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PubMed1991

Hearing loss from gun and railroad noise--relations with ISO standard 1999.

Pure-tone hearing thresholds and anamnestic data pertaining to nosocusis and exposure to gun noise were analyzed for 9778 male railroad train-crew workers. A major portion of losses in hearing sensitivity due to railroad noise are obscured in comparisons of hearing levels of trainmen with the hearing levels of the unscreened samples of United States males given in Annex B, ISO 1999 [ISO 1999 (1990), "Acoustics--Determination of occupational noise exposure and estimation of noise-induced hearing impairment" (International Organization for Standardization, Geneva)]. Comparisons of the hearing levels, adjusted for nosocusis, of trainmen who had used no guns, with the hearing levels of otologically and noise screened males (Annex A, ISO 1999) reveal significant losses due to railroad noise. Additional losses were found at high frequencies in trainmen who had used guns. It appears that the effective Leq8h exposure level of trainmen to railroad noise is about 92 dBA, and 87-89 dBA to gun noise. These results are in general agreement with those of study of railway workers by Prosser et al. [Br. J. Audiol. 22, 85-91 (1988)]. Asymmetries in losses between the two ears, effects of ear protection, losses from nosocusis, and losses from sport, as compared to military, gun noise exposures, are examined.

Adult↗
PubMed2003

Combined effect of smoking and occupational exposure to noise on hearing loss in steel factory workers.

BACKGROUND: Evidence has accumulated concerning the adverse effects of smoking on hearing acuity, but it is not clear whether smoking modifies the association between exposure to noise and hearing loss. AIMS: To examine the synergistic effect of these variables on hearing. METHODS: Data used were derived from periodic health examinations for 4624 steel company workers in Japan and included audiometry testing and information on smoking habits. Occupational exposure to noise was determined based on company records. Logistic regression was used to examine the dose-response association between smoking and hearing loss. The Cochran-Mantel-Haenszel method was used to calculate the prevalence rate ratio (PRR) of hearing loss for each combination of smoking and noise exposure factors, taking non-smokers not exposed to occupational noise as a reference. The interaction between smoking and noise exposure was assessed using a synergistic index, which equals 1 when the joint effect is additive. RESULTS: Smoking was associated with increased odds of having high frequency hearing loss in a dose-response manner. The PRR for high frequency hearing loss among smokers exposed to occupational noise was 2.56 (95% CI 2.12 to 3.07), while the PRR for smokers not exposed to noise was 1.57 (95% CI 1.31 to 1.89) and the PRR for non-smokers exposed to noise was 1.77 (95% CI 1.36 to 2.30). The synergistic index was 1.16. Smoking was not associated with low frequency hearing loss. CONCLUSIONS: Smoking may be a risk factor for high frequency hearing loss, and its combined effect on hearing with exposure to occupational noise is additive.

Adult↗
PubMed2004

Effect of electronic ANR and conventional hearing protectors on vehicle backup alarm detection in noise.

An experiment was conducted wherein masked thresholds (using ascending method of limits) for a backup alarm were obtained in pink and red noise at 85 and 100 dBA for 12 participants immersed in a probability monitoring task and wearing a conventional passive hearing protection device (HPD, an earmuff or a foam earplug), an active noise reduction (ANR) headset, or no HPD at all (only in 85 dBA noise). Results revealed statistically significant between-HPD differences in red noise (from 2.3 to 3.1 dB) and in the 100-dBA noise level (from 2.6 to 4.3 dB). An additional finding, which corroborates other studies using different protocols, was that masked thresholds in 85-dBA noise were significantly lower (from 3.2 to 4.4 dB) for the occluded conditions (wearing an HPD) than for the open-ear (unoccluded) condition. This result refutes the belief among many normal-hearing workers that the use of HPDs in relatively low levels of noise compromises their ability to hear necessary workplace sounds. Actual or potential applications of this research include (a) the selection of appropriate HPDs for low-frequency-biased noise exposures wherein signal detection is important and (b) gaining insight into the appropriateness of ANR-based HPDs for certain industrial noise environments.

Adolescent↗
PubMed2002

Excessive noise levels in the neonatal ICU: potential effects on auditory system development.

