Noise-exposed Workers Research Articles

DNMT1 and DNMT3A haplotypes associated with noise-induced hearing loss in Chinese workers

This study was conducted to explore the effects of DNMT1 and DNMT3A polymorphisms on susceptibility to noise-induced hearing loss (NIHL) in Chinese workers. A total of 2689 industrial workers from a single textile factory were recruited. Venous blood was collected, as were questionnaire and pure-tone audiometry (PTA) data by specialist physicians. Four selected SNPs (rs7578575, rs749131, rs1550117, and rs2228611) in DNMT1 and DNMT3A were genotyped in 527 NIHL patients and 527 controls. Then, main effects of the genotypes and their interactions were evaluated. Results revealed that the GG genotype at rs749131 and the AG/GG genotypes at rs1550117 and rs2228611 [odds ratio (OR) = 1.87, 2.57, and 1.98 respectively], as well as the haplotypes AGGG and TGGA (rs7578578-rs749131-rs1550117-rs2228611) (OR = 1.35 and 1.56, respectively) were associated with an increased risk of NIHL in the Chinese population. Multifactor dimensionality reduction analysis indicated that rs7578575, rs749131, and rs2228611 interact and are related to increased NIHL risk (OR = 1.63). The genetic polymorphisms rs749131 G, rs1550117 G, and rs2228611 G within the DNMT1 and DNMT3A genes are associated with an increased risk of NIHL in the Chinese population and have the potential to act as biomarkers for noise-exposed workers.

Prevalence of Hearing Loss Among Noise-Exposed Workers Within the Health Care and Social Assistance Sector, 2003 to 2012: Erratum.

Prevalence of Hearing Loss Among Noise-Exposed Workers Within the Health Care and Social Assistance Sector, 2003 to 2012: Erratum.

Management at corporate level of noise exposure assessment and control for Petrobras refining

This article presents the work carried out as part of a project aiming to regulate the noise exposure of workers of PETROBRAS refining units. This is a corporate project carried out over a three years’ period (2012 to 2015) by the Supply business unit of the Brazilian company. The uniqueness of this project is due to its scale. Indeed, this encompassed twelve refineries located throughout Brazil. The corporate approach to deal with noise exposure risk leads to an overall data consolidation allowed by a standardized methodology. The methodology used is split into four phases. First, a long but necessary planning stage, then an exhaustive assessment of the current noise situation of production areas was carried out during the first twelve months of the project. This stage allowed the involvement of several important tools used to identify and rank noise exposure issues. This lead to noise maps of every industrial area and an acoustic database of equipment exceeding regulatory limits (sound power level and directivity). Third, every industrial area was modelled into noise prediction software compliant with ISO 9613-2 standard. Finally, acoustic damping solutions were designed and proportioned by size of equipment. This mixed approach of measurement and numerical simulation mobilized a dedicated ACOEM project team comprising of eight acoustic experts. Principal achievement of this project, concluded in 2015, is a clear vision of the noise control priorities allowed by standardized methodology on all refineries in a short time. This achievement leads to a coherent set of controls for the future investments to be done to mitigate noise exposure risks. In addition to highlighting the benefits of integrated Health Safety and Environment (HSE) management, this work provides an understanding on the use of virtual computing doses from propagating acoustic model.

Accuracy of an internet-based speech-in-noise hearing screening test for high-frequency hearing loss: incorporating automatic conditional rescreening

PurposeTo validate the accuracy of an internet-based speech-in-noise hearing screening test for high-frequency hearing loss (HFHL) ‘Occupational Earcheck (OEC)’ incorporating an automatic conditional rescreening, in an occupationally noise-exposed population. Secondary objectives were to assess the effects of age on test accuracy measures, and to assess the test accuracy for different degrees of HFHL.MethodsA study was conducted on cross-sectional data of occupational audiometric examinations, including the index test OEC and reference standard pure-tone air conduction audiometry, of 80 noise-exposed workers. Sensitivity, specificity, and likelihood ratios were calculated for the OEC, after automatic conditional rescreening, for a younger and an older age group, and for two degrees of HFHL (HFHL25: PTA3,4,6 ≥ 25 dB HL, and HFHL35: PTA3,4,6 ≥ 35 dB HL, both for at least one ear).ResultsTest specificity for HFHL25 after a single test was 63%, and improved to 93% after the automatic conditional rescreen. Test sensitivity for HFHL25 decreased from 65% to 59%. Test sensitivity and specificity including automatic conditional rescreening for HFHL35 was 94% and 90%, respectively. The positive likelihood ratio for HFHL25 was 8.4, and for HFHL35 9.4. The negative likelihood ratio for HFHL35 was below 0.1.ConclusionsThe OEC is an appropriate screening test, especially for HFHL35. Normal-hearing workers who obtained a positive test result for the first test for one or two ears, benefit from having an automatic rescreen, resulting in an improvement of the test specificity, and hence prevent unnecessary referral.

