PRACA ORYGINALNA

ORIGINAL ARTICLE

Clinical and audiological values in the early diagnosis of hearing impairments and risk groups among ship repair workers

Оlexander Ye.Kononov, Larysa F. Matiukha, Ganna V. Batsiura, Olha V. Protsiuk, Liliana V. Klymenko, Tatyana V. Veselova

Shupyk National Medical Academy of Postgraduate Education, Kyiv, Ukraine

ABSTRACT

Introduction: The hazardous effect of industrial noise exposure on ship repair workers has been highlighted in a number of studies. However, no data are currently available for studying the effect of noise exposure on the auditory system and general health of ship repair workers.

The aim: The study is focused on the early diagnosis of hearing impairments and identifying risk groups among the workers.

Materials and methods: It was examined two groups of workers of approximately the same age and length of employment. The Group 1 included workers from the Azov Shiprepair Yard (Mariupol city, Ukraine) who were exposed to workplace noise impact of less than 80 dBA threshold level, the workplace noise level in the Group 2 was above 80 dBA. Audiometric testing was conducted in a sound-treated room using the MA 31 clinical audiometer (Germany).

Results: Our findings indicate that all the noise-exposed groups of ship repair workers should be conducted audiometric testing. The hearing levels at the audiometric test frequencies of 4, 6 and 8 kHz, as well as differential thresholds at the audiometric test frequencies of 4 kHz by the Luscher-Zwislocki method should be taken into account. Such complaints as increased annoyance, sleep disorder, tinnitus aurium, hypertension should be considered as most hazardous.

Conclusions: We recommend that the ship repair workers undergo routine medical check-ups and systematic prophylactic observation. All these preventive measures will contribute to the early detection of hearing impairments, thereby timely preventing the development and progression of occupational sensorineural hearing loss.

KEY WORDS: audiometry, early diagnosis, ship repair workers, occupational sensorineural hearing loss

Wiad Lek 2019, 72, 4, 600-603

INTRODUCTION

The hazardous effect of industrial noise exposure on ship repair workers has been highlighted in a number of studies [1, 2, 3]. The excessive noise at the workplace can cause both auditory system hearing impairments and diseases of the cardiovascular system and central nervous system [4]. The existing literature on occupational noise exposure on human health shows that ship repair workers who are subjected to excessive noise beyond tolerated levels at their workplace complain of hearing loss, tinnitus aurium, headache, dizziness, insomnia, etc. [5, 6, 7, 8, 9, 10, 11].

However, no data are currently available for studying the effect of noise exposure on the auditory system and general health of ship repair workers who are exposed to the workplace noise levels of 80 dBA limiting threshold and above 80 dBA, comparatively.

THE AIM

This study was aimed at assessing the effect of workplace noise of less than 80 dBA (the Recommended Exposure Limit) and above 80 dBA threshold levels on the noise-exposed ship repair workers by comparing values of their auditory analyzer and somatic status. The goals of the study included early diagnosis of hearing impairments and identifying risk groups among the workers.

MATERIALS AND METHODS

Considering the workplace noise intensity, we selected and tested two workers’ groups of approximately the same age and length of employment (30 subjects in each group). The first group (Group 1) included workers from the Azov Shiprepair Yard (Mariupol city, Ukraine) who were exposed to workplace noise impact of less than 80 dBA threshold level, the workplace noise level in the second group (Group 2) was above 80 dBA. The age-related changes in hearing were taken into account in the further data analysis. We compared shipyard workers’ complaints of general health and the values of their somatic status by the workplace noise level. Audiometric testing was conducted in a sound-treated room using the MA 31 clinical audiometer (Germany).

In the data analysis we excluded workers with previous craniocerebral trauma, infections, asymmetric hearing and those being routinely exposed to radiation. The control group included 15 healthy subjects aged between 20 and 30 years with normal hearing, without vascular diseases and who were not exposed to the excessive noise. All the subjects had no pathologies of the nose and paranasal sinuses and were not exposed to the radiation.

RESULTS AND DISCUSSION

Our findings revealed the following data. The majority of Group 2 workers, who were exposed to occupational noise impact of higher than 80 dBA hearing threshold level, complained not only of hearing impairment (100,0%), but also tinnitus aurium (90,0%), increased annoyance (96, 7%), sleep disorders (93,3%) and over half of them complained of headache (53,3%).

However, the workers from Group 1, exposed to workplace noise of less than or equal to 80 dBA threshold level, also complained of tinnitus aurium (56,7%), increased annoyance (70,0%), sleep disorders (60.0%) but poorer hearing was reported only in 16,7% of cases. These data are shown in Table I and Figure 1.

Thus, during regular medical check-ups, audiometric testing should be performed for those noise-exposed workers who complain of increased annoyance and tinnitus aurium but their hearing level is considered to be normal. That is when the workplace noise doesn’t exceed the Recommended Exposure Limit. Such workers are referred to the risk group and should be recommended regular clinical and audiometric testing.

