Failure of noise exposure to modify temporal patterns of plasma cortisol in man

Noise, stress, and annoyance in a pediatric intensive care unit

OBJECTIVE

To measure and describe hospital noise and determine whether noise can be correlated with nursing stress measured by questionnaire, salivary amylase, and heart rate.

DESIGN

Cohort observational study.

SETTING

Tertiary care center pediatric intensive care unit.

SUBJECTS

Registered nurses working in the unit.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Eleven nurse volunteers were recruited. An audiogram, questionnaire data, salivary amylase, and heart rate were collected in a quiet room. Each nurse was observed for a 3-hr period during patient care. Heart rate and sound level were recorded continuously; saliva samples and stress/annoyance ratings were collected every 30 mins. Variables assessed as potential confounders were years of nursing experience, caffeine intake, patients' Pediatric Risk of Mortality Score, shift assignment, and room assignment. Data were analyzed by random effects multiple linear regression using Stata 6.0. The average daytime sound level was 61 dB(A), nighttime 59 dB(A). Higher average sound levels significantly predicted higher heart rates (p =.014). Other significant predictors of tachycardia were higher caffeine intake, less nursing experience, and daytime shift. Ninety percent of the variability in heart rate was explained by the regression equation. Amylase measurements showed a large variability and were not significantly affected by noise levels. Higher average sound levels were also predictive of greater subjective stress (p =.021) and annoyance (p =.016).

CONCLUSIONS

In this small study, noise was shown to correlate with several measures of stress including tachycardia and annoyance ratings. Further studies of interventions to reduce noise are essential.

Failure of industrial noise to change the patterns of vanilmandelic acid and 17-hydroxycorticosteroids in the urine of the female weavers with hearing loss

The field experiments were undertaken on two consecutive working days on seven female weavers with noise-induced hearing loss (NIHL), and a control group of seven sewers with normal hearing. The first day, urine was collected during the shift (06:00-14:00 h) and at home (17:00-05:00 h) for measurements of 17-hydroxycorticosteroids (17-OH) levels. The following day, the procedure was repeated, but for vanilmandelic acid (VMA) analysis. No significant changes in the hormone levels were found, both concerning the different occupational noise exposure and the periods of a working day.

Effects of daytime noise load on the sleep-wake cycle and endocrine patterns in man: II. 24 hours secretion of anterior and posterior pituitary hormones and of cortisol

The present study examines the effects of auditory stress on the plasma levels of pituitary hormones and cortisol. Each of twelve healthy male subjects participated in two experimental series; during one of them they were exposed to 85 dB(A) industrial noise from 9:00 to 21:00 h. Blood samples were taken by an indwelling venous catheter for 24 h at intervals of 20 min from 8:00 to 8:00 h. The plasma levels of ACTH, growth hormone, prolactin, oxytocin, vasopressin and cortisol were determined. In all subjects except one noise stress affected the profiles of the pituitary hormones but the responses were interindividually different. The oxytocin level was significantly elevated (p less than .01), ACTH also responded but less clearly, whereas the other hormones reacted only in individual cases. During the subsequent night sleep only PRL concentrations were elevated above the baseline plateau in several subjects. It was concluded that in humans the pituitary responses to noise stress are highly individual.

Noise-induced temporary threshold shifts: the effects of anticipatory stress and coping strategies

Temporary Thresholds Shifts were assessed in five groups from before to after 5-minute exposure to 110 dB SPL white noise and in one additional group without noise exposure. In each group the baseline conditions were designed to elevate psychological stress via anticipation of the noise and venipuncture procedures. In the three experimental groups, procedures to reduce psychological stress were employed: Information, Relaxation, and Behavioral Avoidance. Manipulation checks supported the effectiveness of these arousal-reducing interventions. Temporary threshold shifts were considerably greater in two of the experimental conditions than in the noise-exposed control conditions.