Analysis on characteristics of hearing loss in occupational noise-exposed workers in automotive manufacturing industry

Objective: To investigate the characteristics of hearing loss in occupational noise-exposed workers in automotive manufacturing industry. Methods: According to Technical Specifications for Occupational Health Surveillance (GBZ188-2014) , 530 noise-exposed workers were examined for health and pure tone audiometry during January to June, 2017, and the data were collected for analysis. Poisson regression analysis was used to analysis the relationship between work age and hearing loss. Results: After correction of age and gender, pure-tone threshold of 500, 1 000, 2 000, 3 000, 4 000, 6 000 of the noise-exposed workers in the <3 year-exposure group were 20.15±3.60, 18.80±3.43, 18.54±3.38, 19.10±4.03, 20.32±6.79, 23.48±8.92 dB (A) ; the values in the 3-10 year-exposure group were 20.96±5.38, 19.25±4.76, 19.22±5.29, 20.17±7.50, 21.36±8.88, 25.39±11.60 dB (A) ; the values in the >10 year-exposure group were 20.18±3.67, 18.34±3.60, 18.36±4.25, 18.49±4.41, 20.32±9.24, 22.50±9.57 dB (A) . Poisson regression analysis showed that the relative risk (RR) of hearing loss of the noise-exposed workers compared with the noise-free workers was 4.38 (P<0.05) . Conclusion: The noise-exposed workers in automotive manufacturing industry revealed hearing loss, which was associated with their actual working age of noise exposure.

Developing an Acoustic Sensing Yarn for Health Surveillance in a Military Setting.

Overexposure to high levels of noise can cause permanent hearing disorders, which have a significant adverse effect on the quality of life of those affected. Injury due to noise can affect people in a variety of careers including construction workers, factory workers, and members of the armed forces. By monitoring the noise exposure of workers, overexposure can be avoided and suitable protective equipment can be provided. This work focused on the creation of a noise dosimeter suitable for use by members of the armed forces, where a discrete dosimeter was integrated into a textile helmet cover. In this way the sensing elements could be incorporated very close to the ears, providing a highly representative indication of the sound level entering the body, and also creating a device that would not interfere with military activities. This was achieved by utilising commercial microelectromechanical system microphones integrated within the fibres of yarn to create an acoustic sensing yarn. The acoustic sensing yarns were fully characterised over a range of relevant sound levels and frequencies at each stage in the yarn production process. The yarns were ultimately integrated into a knitted helmet cover to create a functional acoustic sensing helmet cover prototype.

Prevalence of Hearing Loss Among Noise-Exposed Workers Within the Health Care and Social Assistance Sector, 2003 to 2012.

The purpose was to estimate the prevalence of hearing loss for noise-exposed U.S. workers within the Health Care and Social Assistance (HSA) sector. Audiograms for 1.4 million workers (8702 within HSA) from 2003 to 2012 were examined. Prevalences and adjusted risks for hearing loss as compared with a reference industry were estimated for the HSA sector and all industries combined. While the overall HSA sector prevalence for hearing loss was 19%, the prevalences in the Medical Laboratories subsector and the Offices of All Other Miscellaneous Health Practitioners subsector were 31% and 24%, respectively. The Child Day Care Services subsector had a 52% higher risk than the reference industry. High-risk industries for hearing loss exist within the HSA sector. Further work is needed to identify the sources of noise exposure and protect worker hearing.