OBJECTIVE: Several recent studies have found exceedingly high noise levels in the neonatal intensive care unit (NICU) and in incubators. The purpose of this study was to perform a detailed noise assessment in a Canadian NICU. METHODS: A noise level meter was used to evaluate ambient noise levels in three rooms of the NICU and to compare those levels with measurements taken inside an occupied incubator. RESULTS: Mean hourly noise levels measured inside the incubator (61 dB) were significantly higher than those measured outside (55 dB). Ambient noise levels were also significantly higher in rooms where staff activity was greatest (59 dB). In addition, peak noise levels in excess of 120 dB were found. CONCLUSION: These findings are consistent with those of previous studies and suggest that noise levels in the NICU are excessive. Furthermore, staff activity is a significant contributor. The suggestion that noise in the NICU is detrimental to both auditory and central nervous system development is discussed and intervention strategies are recommended.

Child Development↗
PubMed1994

Prolonged exposure to gunfire noise among professional soldiers.

OBJECTIVES: The aim of the study was a retrospective assessment of the exposure of professional soldiers to impulse noise from gunfire. METHODS: A questionnaire on noise exposure and use of hearing protectors was administered to a stratified random sample of 699 army officers (mean age 39.8 years) with an average of 18 years of exposure to shooting noise. For a comparison of the number of shots from different weapons, the peak sound pressure levels of shots were adjusted in relation to one pistol shot according to the equal energy principle. Total exposure time was estimated with the equal energy principle, the number of shots from different weapons, the energy levels of different shots, the effectiveness of hearing protection, and the distance from the noise source being taken into account. RESULTS: Rifles, shotguns, and pistols were the predominant exposure sources. Impulse noise exposure averaged 164,183 shots from different weapons. After adjustment to the energy level of one pistol shot, the average was 78,000 personally fired shots. The total shooting noise exposure averaged 218,000 adjusted shots. Translated into exposure to steady noise of 85 dB(A) for 40 h a week, the exposure to noise from personally fired shots equaled an exposure time of 22.0 years and the total exposure averaged 61.0 years. The heaviest exposure occurred during the first 10-15 years of the men's careers. CONCLUSIONS: Exposure to gunfire noise among professional soldiers is high enough to cause severe hearing deterioration already at early career stages if effective hearing protectors are not worn at all times on shooting occasions.

Adult↗
PubMed2001

Hearing loss from cockpit noise in motor gliders.

BACKGROUND: Over the past 15 yr, remarkable progress has been made in the development of touring motor gliders and self-launching sail-planes with retractable propulsion units (RPU gliders.) Annually, over 50% of the gliders produced have had such units, often two-stroke engines which produce high frequency sound emissions. Sound emission regulations require that all power gliders be insulated to avoid external emissions and noise pollution in the airspace near airfields. However, these regulations do not cover noise within the cockpit. METHODS: To determine the noise level in the cockpits of powered gliders and how this noise affects the hearing of pilots, cockpit noise in six touring motor gliders and nine RPU gliders were measured. RESULTS: Both types of motor gliders have noise levels that may be hazardous to pilots' hearing if they are not equipped with personal noise protection. In extreme cases an exposure time of only 20 seconds to the cockpit noise of an RPU glider may cause permanent hearing loss. CONCLUSION: Pilots must be warned not to fly motor gliders without personal noise protection.

Aerospace Medicine↗
PubMedDate not supplied

[Noise as a stress factor for the onset of hearing disorders in workers using drilling equipment].

INTRODUCTION: Noise is one of the commonest environmental pollutants and it is defined as a sound which bothers, irritates, which is unpleasant and can damage hearing. The degree of negative effects of noise depends on its intensity, spectrum of frequency, nature, duration of exposition and individual sensibility. PURPOSE: This work is supposed to establish the degree of correlation between hearing damage and professional exposition to one of physical stressors of work environment--noise. MATERIAL AND METHODS: Investigation regarding work conditions included intensity and frequency analysis of noise at workplaces. The examination sample included 101 workers of "NIS--Naftagas" section "Hidrosonda" employed as drilling workers. The control group consisted of 50 workers not exposed to noise or any other professional influences, like workers from the examination sample. RESULTS: The results on the observed workplaces show that noise is of high intensity and bad frequency spectrum. Exposition of workers to noise is a highly important factor for hearing damages (p = 0.002). The relative risk for hearing damage is four times greater in relation to the control group (odds ratio 4.1). Attributable fraction (preventive potential) of noise factor is 61%. Smoking associated with exposition to noise multiplies the risk of hearing damage (odds ratio 5.8) while with non-smokers the risk decreases (odds ratio 3.0). DISCUSSION: Professional hearing disorders occur slowly and increase with time spent at noisy workplaces. At the beginning it presents with buzzing in ears and dizziness followed by latent phase after which hearing disorders occur. Tone audiometry is used to register first signs of hearing loss, whereas manifestations in social contacts come later. CONCLUSION: Once diagnosed hearing disorders cannot be cured so a lot more care should be paid to this problem. It is necessary to provide adequate work conditions by applying appropriate technologies, tools, work organisation, personal protection equipment, as well as previous and periodical examinations of hearing by tone audiometry before employing workers and during their work in noisy conditions.

