Efeitos da dupla proteção auditiva na saúde do trabalhador: revisão de literatura / Effects of double hearing protection on occupational health: a literature review / Efectos de la doble protección auditiva en la salud de los trabajadores: revisión de la literatura

O uso da proteção auditiva pode representar uma série de preocupações de segurança quando considerados o treinamento e orientação, os prejuízos à comunicação e o ambiente ocupacional. O objetivo deste estudo foi verificar os benefícios da dupla proteção auditiva em risco de ruído ocupacional. Os artigos científicos de embasamento foram selecionados pelas bases de dados MEDLINE (Pubmed), Lilacs, Scielo, SCOPUS e Web of Science, sem restrição de idioma, período e localização. Foram localizados 197 artigos em que três atenderam aos critérios de admissão desta pesquisa. Os Equipamentos de Proteção Individual (EPIs) exigem controle rigoroso quanto ao seu uso adequado, que por vezes é negligenciado na rotina diária de trabalho. Conclui-se que a modernização e o uso de tecnologias mais seguras tem o intuito de diminuir o impacto da exposição ao ruído, entretanto, as barreiras entre a economia e a adesão pelos trabalhadores ainda precisam ser minimizadas.

Use of hearing protection can raise a series of safety concerns when considering training and guidance, communication impairments, and occupational environment. Hence, this study assessed the benefits of dual hearing protection in occupational noise risk. Scientific articles were selected from the MEDLINE (PubMed), LILACS, SCIELO, SCOPUS, and Web of Science databases, with no language, period, or location restrictions. A total of 197 articles were located, of which three met the inclusion criteria. Proper PPE (Personal Protective Equipment) usage requires strict monitoring, which is sometimes overlooked in the daily work routine. Modernization and use of safer technologies aim to reduce the impact of noise exposure; however, the barriers between the economy and worker adherence still need to be mitigated.

El uso de protección auditiva puede implicar una serie de preocupaciones de seguridad al considerar el entrenamiento y orientación, el daño a la comunicación y el ambiente laboral. El objetivo de este estudio fue determinar los beneficios de la doble protección auditiva en riesgo de ruido laboral. Se seleccionaron los artículos científicos de las bases de datos MEDLINE (PubMed), LILACS, SciELO, Scopus y Web of Science, sin restricciones de idioma, período y ubicación. Se encontraron 197 artículos, de los cuales tres cumplieron con los criterios de inclusión para este estudio. Los equipos de protección individual (EPI) requieren un riguroso control sobre su adecuado uso y, muchas veces, no son utilizados por los trabajadores durante su rutina laboral. Se concluye que la modernización y el uso de tecnologías más seguras pueden reducir el impacto de la exposición al ruido, sin embargo, las barreras entre la economía y el uso de estos equipos por los trabajadores aún necesitan mitigarse.

[Analysis on the quality control of suspected occupational disease from the characteristics of applicants diagnosed with noise deafness].

Objective: To analyze the audiology and occupational health data of applicants diagnosed of occupational noise deafness, and to explore the influencing factors in the diagnosis of suspected occupational noise deafness. Methods: In May 2022, the information of patients diagnosed with occupational noise deafness in Peking University Third Hospital from January 2018 to December 2021 was collected, and the occupational health data of their working environment, clinical audiological examination results and diagnosis basis of occupational noise deafness were collected and analyzed. Multi-factor unconditional logistic regression analysis was used to analyze independent risk factors for the diagnosis of occupational noise deafness. Results: A total of 129 subjects were included, all of which were suspected cases of occupational noise deafness found in various occupational health examination institutions. Eight cases (6.20%) were diagnosed as occupational noise deafness, and 121 cases (93.80%) were non-occupational noise deafness. After hearing examination, only 27.27% (24/88) of the patients' audiological changes were consistent with the starting point of occupational noise deafness diagnosis. Further analysis of the noise intensity in the workplace showed that 16 patients were identified as non-occupational noise deafness because the noise intensity of the working environment was less than 85 dB. Logistic regression analysis showed that the working hours were more than 8 hours (OR=9.274, 95%CI: 1.388-61.950, P=0.022) and the noise intensity of the working environment (OR=1.189, 95%CI: 1.059-1.334, P=0.003) were independent risk factors for the diagnosis of occupational noise deafness. Conclusion: The exclusion rate of suspected occupational noise deafness found in occupational health examination is higher after adequate rest. The test results of working environment noise intensity provided by the employer can help to determine occupational noise deafness.