Analysis on hearing status and related influencing factors in workers exposed to noise in an automobile manufacture enterprise

Objective: To study the hearing status and analyze the related influencing factors in noise-exposed workers in an automobile manufacture enterprise, and put forward suggestions for prevention of noise-induced hearing loss. Methods: Noise exposure level testing, audiometry testing and questionnaires were performed for noise exposed workers in the automobile manufacture enterprise. To analyze the relationship between different factors and noise-induced hearing loss by cumulative noise exposure(CNE) calculated 8-hour continuous A-weighted equivalent noise level and seniority. Results: The detection rate of hearing loss in noise-exposed workers was 22.8%. The noise exposure intensity of stamping workshop is higher than other workshop, and the hearing loss detection rate of stamping workshop workers is higher than other workshop workers. The detection rate of hearing loss has significant difference in L(Aeq·8 h), seniority, CNE, age, high temperature and wearing earplugs (P<0.05). The results of logistic regression analysis showed that CNE, age and high-temperature were risk factors for noise-induced hearing loss (P<0.05 and OR>1) and there was an increasing tendency of hearing loss with increase in length of service and CNE, while using of earplugs was a protective factor (P<0.05 and OR<1). With the increase of CNE, the incidence of hearing loss is the rising trend. Conclusion: It is suggested to strengthen the noise control and individual protection and improve the high-temperature working environment, which plays an important role in reducing the occurrence of noise-induced hearing loss.

Cost-Effectiveness Analysis of a Military Hearing Conservation Program.

Occupational noise threatens U.S. worker health and safety and commands a significant financial burden on state and federal government worker compensation programs. Previous studies suggest that hearing conservation programs have contributed to reduced occupational hearing loss for noise-exposed workers. Many military personnel are overexposed to noise and are provided hearing conservation services. Select military branches require all active duty personnel to follow hearing conservation program guidelines, regardless of individual noise exposure. We evaluated the cost-effectiveness of a military hearing conservation program, relative to no intervention, in relation to cases of hearing loss prevented. We employed cost-effectiveness analytic methods to compare the costs and effectiveness, in terms of hearing loss cases prevented, of a military hearing conservation program relative to no program. We used costs and probability estimates available in the literature and publicly available sources. The effectiveness of the interventions was analyzed based on whether hearing loss occurred over a 20-yr time frame. The incremental cost-effectiveness ratio of the hearing conservation program compared with no intervention was $10,657 per case of hearing loss prevented. Workers were 28% less likely to sustain hearing loss in our model when they received the hearing conservation program compared with no intervention, which reflected the greater effectiveness of the hearing conservation program. Cost-effectiveness results were sensitive to estimated values for the probability of acquiring hearing loss from both interventions and the cost of hearing protection. We performed a Monte Carlo probabilistic sensitivity analysis where we simultaneously varied all the model parameters to their extreme plausible bounds. When we ran 10,000 Monte Carlo iterations, we observed that the hearing conservation program was more cost-effective in 99% of cases when decision makers were willing to pay $64,172 per case of hearing loss prevented. Conceding a lifetime cost for service-related compensation for hearing loss per individual of $64,172, the Department of Defense Hearing Conservation Program is an economically reasonable program relative to no intervention, if a case of hearing loss avoided costs $10,657. Considering the net difference of the costs and comparative benefits of both treatment strategies, providing a hearing conservation program for all active duty military workers may be a cost-effective intervention for the Department of Defense.

Analysis of the Relationship of Noise Exposure and Hearing Loss in PPSU Workers in North Jakarta

Hearing loss is one of the many health problems experienced by workers in high noise exposure areas. The purpose of this study was to analyze the relationship between noise intensity and hearing loss in PPSU workers in North Jakarta. This type of research is quantitative analytic using cross-sectional design involving 45 PPSU workers in North Jakarta. Hearing loss was identified by audiometric examination with air conditioning (AC), while noise intensity in the worker's area was measured using a sound level meter. The results of this study showed that 60% of respondents experienced hearing loss, and 51.1% of the areas had noise intensity ≥ 75 dB. The results of categorical analysis showed that there is a relationship between noise intensity and hearing loss with prevalence of ratio was 5.2. Logistic regression analysis showed that respondents who work in areas with noise intensity ≥ 75 dB had the opportunity 7 times to experience hearing loss after being controlled by variable smoking behavior, and hobbies towards noise. Exposure to high noise is something that cannot be avoided by PPSU workers, therefore to reduce or prevent the occurrence of hearing loss, the workers should use earplugs while working, and should reduce smoking and listening music with earphones. In addition, the workers should conduct regular audiometric examinations and attend health counseling at the workplace.

