[On the reaction of finger pulse amplitude to noise (author's transl)]

Associations between traffic noise, particulate air pollution, hypertension, and isolated systolic hypertension in adults: the KORA study

BACKGROUND

Studies on the association between traffic noise and cardiovascular diseases have rarely considered air pollution as a covariate in the analyses. Isolated systolic hypertension has not yet been in the focus of epidemiological noise research.

METHODS

The association between traffic noise (road and rail) and the prevalence of hypertension was assessed in two study populations with a total of 4,166 participants 25-74 years of age. Traffic noise (weighted day-night average noise level; LDN) at the facade of the dwellings was derived from noise maps. Annual average PM2.5 mass concentrations at residential addresses were estimated by land-use regression. Hypertension was assessed by blood pressure readings, self-reported doctor-diagnosed hypertension, and antihypertensive drug intake.

RESULTS

In the Greater Augsburg, Germany, study population, traffic noise and air pollution were not associated with hypertension. In the City of Augsburg population (n = 1,893), where the exposure assessment was more detailed, the adjusted odds ratio (OR) for a 10-dB(A) increase in noise was 1.16 (95% CI: 1.00, 1.35), and 1.11 (95% CI: 0.94, 1.30) after additional adjustment for PM2.5. The adjusted OR for a 1-μg/m3 increase in PM2.5 was 1.15 (95% CI: 1.02, 1.30), and 1.11 (95% CI: 0.98, 1.27) after additional adjustment for noise. For isolated systolic hypertension, the fully adjusted OR for noise was 1.43 (95% CI: 1.10, 1.86) and for PM2.5 was 1.08 (95% CI: 0.87, 1.34).

CONCLUSIONS

Traffic noise and PM2.5 were both associated with a higher prevalence of hypertension. Mutually adjusted associations with hypertension were positive but no longer statistically significant.

Circulatory effects of noise

Thirteen patients with mild essential hypertension, mean age 44 years (range 21-59), were studied during "stress" before and after postsynaptic alpha-adrenoceptor blockade and combined postsynaptic alpha- and non-selective beta-adrenoceptor blockade. Loud broad band noise (100 dBA for 10 min) was used as the stress stimulus. Exposure to noise caused a significant increase in systolic (7%, p less than 0.05), diastolic (9%, p less than 0.01) and mean arterial pressure (6%, p less than 0.01). The blood pressure elevation was caused by an increase in total peripheral resistance (12%, p less than 0.05). There was no significant change in heart rate, stroke volume or cardiac output. The blood pressure response during noise stimulation was not affected by postsynaptic alpha-adrenoceptor blockade (prazosin, 2 mg orally). The hemodynamic reaction pattern, however, was totally reversed. Thus, the cardiac output increased significantly (9%, p less than 0.05), while the total peripheral resistance tended to decrease. Combined postsynaptic alpha- and non-selective beta-adrenoceptor blockade (labetalol, 200 mg orally) inhibited the increase in systolic blood pressure caused by noise, while the diastolic and mean arterial pressures still increased significantly (5%, p less than 0.01). Labetalol effectively blocked the stress-induced increase in total peripheral resistance and there was no significant increase in cardiac output after combined alpha- and beta-adrenoceptor blockade. Exposure to noise caused a significant increase in circulating noradrenaline (20%, p less than 0.05). Plasma adrenaline and plasma renin activity were not affected by noise stimulation. These results suggest that blood pressure elevation is essential during "stress" but that the hemodynamic pattern causing blood pressure elevation may vary and may be affected by pharmacological blockade of various parts of the sympathetic nervous system.

Traffic Noise and Risk of Myocardial Infarction

BACKGROUND

The biologic plausibility for noise stress-related cardiovascular responses is well established. Epidemiologic studies on the relationship between transportation noise and ischemic heart disease suggest a higher risk of myocardial infarction in subjects exposed to high levels of traffic noise.

METHODS

To determine the risk of road traffic noise for the incidence of myocardial infarction (MI), we carried out a hospital-based case-control study in the city of Berlin. We enrolled consecutive patients (n=1881), age 20-69 years, with confirmed diagnosis of MI from 1998 through 2001. Controls (n=2234) were matched according to sex, age, and hospital. Outdoor traffic noise level was determined for each study subject based on noise maps of the city. Standardized interviews were conducted to assess possible confounding factors and the annoyance from various noise sources.