[Analysis of noise reduction measures in a noise workshop handover control room].

Objective: To explore the sound insulation, sound absorption and other noise reduction transformation methods in a noise workshop handover control room. Methods: In December 2021, through the occupational health investigation and on-site testing of the handover control room of a noise workshop, the causes of excessive noise were analyzed, and the transformation design scheme to reduce noise was proposed and the effect was analyzed. Results: Before the transformation, the peak frequency band noise intensity of the noise workshop handover control room was 112.8 dB (A), and the peak frequency was 1000 Hz. After noise reduction, the theoretical calculated control value was 61.0 dB (A), and the measured noise intensity was 59.8 dB (A) . Conclusion: The noise intensity of the handover control room is reduced after noise reduction, which is in line with the contact limit requirements of the control room in GBZ 1-2010 "Hygienic Standards for the Design of Industrial Enterprises", and has reference significance for noise control engineering.

[Bibliometric and bioinformatics analysis of genetic literature on susceptibility to noise induced hearing loss].

Objective: To summarize and analyse of literature on the susceptibility genes of noise induced hearing loss (NIHL) , and the key genes were screened and obtained by bioinformatics method, so as to provide reference for the prevention research of NIHL. Methods: In September 2021, Based on CNKI, NCBI Pubmed database and Web of Science database, this paper conducted bibliometric analysis and bioinformatics analysis on the genetic literature related to the susceptibility to noise-induced hearing loss from 1999 to 2020. Endnote X9 software and the WPS office software were used for bibliometric analysis, and online software STRING and Cytoscape software were used for bioinformatics analysis. Results: A total of 131 literatures were included in the study, involving 40 genes in total. Bibliometric analysis shows that 131 papers which included 36 Chinese articles and 95 English articles were published in 63 biomedical journals; the highest number of published articles was 19 in 2020. Bioinformatics analysis suggests that GAPDH、SOD2、SOD1、CAT、CASP3、IL6 and other genes play a key role in the interaction network. The involved pathways mainly include MAP2K and MAPK activations, PTEN regulation, P53-depardent G1 DNA damage response, signaoling by BRAF and RAF fusions and soon. Conclusion: The study of noise induced hearing loss involves multi gene biological information, and bioinformatics analysis is helpful to predict the occurrence and development of noise induced hearing loss.

[Research on early warning model of the hearing loss of workers exposed to noise].

Objective: To explore the change of hearing threshold of workers exposed to noise, establish an individual-based hearing loss early warning model, accurately and differentiated the health of workers exposed to noise. Methods: In September 2019, all physical examination data of 561 workers exposed to noise from an enterprise were collected since their employment. Three indicators of average hearing threshold of the better ear, namely, at high frequency, 4000 Hz and speech frequency, were constructed. The generalized estimating equation (GEE) was used to adjust gender and age and establish the warning model of each indicator. Finally, sensitive indicators and warning models were screened according to AUC and Yoden index. Results: Among the 561 workers exposed to noise, 26 (4.6%) workers had hearing loss. The sensitivity indicators were the average hearing threshold at speech frequency ≥20 dB, high frequency ≥30 dB and 4000 Hz ≥25 dB. The AUC of each index was 0.602, 0.794 and 0.804, and the Youden indexes were 0.204, 0.588 and 0.608, respectively. In GEE of hearing loss warning models, high-frequency hearing threshold ≥20 dB and 4000 Hz hearing threshold ≥25 dB were the optimal models, with AUC of 0.862. Conclusion: Combined with the changes of individual hearing threshold over the years, can accurately assess the risk of individual hearing loss of workers exposed to noise.