Questionnaire-based algorithm for assessing occupational noise exposure of construction workers

ObjectivesOccupational noise exposure is a major cause of hearing loss worldwide. In order to inform preventative strategies, we need to further understand at a population level which workers are most...

Analysis on occupational noise-induced hearing loss of different type workers in underground mining

Objective: To investigate hearing loss status of blasters, drillers mechanics and so on in underground mining, and put forward suggestion diagnosis of occupational explosive deafness and occupational deafness. Methods: Underground excavation workers in a metal mine were recruited in this study, those with a history of ear disease and non-occupational deafness were all excluded. Finally, the features of pure tone audiometry of 459 noise-exposed workers were analyzed. Results: High-frequency hearing loss occurred on 351workers and the positive detection rate was 74.29%, workers who had both high-frequency and linguistic frequency hearing loss were 51 and the positive detection rate was 11.11%. The positive detection of high-frequency hearing loss in right ear (χ(2)=9.427 and P= 0.024) and in left ear (χ(2)=14.375, P=0.002) was significantly different between different exposure age groups. The positive detection of high-frequency hearing loss of driving group was the highest, followed by blasting group, mining group and machine repair group. The characteristics of the hearing loss caused by drilling noise of the blasting workers with no accident occurred were in line with that of noise-induced hearing loss. Conclusion: The diagnosis grading should be carried out according to the diagnostic criteria of occupational noise-induced deafness for the employees who engaged in the blasting operation with no record of blast accident.

Analysis of hearing test results of 438 metal smelting workers

Objective To investigate the auditory performance of noise-exposed workers in a metal smelting factory, and to analyze the relationship between different noise-age, hearing protection and noise damage, and to provide the basis for the prevention and control of noise. Methods According to GBZ188-2014 Occupational Health Surveillance Technical Specification, the pure tone audiometry test results of 438 workers in a special metal smelter in this city were analyzed statistically. Results The detection rate of hearing impairment was 25.6%.The incidence of hearing impairment in different occupational groups was statistically significant( 10 years 40.0%)(χ2=15.10, P<0.01). The incidence of hearing loss was compared between the hearing protection with wearing earplugs group(the earplug group) and without wearing earplugs group(the control group), the difference was statistically significant(20.0% in the earplug group and 31.2% in the control group, χ2= 20.15, P<0.01), and the noise detection rate was significantly higher in the earplug group than in the control group(4% in the earplug group and 12% in the control group, χ2=9.14, P<0.01). Conclusion Noise in the special metal smelting factory is more than that of the workers, so it is necessary to perfect the hearing protection measures as soon as possible. Key words: Noise, Occupational; Hearing Impaired Persons; Hearing Tests; Ear Protective Devices

Polymorphisms of heat shock protein 70 genes (HSPA1A, HSPA1B and HSPA1L) and susceptibility of noise-induced hearing loss in a Chinese population: A case-control study.

Noise-induced hearing loss (NIHL) is the second-most frequent form of sensorineural hearing loss. When exposed to the same noise, some workers develop NIHL while others do not, suggesting that NIHL may be associated with genetic factors. To explore the relationship between single nucleotide polymorphisms (SNPs) in heat shock protein 70 (HSP70) genes (HSPA1A, HSPA1B and HSPA1L) and susceptibility to NIHL in Han Chinese workers exposed to noise, a case-control association study was carried out with 286 hearing loss cases and 286 matched with gender, age, type of work, and exposure time, drawn from a population of 3790 noise-exposed workers. Four SNPs were selected and genotyped. Subsequently, the effects of the alleles and genotypes of the three HSP70 genes (HSPA1A, HSPA1B and HSPA1L) on NIHL were analyzed by using a conditional logistic regression. A generalized multiple dimensionality reduction (GMDR) was applied to further detect an interaction between the four SNPs. Compared with the combined genotypes CC/TC, carriers of the TT genotype of rs2763979 appeared to show greater susceptibility to NIHL (P = 0.042, adjusted OR = 1.731, 95% CI 1.021–2.935). A significant interaction between rs2763979 and CNE was found (P = 0.029), and a significant association was found between TT of s2763979 and NIHL (P = 0.024, adjusted OR = 5.694, 95%CI 1.256-25.817) in the 96 dB (A)≤CNE<101 dB (A) group. The results suggest that the rs2763979 locus of the HSP70 genes may be associated with susceptibility to NIHL in Chinese individuals, and other HSP70 genes may also be susceptibility genes for NIHL, but the results must be further replicated in additional independent sample sets.

