The Relationship Of Occupational Noise,Smoking And Shift Work With Hearing Loss And Hypertension

Occupational noise is a kind of sound which is boring,it is induced during the production,and its frequency and intensity is irregular.It is also called as industrial noise.Occupational noise is a common kind of occupational hazards,and it affects the health of workers seriously.It is estimated that approximately 600 million workers worldwide and 30 million American workers are exposed to occupational noise.In Europe,it is reported that almost 28% of workers worked in occupational settings with noise levels between 85 and 90 A-weighted decibels(d BA).And it may be more serious in China owing to its larger industrial population.Therefore,we hoped to study the relationship of occupational noise,smoking,shift work with hearing loss and hypertension among large scale participants.Part One The relationship of occupational noise,smoking andshift work with hearing loss Objectives: To explore the relationship of occupational noise,smoking and shift work with hearing loss;meanwhile,to study the combined effect of smoking and occupational noise exposure on hearing loss,and the combined effect of shift work and occupational noise exposure on hearing loss.Methods: The basic information was collected by face-to face investigation,including basic characteristics,smoking status,shift work,and occupational history.The industrial noise level for each job title at workplace came from the company records which were measured by qualified industrial hygienists or estimated by using monitoring data from similar job titles.The occupational noise exposure was defined as exposed to the normalized continuous A-weighted sound pressure level equivalent to an eight-hour per day of 80 d B(A)or above(LEX,8h ?80 d B(A))for at least a year.Pure-tone audiometry was performed in a sound-isolated room by certified audiologists.Air conduction thresholds were determined for each ear at 0.5,1,2,4 and 8 k Hz across an intensity range of-10 to 120 d B.Hearing loss was defined as a pure-tone average of 25 d B or higher at 0.5,1,2,and 4 k Hz in either ear.Logistic regressions were used to analyze the independent effect of occupational noise,smoking,and shift work on hearing loss,the combined effect of occupational noise and smoking on hearing loss,the combined effect of occupational noise and shift work on hearing loss.We also divided hearing loss into exclusive unilateral,bilateral and either ear categories.Results: A total of 11196 subjects were included in this part.Among them,5060 participants(45.2%)were males and 6136 participants(54.8%)were females.Overall,3878 individuals(34.6%)reported to occupational noise exposure,and the number of smokers,non-smokers,and ex-smokers was 2063(18.4%),7484(66.8%),and 1649(14.8%).In addition,4952 individuals(44.2%)reported to shift work,and the number of hearing loss for unilateral,bilateral and either ear was 1800(16.1%),6888(61.5%)and 8688(77.6%)respectively.For relationship between occupational noise and hearing loss,compared with participants not exposed to occupational noise,the risk of hearing loss was significantly higher among noise exposure duration for 20 years or more group(OR=1.45,95%CI=1.28-1.65),after adjusting for potential confounders.And the associations were more pronounced among males(OR=1.74,95%CI=1.45-2.08),aged 60-<70(OR=1.37,95%CI=1.17-1.61)and aged over 70(OR=1.74,95%CI=1.30-2.33).For relationship between smoking and hearing loss,compared with nonsmokers,current smokers had higher risk of hearing loss,and the risk increased with the amount of cigarette,especially for bilateral hearing loss.The odds ratios for pack-years of 0-<25 and ?25 and bilateral hearing loss were 1.29(1.10-1.51)and 1.42(1.21-1.66).This association was more evident among males,though it was also significant between pack-years of 0-<25 and bilateral hearing loss among females(OR=1.54,95%CI=1.02-2.33).When occupational noise and smoking were combined,the association was additive,and the synergy index was 1.621.Individuals with longer noise exposure duration(?20 years)and more pack-years of smoking(?25 pack-years)got the highest risk(OR=2.41,95%CI=1.78-3.28).For relationship between shift work and hearing loss,compared with participants with no shift work,the risk between shift work and bilateral hearing loss was significant(OR=1.12,95%CI=1.03-1.22),and