These groups of workers often had slightly decreased hearing level at the audiometric test frequency of 8 kHz and a relatively reduced differential threshold at the audiometric test frequencies of 4 kHz by the Luscher-Zwislocki method. They should be referred to the risk group and timely undergo medical check-ups in order to prevent occupational sensorineural hearing loss.

Considering the somatic status of the noise-exposed groups of ship repair workers (Groups 1 and 2), the intensity of workplace noise exposure was taken into account (Table II and Figure 2). Hypertension of different stages was found in 90.3% of cases in Group 2. It should be noted that Group 2 workers also suffered from encephalopathy, vegetative-vascular dystonia of hypertensive type, peptic ulcer and other diseases. However, in the analysis we compared the somatic status of workers which was observed in both groups.

Group 1 workers had stage I hypertension in 33,3% of cases. Stage II-III hypertension was present in the overwhelming majority of Group 2 workers (90,0%). There were no apparently healthy subjects in Group 2, but 10% was observed in Group 1. Periodic rise in blood pressure mostly occurred in Group 1. As above mentioned, the workers mostly complained of increased annoyance (70.0%), sleep disorders (60,0%) and tinnitus aurium (56,7%). Headache was observed in 16,7% of cases in Group 1, and only 13,3% of the subjects had hearing impairments. It should be also noted that the Group 1 workers had slightly decreased hearing level (28,2 ± 2,3 dB, 21,8 ± 2,4dB and 22,7 ± 2,1dB) at the audiometric test frequencies of 4, 6, and 8 kHz. And these workers had a relatively reduced differential threshold (0,72 ± 0,03 dB) at the audiometric test frequencies of 4 kHz by the Luscher-Zwislocki method. Consequently, the noise-exposed workers of both groups, regardless the workplace noise levels, who complain of tinnitus aurium, sleep disorders, increased annoyance, periodic rise in blood pressure should be referred to the “risk” group and recommended timely medical check-ups and systematic prophylactic observation.

It is of particular relevance the fact that among the workers from Group 1, exposed to the excessive workplace noise above 80 dBA threshold level, there were no apparently healthy subjects. But Group 1 included 10% of apparently healthy subjects, that is when occupational noise impact was less than 80 dBA threshold level.

CONCLUSIONS

The study findings indicate that all the noise-exposed groups of ship repair workers regardless whether or not they are subjected to the workplace noise impact above the Recommended Exposure Limit should be conducted regular audiometric testing.

The hearing levels at the audiometric test frequencies of 4, 6 and 8 kHz, as well as differential thresholds at the audiometric test frequencies of 4 kHz by the Luscher-Zwislocki method should be taken into account. Besides, we recommend for the ship repair workers to undergo routine medical check-ups and systematic prophylactic observation. Such complaints as increased annoyance, sleep disorder and tinnitus aurium should be considered as most hazardous. There is also recommended regular monitoring of the noise-exposed ship repair workers’ somatic status, their complaints of high blood pressure and hypertension are of the most alarming ones. All these preventive measures will contribute to the early detection of hearing impairments, thereby timely preventing the development and progression of occupational sensorineural hearing loss.

REFERENCES

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Authors’ contributions:

According to the order of the Authorship.

Conflict of interest:

The Authors declare no conflict of interest.

CORRESPONDING AUTHOR

Оlexander Ye. Kononov

Shupyk National Medical Academy of Postgraduate Education

9 Dorohozhytska str., 04112 Kyiv, Ukraine

tel: +38 (044) 288-10-34 (33)

e-mail: doctorkononov@yandex.ru

Received: 07.02.2019

Accepted: 01.04.2019

Table I. Noise-exposed groups of ship repair workers (Group 1 and 2) by their complaints of health.

Groups

Number of subgects

Workers’ complaints

In absolute figures

Percentage to the total number %

Hearing impairment

Tinnitus aurium

Increased annoyance

Sleep disorders

Headache

Hearing impairment

Tinnitus aurium

Increased annoyance

Sleep disorders

Headache

1

30

4

17

21

18

5

13,3

56,7

70,0

60,0

16,7

2

30

30

27

29

28

16

100,0

90,0

96,7

93,3

53,3

Fig. 1. Noise-exposed groups of ship repair workers (Groups I and II) by their complaints of general health.

Fig. 2. Noise-exposed groups of ship repair workers (Groups I and II) by their somatic status.

Table II. Noise-exposed groups of ship repair workers (Group1 and 2) by their somatic status.

Worker groups

Total number

Somatic status of workers

In absolute figures

Percentage to the total number %

Apparently healthy

Hypertension

Occasional high blood pressure

Apparently healthy

Hypertension

Occasional high blood pressure

1

30

3

10

17

10,0

33,3

56,7

2

30

27

3

90,0

10,0