Noise exposure in occupational setting associated with elevated blood pressure in China

BackgroundHypertension is the primary out-auditory adverse outcome caused due to occupational noise exposure. This study investigated the associations of noise exposure in an occupational setting with blood pressure and risk of hypertension.MethodsA total of 1,390 occupational noise-exposed workers and 1399 frequency matched non-noise-exposed subjects were recruited from a cross-sectional survey of occupational noise-exposed and the general population, respectively. Blood pressure was measured using a mercury sphygmomanometer following a standard protocol. Multiple logistic regression was used to calculate the odds ratio (OR) and 95% confidence interval (CI) of noise exposure adjusted by potential confounders.ResultsNoise-exposed subjects had significantly higher levels of systolic blood pressure(SBP) (125.1 ± 13.9 mm Hg) and diastolic blood pressure (DBP) (77.6 ± 10.7 mm Hg) than control subjects (SBP: 117.2 ± 15.7 mm Hg, DBP: 70.0 ± 10.5 mm Hg) (P < 0.001). Significant correlations were found between noise exposure and blood pressure (SBP and DBP) (P < 0.001). However, the linear regression coefficients with DBP appeared larger than those with SBP.The prevalence of hypertension was 17.8% in subjects with noise exposure and 9.0% in control group (P < 0.001). Compared with the control group, the subjects with noise exposure had the risk of hypertension with an OR of 1.941 (95% CI = 1.471– 2.561) after adjusting for age, sex, smoking, and drinking status. Dose–response relationships were found between noise intensity, years of noise exposure, cumulative noise exposure and the risk of hypertension (all P values < 0.05). No significant difference was found between subjects wearing an earplug and those not wearing an earplug, and between steady and unsteady noise categories (P > 0.05).ConclusionsOccupational noise exposure was associated with higher levels of SBP, DBP, and the risk of hypertension. These findings indicate that effective and feasible measures should be implemented to reduce the risk of hypertension caused by occupational noise exposure.

A cohort study on occupational noise induced hearing loss in workers at an iron and steel plant

Objective: To analyze the incidence rate of occupational noise-induced hearing loss in noise-exposed workers in an iron and steel plant from 2006 to 2015. Methods: Using a cohort study method, workers exposed to occupational noise from Jan 1, 2006 to Dec 12, 2015 were followed up and the pure tone hearing test was conducted. In total, 6 297 subjects completed two or more physical checks and the pure tone hearing test and were included in the analysis. The noise exposure level at the workplace and the equivalent continuous A-weighted sound pressure level for workers was monitored and the cumulative noise exposure dose was evaluated. The subjects were divided into low, middle and high exposure groups according to the noise exposure level, and the equivalent continuous A-weighted sound pressure level for 8 hours for each group was 80.6-85.0, 85.1-90.0 and 90.1-103.4 dB (A), respectively. While the RR and 95% CI were derived from unconditional logistic regression models. In logistic regression analysis, confounding factors such as age, gender, smoking habit, drinking habit, high temperature exposure and chemical hazards exposure level were controlled. Results: During the follow-up period, 392 cases of occupational noise-induced hearing loss were diagnosed among the 6 297 subjects, with an incidence rate of 6.23%; 318 cases of high-frequency hearing loss were diagnosed, with an incidence rate of 5.05%; and 74 cases of occupational noise-induced deafness were diagnosed, with an incidence rate of 1.18% . The incidence rates of hearing loss among the high, medium and low exposure groups were 9.22% (158/1 737), 6.49% (204/3 142) and 2.08% (30/1 442), respectively; the rates of high-frequency hearing loss were 7.41% (127/1 737), 5.25% (165/3 142) and 1.80% (26/1 442), respectively; and the rates of occupational noise-induced deafness were 1.81% (31/1 737), 1.24% (39/3 142) and 0.28% (4/1 442), respectively. For the groups corresponding to cumulative noise exposure doses of ≤84.99, 85.00- 87.99, 88.00- 90.99, 91.00- 93.99, 94.00- 96.99, 97.00- 100.99, 101.00- 102.99 and ≥103.00 dB (A) · year, the incidence rates of hearing loss were 0 (0/185), 1.22% (2/164), 2.52% (17/674), 3.83% (35/913), 5.80% (106/1 827), 6.02% (67/1 113), 9.20% (95/1 003) and 18.04% (70/388), respectively. Compared with the low exposure group, the RR of hearing loss, high-frequency hearing loss and occupational noise-induced deafness for the high exposure group were 4.78 (95% CI: 3.22- 7.11), 4.36 (95% CI: 2.84- 6.69) and 6.63 (95% CI: 2.33- 18.82), respectively; and for the medium exposure group were 3.27 (95% CI: 2.22-4.82), 3.02 (95% CI: 1.99-4.59) and 4.52 (95% CI: 1.61-12.67), respectively. Conclusion: The incidence rate of hearing loss for workers exposed to noise in an iron and steel plant was related to the cumulative noise exposure dose, gender, age, educational level, smoking habits, drinking habits and exposure to high temperature.

