[Estimation of Health Risk Posed by Road Traffic Noise in Japan Based on the Environmental Noise Guidelines for the European Region].

OBJECTIVES: Traffic noise exposure is associated with adverse health effects such as environmental sleep disorder, ischaemic heart disease (IHD), stroke and diabetes. The health risks posed by traffic noise were estimated to be quite high in European countries. However, in Japan, no estimation has ever been conducted. In the present study, we estimated the health risk posed by road traffic noise in Japan. METHODS: We estimated the risks of environmental sleep disorder (high sleep disturbance) and IHD caused by road traffic noise in Japan as of 2015 on the basis of existing noise-exposure estimates, vital statistics of deaths, and patient survey with exposure-response relationships proposed by the Environmental Noise Guidelines for the European Region issued in 2018. We employed old information on noise exposure in 1994 because it is the only information currently available in Japan. We also estimated the health risks of noise exposure levels that were equivalent to the Japanese environmental quality standards. RESULTS: The estimated numbers of patients with environmental sleep disorder and IHD caused by road traffic noise were approximately 1,200,000 and 9,000, respectively. The estimated number of mortalities from IHD was approximately 1,700. The noise exposure level equivalent to the Japanese noise standards caused a lifetime mortality rate of more than 10-2, which was extremely high as an environmental health risk. CONCLUSIONS: As in European countries, road traffic noise was one of the most important environmental risk factors in Japan. However, the current Japanese noise standards are insufficient for the protection of public health.

Development of a new night-time noise index: Integration of neurophysiological theory and epidemiological findings.

BACKGROUND: The effects of environmental noise on sleep are of great interest to public health. Numerous studies have been conducted to investigate these effects; however, these previous studies applied existing sound-level statistics that were not based on neurophysiology. AIMS: This study aimed to develop a new night-time noise index based on neurophysiology and epidemiology. METHODS: First, we derived a formula for predicting the noise effects on sleep based on a neurophysiological model of brainstem sleep regulation, where awakening was associated with greater electrical potentials in the brainstem. Second, we investigated the noise effects on sleep using the results of an epidemiological study conducted in the vicinity of the Kadena military airfield in Okinawa, Japan. Thirty volunteers participated in the study. Vibrations of whole-body movements were recorded using sheet-shaped sleep monitors for 26 consecutive nights. The onset of motility, which was defined by monitor vibrations, was used to index awakening reactions. RESULTS: Our statistical model could properly predict the fluctuating risk of motility onset. The new index, which is the mean of the sound level above 60 dB, can be successfully used, irrespective of the duration of noise exposure. Additionally, it out-performed existing event-related noise indices. CONCLUSIONS: We derived a new night-time noise index for evaluating the noise effects on sleep. To our knowledge, this is the first study to explain the noise effects on sleep with the consideration of neurophysiology and epidemiology.

Night-Time Noise Index Based on the Integration of Awakening Potential.

Sleep disturbance induced by night-time noise is a serious environmental problem that can cause adverse health effects, such as hypertension and ischemic heart disease. Night-time noise indices are used to facilitate the enforcement of permitted noise levels during night-time. However, existing night-time noise indices, such as sound exposure level (SEL), maximum sound level (LA max) and night equivalent level (L night) are selected mainly because of practical reasons. Therefore, this study proposes a noise index based on neurophysiological determinants of the awakening process. These determinants have revealed that the potential on awakening is likely integrated into the brainstem that dominates wakefulness and sleep. From this evidence, a night-time noise index, N awake,year, was redefined based on the integration of the awakening potential unit (p unit) estimated from the existing dose-response relationships of awakening. The newly-defined index considers the total number of awakenings and covers a wide-range and number of noise events. We also presented examples of its applicability to traffic noise. Although further studies are needed, it may reveal a reasonable dose-response relationship between sleep disturbance and adverse health effects and provide a consistent explanation for the risks of different sound sources where the characteristics of noise exposure are quite different.