Adult↗
PubMed2001

[Tinnitus in noise-induced hearing impairment].

The analysis of the epidemiological data indicates that exposure to noise is widespread and it is one of the most common causes of tinnitus, estimated at about 20.7% according to Hazell; 28% according to Axelsson; and 42% according to Palmer. Bearing in mind the scantiness of reliable data on the incidence and nature of tinnitus in persons exposed to industrial noise, and especially the need for the objectivity of this subjective symptom, the authors have decided to undertake the study aimed at assessing the interrelation between tinnitus, the magnitude and kind of hearing impairment, and otoacoustic emission. The study group included 191 persons aged 42.5 +/- 7.6 years (range, 25 to 65), occupationally exposed to noise at the levels of 88-92 dB(A) for 26.9 +/- 4.6 years (range, 9 to 30) who had reported hearing disorders and tinnitus. The control group, matched by similar age and duration of employment, consisted of 80 persons with perceptive hearing impairment induced by industrial noise who had not complained of tinnitus. The results of the study revealed that in 59.7% of the study subjects, noise proved to be one of the most probable factors responsible for the development of tinnitus. The presence of tinnitus was found in 22.5% and in 46% of the study subjects after 10 years and 11-20 years of noise exposure, respectively. In 95.8% of workers, tinnitus was associated with hearing loss, and only in 4.2% of cases it occurred in ears with normal hearing. In persons exposed to noise, tinnitus was most frequently (59.2%) bilateral and permanent. Following the audiologic examinations, verified by objective audiometry (tympanometry, ABR), cochlear hearing impairment was found in 68.6%; retrochochlear in 8.37%; mixed and other forms of impairment, e.g. presbyacousis, in 19.4% of subjects. The audiologic assessment of tinnitus demonstrated that in 62.3% of persons, tinnitus occurred at high frequencies and correlated with the magnitude of hearing impairment in the tonal audiogram. The tinnitus intensity ranged between 10-15 dB and 45 dB. In 40.3% of those under study, noise was not the only tinnitus-risk factor. In this group of persons, the presence of predisposing diseases was also observed, e.g. hypertension, diabetes, atherosclerosis, disturbed lipid metabolism and other etiologic factors that might have impact on the tinnitus incidence, ototoxic drugs, for example. The measurements of evoked otoacoustic emission (EOAE and DPOAE) revealed in 58.63% of persons significant differences (p < 0.01) in the amplitude and spectrum of EOAE in the ears with tinnitus as compared to the ears without tinnitus with a similar hearing threshold. Whereas in 27.74% of subjects, no differences in the EOAE measurements in the ears with or without tinnitus were observed. The results of DPOAE measurements showed in 62% of subjects significant differences in DP-grams in the ears with tinnitus as compared to the ears without tinnitus (p < 0.01). Interestingly, the differences in measurements of both types of evoked emissions (EOAE and DPOAE), expressed by the lowered amplitude, narrowed spectrum, reduction of emission or its complete fading in a limited area of high frequencies, were demonstrated in the ears with tinnitus only in retrocochlear hearing impairment, as compared to those free from tinnitus. The evaluation of the EOAE and DPOAE measurements seems to prove that this method may be useful in assessing the contribution of the cochlear mechanisms to the incidence of tinnitus and in distinguishing between tinnitus generated in cochlea and tinnitus with the source at other levels of the hearing organ or beyond it. Our study failed to determine the interrelation between tinnitus and spontaneous emissions as the emission was registered only in about 12% of persons exposed to noise, including 2% of those with normal hearing.

Adult↗
PubMed1976

[Longitudinal audiometric studies concerning progression of noise induced hearing loss (author's transl)].

