Applicability Of Three Assessment Models In Risk Assessment Of Complex Noise-induced Hearing Loss

Objectives This study aim to explore the application of three assessment models including occupational hazard risk index method,ISO 1999:2013 model and kurtosis modified cumulative noise exposure method in the risk assessment of complex noise-induced hearing loss in metal tool manufacturing enterprise,and compare applicability.The ISO 1999:2013 model can guide enterprise to risk management,protect the health of workers,and provide scientific basis for the formulation of occupational health risk assessment standard or technical guidelines for noise in China.Methods The cross-section method was used,noise-exposed workers from three metal tool manufacturing enterprises in Hebei Province from April 2021 to December 2021 were selected as study subjects.Occupational hygiene investigation,questionnaire survey,noise characteristics detection and pure tone air conduction threshold audiometry test were conducted.The occupational hazard risk index method was used to risk assessment.The ISO 1999:2013 model was used to calculate the risk of hearing loss and occupational noise deafness among workers,followed by the risk classification.Pearson correlation analysis was used to analyze the relationships of hearing loss risk with noise intensity,age and exposure years.The median NIPTS compared to N₅₀ of ISO 1999:2013 by paired t-test.The distributions of noise intensity and kurtosis were analyzed.Cumulation noise exposure（CNE）was calculated from noise intensity and working age,and the CNE was adjusted by using noise kurtosis（CNE’after adjustment）.The trend Chi-square test and Kruskal-Wallis H test were used to analyze the relationship of the rate of high-frequency hearing loss and high-frequency hearing threshold with working age,noise intensity,kurtosis,CNE and CNE’.Linear regression analysis was used to analyze the correlation between CNE and the rate of high-frequency hearing loss before and after kurtosis adjustment was analyzed.Results A total of 279 workers were surveyed,of which 59.50%were male,age ranged from 20～61 year,exposure years ranged from 1～35 years.Noise exposure exceeded the national occupational exposure limit accounted for 81.36%,and the detection rates of high-frequency hearing loss were 40.14%.The noise intensity ranged from 83.28～108.10d B（A）and the kurtosis ranged from 4.79～70.50.The noise exposure of workers was 90～95d B（A）,accounting for 34.41%,and kurtosis＞10 accounted for 37.89%.The results of occupational hazard risk index method showed that the risks of all positions were medium.The risk prediction results of ISO 1999:2013 showed that the risk of high-frequency hearing loss ranged from 0.0%～85.9%,0.0%～75.8%and 0.0%～64.8%,and the risk of noise deafness ranged from 0.0%～85.8%,0.0%～68.2%and 0.0%～51.6%in three enterprises.The risk of high-frequency hearing loss of the workers was increased with the extension of noise exposure years and noise intensity（r=0.414,P<0.05;r=0.852,P<0.05）.The risk of noise deafness of the workers was increased with the extension of noise exposure years and noise intensity（r=0.336,P<0.05;r=0.817,P<0.05）.The N₅₀ of ISO1999:2013 was lower than the actual median NIPTS accounted for 84.21%,with the difference ranged from 0.4～36.1d B（A）,of which 60.78%were underestimated more than10d B（A）.There was an difference between the 1000～6000 Hz and 2000～6000 Hz hearing threshold of workers in different CNE and CNE’groups（P<0.05）,and the hearing thresholds of workers at 3000Hz,4000Hz and 6000Hz were relatively higher.The trend Chi-square test showed that the rate of high-frequency hearing loss of the workers was increased with the extension of noise exposure years and noise intensity,CNE and CNE’(χ_trend²=9.807,P<0.05;χ_trend²=18.382,P<0.05;χ_trend²=19.134,P<0.05;χ_trend²=14.929,P<0.05).The correlation between CNE’（R²=0.972）and the rate of high-frequency hearing loss was better than that CNE（R²=0.891）.Conclusions 1 The noise positions in three enterprises exceed the national occupational exposure limit seriously,and the rate of hearing loss was high.Cutting edge worker,punching worker are the key control points of noise hazard.2 The three assessment models can be used to assess the risk of hearing loss of workers exposed to noise in complex noise enterprises.3 The occupational hazard risk index method is simple and feasible,but the disadvantage is that the risk of hearing loss cannot be effectively graded.4 ISO 1999:2013model can identify noise critical positions,which is beneficial to enterprise risk management,but the disadvantage is that it may underestimate the risk of hearing loss.5Kurtosis as an auxiliary parameter can be used to assess the risk of complex noise-induced hearing loss,but the dose-response relationship between kurtosis and the detection rate of hearing loss of workers needs further study.Figure 1;Table 11;Reference 80...