Noise exposure and hearing loss among sand and gravel miners

The objectives of this study were to describe workplace noise exposures, risk factors for hearing loss, and hearing levels among sand and gravel miners, and to determine whether full shift noise exposures resulted in changes in hearing thresholds from baseline values. Sand and gravel miners (n = 317) were interviewed regarding medical history, leisure-time and occupational noise exposure, other occupational exposures, and use of hearing protection. Audiometric tests were performed both before the work shift (following a 12-hour noise-free interval) and immediately following the work shift. Full shift noise dosimetry was conducted. Miners' noise exposures exceeded the Recommended Exposure Limit (REL) of the National Institute for Occupational Safety and Health (NIOSH) for 69% of workers, and exceeded the Mine Safety and Health Administration's action level for enrollment in a hearing conservation program for 41% of workers. Significantly higher noise exposures occurred among employees of small companies, among workers with a job classification of truck driver, among males, and among black workers. Hearing protection usage was low, with 48% of subjects reporting that they never used hearing protection. Hearing impairment, as defined by NIOSH, was present among 37% of 275 subjects with valid audiograms. Black male workers and white male workers had higher hearing thresholds than males from a comparison North Carolina population unexposed to industrial noise. Small but statistically significant changes in hearing thresholds occurred following full shift noise exposure among subjects who had good hearing sensitivity at baseline. In a logistic regression model, age and history of a past noisy job were significant predictors of hearing impairment. Overall, sand and gravel workers have excessive noise exposures and significant hearing loss, and demonstrate inadequate use of hearing protection. Well-designed hearing conservation programs, with reduction of noise exposure, are clearly needed.     

Comparison of NIOSH noise criteria and OSHA hearing conservation criteria

BACKGROUND: This study was conducted to compare noise exposure measurements based on the recently revised noise exposure criteria recommended by the U.S. National Institute for Occupational Safety and Health (NIOSH) and the current U.S. Occupational Safety and Health Administration (OSHA) Hearing Conservation Amendment to the occupational noise standard. METHODS: Daily 8-hour time-weighted average (TWA) personal noise exposures were obtained for 61 workers using dosimeters set simultaneously to the NIOSH and OSHA Hearing Conservation Amendment (OSHA-HCA) criteria. A variety of work groups with the potential for noise exposure were evaluated as a part of this investigation. RESULTS: Noise dose based on the NIOSH criteria was higher than the corresponding OSHA-HCA noise dose with differences in noise exposures measured under the two criteria equal to 6.6 dBA. Should the new NIOSH recommendation on noise measurement be adopted as standard, the number of workers to be enrolled in a hearing loss prevention program was estimated to increase by 2. 7-fold from 23% to 75% of the study population. CONCLUSIONS: The results of this study indicate that if the NIOSH criteria are to be adopted as an OSHA standard, there is likely to be a substantial increase in the number of workers in hearing conservation programs.     

Job stress and depressive symptoms among Japanese fire fighters

BACKGROUND: Associations between job stresses, as assessed by theoretical job stress model and depressive symptoms among fire fighters have not been fully investigated. The purpose of this study is to clarify the factors of job stress that influence the depressive symptoms in Japanese fire fighters. METHODS: The subjects involved 1,672 fire fighters from a local government. The questionnaire comprised age, gender, job type, job class, martial status, smoking, and drinking habit, the Center for Epidemiologic Studies Depression Scale (CES-D), and The National Institute for Occupational Safety and Health (NIOSH) generic job questionnaire. RESULTS: A group showing depressive symptoms (CES-D > or = 16) included 373 subjects (22.3%). In a multivariate logistic regression analysis, high variance in workload, high intergroup conflict, high role conflict, and low self-esteem had significantly higher odds ratio for depressive symptoms. CONCLUSIONS: High variance in workload, high intergroup conflict, high role conflict, and low self-esteem were significantly related to depressive symptoms among Japanese fire fighters. Further prospective studies are needed to clarify the influence of these stress factors on other health outcomes, and to elucidate whether alleviation of these stress factors improve the mental health among fire fighters.     

Assessment of noise exposure for indoor and outdoor firing ranges

The National Institute for Occupational Safety and Health (NIOSH) received an employee request for a health hazard evaluation of a Special Weapons Assault Team (SWAT) in January 2002. The department was concerned about noise exposures and potential hearing damage from weapons training on their indoor and outdoor firing ranges. NIOSH investigators conducted noise sampling with an acoustic mannequin head and 1/4 -inch microphone to characterize the noise exposures that officers might experience during small arms qualification and training when wearing a variety of hearing protection devices provided by the department. The peak sound pressure levels for the various weapons ranged from 156 to 170 decibels (dB SPL), which are greater than the recommended allowable 140 dB SPL exposure guideline from NIOSH. The earplugs, ear muffs, and customized SWAT team hearing protectors provided between 25 and 35 dB of peak reduction. Double hearing protection (plugs plus muffs) added 15-20 dB of peak reduction.     