The development of occupational hearing loss is very important for the recommendation to change the work place. 1960 Dieroff has described a phasic development of noise induced hearing loss. After ten years in noisy environment no further development of hearing impairment was determinable. Recent investigations point to a logarithmical respectively linear dependence of noise induced permanent threshold shift on the duration of exposure to noise. During our observation over a period of two years of employees working on noisy jobs, no stay of noise induced permanent threshold shift proceeding could be stated after ten or twenty years. As the raiting sound level of the working places, which we have studied, had only approx. 60 to 100 dB(A), it can be assumed, that under these conditions the noise induced hearing loss developes delayed and the noise induced permanent threshold shift increases as long as it must be worked under noisy conditions. The noise induced hearing loss depends on the intensity of noise exposure of the different groups. Also the group of storehouse- and court personnel as well as the drivers, being exposed only to a raiting sound level of approx. 65-75 dB(A), showed a significant higher noise induced permanent threshold shift than the group of administrative employees.

Adult↗
PubMed2004

Temporary changes in hearing after exposure to shooting noise.

OBJECTIVES: Firearm is a common source of impulse noise that may potentially damage hearing organ. It has been suggested that otoacoustic emissions, particularly transient-evoked otoacoustic emissions (TEOAE), might be more sensitive than pure-tone audiometry (PTA) in the assessment of changes to cochlea caused by noise. The aim of this study was to: (i) evaluate exposure to impulse noise from small-caliber weapons, (ii) compare the post-exposure changes in hearing measured by PTA and TEOAE and correlate them with noise parameters. MATERIALS AND METHODS: The study included 18 male hunters (group I) and 28 candidate policemen (group II) exposed to impulse noise from small firearms during target practices. Group I was unprotected during shooting, whereas group II used commonly available hearing protectors. PTA and TEOAE were performed before and 2-10 min after shooting. Exposure to impulse noise was evaluated by in situ measurements. RESULTS: Groups I and II were exposed to 3-4 and 4-144 impulses of noise at mean C-weighted peak sound pressure levels of 154 dB and 156 dB, respectively. No post-exposure audiometric threshold shift was observed in group I. Significant reductions of TEOAE levels were found both for the whole response (-2.2 dB SPL) and for 1/2 -octave band responses in the frequency range of 1000-4000 Hz (from -1.6 to -3.0 dB SPL). These changes were not correlated with C-weighted peak sound pressure levels or equivalent-continuous A-weighted sound pressure level. Significant correlation was found for peak sound pressure and maximum sound pressure levels in 1/3-octave bands in the frequency range corresponding with the main part of the acoustic energy of impulses (correlation coefficients r from -0.58 to -0.77, p < 0.05). In group II neither PTA nor TEOAE showed significant hearing impairment after shooting. CONCLUSIONS: The results show that even short-term exposure to impulse noise from small-calibre firearms might cause temporary hearing impairment measured by TEOAE. Therefore, the use of earmuffs is strongly recommended, because most of them seem to effectively attenuate impulse noise from small-calibre firearms.

Adult↗
PubMed2004

[Assessment of annual exposure to noise and risk of occupational hearing loss among private farmers specializing in plant production].

BACKGROUND: In agriculture noise is the most frequent hazard, but until now very poorly recognized. It affects the hearing organ in private farmers. Because of a great variety of machines used on farms and a changing magnitude of exposure to noise, this agent has to be studied over the whole annual cycle. The aim of the study was to recognize and evaluate annual exposure to noise among private farmers engaged in plant production. MATERIALS AND METHODS: The study covered 17 family farms with arable land, ranging from 10 to 50 ha (mean, 22.3 ha). They were equipped with agricultural tractors and a set of agricultural accessories, wood-cutting saws, self-propelled and workshop machines. Based on detailed time-schedule records of agricultural activities and dosimetric measurements conducted during the whole year, two acoustic parameters were determined, total monthly exposure and equivalent daily exposure. RESULTS: The study showed that the highest values of the total monthly exposure to noise (E(A,T)) occurred in the summer-autumn (July, September, October) and winter (December, January) seasons. During the former, the degree of noise load among farmers was directly associated with intensity of field works and transport activities, whereas during the latter with the frequency of using wood-cutting machines and repair activities. The calculated mean equivalent daily exposure to noise revealed the highest values in two months, December (6.01 Pa2 h) and September (5.51 Pa2 h), and the lowest values were observed in the other months (3.67-4.28 Pa2 h). The mean value for the whole year was 4.35 Pa2 h (the standard was exceeded by 4.4 times). CONCLUSIONS: The study showed that the mean annual noise load among farmers engaged in plant production was characterized by the level equal to 91.3 dB-A with the highest hearing risk in December and September. In those two months, maximum allowable exposure to noise was exceeded by six times (E(A,8h)). Owing to the precision of the obtained values and their strong uniformity, they may be used in practice by relevant services to evaluate the degree of noise risk among private farmers engaged in plant production.