RESULTS

The adjusted odds ratio for men exposed to sound levels of more than 70 dB(A) during the day was 1.3 (95% confidence interval=0.88-1.8) compared with those where the sound level did not exceed 60 dBA. In the subsample of men who lived for at least 10 years at their present address, the odds ratio was 1.8 (1.0-3.2). Noise-exposed women were not at higher risk.

CONCLUSIONS

The results support the hypothesis that chronic exposure to high levels of traffic noise increases the risk for cardiovascular diseases.

Study of some cardiovascular parameters after chronic exposure to noise

Research has focussed lately on noise as a risk factor for cardiovascular diseases. Recent findings, which have not been well confirmed, indicate that it does appear to affect heart rate, blood pressure and the electrocardiogram. This study involved two groups of subjects (with 75 and 225 in each, respectively) classified on the basis of different intensity of exposure to noise. Non-occupational risk factors studied (cholesterol, blood glucose, smoking, body mass index, family history of cardiovascular problems) revealed no significant differences between the two groups. Audiometric deficits and time exposure to noise were also studied. Blood pressure was measured at rest, an electrocardiogram was taken, and a cycloergometric stress test was made. The prevalence of hypertension and electrocardiographic modifications in basal conditions and under the stress test differed to a significant extent in relation to the different exposures to noise.

Vibration disease

Today, in this age of technology, vibration caused by machinery is an almost universal hazard. Vibration transferred from a machine to the human body may cause discomfort, a reduction of performance, and even injury. Vibratory manual tools may cause damage to the circulatory system of the upper extremities (Raynaud's syndrome), to the peripheral nerves (peripheral neuropathy), and to the bones and joints (aseptic necrosis, fatigue fractures, degenerative joint disease). Vehicles and machines causing floor vibration cause degenerative disc disease of the lumbar spine. The pathogenesis of vibration injuries is still not completely clear and there is no effective treatment. Some of the abnormalities are irreversible and may cause permanent decrease of working ability, and even unemployment. This is why prevention is so important. Prevention is complex, including technical and organizational measures, use of individual protective clothing and footwear, and medical supervision both before and during employment. Workers who are exposed to vibration should be protected against other aggravating factors such as cold and noise, etc. Vibration-induced injuries are recognized in law in many countries as grounds for financial compensation. Their cost to industry is rising and, unless a means of prevention or cure is found, will continue to do so in the foreseeable future.

Non-auditory effects of noise in industry. VII. Evaluation, conclusions and recommendations

The results of epidemiological studies on non-auditory effects of noise in industry are commented upon. The present state of the art does not permit any definite conclusion to be drawn about the risk of hypertension. Annoyance by noise is widespread; it has many different aspects and it has been studied in detail in this project. Combinations of working conditions should be studied that produce interaction effects overloading psychological or physiological systems. Some examples are given. Standards and guidelines for industrial exposure to noise should also prevent wellknown, non-auditory effects, such as communication problems, which result in social isolation.

Traffic noise and hypertension: an epidemiological study on the role of subjective reactions

Traffic noise is discussed as a possible risk factor for hypertension. However, no data are available concerning the moderating effect of the subjective reactions and the noise attitudes. In the present epidemiological study the relationship between these subjective factors and blood pressure was investigated separately for the inhabitants of two residential areas. One area had high traffic volumes, resulting in a high sound level (Leq greater than 73 db (A), noisy area); the other was socially comparable but with an essentially low sound level (Leq less than 51 db (A), control area). The relationship between the subjective reactions and blood pressure was checked by analyzing the incidence of treatment for hypertension (n = 919) and by analyzing the change of casual blood pressure after living 2.25 years in the respective residential area in a subgroup of those who had been normotensive (n = 36). The results obtained by either of these approaches indicate that the subjective factors do not modify the risk of hypertension in noisy areas, whereas they seem to be relevant for medium size stimuli. It is concluded that one can physiologically cope with low stimuli, but this is impossible for extreme stimuli. The results suggest also that the subjective reaction to extreme stimuli is strongly biased by attitudes which cannot be related to blood pressure. The family history of hypertension was found to be independent of the subjective reactions to noise.