Presenteeism and noise perception at work: a cross-sectional study using association analysis

ABSTRACT BACKGROUND: Presenteeism refers to the presence of a worker at work with reduced performance due to illness, and it is a common public health problem. Exposure to noise during production processes brings risk to workers' health. OBJECTIVE: To analyze the health profile of workers in the automotive industry and identify the association between noise perception and presenteeism among workers in the Brazilian automotive industry. DESIGN AND SETTING: This was a cross-sectional study utilizing a case study design analyzing the automotive industry in the interior of São Paulo state, Brazil. METHODS: This study included 306 workers using the Presenteeism Work Limitations Questionnaire protocol. Multiple logistic regression was used for data analysis. RESULTS: Male workers with reports of headache, tension, and limited well-being at work, having perceived that noise exposure interferes with productivity, showed a positive association with the occurrence of presenteeism. Physical demand had the highest score in terms of interfering with the presenteeism index. CONCLUSION: Workers' perceptions of noise were associated with presenteeism.

[Analysis of influencing factors of high frequency hearing loss in workers exposed to noise based on multilevel model].

Objective: To understand the current situation of high-frequency hearing loss of workers exposed to occupational noise in Hubei Province and its multi-level influencing factors. Methods: In June 2021, the basic information, occupational history, physical examination results and other relevant information in the "Occupational Health Examinations Case Cards" for noise workers in Hubei Province in 2020 were extracted from the subsystem of the "China Disease Prevention and Control Information System". Multilevel level of logistic model was used to analyze the related factors of high-frequency hearing loss of noise-exposed workers. Results: In 2020, the incidence rate of occupational high-frequency hearing loss in Hubei Province was 8.25% (6450/78152), and the incidence rate in various regions of the province ranged from 1.13% to 19.87%. At the individual level, male, ≥ 30 years of age, 6-10 years of service, small and micro enterprises, as well as construction, mining, manufacturing, transportation and rental services were the risk factors for high-frequency hearing loss (P<0.05). The risk of high-frequency hearing loss among workers in foreign-funded enterprises was significantly lower than that of workers in state-owned/collective enterprises (P<0.05). At the regional level, the younger the age of the employees, the lower the risk of high-frequency hearing loss (P<0.05). There was no significant correlation between the regional economic level and the risk of high-frequency hearing loss (P>0.05) . Conclusion: The incidence rate of occupational high-frequency hearing loss in Hubei Province is low in 2020, but the incidence rate varies greatly in different regions of the province, mainly due to differences in employment age, while the development of regional economic level has not reduced the risk of occupational high-frequency hearing loss.

[A case-control study of occupational noise exposure induced high-frequency hearing loss and the risk of hypertension].

Objective: To investigate the relationship between high frequency hearing loss caused by occupational noise and the risk of hypertension. Methods: In March 2020, a case-control study was conducted. All noise exposed workers who participated in occupational health examination in Wuxi City in 2019 were selected as the study subjects (95432 cases in total) . The hypertension group was defined as the case group, and the normotensive group was defined as the control group. According to the hearing threshold, they were divided into the non high frequency hearing loss group (<40 dB) and the high frequency hearing loss group (≥ 40 dB) . Univariate statistical method and binary logistic regression were used to evaluate the relationship between high-frequency hearing loss and hypertension risk. Stratified analysis was used to compare the risk of hypertension among workers with high-frequency hearing loss of different ages and length of service. Results: There were significant differences in gender, age, length of service, enterprise scale, economic type and high-frequency hearing loss between control group and hypertension group (P<0.05) . Binary logistic regression analysis showed that after adjusting for gender, age, length of service, enterprise scale and economic type, the risk of hypertension in the high-frequency hearing loss group was still increased (OR=1.062, 95%CI: 1.007~1.121, P=0.027) . The risk of hypertension in high-frequency hearing loss patients was higher than that in non high-frequency hearing loss patients in 20-39 years old and 40-59 years old age groups (OR=1.536, 95%CI: 1.353~1.743; OR=1.179, 95%CI: 1.111~1.250; P<0.05) . The risk of hypertension in high-frequency hearing loss patients in <5years, 5-9years, 10-14 years, 15-19 years and ≥20 years working age groups were higher than that in non high-frequency hearing loss groups (OR=1.926, 95%CI=1.007-1.121; OR=1.635, 95%CI=1.478-1.810; OR=1.312, 95%CI=1.167-1.474; OR=1.445, 95%CI=1.238-1.686; OR=1.235, 95%CI=1.043-1.463; P<0.05) . Conclusion: There is a certain relationship between high-frequency hearing loss caused by occupational noise and the risk of hypertension, and the risk of hypertension is different among high-frequency hearing loss patients of different ages and working years.

