SI “Ukrainian Scientific Research Institute of Industrial Medicine”, Krivyi Rig
Introduction. At present, different precise and objective methods are used in order to define early signs of occupational noise sensorineural hearing loss and to prognose unfavorable course of diseases in workers. But even before changes are occurred in the organ of hearing, non-specific effects of noise can be recorded: neurotic and asthenic syndromes in combination with vegetative dysfunction, disorders of secretory and motor functions of the gastrointestinal tract. Under exposure to noise of high intensity changes can occur simultaneously in the cardiovascular, neuroendocrine and immune systems.
The development of clinical types of diseases is preceded by well-defined disorders in the functional state of the body, being of a border character. For prevention of occupational diseases, it is important to timely identify pre-morbid states, to establish and eliminate the risk factors in their occurrence. Such timely measures can prevent the development of the pathological process.
Purpose of the study – to determine and evaluate an individual risk of development of hearing disorders and to predict possible (probable) hearing losses in workers of mining and metallurgical industry by conducting periodic medical examinations, according to the studies of working conditions.
Materials and methods. 90 people with a long-term work experience in conditions of the increased level of production noise were investigated in periodic medical examinations, For numerical characteristics of the functional vocal disorders, a harmony coefficient of the worker's voice (Khar) was used, the maximum time of phonation of sounds "Z" and "S" in seconds was determined. Those indicators were supplemented by indices of the functional state of the cardiovascular system, anthropometric measurements and biochemical data.
Results of research and their discussion. For the numerical characteristics of the functional vocal disturbances, a harmony coefficient of the worker's voice (Khar) was calculated. For healthy harmonic voices it makes 1,309. The deviation from this value by more than 2% points to pathology.
The analysis of audiograms in workers after periodical medical examinations showed that the workers with the decreased hearing sensitivity in the high frequency area had the following statistically significant meanings (Р > 95 %): Khar less than 1,282, diastolic arterial pressure > 85 mm Hg or hn > 60%, or Garkavi index > 0,49 c.u., leukocyte index > 0,46 c.u., L4 > L2.
As it is shown by the statistical analysis when Khar is less than 1,282 and when/or diastolic arterial pressure is > 85 mm Hg or hn > 60%, or Garkavi index > 0,49 c.u., or leykocyte index > 0,46 c.u., or L4 > L2, it is possible to predict changes in the threshold of auditory sensitivity in accordance with the level of active production noise at workplace for the next five years. Such workers can be referred to the group of "unfavorable prognosis".
If Khar is more than 1,335 and if tz < 9s or tz / ts ≤ 0,74, a worker has a great risk of hearing sensitivity at high frequencies and is referred to a "premorbid" group.
With Khar is more than 1,282 and less than 1,335 risk of hearing changes is middle population, a period of the increased changes in auditory sensitivity is stretched in time, according to the level of acting production noise at workplace.
Conclusions. The dependence of probable hearing disorders in workers of mining and metallurgy industry on the state of the tone of the vocal cords (coefficient of voice harmony) has been defined. According to periodic medical examinations, it is possible to calculate indicators of the body adaptation, which determine the risk of disorders, and to predict the development of probable changes in the threshold of auditory sensitivity in workers and to refer him/her to one of risk groups.
Key words: workers of mining and metallurgical industry, a harmony coefficient of a worker's voice, prognosis of probable changes in the threshold of auditory sensitivity, individual risk of hearing loss, pre-nosological states, production noise.
ORCID ID of authors and their contribution to the preparation and writing of the article:
Kovalchuk TA (ORCID ID 0000-0002-2580-3032) - writing an introduction covering the problem in its general form, analyzing recent research and publications, forming the goals of the article, drawing conclusions from the results of the research;
Dedunov SV (ORCID ID 0000-0001-9828-8900) - choice of research methods, research, statistical processing of research materials, writing of the section "Research results".