Study Of Genetic Susceptibility To Occupational Noise-Induced Hearing Loss

Industrial noise pollution, as one of the most prevalent occupational hazards, plays an reverse effects on workers’ health and then increases the cost of business management and social health burden. In the first part of this study, a hygienic investigation to industrial noise pollution and workers’ health in an automobile manufacturing enterprise was conducted, and the health risks of occupational noise exposure to young workers was also explored. In the second part, the correlation of KCNQ4, GJB2 genetic polymorphisms and occupational noise-induced hearing loss in workers exposed to noise was used to explore the hereditary susceptibility in the noise-induced hearing loss (NIHL). Besides, whole-exome sequencing was applied to find SNPs of susceptibility genes of NIHL in the noise sensitive workers. In the last part, the effects of health education in occupational noise exposed workers and health intervention in workplace was conducted to prevent the hearing loss for noise exposed workers and the effects of education and intervention were evaluated.1. Hygienic Investigation to Industrial Noise Pollution and Workers’Health in an Automobile Manufacturing EnterpriseThe cross-sectional study was used to investigate the level of noise exposure and workers’health situations. The correlation between the blood pressure, electrocardiogram and high frequency hearing loss in workers were analyzed. Meanwhile, the influence to high frequency hearing loss on workers with different demographic characteristic, noise exposure level and the habits of smoking and drinking were exploredThe working position with noise exposure in the enterprise are generally exceed national standards, the proportion of the occupational hazard position in two stamping shops was 94.12%(16) and 82.36%(14), respectively,14.39%(4) and 37.50%(12) in two welding shops, respectively.The incidence rate of workers with high frequency hearing loss is relatively high. The ratio of workers whose high frequency threshold≥40dB was 8.98%(66), the ratio of suspected noise deafness was 2.45%(18). There’s no correlation between changes of blood pressure, electrocardiogram and workers’ high frequency hearing loss. The incidence rate of high frequency hearing loss in welding shop was different in gender. High frequency hearing loss rises with the age and exposed time. With the rise of noise sound pressure, the incidence of high frequency hearing loss is increasing.2. The Investigation on the Influence of Hearing and Cardiovascular System in New and Young Workers Exposed to Occupational NoiseA total of 367 workers, less than 30 years old, with normal hearing during the entry examination were admitted to the study identified from Occupational health examination institutes in Nanjing from 2011 to 2013. The difference of hearing, blood pressure and ECG were analyzed using the 3 times healthy examination data before and after the exposure to occupational noise within 2 years.The detection rate of noise induced hearing loss (NIHL) (> 25dB (A))on high frequency hearing threshold in young workers was 4.63% within one-year noise exposure, and 3.94% within two-year noise exposure. There were 3 workers diagnosed with noise-sensitive after one-year noise exposure. Systolic blood pressure (SBP) of young worker was significantly increased after one-year noise exposure. The prevalence of hypertension in female workers increased after one-year noise exposure. Male workers’ abnormal ECG rates including cardiac arrhythmias and other abnormalities like bundle branch block, ST-T change had a significant increase after one-year noise exposure.3. Correlation of KCNQ4, GJB2 Genetic Polymorphisms and Occupational Noise-induced Hearing Loss1:1 matched case-control design was used in this study. The genetic polymorphisms of KCNQ4(rs34287852) and GJB2 (rs3751385) were detected by polymerase chain reaction and direct sequencing in 103 pairs of hearing loss workers and normal workers with the same noise exposure. The relationship between target SNPs and noise induced hearing loss (NIHL) were analyzed.There is no statistical difference of the frequency of T, G alleles and genotypes in KCNQ4(rs34287852) between cases and controls. The frequency of C allele and CC mutation genotype in GJB2 (rs3751385) was significantly higher in case group than that in control group. Workers carried CC homozygous mutations were at the 2.78 fold risk of developing hearing loss than individuals with TT wild homozygous type when they were exposed to the occupational noise.4. Study of Candidate Susceptibility Gene SNPs of Noise-induced Hearing Loss through Whole-exome SequencingFive workers were chosen for the study, whose hearing was normal when they began to work, high frequency hearing loss (≥40dB(A)) was then happened in three years after industrial noise exposure. DNA from peripheral blood was extracted, conducted high-throughput sequencing. The final SNPs numbers in exon region were 21016,21510,21333,20815,21013, respectively. Compared with the 1000 Gene Pool, acquired mutation points and genes with the demanding of Minor Allele Frequency(MAF)<0.2 basis on the Pool,55 SNPs from 45 genes with non-synonymous located in exon region were selected, which were involved in energy metabolism, redox, transcriptional regulation, structural maintenance and other functions. Combined with genetic information and relevant references, we proposed several susceptibility candidate gene SNPs related to noise-induced hearing loss as follows:PARP15 (rs7632426), GSTT2 (rs2301423), MYH13 (rs3744550), SDC3 (rs2282440), TCF3 (rs2074888).5. Evaluation on Health Education in Occupational Noise Exposed Workers and Health Intervention in workplaceAccording the results of noise related KAP baseline investigation, targeted health education and intervention were carried out. The effects of heath education and intervention were also evaluated by comparing the education questionnaire and physical examination before and after the interventionAfter the health education, both of the managers and workers’knowledge and attitude make improvements, that including the of usage earplugs and proper wear, development process of noise deafness, correct understanding of hearing fatigue, medication on noise deafness, noise-exposed contraindications. Meanwhile, occupational health management and supervision were carried out to prevent noise induce hearing loss by the factory.It showed the workers protection practice for noise had also improved one year after the health education and intervention and the rate of high-frequency hearing loss also declined in the next occupational health examination.6. ConclusionNoise pollution in stamping workshop and welding workshop is widespread. There is certain correlation between noise-induced hearing loss and age, exposure time, and the level of noise exposure. Newly recruited young workers, who have been exposed in noise for 2 years, are in the occupational health risk, and those who are exposed in noise for 1 year, are faced with a much higher rate of incidence of high frequency hearing loss. It might be associated with some young workers susceptible to noise exposure.There is correlation between GJB2 (rs3751385) mutation and NIHL, and the CC genotype might be one of the susceptible genotype of NIHL.Through whole-exome sequencing,55 SNPs in 45 genes were obtained, which involved in energy metabolism, redox, transcriptional regulation, structural maintenance and other functions. Combined with genetic information and relevant references, several SNPs were selected for candidate susceptibility SNPs related to noise-induced hearing loss:PARP15 (rs7632426), GSTT2 (rs2301423), MYH13 (rs3744550), SDC3 (rs2282440), TCF3 (rs2074888).Some insufficient on noise related KAP was still existed for the workers in the automobile manufacturing workers. After attending occupational health education along with health intervention, the workers made an improvement on protection practice and the incidence of high frequency hearing loss were also reduced.