Investigation into the relationship between mitochondrial 12 S rRNA gene, tRNA gene and cytochrome oxidase Ⅱ gene variations and the risk of noise-induced hearing loss

Objective: To explore the relationship between mitochondrial 12 S rRNA gene variation, tRNA gene variation and cytochrome oxidase Ⅱ gene point mutations and the risk of noise-induced hearing loss (NIHL). Methods: A nested case-control study was performed that followed a cohort of 7 445 noise-exposed workers in a steel factory in Henan province, China, from January 1, 2006 to December 31, 2015. Subjects whose average hearing threshold was more than 40 dB(A) in high frequency were defined as the case group, and subjects whose average hearing threshold was less than 35 dB(A) in high frequency and less than 25 dB (A) in speech frequency were defined as the control group. Subjects was recruited into the case group (n=286) and the control group (n=286) according to gender, age, job category and time of exposure to noise, and a 1∶1 case-control study was carried out. We genotyped eight single nucleotide polymorphisms in the mitochondrial 12 S rRNA gene, the mitochondrial tRNA gene and the mitochondrial cytochrome oxidase Ⅱ gene using SNPscan high-throughput genotyping technology from the recruited subjects. The relationship between polymorphic sites and NIHL, adjusted for covariates, was analyzed using conditional logistic regression analysis, as were the subgroup data. Results: The average age of the recruited subjects was (40.3±8.1) years and the length of service exposure to noise was (18.6±8.9) years. The range of noise exposed levels and cumulative noise exposure (CNE) was 80.1- 93.4 dB (A) and 86.8- 107.9 dB (A) · year, respectively. For workers exposed to noise at a CNE level<98 dB (A) · year, smokers showed an increased risk of NIHL of 1.88 (1.16-3.05) compared with non-smokers; for workers exposed to noise at a CNE level ≥98 dB(A) · year, smokers showed an increased risk of NIHL of 2.53 (1.49- 4.30) compared with non-smokers. For workers exposed to noise at a CNE level<98 dB (A) · year, the results of univariate analysis and multifactor analysis, adjusted by smoking and CNE, suggested that the risk of NIHL in workers exposed to noise carrying the GG genotype (G827A) was lower than that of NIHL workers exposed to noise carrying the AA genotype (G827A) [OR (95% CI) were 0.18 (0.04- 0.82) and 0.19 (0.04- 0.88), respectively]. Conclusion: Smoking increased the risk of NIHL in the present study. For workers subjected to a CNE<98 dB(A)·year, the mitochondrial genetic variant G827A was found to be significantly associated with the risk of NIHL.

Association between variations in protocadherin 15 gene and occupational noise-induced hearing loss

