Improving methods for diagnosing occupational hearing loss

Introduction. Since the share of sensorineural hearing loss in the structure of occupational morbidity in the Russian Federation increased by 1.5 times in 2018 compared to 2007, it is essential to ensure the reliability of the results of diagnostic studies to establish the fact of hearing impairment as a result of occupational noise. Materials and methods. Retrospectively for the period 2008-2017 the analysis of the prevalence and dynamics of occupational hearing loss in the Republic of Bashkortostan (RB) was carried out. Objectification of the state of the auditory sensory analyzer was carried out in 30 patients with occupational hearing loss using tonal threshold audiometry and registration of short-latency auditory evoked potentials. Results. In the RB, the number of occupational diseases caused by exposure to physical factors has doubled, mainly due to occupational hearing loss with a mild course of the process. The obtained indicators of short-latency auditory evoked potentials determined the difference in the latencies of the recorded potentials, amplitudes and intervals in persons with impaired auditory function of professional origin and in a group of persons from the control group who did not have industrial acoustic contact. Conclusion. The increase in the number of patients with occupational hearing loss requires the development of measures for their timely and objective diagnosis and medical care. The method of recording short-latency auditory evoked potentials is sensitive and quite informative in diagnosing hearing loss from exposure to occupational noise.

Current aspects of occupational hearing loss in agricultural workers

Introduction. Agricultural workers belong to the cohort of increased risk of developing occupational hearing loss (OHL). When studying occupational sensorineural hearing loss (SHL), researchers usually limit themselves to stating its share in the structure of occupational diseases without a comprehensive analysis of the initiating occupational factors and the relationship between the development of the disease with the age of employees and occupational experience. Materials and methods. The study is based on data on working conditions and occupational diseases by type of economic activity “Agriculture, forestry, hunting, fishing and fish farming” in the Saratov region from 2000 to 2019. The assessment of the factors of working conditions was carried out using the methods of the current hygienic classification. Generally accepted indicators were used to characterize occupational diseases. Linear regression analysis and polynomial equations were used to describe trend models of the prevalence of occupational diseases. Calculations and data analysis was carried out based on Microsoft Excel and Statistica application software packages. Results. Occupational hearing loss occupied the fourth rank after dorsopathies, vibration disease and chronic brucellosis in the nosological structure of accumulated occupational diseases. The level of primary incidence of SHL was in the range of 0.11 - 0.71 per 10000 workers. All cases of OHL were detected in agricultural machine operators whose harmful working conditions were characterized by a synergy of industrial noise (classes 3.1-3.3) and general vibration (classes 2-3.2). For the most part, SHL was diagnosed in workers aged 50 to 60 years with a work experience of 8 to 42 years in the profession and acted as the second or third concomitant occupational disease associated with dorsopathy, vibration disease or bronchopulmonary diseases. Conclusion. The absence of a statistically significant decrease in the level of PPP among agricultural workers during the observation period indicates the insufficient effectiveness of preventive measures to minimise occupational noise exposure.

NEW ETIOLOGICAL FACTORS OF OCCUPATIONAL HEARING LOSS

Annotation. On the example of railway and air transport, a number of new issues of occupational hearing loss are shown, requiring study and subsequent implementation in practical health care, as new etiological factors in the development of hearing loss. This concerns the factor of labor intensity, which has a potentiating, pathogenetic significance, along with noise, in the development of hearing loss due to the formation of chronic stress, leading to additional ischemia of the vascular stria and damage to the neuroepithelium of the inner ear. There is a need, along with the development of a methodology for assessing the factor of labor intensity for SOUT of workplaces, to determine the criteria for its negative action when used for the examination of the connection between the disease of the organ of hearing and the profession. In the «List of occupational diseases» in clause 2.4.2. indicated diseases associated with exposure to infrasound (IZ), among the manifestations of which, called sensorineural hearing loss bilateral. However, IZ, as well as low-frequency noise (LFN), were not previously considered as significant adverse factors in relation to the hearing organ in mass clinical trials, therefore, there are no expert criteria for the relationship between hearing loss and their impact, which could be applied in practice, which requires accumulation of evidence base for the subsequent substantiation of an independent nosological form of a disease of the organ of hearing, associated with mechanoacoustic exposure.

Immunological mechanisms of occupational hearing loss in workers of oil-producing and petrochemical industries

Most jobs in the oil and petrochemical industries are characterized by exposure to industrial noise, air pollution of the working area with harmful chemicals, dynamic and static loads, forced working posture, and nervous and emotional overstrain. The complex, long-term impact of these factors on workers leads to the development of fatigue, disruption of the adaptive mechanisms of the body and the formation of pathology of the hearing organ. These changes are most pronounced at the initial stages of the formation of professional hearing loss. In order to study the role of immune mechanisms in the pathogenesis of occupational hearing loss, major groups of immunoglobulins (A, M, G, E) in blood serum were determined. The identification of mature T-cell populations was carried out by indirect immunofluorescence method with monoclonal antibodies of the ICO series (CD3+, CD4+, CD8+, CD16+, CD20+) in 120 workers. The state of the immune status of employees of the main professions can be characterized by the presence of a tendency to form a secondary immunodeficiency state, manifested by the suppression of both cellular and humoral links. Violations of individual parts of the immune system among employees of «noise» industries reflect the level of adaptive reactions of the body and correlate with changes in the auditory analyzer and can develop long before the clinical manifestations of the disease. Identification of subclinical changes in the indicators of the immune system of the body of employees will allow timely preventive and pathogenetically justified rehabilitation measures, prevent the progression of the process and its transformation into professional hearing loss and preserve their ability to work for a long period.

Occupational Hearing Loss

Occupational hearing loss received attention after the Industrial Revolution and through World Wars I and II. It currently accounts for the largest portion of occupational diseases, and a third of all hearing loss is due to noise. Occupational hearing losses include noise-induced hearing loss (NIHL), hearing loss caused by ototoxic substances and hearing loss caused by their complex interactions. In the case of NIHL, even when exposed to the same noise, the degree of hearing damage and recovery may vary from person to person, and also be affected by other noise in daily life. Various organic solvents and some heavy metals exposed in workplace are important causes of ototoxic hearing loss, and they are known to have additive or synergistic effects when accompanied by noise. In Korea, NIHL is the most common occupational disease and has been increasing continuously since the 1990s. The number of claims for compensation has also been increasing steadily. However, the developed country including Korea almost never considered the effects of chemicals on the diagnosis and compensation for hearing loss workers. Occupational hearing loss can be prevented through hearing conservation programs. In this chapter, we will introduce the scientific basis of noise induced hearing loss, the impacts of ototoxic substance and co-existence impact on hearing loss.