Agricultural Workers' Diseases↗
PubMedDate not supplied

[Industrial noise and presbyacusia in the determination of hearing damage: studies in chemical industry workers].

An audiometric investigation was carried out on 710 workers of a chemical plant in order to ascertain the role of industrial noise and presbysocio-acusia in causing hearing loss. The workers underwent an audiometric test both aerial and via bone, in a sound-proof chamber, after a 16-hour rest from noise. The subjects also answered a questionnaire on nonoccupational noise exposure and previous hearing and dysmetabolic disorders. Noise exposure was assessed on the basis of a cumulative exposure index obtained for each subject by multiplying the mean daily exposure level by seniority in the job. The results showed that in workers not exposed to high noise levels, industrial noise and presbysocio-acusia induce, via a direct mechanism, either separately or together, only slight damage to social hearing frequencies, i.e., those of normal conversation. At frequencies of 4 and 6 kHz, however, presbysocio-acusia seems to play a more important role than industrial noise in causing hearing loss. The practical implications arising from this study concern the frequencies that should be used for a medicolegal assessment of industrial noise induced hearing loss and the the threshold for these frequencies above which assessment of hearing loss should begin. As regards the first point, the results obtained in this study suggest the use of medicolegal methods based on normal conversation frequencies since presbysocio-acusia should not in any case be taken from these frequencies as it affects them only marginally. As regards the second point, the results show that assessment of hearing loss should begin when the hearing threshold at the above frequencies exceeds 25 dB. The study also showed that in epidemiological investigations on subjects exposed to industrial noise, the cumulative exposure index is better correlated with the rise in hearing threshold at the various frequencies than with seniority.

Audiometry↗
PubMed1991

Influence of noise spectra on auditory frequencies & degree of temporary threshold shift.

Influence of noise spectra on auditory frequencies of 131 audiometrically normal human volunteers was assessed. Each subject was exposed to four different types of noise on different days for a period of 30 min. Noises utilized in this study were broadband noise (100 dBA), broadband noise (BBN) mixed independently with tones of 0.5, 1.2 and 4 kHz at three intensity levels (85, 95 and 105 dBA) and noises of different bandwidths (100 dBA) around the above tones as centre frequencies. BBN produced maximum TTS2 at 4 kHz (21.42 +/- 0.61 to 26.15 +/- 1.00 dB), while concentration of sound energy around these tones, affected hearing at one-half octave above the point of concentration of sound energy. TTS2 produced by 4 kHz tonal component of 95 and 105 dBA and 2 kHz of 105 dBA were significantly higher than the one produced by BBN at 4 kHz. The single tones of 2 and 4 kHz and noise of 1/3rd octave bandwidth (cf 4 kHz) produced TTS2s which were significantly higher as compared to that of BBN at 4 kHz. At the same centre frequency, noise concentrated in thinner bands was more injurious than that in the thicker bands. Lower frequencies of hearing appears to be more resistant to noise as for the same sound pressure level the TTS2 observed in low frequencies was less as compared to higher frequencies.

Acoustic Stimulation↗
PubMedDate not supplied

Establishing a noise measurement protocol for neonatal intensive care units.

OBJECTIVES: To compare three noise exposure measurement methods and determine the effect of location within the nursery, time of day, day of week, shift, and activities such as nursing shift change and physicians' rounds on noise measurements. STUDY DESIGN: We performed a noise distribution survey, central site measurements, and quadrant area measurements in our nursery. The measurements made were sound pressure level and hourly LEQ, LMAX, and L10. RESULTS: The noise distribution survey method was least useful because steady-state noise sources were the exception. Differences between central site and quadrant area measurements were minimal. There was no significant effect of time of day, shift change, or physician rounds on the noise measurements. CONCLUSIONS: In an open nursery with excessive noise levels central site measurements over a relatively short time accurately reflect the noise exposure. A protocol for measuring noise exposure in the neonatal intensive care unit is appended.

Female↗
PubMed1998

[Environmental medical action required on exposure to noise].