Objective: The aim of this study was to investigate whether genetic variability in the protocadherin 15 (PCDH15) gene may correspond with increased susceptibility to noise-induced hearing loss (NIHL) in a Chinese population. Methods: A nested case-control study was performed that followed a cohort of 7 445 noise-exposed workers in a steel factory of Henan province in China from January 1, 2006 to December 31, 2015. In this study, 394 cases who had an average hearing threshold of more than 40 dB (A) in high frequency were defined as the case group, and 721 controls who had an average hearing threshold of less than 35 dB (A) in high frequency and less than 25 dB (A) in speech frequency were defined as the control group. A questionnaire was completed by participants and a physical test was also conducted. SNP genotyping was performed using the SNPscanTM Kit. Multivariate unconditional logistic regression additive models were used to analyze the genotypes in different groups, and the association with NIHL. Unconditional logistic regression models were used to assess the associations between the genotypes and NIHL. Results: The average age of study participants was (40.5±8.3) years and the median number of noise-exposed working years M (P25, P75) was 21.1 (9.1, 27.3). The range of noise exposed levels and the levels of cumulative noise exposure (CNE) were 80.1- 98.8 dB(A) and 86.6- 111.2 dB(A), respectively. Only the distribution of the genotypes (TT/CC/CT) of rs11004085 in the PCDH15 gene showed a significant difference between the case and control groups (P=0.049). In the case group, the distribution was 370 (93.9%), 24 (6.1%) and 0; in the control group, the distribution was 694 (96.3%), 23 (3.2%) and 1 (0.1% ). After smoking, drinking, hypertension, height and CNE adjustment, compared with the TT genotype individuals with the CC/CT genotype had a 1.90-fold increased risk of NIHL (95% CI: 1.06- 3.40). After stratified these data by the noise exposure level or CNE when the noise exposure level was>85 dB (A), compared with cases with the AA genotype of rs10825113, individuals with the GA/GG genotype had a 2.63-fold increased risk of NIHL (95% CI: 1.12- 6.14). When the CNE was ≤ 98 dB(A), compared with cases with the TT genotype of rs11004085, individuals with the CC/CT genotype had a 2.96-fold increased risk of NIHL (95% CI: 1.33- 6.56). However, these differences were not significant after Bonferroni correction had been applied. Conclusions: The results confirmed that genetic variation within the PCDH15 gene may affect the susceptibility to NIHL.

Prevalence of Hazardous Occupational Noise Exposure, Hearing Loss, and Hearing Protection Usage Among a Representative Sample of Working Canadians.

Objective:The aim of this study was to estimate the prevalence of hearing loss (HL), self-reported occupational noise exposure, and hearing protection usage among Canadians.Methods:In-person household interviews were conducted with 3666 participants, aged 16 to 79 years (1811 males) with 94% completing audiometry and distortion-product otoacoustic emission (DPOAE) evaluations. Occupational noise exposure was defined as hazardous when communicating with coworkers at an arm's length distance required speaking in a raised voice.Results:An estimated 42% of respondents reported hazardous occupational noise exposure; 10 years or more was associated with HL regardless of age, sex or education. Absent DPOAEs, tinnitus, and the Wilson audiometric notch were significantly more prevalent in hazardous workplace noise-exposed workers than in nonexposed. When mandatory, 80% reported wearing hearing protection.Conclusions:These findings are consistent with other industrialized countries, underscoring the need for ongoing awareness of noise-induced occupational HL.

Simplified risk assessment of noise induced hearing loss by means of 2 spreadsheet models.

The objective of this study has been to test 2 spreadsheet models to compare the observed with the expected hearing loss for a Norwegian reference population. The prevalence rates of the Norwegian and the National Institute for Occupational Safety and Health (NIOSH) definitions of hearing outcomes were calculated in terms of sex and age, 20-64 years old, for a screened (with no occupational noise exposure) (N = 18 858) and unscreened (N = 38 333) Norwegian reference population from the Nord-Trøndelag Hearing Loss Study (NTHLS). Based on the prevalence rates, 2 different spreadsheet models were constructed in order to compare the prevalence rates of various groups of workers with the expected rates. The spreadsheets were then tested on 10 different occupational groups with varying degrees of hearing loss as compared to a reference population. Hearing of office workers, train drivers, conductors and teachers differed little from the screened reference values based on the Norwegian and the NIOSH criterion. The construction workers, miners, farmers and military had an impaired hearing and railway maintenance workers and bus drivers had a mildly impaired hearing. The spreadsheet models give a valid assessment of the hearing loss. The use of spreadsheet models to compare hearing in occupational groups with that of a reference population is a simple and quick method. The results are in line with comparable hearing thresholds, and allow for significance testing. The method is believed to be useful for occupational health services in the assessment of risk of noise induced hearing loss (NIHL) and the preventive potential in groups of noise-exposed workers. Int J Occup Med Environ Health 2016;29(6):991-999.