Epidemiological Investigation Of Noise-Induced Hearing Loss And Its Influencing Factors In Shipbuilding Enterprises

Objective:The purpose of this study is to investigate the noise exposure level and noise-induced hearing loss of workers in China's shipbuilding enterprises,explore the relationship between related influencing factors and NIHL(Noise-induced hearing loss),and provide a scientific basis for preventing hearing loss.Methods:In this study,the method of cross-sectional survey was adopted to select 5157 noise exposure workers from 5 shipbuilding enterprises for questionnaire survey,individual noise exposure level detection and pure tone gas conduction threshold test(pure tone gas conduction threshold test with 6 frequencies of 0.5 kHz,1 kHz,2 kHz,3 kHz,4 kHz and 6 kHz in both ears).According to the inclusion and exclusion requirements,4726 male workers were finally identified as the objects of this survey.Kruskal-wallis H test was used to analyze the prevalence of conscious hearing loss and tinnitus frequency under different CNE.The prevalence of actual hearing loss under different frequencies of conscious hearing loss and tinnitus.Spearman rank correlation was used to analyze the correlation between CNE and perceived hearing loss and tinnitus frequency.The correlation between perceived hearing loss,tinnitus frequency and actual hearing loss.The relationship between smoking and NIHL was analyzed by chi-square test.Using the Cochran-Armitage trend test,the trends of daily smoking amount,smoking age,smoking index and prevalence of NIHL,as well as the trends of Cumulative noise exposure(LAeq.sh),working age,Cumulative noise exposure(CNE)and prevalence of NIHL were analyzed.Univariate and multivariate Logistic regression models were used to determine the effects of age,CNE,smoking,and HPD use on the prevalence of NIHL,and the OR value and 95%confidence interval(95%CI)were used to estimate the risk of NIHL.In addition,this research also another selection in 2015 and 2017 annual occupational health monitoring and occupational health of some ships enterprise 224 noise workers as the research object,using the method of retrospective cohort study to collect data,including the general situation of workers,pure tone air conduction audibility threshold test results and the field noise monitoring data,using a paired t test analysis 224 noise exposed workers themselves before and after two years of high frequency and frequency changes of hearing.Results:1.According to the inclusion and exclusion criteria,the survey finally included 4726 male noise-exposed persons,with an average age of(38.10±8.78)years,ranging from 18 to 66 years;The average duration of noise exposure was(7.69±4.50)years,ranging from 1 to 40 years;the average noise exposure level(LAeq.8h)is(94.73±4.66)dB(A),ranging from 84 to 108dB(A).2.The average of the study subjects' high-frequency hearing threshold(3 kHz,4 kHz and 6 kHz)was(33.65±15.09)dB HL,and the average of the language frequency hearing threshold(0.5 kHz,1 kHz,2 kHz)was(24.11±8.71)dB HL.The usage of personal protective equipment showed that the workers who frequently used HPD(88.74%)were higher than the infrequent users(11.26%).The results of hearing loss showed that 1547 subjects(32.73%)had simple high-frequency hearing loss,1010 subjects(21.37%)had achieved the noise-induced deafness(NID)standard,among which 808 workers(80.00%)had mild NID,182 workers(18.02%)had moderate NID,and 20 workers(1.98%)had severe NID.3.Kruskal-wallis H test and Spearman rank correlation analysis results showed that CNE was positively correlated with conscious hearing loss and tinnitus frequency,and the prevalence of conscious hearing loss and tinnitus was mainly concentrated in CNE>101dB(A)"years workers.There is a positive correlation between conscious hearing loss,tinnitus frequency and the prevalence of actual hearing loss,that is,the more serious the workers' conscious hearing loss and tinnitus frequency are,the more serious their actual hearing loss is.4.Cochran-Armitage trend test results showed that as the LAeq,8h,length of service and the enlargement of the CNE,high frequency hearing loss and the prevalence of noise deafness is rising trend,showing obvious dose response relationship,of which 98 dB(A)·years<CNE?104 dB(A)·years,in high frequency increase in the incidence of hearing loss and noise deafness speed slow,and when the CNE>104 dB(A)·years,in high frequency rate of increase in the incidence of hearing loss and noise deafness and began to grow fast.The retrospective cohort study found that at different LAeq.8h levels,after two years of operation in the same noise environment,both the high-frequency and speech frequency hearing thresholds of the study object increased to different degrees.When LAeq.8h>95dB(A),the increase range of the high-frequency hearing threshold decreased,while the speech frequency hearing threshold did not change significantly.5.Chi-square test results showed that when the cumulative noise exposure dose(CNE)of workers exposed to noise was<100dB(A)·years,smoking behavior might have an impact on the occurrence of high-frequency hearing loss,while when CNE>100dB(A)·years,smoking behavior might have an impact on both high-frequency and speech frequency hearing loss.6.The results of the Cochran-Armitage trend test showed that among workers aged?<45 years old,when the CNE?100dB(A)·years,the prevalence of hearing loss at high frequency increased with the increase of daily smoking amount or smoking age,and all showed an obvious linear trend.When CNE>100dB(A)·years,the prevalence of hearing loss at high frequency also increased with the increase of smoking age,but in the range of speech frequency,only the prevalence of hearing loss at 2kHz increased with the increase of smoking age.After the analysis of the smoking index,the results showed that among workers less than 45 years old,when the CNE?100dB(A)·years,the prevalence of hearing loss at high frequency also increased with the increase of the smoking index,presenting an obvious linear trend.In the CNE>100dB(A)·years,in the high frequency range,the prevalence of hearing loss of 4kHz and 6kHz increased with the increase of smoking index,but in the speech frequency range,only the prevalence of hearing loss of 2kHz increased with the increase of smoking index.7.The results of multivariate Logistic regression showed that after model correction,age,CNE,smoking behavior were significantly correlated with the incidence of NIHL.The OR value of high-frequency increased by 5.8%for every 1 year of worker's age(OR:1.058;95%CI:1.050-1.067),the OR value of NID increased by 4%(OR:1.040;95%CI:1.030-1.050).For each 1 dB(A)·years increase in CNE,the OR value of high-frequency hearing loss increased by 11.2%(OR:1.112;95%CI:1.094-1.130),The OR value of NID increased by 12.5%(OR:1.125;95%CI:1.104-1.146).Compared with non-smoking workers,the OR value of high-frequency hearing loss in smoking workers increased by 78.7%(OR:1.787;95%CI:1.566-2.039),the OR value of NID increased by 112%(OR:2.120;95%CI:1.824-2.465).Conclusion:Noise is the main occupational hazard of China's shipbuilding enterprises.The level of noise exposure is high in all positions exposed to noise,and the exposure level of positions exposed to high levels of noise is above 100dB(A).The hearing level of workers exposed to noise has decreased significantly,and the research results Shows that age,CNE,and smoking behavior are risk factors for NIHL.To this end,it is urgent to strengthen the hearing protection work of noise-exposed workers in shipbuilding enterprises,such as strengthening noise engineering protection and individual hearing protection,increasing the frequency of pure audiometry,and strengthening publicity and education,Carry out tobacco control actions,etc.to effectively protect the physical health of workers.