[Health hazards and hearing loss risk assessment of workers exposed to noise in an automobile manufacturing enterprise].

Objective: To investigate the current situation of occupational exposure to noise among noise workers in an automobile manufacturing enterprise in Tianjin, understand the impact of noise on workers＇ nervous system and hearing, and assess the risk of hearing loss among noise workers. Methods: In May 2021, 3516 workers in an automobile manufacturing enterprise were investigated by using a self-made questionnaire＂Noise Workers Questionnaire＂ and cluster sampling method. The occupational noise hygiene survey and occupational hazards detection were carried out in their workplaces. They were divided into noise exposure group and non-noise exposure group according to whether they were exposed to noise or not. The general characteristics, hearing and nervous system symptoms of the two groups of workers were compared, and the risk of hearing loss was assessed. Results: There were 758 workers in the noise exposure group, aged (26±5) years old, with a working age of 3.0 (2.0, 6.0) years exposed to noise. 2758 workers in the non-noise exposure group, aged (25±6) years old, with a working age of 2.0 (1.0, 4.0) years. There were statistically significant differences in the distribution of workers＇education level, working age and memory loss between the two groups (χ(2)=37.98, 38.70, 5.20, P<0.05). The workers in the noise exposure group showed a decreasing trend of insomnia, dreaminess, sweating and fatigue with the increase of working age (χ(2trend)=6.16, 7.99, P<0.05). The risk classification of binaural high-frequency hearing loss for workers in all noise positions until the age of 50 and 60 was negligible, the risk of occupational noise deafness was low for workers in stamping and welding noise positions until the age of 60. Conclusion: The occupational noise exposed to automobile manufacturing workers may cause certain harm to their nervous and auditory systems. Noise protection measures should be taken to reduce the risk of hearing loss and occupational noise deafness.

[Noise exposure and its impact on health in an auto parts manufacturing enterprise].

Objective: To learn about the noise exposure and health status of workers and analyze factors that may affect the health outcomes of workers in an auto manufacturing enterprise in Tianjin City. Methods: In September 2020, occupational hygiene survey, noise exposure level detection and occupational health examination data collection were carried out in an auto parts manufacturing enterprise. Chi square test and unconditional logistic regression analysis were used to analyze the health effects of noise exposure and hearing loss of 361 noise exposure workers. Results: The rates of over-standard noise exposure, hearing loss and hypertension were 69.39% (34/49) , 33.24% (120/361) and 11.36% (41/361) , respectively. There were upward trends on age and noise-working years for hearing loss and hypertension rates (χ(2)=-5.95, -6.16, -2.81, -2.74, P<0.05) . Unconditional logistic regression analysis showed that age>35 years old, noise exposure length of service >10 years and noise L(EX, 8 h)>85 dB (A) were risk factors for hearing loss (OR=3.57, 95%CI: 1.09, 11.75; OR=4.05, 95%CI: 1.97, 8.25; OR=1.75, 95%CI: 1.00, 3.05; P=0.036, 0.001, 0.047) . Conclusion: This company has a high rate of job noise exceeding the standard, and noise-exposed workers have more serious hearing loss. Age, noise exposure and high noise exposure are risk factors for hearing loss.

[Application of three risk assessment methods to noise risk assessment in an automobile foundry enterprise].

Objective: To explore the applicability of three different kinds of noise occupational health risk assessment methods to the occupational health risk assessment of noise exposed positions in an automobile foundry enterprise. Methods: In July 2020, the occupational-health risk assessment of noise-exposed positions was conducted by using the Guidelines for risk management of occupational noise hazard (guideline method) , the International Commission on Mining and Metals Guidelines for Occupational Health Risk Assessment (ICMM) method and the Occupational-health risk index method (index method) respectively, and the results were analyzed and compared. Results: Through the occupational health field investigation, the noise exposure level of the enterprise's main workstations was between 80.3 and 94.8 dB (A) , among which the noise of the posts of shaking-sand, cleaning and modeling was greater than 85 dB (A) ; The noise risk of each position was evaluated by the three methods, and the adjustment risk level was between 2 and 5 assessed using the guideline method, between 2 and 3 assessed using the index method, and 5 evaluated using the ICMM model. Conclusion: Each of the three risk assessment methods has its own advantages and disadvantages. The ICMM model has a large difference in value assignment, and values in the results are larger than expected. The evaluation results of the guideline method and the index method are consistent in some positions, there is certain subjectivity in the evaluation using the index method, and the guideline method is more objective.