Environmental noise and human prenatal growth

To determine whether chronic exposure to relatively loud noise has demonstrable biological effects in humans, a study was conducted on the effect of mother's exposure to airport noise while pregnant, and of social and biological characteristics of the family upon birthweight and gestation length. The sample of births was drawn from a community located adjacent to an international airport in the U.S., where noise levels had been measured previously. Mother's noise exposure was based upon noise levels near her residence in the community while she was pregnant. Data from 115 births were used, these being from mothers whose noise exposure history was most complete throughout the pregnancy. Using multivariate analysis to correct for family characteristics, the partial correlation coefficient for noise exposure and gestation length was negative, large, and significant in girls (r = -0.49, p less than 0.001). In boys the partial correlation coefficient was also negative but was smaller and did not quite reach statistical significance. Partial correlations with birthweight were smaller in both boys and girls and not significant. These results agree best with previous studies that suggest that noise may reduce prenatal growth. The size of the observed effects may be related to a conservative research design biased towards underestimation, as well as to the real effects of noise upon human prenatal growth.

Biochemical effects of chronic exposure to noise in man

Biochemical parameters in 75 normal healthy male subjects exposed to intense noise of 88-107 dB(A)(6-8 h/day) for 10 to 15 years during their work situation have been monitored and compared with 35 normal unexposed subjects. Levels of free cholesterol (P less than 0.001), gamma-globulin (P less than 0.01) and cortisol (P less than 0.01) were found to be significantly higher in the exposed subjects. Significant changes in free cholesterol also altered the ratio of free to esterified cholesterol significantly (P less than 0.001). The value of the A/G ratio was also lower in the exposed group. Uric acid did not show any change. The study shows that in the exposed group the esterification process of cholesterol was modified. There was an effect on pituitary-adrenal axis as well as host-defence mechanism.

Plasma catecholamines and pituitary adrenal hormones related to mental task demand under quiet and noise conditions

Plasma levels of catecholamines and pituitary adrenal hormones were measured in 20 min samples from eight subjects, in one control session and two experimental sessions, while they performed a short-term memory task under quiet of noise conditions. Performing the task led to significant increase in the plasma levels of cortisol, adrenaline and noradrenaline, whereas no variations in growth hormone and dopamine were observed. Similarly, significant changes occurred in urinary catecholamine excretion. A significant correlation was found between individual plasma cortisol increments and error-rates assessed from an accuracy of recall variable. For adrenaline and noradrenaline, an early response apparently linked with an anticipatory process preceded the task. Exposure to noise did slightly amplify cortisol response to the task, but during the first experimental session, with or without noise, the task elicited greater cortisol increases in all subjects than during the second session. These results provide evidence for a relationship between sympathoadrenocortical activity and attentional demand, whereas cortisol increments seem to be more specifically related to better coping with the task. Frequent hormone level measurements during a prolonged mental task might clarify the complex relationship between time-related bodily hormonal changes, performance and subjective feelings.

Plasma catecholamines and pituitary adrenal hormones in response to noise exposure

To evaluate the immediate effect of exposure to a high level of noise on the sympatho-adrenal and pituitary-adrenal systems, measurements were made of circulating catecholamines, growth hormone, ACTH, and cortisol in seven normal male subjects. They were studied on two random experimental days: a control day and a noise-exposure day with an intermittent noise alternating between 99 dB (A) and 45 dB (A) for 2 h. Analysis did not reveal any variation in the plasma levels of norepinephrine (NE), epinephrine (E) or dopamine (D), measured every 20 min, which might have been related to noise exposure. Similarly, analysis of the 2-h urine samples collected from 8 a.m. to 2 p.m. revealed no significant changes in urinary catecholamine excretion. Plasma levels of GH and ACTH did not differ significantly from those for control days, but cortisol showed a brief, significant levelling-off in its pattern during the exposure period. The data demonstrate that exposure to a high level of noise, although considered as "unpleasant", does not induce any important endocrinological changes in man. These conclusions differ from those for studies on animals where reactions to noise may be related to a more general stressing situation.