Effects Of Noise On The Hearing And Cardiovascular System In Noise-exposed Workers

As is known to all, hearing loss is the most important one of the occupational hazards of industrial noise. A large number of epidemiological data showed that long-term exposure can result in the multisystem damage including the cardiovascular system. Noise is an important risk factor which can lead to the abnormal level of blood lipid, blood pressure and cardiovascular related biochemical indicators. But the results are not consistent. Occupational noise is a source of stress and can cause the oxidative stress reaction of the body. The study found that homocysteine(Hcy) is a kind of markers of oxidative stress and the changes of the fibrinogen(Fib) are also associated with the body’s stress response. Homocysteine and fibrinogen are independent risk factors for cardiovascular disease. But the related research in the crowd of professional people is almost none.【Objective】1. To survey the density of noise in workplace and analyze the effects of density of noise on noise-induced hearing loss.2. To analyze the levels of serum homocysteine and plasma fibrinogen in workers. And research the correlation between the serum Hcy and the blood pressure, blood lipid level and abnormal electrocardiogram. To explore the feasibility of serum homocysteine as the early biomarkers of noise-induced CVD.【Methods】1. According to “the physical factors measurement in workplaces part 8: noise”(GBZ/T189.8-2007), three noise operational factories were selected for occupational health survey.2. Based on the cluster sampling method and using the self-made questionnaire, workers’ general condition were investigated by us. Focus on the medical history and symptoms of the cardiovascular system and ear problems past medical history. According to “the occupational health technical specification”(GBZ188-2014), physical examination(including blood pressure,height, weight), otology routine inspection(pure tone audiometry, pinnaouterear) and internal medical routine inspection(electrocardiogram) were undertaked.3. To measure the serum homocysteine with cycling enzymatic method, and plasmafibrinogen was measured by coagulation method. The levels of TG, CHOL, HDL and LDL were determined.The obtained data were inputed into Epidata 3.1 database by dual record, and analysed by SPSS19.0 statistical analysis software. Through chi-square test, covariance analysis,multivariate regression analysis.【Results】1. The intensity of noise monitoring results show that the exceeding standard rate is44.4%~50.0% in the three factory noise assignments. Detection rate of abnormal audition in exposed group(22.24%) is higher than the control group(1.52) and the differences has statistically significant(P<0.05).2. The levels of Hcy in the control group are lower than those of the exposure group(P<0.05). The total detection rates of HHcy is 75.96%. The detection rates of HHcy in the exposedgroup is significantly higher than the control group(91.49% vs 56.57%), and the difference is statistically significant(P<0.05). The detection rate of HHcy increases with the raising of noise exposure quantity in workers who exposed to noise(P<0.05).3. The levels of systolic blood pressure, diastolic blood pressure and TG in the noise exposure group were significantly higher than that of the control group, and the differences has statistically significant(P<0.05). and the level of CHOL, LDL and HDL has no statistical significance(P>0.05). The detection rate of hypertension in the noise exposure group were significantly higher than that of the control group(28.74% vs 15.15%), and the differences has statistically significant(P<0.05). The detection rate of high-normal blood pressure has no statistically significant difference between the noise exposure group and the control group(57.89% vs 54.04%, P>0.05). The detection rate of abnormal electrocardiogram in exposed group is higher than the control group(22.70% vs 5.56%) and the differences has statistically significant(P<0.05). The detection rate of hypertension and abnormal electrocardiogram increases with the raising of noise exposure quantity in workers who exposed to noise(P<0.05).4. By the partial correlation analysis, the results showed that the levels of systolic blood pressure, CHOL, TG, LDL, CHOL/HDL and LDL/HDL increased with the rising of serum Hcy and it showed a positively correlated(P<0.05). The levels of HDL, diastolic bloodpressure levels decreased with the increase of serum Hcy and it showed a negative correlation(P<0.05). The multiple Logistic regression analysis indicated that TG, systolic and diastolic blood pressure are the independent risk factors for Hcy(P<0.05).5. The level of Fibrinogen between noise exposure group and control group has no statistical significance(P>0.05).6. The abnormal detection rate of serum Hcy, TG, LDL, HDL, high blood pressure and electrocardiogram in workers who wearing protective equipment is higher than the control group(P<0.05).【Conclusions】Occupational noise exposure can elevate the levels of Hcy and the detection rate of HHcy. The detection rate of HHcy increases with the raising of noise exposure quantity in workers who exposed to noise. It has linear correlation between serum Hcy and blood pressure, blood lipid. It has the feasibility of serum homocysteine as early biomarkers of noise-induced CVD, but it needs further research and discuss. So the detection of serum Hcy levels in combination with the traditional indicators, such as blood pressure, blood lipids and electrocardiogram have a great significance to reduce the occurrence of cardiovascular events in work and daily health eximination.