[Literature analysis of hot topics on occupational noise-induced hearing loss].

Objective: To analyze the literature of related research reports on occupational hearing loss (ONIHL) , study the characteristics of the subject and determine the research hotspots. Methods: In December 2020, PubMed database was searched by bibliometrics for ONIHL published in PubMed database from January 1971 to December 2020. Bicomb 2.03 software was used to extract the subject. The publication year, publication country, source magazine and subject words were summarized and analyzed. Results: A total of 1 473 papers were included in this study, and the number of papers was 66 from 1971 to 1980, and 628 from 2011 to 2020, an increase of nearly 10 times. The top three countries were the United States, China and Germany, with 31.5% (464/1473) , 11.5% (171/1473) and 6.2% (91/1473) ; The cross-sectional study was the most applied type; The top five words for 2011-2020: Mental Illness, polymorphism, cardiovascular disease, high frequency hearing impairment and standards and regulations. Conclusion: Susceptibility Genes, Psychological Disorders, Cardiovascular Diseases and Risk Assessment are hot areas in ONIHL at present. Researchers should focus on major fields and grasp future trends as a whole.

[Association between occupational noise exposure and the risk of cardiovascular diseases].

Objective: To explore the association between occupational noise exposure and cardiovascular disease (CVD) risk in a large Chinese population. Methods: In December 2019, the study included 21412 retired participants from the Dongfeng-Tongji Cohort Study at baseline from September 2008 to June 2010, occupational noise exposure was evaluated through workplace noise level and/or the job titles. In a subsample of 8931 subjects, bilateral hearing loss was defined as a pure-tone mean of 25 dB or higher at 0.5, 1 , 2, and 4 kHz in both ears. Logistic regression models were used to explore the association of occupational noise exposure, bilateral hearing loss with 10-year CVD risk. Results: Compared with participants without occupational noise exposure, the 10-year CVD risk was significantly higher for noise exposure duration ≥20 years (OR=1.20, 95%CI:1.01-1.41 , P=0.001) after adjusting for potential confounders. In the sex-specific analysis, the association was only statistically significant in males (OR=2.34, 95%CI: 1.18-4.66, P<0.001) , but not in females (OR=1.15, 95%CI:0.97-1.37, P=0.153). In the subsample analyses, bilateral hearing loss, which was an indicator for exposure to loud noise, was also associated with a higher risk of 10-year CVD (OR= 1.17, 95% CI:1.05-1.44, P <0.001) , especially for participants who were males (OR =1.24, 95% CI:1.07-2.30, P<0.001) , aged equal and over 60 years old (OR=2.30, 95%CI: 1.84-2.88, P<0.001) , and exposed to occupational noise (OR=1.66, 95%CI: 1.02-2.70, P=0.001). Conclusion: Occupational noise exposure may be a risk factor for CVD.

[Association between polymorphism of CASP and NOX3 with risk of noise-induced hearing loss].

