need to devote resources to better understand the reasons for these higher risks and to develop, test, and implement targeted risk-reduction strategies. Future studies should attempt to link verified contaminated water exposures with adverse health outcomes and calculate risks based on criteria such as age and dive factors. [ABSTRACT FROM AUTHOR]

Introduction Military medical evacuations (MEDEVACs) are resource intensive and can disrupt operations and decrease readiness. Medical evacuations are a concern for the submarine force because of the limited medical resources onboard, the impact of manpower loss on smaller crews, and the compromise of operational stealth. Although some medical emergencies cannot be avoided, some MEDEVACs may be preventable. However, there is limited knowledge of the underlying causes and risk factors associated with submarine MEDEVACs. This work describes an approach to identify individual characteristics associated with submarine MEDEVACs by presenting preliminary results and next steps. Identifying those most at risk for a MEDEVAC will foster prevention strategies that lead to fewer MEDEVACs, military operation disruptions, missed work and limited duty days, unplanned losses, early separations, and disability compensation claims among navy submariners. Materials and Methods This retrospective study examines MEDEVACs from U.S. Navy submarines from January 1, 2012 to December 31, 2020. Medical evacuation causes were classified by 3 major diagnostic categories: Injury, psychiatric, and medical (i.e. all other non-injury medical events, including dental issues). Diagnostic subcategories were grouped by body region (for injuries) and body system (for non-injuries). Identifiable information from MEDEVAC records were linked to personnel files to capture demographic and occupational variables. Trends across the years were examined, and frequencies and percentages of MEDEVAC cases by both major and sub-diagnostic categories were presented. For cases where both the major diagnostic categories and characteristics were both available, we assessed associations between major diagnostic categories and demographic and occupational characteristics, using Pearson's χ2 test for proportions and Fisher Freeman–Halton exact tests. Pairwise z -tests for proportions were used to determine which proportions differed significantly. Results A total of 1,283 MEDEVACs were confirmed from 2012 to 2020, with an annual average of 143. Across the years, 24.3% were caused by psychiatric issues (e.g. suicidal ideation), 18.4% were caused by injuries (e.g. blunt trauma), and the remaining 57.3% were caused by other medical emergencies (e.g. gastrointestinal issues). Among the cases linked to personnel files, the major diagnostic category was associated with age, rank, department, and submarine qualification status (group size varied). By age (n  = 973), large differences in MEDEVAC causes were seen among submariners 21 to 25 years old who represented 52.4% of psychiatric versus 37.5% of medical MEDEVACs. In contrast, those 35 and older represented 17.0% medical versus 2.7% psychiatric MEDEVACs. Conclusions Medical, non-injury cases were the most common cause for a MEDEVAC. There were proportionately more psychiatric than medical cases among younger, less experienced submariners. Conversely, there were proportionately more medical than psychiatric cases among older submariners. A centralized approach to collecting MEDEVAC data is needed. This is the most comprehensive study examining risk factors associated with submarine MEDEVACs. Follow-on work will include adding prior medical waiver requests, health indicators, and confirmed diagnoses to the dataset to conduct a risk analysis. Considering submarines have smaller crews than most surface ships, limited medical assets, and often operate in austere environments, examination of submarine MEDEVACs should be distinct from other navy and military MEDEVACs. [ABSTRACT FROM AUTHOR]

Objective To evaluate the effectiveness of the US Navy and Marine Corps tobacco policy in protecting submariners from secondhand smoke (SHS) by determining if non-tobacco users experienced a significant increase in urinary cotinine levels at sea when compared with in port levels. Methods From February to August 2009, 634 volunteers recruited from nine US Navy submarines completed a survey to collect demographic data, information on tobacco use and pre-deployment exposure to SHS. Non-tobacco users (n¼239) were requested to provide two urine samples (pre-deployment and while at sea) to quantify exposure to SHS using urinary cotinine as a biomarker. Matched samples were analysed using liquid chromatographyetandem mass spectrometry. Results Overall, deployed cotinine levels were 2.1 times the in port levels in non-tobacco using submariners (95% CI 1.8 to 2.4, p<0.001, n¼197). A significant increase in deployed urinary cotinine levels was found aboard six of nine submarines (p<0.05). A subgroup of submariners (n¼91) who reported no SHS exposure within 10 days prior to in port cotinine sampling had deployed cotinine levels 2.7 times the in port levels (95% CI 2.2 to 3.3, p<0.001). Applying a 4.5:1 urine cotinine to serum cotinine correction factor, submariners’ deployed geometric means are similar to recent US male population values at the 75th percentile. Conclusions This study provides evidence that nontobacco using submariners were exposed to SHS. Exposure was seen in all submarine classes and was not limited to personnel working in proximity to the smoking area. The existing policy was inadequate to protect nonsmokers from exposure to SHS and required revision. As a result of a policy review, informed by this study, smoking below decks was banned aboard all US Navy submarines effective 31 December 2010. [ABSTRACT FROM AUTHOR]

In a longitudinal study with 338 volunteers, audiometric thresholds and otoacoustic emissions were measured before and after 6 months of noise exposure on an aircraft carrier. While the average amplitudes of the otoacoustic emissions decreased significantly, the average audiometric thresholds did not change. Furthermore, there were no significant correlations between changes in audiometric thresholds and changes in otoacoustic emissions. Changes in transient-evoked otoacoustic emissions and distortion-product otoacoustic emissions were moderately correlated. Eighteen ears acquired permanent audiometric threshold shifts. Only one-third of those ears showed significant otoacoustic emission shifts that mirrored their permanent threshold shifts. A Bayesian analysis indicated that permanent threshold shift status following a deployment was predicted by baseline low-level or absent otoacoustic emissions. The best predictor was transient-evoked otoacoustic emission amplitude in the 4-kHz half-octave frequency band, with risk increasing more than sixfold from approximately 3% to 20% as the emission amplitude decreased. It is possible that the otoacoustic emissions indicated noise-induced changes in the inner ear, undetected by audiometric tests. Otoacoustic emissions may therefore be a diagnostic predictor for noise-induced-hearing-loss risk. [ABSTRACT FROM AUTHOR]