A Neurophysiological Approach for Evaluating Noise-Induced Sleep Disturbance: Calculating the Time Constant of the Dynamic Characteristics in the Brainstem.

Chronic sleep disturbance induced by traffic noise is considered to cause environmental sleep disorder, which increases the risk of cardiovascular disease, stroke, diabetes and other stress-related diseases. However, noise indices for the evaluation of sleep disturbance are not based on the neurophysiological process of awakening regulated by the brainstem. In this study, through the neurophysiological approach, we attempted (1) to investigate the thresholds of awakening due to external stimuli in the brainstem; (2) to evaluate the dynamic characteristics in the brainstem and (3) to verify the validity of existing noise indices. Using the mathematical Phillips-Robinson model, we obtained thresholds of awakening in the brainstem for different durations of external stimuli. The analysis revealed that the brainstem seemed insensitive to short stimuli and that the response to external stimuli in the brainstem could be approximated by a first-order lag system with a time constant of 10-100 s. These results suggest that the brainstem did not integrate sound energy as external stimuli, but neuroelectrical signals from auditory nerve. To understand the awakening risk accumulated in the brainstem, we introduced a new concept of "awakening potential" instead of sound energy.

ICBEN review of research on the biological effects of noise 2011-2014.

The mandate of the International Commission on Biological Effects of Noise (ICBEN) is to promote a high level of scientific research concerning all aspects of noise-induced effects on human beings and animals. In this review, ICBEN team chairs and co-chairs summarize relevant findings, publications, developments, and policies related to the biological effects of noise, with a focus on the period 2011-2014 and for the following topics: Noise-induced hearing loss; nonauditory effects of noise; effects of noise on performance and behavior; effects of noise on sleep; community response to noise; and interactions with other agents and contextual factors. Occupational settings and transport have been identified as the most prominent sources of noise that affect health. These reviews demonstrate that noise is a prevalent and often underestimated threat for both auditory and nonauditory health and that strategies for the prevention of noise and its associated negative health consequences are needed to promote public health.

Noise sensitivity and subjective health: questionnaire study conducted along trunk roads in Kusatsu, Japan.

A questionnaire study was conducted in a residential area along trunk roads in Kusatsu, Japan, in order to investigate the association between noise exposure, noise sensitivity, and subjective health. Subjective health of the respondents was measured by the General Health Questionnaire (GHQ-28) which yields the total score as an index of psychiatric disorder and four subscales. Noise sensitivity was measured by the improved version of the Weinstein's noise sensitivity scale named WNS-6B. The original WNS and a single question directly asking respondents' noise sensitivity were also applied to confirm the validity of the WNS-6B for investigating the effects of road traffic noise on subjective health. Respondents were also asked about disturbances of daily life due to noise exposure to find the cause of the health effects. Three hundred and twenty three answers were entered into the analysis. Applying the WNS-6B as the noise sensitivity measurement scale, a significant correlation was found between subjective health and noise exposure in the noise-sensitive group, while no significant correlation was observed in the insensitive group. These results suggest that the adverse health effects may exist especially in the sensitive group. Application of the other two noise sensitivity measurement scales showed no significant relationship either in the sensitive group or in the insensitive group. The WNS-6B would have greater advantage for detecting adverse health effects than the other scales. Furthermore, the primary cause of the adverse health effect was investigated. The results of the analysis indicated that the adverse health effects were mainly caused by the sleep disturbance and were not caused by hearing interference.

[Effects of aircraft noise on preschool children's misbehaviours: results of research around the Kadena and Futenma airfields in Okinawa].