Basing on request for an expertise on the medical effects of noise on healthy adults, permissible values for mainly traffic noise were estimated from the literature. If the permissible values are exceeded, preventive medical action is necessary. Below these values the probability of noise-induced health hazards is essentially zero. The authors presume that noise levels above these permissible values, but below the limit of bearability, are an increasing danger to health. Preventive medical action must be weighed against the risk involved in persistent noise, depending on the situation and the need protection. The effect of noise as a health hazard is, apart from the mechanical damage to the inner ear, a psycho-physiological deregulation which can be either indirectly due to the annoyance or directly caused by stress of the vegetative-hormonal system. Therefore different permissible values for annoyance, the stress on the vegetative-hormonal system and for the loss of hearing are suggested, for both continual and maximum noise levels. In addition, de-regulation depends on the time of acoustic exposure because the sensitivity to noise follows a 24-hour cycle (circadian rhythm). It is therefore necessary to determine personal permissible limits for the nocturnal noise (sleep disorder). Permissible values for children are also suggested.

Adolescent↗
PubMed1989

Combined effects of aspirin and noise in causing permanent hearing loss.

Several authors have investigated the interaction of noise and aspirin in hearing loss, with conflicting results. We studied the combined effects of noise and high doses of aspirin on hearing in rats. Thirty-eight Sprague-Dawley rats were divided into the following five groups: (1) controls; (2) aspirin only; (3) noise only; (4) 8-day per 200 mg of aspirin per noise; and (5) 12-day per 200 mg of aspirin per noise. Auditory brain-stem-evoked responses were measured in each animal prior to, 24 hours after, and 3 weeks after aspirin and noise exposure. The animals were killed and hair cells were counted in 200-micron segments and expressed graphically. Results showed significant differences in permanent threshold shift and hair cell loss between all noise-exposed animals and non-noise-exposed animals. There was also a significantly greater amount of hair cell loss in group 5 when compared with groups 3 or 4. The 12-day per 200 mg of aspirin per noise regimen (group 5) also proved to be fatal for 6 of 15 of these animals, and caused significant weight loss in the survivors. No weight loss or deaths were noted in any other group.

Animals↗
PubMed1995

Prevention of noise-induced hearing loss.

OBJECTIVES: To review the evidence suggesting that occupational hearing conservation programs prevent noise-induced hearing loss; to describe the features, prevalence, and handicap associated with noise-induced hearing loss; and to describe the otolaryngologist's role in prevention of noise-induced hearing loss. DATA SOURCES: Recent statements from the American College of Occupational Medicine, the National Institutes of Health, and the International Organization for Standardization are supplemented by published articles known to the author (no formal literature search was done). STUDY SELECTION: Articles that purported to measure the effects of occupational hearing conservation programs on preventing noise-induced hearing loss. DATA EXTRACTION: Each article was separately critiqued without a priori assessment criteria. DATA SYNTHESIS: Several studies suggest that occupational hearing conservation programs prevent noise-induced hearing loss, but none of these are conclusive. No randomized clinical trial has been reported, of which I am aware, and previously reported data suffer from one or more of the following shortcomings: failure to match treatment and control groups for age, nonoccupational noise exposure, and/or prior hearing loss; failure to control for audiometric learning effects; and inclusion of workers who had already worked long careers without hearing protection (and thus had little risk of additional noise-induced loss). CONCLUSION: Although noise reduction for individuals obviously can prevent noise-induced hearing loss, to my knowledge, no single study offers convincing evidence of the efficacy of occupational hearing conservation programs, primarily due to methodologic flaws.

Hearing Loss, Noise-Induced↗
PubMed2002

Low frequency noise and whole-body vibration cause increased levels of sister chromatid exchange in splenocytes of exposed mice.

Chronic exposure to low frequency (LF) noise and whole-body vibration (WBV) induces both physiological and psychological alterations in man. Recently, we have shown that long-term occupational exposure to LF noise and WBV produces genotoxic effects in man expressed as an increase in sister chromatid exchange (SCE) levels in lymphocytes. The objectives of the present study were to investigate whether the observed effect could be reproduced in a murine model and, if so, which of the agents, LF noise alone or in combination with WBV, would be instrumental in the SCE induction. SCEs were analyzed in spleen lymphocytes of mice exposed to LF noise alone and in combination with WBV for 300 and 600 hr. An effect at the cell cycle kinetics level was also investigated. The results revealed significant increases in the mean SCE number per cell and in the proportion of cells with high frequency of SCEs (HFCs) in lymphocytes of mice submitted to combined noise and WBV over controls. No significant differences were found between single noise-exposed and control mice. A cell cycle delay was observed exclusively in the noise and WBV exposure groups. In conclusion, we demonstrated that, as in exposed workers, prolonged exposure to the combination of LF noise and WBV determines an increase in SCE level in mice while LF noise alone is not effective in SCE induction.

Animals↗