Objective: To explore the effect of gene polymorphism on workers suffering from noise induced hearing loss (NIHL) . Methods: In May 2019, a case-control study was conducted to select noise exposed workers in five factories in Zhejiang Province from 2017 to 2018. The average hearing threshold of binaural high frequency (3, 4, 6 kHz) was >25 dB (A) as the NIHL group, and the hearing threshold of any language frequency (0.5, 1, 2 kHz) was ≤25 dB (A) as the non NIHL group, with 307 people in each group. The general demographic data, occupational history, pure tone audiometry results and oral swab mucosal samples of noise exposed workers were collected, and the DNA of oral mucosal cells was extracted. The relationship between genetic risk score (GRS) and NIHL was analyzed, single nucleotide polymorphisms (SNP) were genotyped, the relationship between genotype and NIHL was analyzed by logistic regression, and the relationship between haplotype and NIHL was analyzed by R language. Results: After adjusting for gender, age, education and working years, the risk of NIHL among workers carrying cysteine-aspartic acid protease 3 gene (CASP3) rs1049216 recessive model GG genotype, rs6948 recessive model TT genotype, NADPH oxidase 3 gene (NOX3) rs12195525 additive model GT genotype and dominant model TT+GT genotype decreased (P<0.05) , the risk of disease was higher in workers with AA genotype carrying cysteine-aspartic acid protease 7 gene (CASP7) rs12415607 additive model (P<0.05) . There was a strong linkage disequilibrium (LD) relationship between rs1049216 and rs6948 (D'>0.8) . Haplotype AT and GG composed of rs1049216-rs6948 increased the risk of NIHL (P<0.05) . The risk of NIHL increased with the increase of GRS (OR=2.69, P<0.05) . Conclusion: Genotype polymorphisms at rs1049216 and rs6948 (CASP3) , rs12195525 (NOX3) , rs12415607 (CASP7) may be associated with susceptibility to NIHL.

[Investigation of noise annoyance among the exposed anesthesiologists in a hospital].

Objective: To investigation noise annoyance among the exposed anesthesiologists, and to analyze the influencing factors of noise annoyance. Methods: From January to May 2017, cluster sampling was used to select 62 anesthesiologists from Peking University Third Hospital as the survey subjects. The Likert Scale (five-level) and the Visual Analog Scale (0-10 points) were used to conduct noise annoyance and noise sensitivity survey. Linear regression was used for multi-factor analysis to explore the influencing factors of noise annoyance. Results: The age of the research subjects was (32.3±6.1) years old, the working experience was 4.9 (2.0, 8.9) years, and the daily working hours were (9.8±2.8) h. The noise level in the operating room on the measurement day was (64.4±1.7) dB (A) . In the Likert Scale and the Visual Analog Scale, 88.7% (55/62) and 95.2% (59/62) anesthesiologists believed that operating room noise had adverse reactions, 6.5% (4/62) and 14.5% (9/62) anesthesiologists measured a high degree of annoyance. The results of linear regression analysis showed that noise sensitivity was an independent factor influencing the anesthesiologists' noise annoyance in the Likert Scale and the Visual Analog Scale (r=0.524, 0.700, P<0.05) . Conclusion: Noise in the operating room can cause anesthesiologists to feel annoyed and is a hidden danger to the quality of medical services, which should be paid attention to by the academic and management departments.

[Application and prospect of multiomics techniques in susceptibility to occupational noise hearing loss].

With the continuous innovation of technology, genomics and other omics techniques, such as transcriptomics, proteomics, and metabolomics, are increasingly becoming an important basis for precision medicine. Current research on susceptibility to occupational noise hearing loss (ONHL) has focused on genomics. Building the future of precision medicine is the focus of current ONHL research. Compared to single-omics studies, the use of multi-omics analysis can provide an integrated flow of information on ONHL susceptibility. This paper outlines the advantages and limitations of different histological techniques and the application of each histology in the disease, and focuses on the feasibility of applying multi-omics techniques in ONHL susceptibility research. The analysis of multi-omics techniques can better guide the comprehensive understanding of the disease in clinical research.

[Investigation of occupational noise exposure and hearing loss among automobile manufacturing workers].