OBJECTIVES: To investigate the association between aircraft noise exposure as expressed by Weighted Equivalent Continuous Perceived Noise Level (WECPNL) and preschool children's misbehaviours around the Kadena and Futenma airfields in Okinawa. METHODS: A questionnaire survey on children's misbehaviour was conducted in nursery schools and kindergartens around the Kadena and Futenma airfields. The children living around the Kadena airfield were divided into four groups according to WECPNL at their residences and those around the Futenma airfield into three groups according to WECPNL. The subjects were 1,888 male and female preschool children, 3 to 6 years of age, whose parents, caregivers, and teachers answered the questions. The answers used for the analysis were limited to those of respondents fulfilling the following conditions: parents living with their children, fathers with a daytime job, and mothers with a daytime job or no job. Thus, the number of valid answers was 1,213. The responses were analysed using logistic regression models taking the number of misbehaviours related to the items of Biological Function, Social Standard, Physical Constitution, Movement Habit, or Character as the dependent variables, and WECPNL, age, sex, size of family, birth order, mother's age at birth, mother's job, caregiver's career, and category of subject as the independent variables. RESULTS: A significant dose-response relationship was found between the odds ratio and WECPNL for the outcomes of Physical Constitution around the Kadena and Futenma airfields. CONCLUSIONS: It would be reasonable to conclude that the aircraft noise exposure is a factor that increases the number of preschool children's misbehaviours.

Salivary chromogranin A as a measure of stress response to noise.

Effects of noise on the secretion of salivary chromogranin A (CgA), which is considered to be a substitute measure of catecholamines, were investigated in a laboratory experiment. This study included 20 male subjects with normal hearing; their ages ranged from 21 to 24 years. Prior to the experiment, the subjects were asked to answer a questionnaire containing the 28-item General Health Questionnaire (GHQ-28) and Weinstein's noise sensitivity scale. White noise at 90 dB was presented to the subjects for 15 min with 15-minute-rest periods before and after noise exposure. It was shown that salivary CgA levels increased significantly during noise exposure and decreased immediately after it (Friedman's test, p = 0.001, two tailed). This result suggests that salivary CgA can be used to measure the stress response to noise. Furthermore, individual differences in the change in salivary CgA levels were discussed in relation to the subjective responses of the participants to the questionnaire. Some subjects showed prolonged elevation in the salivary CgA levels and the others showed immediate recovery or no effects. These individual differences correlated with the score on the somatic symptoms in GHQ-28; this implies that the score on the somatic symptoms in GHQ-28 could be a measure of physiological sensitivity to noise.

[Association between the rates of low birth-weight and/or preterm infants and aircraft noise exposure].

OBJECTIVES: Intense noise exposure having been observed in vicinal areas around the U.S. military airfields in Okinawa, Japan, suggests the possibility of adverse effects on fetal growth, as studies have reported such effects around other airfields. This study analyzes the birth records in Okinawa prefecture and investigates whether lower birth weights of infants and shorter gestation periods are observed around the airfields. METHODS: The records of 160,460 births in 15 municipalities around the Kadena and Futenma airfields from 1974 to 1993 were subjected to analysis. Average WECPNL among residents in each municipality was calculated as a measure of noise exposure, since the birth records did not contain information on precise birth addresses but only the municipalities. The odds ratios of low birth weight, i.e. under 2,500 grams, and preterm birth, i.e. less than 37 weeks, were obtained by multiple logistic regression analysis with adjustment for the primary factors that would be related to fetal growth. The factors included sex, maternal age, live birth order, occupation of householder, legitimacy of the infant, year of birth and interaction between maternal age and live birth order. RESULTS: The logistic regression analysis showed a significant dose-response relationship between low birth weight and noise exposure. The significance probability of trend test was less than 0.0001. The adjusted odds ratio was 1.3 in the highest noise exposure area, which was Kadena Town, located in the immediate vicinity of the Kadena airfield. Significantly higher rates of preterm births were also found across the noise exposed municipalities. Although the obtained results were not adjusted for some confounding factors like smoking habit, another survey conducted by the present authors did not show particular differences in the female smoking rate between Kadena Town and the other municipalities around the Kadena airfield. CONCLUSION: Aircraft noise exposure is most likely to cause adverse effects on fetal growth, raising the rates of low birth weight and preterm infants around the Kadena airfield.