it was also significant among females(OR=1.13,95%CI=1.01-1.27),not among males.When occupational noise and shift work were combined,the association was additive,and the synergy index was 1.569.Individuals with the longest noise exposure duration(?20 years)and longest shift work duration(?10 years)got the highest risk(OR=1.91,95%CI=1.58-2.31).Conclusions: Long-term exposure to occupational noise could increase the risk of bilateral hearing loss.Smoking and shift work may be independent risk factors for hearing loss.The relationship between smoking and hearing loss was in a dose-response way,the risk increased with the amount of cigarettes.Smoking and shift work could both increase the risk of hearing loss when combined with occupational noise.Part Two The relationship of occupational noise,smoking andshift work with hypertension Objectives: To explore the relationhip of occupational noise,smoking and shift work with hypertension;meanwhile,to study the combined effect of smoking and occupational noise exposure on hypertension,and the combined effect of shift work and occupational noise exposure on hypertension.Methods: The basic information,occupational noise and pure-tone audiometry were the same as part one.Hypertension was defined as blood pressure 3140/90 mm Hg or self-reported physician diagnosis of hypertension or self-reported current use of antihypertensive medication.Logistic regressions were used to analyze the independent effect of occupational noise,smoking,and shift work on hypertension,the combined effect of occupational noise and smoking on hypertension,the combined effect of occupational noise and shift work on hypertension.We also used hearing loss as an indicator to verify the association of occupational noise and hypertension,when explore the relationship between occupational noise and hypertension.Results: A total of 22450 subjects were included in this part.Among them,10097 participants(45.0%)were males and 12353 participants(55.0%)were females.Overall,8587 individuals(38.2%)reported to occupational noise exposure,and the number of smokers,non-smokers,and ex-smokers was 3978(17.7%),15772(70.3%),and 2700(12.0%).In addition,10579 individuals(47.1%)reported to shift work,and the number of hypertension and normotension was 11799(52.6%)and 10651(47.4%).For relationship between occupational noise and hypertension,compared with participants not exposed to occupational noise,the risk of hypertension was significantly higher among noise exposure duration for 20 years or more group(OR=1.09,95%CI=1.00-1.19),after adjusting for potential confounders.And the associations were more pronounced among males(OR=1.16,95%CI=1.03-1.31),not among females(OR=1.01,95%CI=0.88-1.41).When we used the hearing loss as an indicator for exposure to loud noise,it was also revealed that bilateral hearing loss was associated with hypertension,and got the highest risk(OR=1.39,95%CI=1.24-1.54),after adjusting for potential confounders.For relationship between smoking and hypertension,compared with nonsmokers,pack-years of ?25 was associated with hypertension(OR=1.22,95%CI=1.03-1.45).When occupational noise and smoking were combined,the association was additive,and the synergy index was 1.677.Individuals with longer noise exposure duration(?20 years)and more pack-years of smoking(?25 pack-years)got the highest risk(OR=1.52,95%CI=1.19-1.94).For relationship between shift work and hypertension,compared with participants with no shift work,the risk between shift work and hypertension was almost not statistically significant,whether for the shift work(OR=1.01,95%CI=0.95-1.07)or the duration of shift work(OR=1.02,95%CI=0.94-1.12;OR=1.00,95%CI=0.93-1.07).When occupational noise and shift work were combined,the association was also not statistically significant.Conclusions: Long-term exposure to occupational noise could increase the risk of hypertension,and the result was also verified when we used hearing loss as an indicator for exposure to loud noise.Smoking may be independent risk factors for hypertension,pack-years of smoking(?25 pack-years)was associated with higher risk of hypertension.The combined effect of smoking and occupational noise exposure was additive,it could increase the risk of hypertension when combined with occupational noise.The results provided limited evidence for the association between shift work and hypertension.