Objective: To investigation the situation of occupational noise exposure and hearing loss among workers in automobile manufacturing enterprise during 2017-2019 in Wuhan. Methods: Workers in automobile manufacturing who underwent physical examination in Wuhan Hospital for the Prevention and Treatment of Occupational Diseases from 2017 to 2019 were included as subjects in the cross-sectional survey. Questionnaire survey, noise detection and pure tone threshold test were used. Excluding individuals with working time less than 3 years and information deficiency, 3 948 individuals were finally included in the study. Results: Among 3 948 workers, 128 workers had hearing loss and the rate of hearing loss was 3.24%, among which 101 workers had high-frequency hearing loss and 27 workers were diagnosed as occupational noise deafness. The prevalence of hearing loss among workers previously exposed to noise was significantly higher than that without prior exposure (12.10%, 0.96%, P<0.05) . The prevalence of hearing loss among workers with occupational noise exposure <80 dB (A) , 80~<85 dB (A) and ≥85 dB (A) was 1.83%, 2.69% and 5.09%, respectively. The prevalence of high frequency hearing loss was 1.60%, 2.05% and 3.71%, respectively. The prevalence of occupational noise deafness was 0.23%, 0.64% and 1.38%, respectively. The prevalence of hearing loss and high frequency hearing loss among workers exposed to different occupational noise was statistically significant (P<0.05) , while the prevalence of occupational noise deafness was not statistically significant (P>0.05) . There were statistically significant differences in the prevalence of hearing loss (2.88%, 4.45%) and occupational noise deafness (0.46%, 1.41%) between those who used protective equipment and those who did not (P<0.05) . Compared with workers exposed to occupational noise <80 dB (A) , workers exposed to occupational noise ≥85 dB (A) had A 3.16-fold increased risk of hearing loss (OR=3.16, 95%CI: 1.44~6.95, P<0.05) . Compared to workers using hearing protective equipment, the risk of hearing loss (OR=1.96, 95%CI: 1.25~3.06, P<0.05) and occupational noise deafness (OR=3.46, 95%CI: 1.51-7.96, P<0.05) significantly increased among those without using hearing protective equipment. Conclusion: The risk of hearing loss in automobile manufacturing workers is significantly associated with occupational noise exposure and the use of hearing protective equipment. Good hearing protection may reduce the risk of occupational noise-induced hearing loss and occupational noise deafness.

[Evaluation of kurtosis on hearing loss caused by non-steady state noise in general equipment manufacturing industry].

Objective: To study the effect of occupational exposure to non-steady state noise on hearing loss in the general equipment manufacturing industry, and to explore the feasibility of applying kurtosis index to evaluate hearing loss caused by non-steady state noise. Methods: A total of 233 workers exposed to non-steady state noise in 6 general equipment manufacturing enterprises were selected as the observation group, and 237 workers exposed to steady noise in 4 textile enterprises were selected as the control group between 2012 and 2018. Personal normalized continuous A-weighted sound pressure level equivalent to an 8 h-working-day (L(Aeq, 8 h)) was determined by a noise dosimeter. Cumulation noise exposure (CNE) was calculated from L(Aeq, 8 h) and related working age, and the CNE was adjusted by using noise kurtosis (CNE' after adjustment) . Meanwhile, questionnaires and hearing loss tests were performed for all subjects. The changes in the threshold of high-frequency hearing and the incidence of high-frequency hearing loss caused by noise in the two groups were compared before and after the adjustment of the kurtosis of CNE. The correlation between CNE and the incidence of high-frequency hearing loss before and after kurtosis adjustment was analyzed. Results: There was an difference between the 3000-8000 Hz hearing threshold of workers in different CNE groups (P<0.05) . logistic regression analysis showed that CNE was a risk factor of high-frequency hearing loss for workers in the observation group (OR=1.189, P<0.05) , and trend Chi-square test showed that the incidence of high-frequency hearing loss increased with CNE levels (χ(2)(trend)=34.415, P<0.05) .Before the kurtosis adjustment, in the CNE 95~<110 dB (A) ·year level group, the incidence of high-frequency hearing loss and the high-frequency hearing threshold in the observation group were significantly higher than those in the control group (P<0.05) . After kurtosis adjustment, there was no significant difference in the incidence of high-frequency hearing loss between the observation group and the control group in each level group (P>0.05) . The correlation between CNE after kurtosis adjustment and the incidence of high-frequency hearing loss was better than that before adjustment (after R(2) adjustment >before R(2) adjustment) . Conclusion: The effect of non-steady state noise on high-frequency hearing loss of workers in general equipment industry increases with the increase of CNE, and the effect of non-steady state noise on high-frequency hearing loss of workers is greater than that of steady noise. CNE' can be used to evaluate the hearing loss caused by non-steady state noise.

[Investigation on noise exposure level and health status of workers in transportation equipment manufacturing industry].

Objective: To explore the noise exposure level and the health status of workers in transportation equipment manufacturing industry, and provide a scientific basis for guidance and implementation of intervention measures. Methods: From January to December in 2019, a total of 2088 noise workers from a large enterprise were selected by cluster sampling method in railway transportation equipment manufacturing, automobile manufacturing and aerospace aircraft manufacturing enterprises. The worker's noise exposure level was detected. Occupational health checkups were performed on the noise workers including electrical audiometry, blood pressure and electrocardiogram. χ(2) test and trend χ(2) test were used to analyze the data. Results: The noise exposure level of 66.9% (1396/2088) workers exceeded 85 dB (A) , and the median noise level was 87.9 (84.3-90.3) dB (A) . Among them, workers of railway transportation equipment manufacturing enterprises had the highest noise exposure level[89.9 (87.8-91.6) dB (A) ]. The detection rate of high-frequency hearing loss, abnormal blood pressure and abnormal electrocardiogram of noise workers were 15.7% (327/2088) , 18.1% (378/2088) and 6.1% (128/2088) , respectively. The differences in the detection rates of high-frequency hearing loss, abnormal blood pressure, and abnormal electrocardiogram in workers of railway transportation equipment manufacturing enterprises, automobile manufacturing enterprises, and aerospace manufacturing enterprises were statistically significant (P<0.05) . Workers of railway transportation equipment manufacturing enterprises had higher detection rates of high-frequency hearing loss (17.6%, 186/1056) . Workers of aerospace manufacturing enterprises had higher detection rates of abnormal blood pressure and abnormal electrocardiogram (26.3%, 169/642; 10.0%, 64/642) . The differences in the detection rates of high-frequency hearing loss, abnormal blood pressure and abnormal electrocardiogram of noise workers were statistically significant in different age and working age groups, and gradually increased with age and working age (P<0.05) . The difference in the detection rate of high-frequency hearing loss of noise workers was statistically significant in different noise intensity groups, and the overall trend was increasing (P<0.05) . Conclusion: The transportation equipment manufacturing industry has serious noise hazards, especially the railway transportation equipment manufacturing industry. Long-term occupational noise exposure can adversely affect workers' hearing and cardiovascular system. Enterprises should strengthen occupational health inspections, and at the same time, take personal protective measures to protect the health of workers.

[Dose-response relationship between noise kurtosis and noise-induced hearing loss].

Objective: To analyse the dose-response relationships between the kurtosis metric of noise and noise-induced hearing loss (NIHL) and study the role of kurtosis in the evaluation of NIHL associated with non-Gaussian noise. Methods: From January 2012 to December 2017, a total of 1869 workers in seven manufacturing industries were selected as the study subjects. The basic data of the workers were investigated by questionnaire, personal noise waveform was collected for a long time, and pure tone hearing threshold was tested. The 8-hour continuous equivalent A sound level (L(Aeq, 8 h)) , cumulative noise exposure (CNE) and kurtosis structure indexes were calculated. The dose-response relationships between kurtosis and NIHL were analyzed by stratification analysis method, which controlled the influence of CNE, L(Aeq, 8 h), exposure duration, age and sex on hearing loss using high-frequency noise-induced permanent threshold shift (NIPTS(346)) and high-frequency noise-induced hearing loss (HFNIHL) as outcome indicators. Results: When CNE was <90 dB (A) ·year and ≥100 dB (A) ·year, NIPTS(346) in the extremely high kurtosis group was significantly greater than that in the Gaussian kurtosis, low kurtosis and medium kurtosis group (P<0.05) . In the workers exposed to L(Aeq, 8 h)<85 dB (A) and ≥94 dB (A) , NIPTS(346) in the extremely high kurtosis group was significantly greater than that in the Gaussian kurtosis group (P<0.05) . Among workers under the age of 50 or male workers, NIPTS(346) in the extremely high kurtosis group was significantly greater than that in the Gaussian kurtosis, low kurtosis and medium kurtosis group (P<0.05) . Kurtosis was positively correlated with NIPTS(346) (r=0.121, P<0.05) . When CNE was <100 dB (A) ·year, the detection rate of HFNIHL increased with the increase of kurtosis level (P<0.01) . Logistic regression analysis showed that kurtosis was an important influencing factor for HFNIHL (OR=1.321) . Conclusion: Kurtosis has a dose-response relationship with the detection rate of HFNIHL in noise exposed workers, and noise kurtosis is an influencing factor of NIHL.