Comparison of criteria for significant threshold shift in workplace hearing conservation programs

The National Institute for Occupational Safety and Health (NIOSH) recommended that the Standard Threshold Shift (STS) be replaced as the sentinel indicator of hearing loss in workplace audiometric surveillance programs. We conducted a retrospective cohort study of 1220 workers followed for eight consecutive years in the hearing conservation program at the Hanford nuclear facility, to evaluate the relative accuracy of eight candidate threshold-shift criteria for detecting hearing loss over time, using two evaluation methods and comparing to NIOSH findings. The NIOSH-recommended criterion was one of the better criteria. However, the differences between better criteria were less evident using a different evaluation method than the one described by NIOSH. Also, when we compared our findings with those underlying the NIOSH recommendation, the between-database differences were large enough that the smaller between-criteria differences may have limited importance.     

Occupational Noise Exposures Among Three Farm Families in Northwest Ohio

ABSTRACT

A pilot project was conducted to evaluate occupational noise exposures of three families living and working on farms in Northwest Ohio. Noise exposures were measured continuously for 7 consecutive days for each participant for 1 week each during planting, growing, and harvesting seasons. The dosimeters were programmed to evaluate noise exposures using both the Occupational Safety and Health Administration (OSHA) action level and the National Institute for Occupational Safety and Health (NIOSH)/American Conference of Governmental Industrial Hygienists (ACGIH) guidelines. One family was evaluated per year and a total of nine family members (six adults and three children) participated. Adult noise exposures for on-farm activities (occupational exposures) ranged from 46.1 to 89.6 decibels on the A-weighted scale (dBA) as an 8-hour time-weighted average (8HR TWA) using the OSHA action level and from 62.6 to 92.1 dBA 8HR TWA using the NIOSH/ACGIH guidelines. Occupational noise exposures for the children ranged from 15.4 to 81.2 dBA 8HR TWA using the OSHA action level and from 42.4 to 85.5 dBA 8HR TWA using the NIOSH/ACGIH guidelines. Six of 45 exposures among the adults and none of the 11 exposures among the children exceeded the OSHA action level. In addition, 10 of 45 exposures among the adults and 1 of 11 exposures among the children exceeded the NIOSH/ACGIH guidelines. The results of this pilot project indicate noise exposures among farm families can exceed recommended levels.     

Occupational exposures in California wildland fire fighting.

Industrial hygiene measurement of exposures to wildland fire fighters was conducted in northern California during three consecutive fire seasons (1986-1989) in conjunction with three separate health effects studies. Chemicals that were monitored included carbon monoxide, total and respirable particulates, polyaromatic hydrocarbons (PAHs), crystalline silica, aldehydes, and benzene. Measurements were taken at both wildland fires and prescribed (planned) burns. A variety of collection methods were employed--colorimetric detector tubes and a CO monitor were used for direct-reading area measurements; colorimetric diffusion tubes, filter cassettes, sorbent tubes, and passive vapor monitors were used for determining personal time-weighted average exposures. A new screening method (National Institute for Occupational Safety and Health Method 2539) was used to identify the presence of specific aldehydes. Results show that wildland fire fighters may at times be exposed to concentrations of carbon monoxide, total or respirable particulates, or silica at levels near or higher than recommended occupational exposure limits, although group means were generally well below the limits. Time-weighted average formaldehyde levels, measured in a few instances above 0.37 mg/m3 (0.3 ppm), indicate a potential for formaldehyde-induced eye or respiratory irritation under these conditions. Certain characteristics of the work such as high altitude, temperature, and breathing rate; extended work shifts; and additional off-shift exposures suggest that adjustment of 8-hr exposure limits may be necessary to provide adequate protection. In part, because of the rigors of performing industrial hygiene measurements under fire fighting conditions, data are limited and could not be considered representative of the full range of exposures fire fighters may encounter.(ABSTRACT TRUNCATED AT 250 WORDS)     

Occupational hearing loss

Hearing loss is a significant and unfortunately common occupational malady. Over the past several decades both the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) have initiated efforts to better understand and to limit the occurrence of occupational hearing loss, particularly as it relates to excessive noise exposure. This paper briefly addresses the pathophysiology of noise-induced hearing loss and then describes the occupational and non-occupational factors which influence a worker's risk of hearing loss. The primary foci of this discussion are the clinical evaluation, diagnosis, and management of occupational hearing loss. Issues of prevention, OSHA-mandated hearing conservation efforts and compensation are reviewed.     

An assessment of occupational noise exposures in four construction trades

Three hundred thirty-eight noise exposure samples were collected from 133 construction workers employed in 4 construction trades: carpenters, laborers, ironworkers, and operating engineers. Four sites using a variety of construction techniques were sampled at least 12 times on a randomly chosen date over a 22-week period. Up to 10 volunteer workers were sampled for an entire work shift on each sampling day using datalogging noise dosimeters, which recorded both daily time-weighted averages (TWAs) and 1-min averages. Workers also completed a questionnaire throughout the workday detailing the tasks performed and tools used throughout the day. Regression models identified work characteristics associated with elevated exposure levels. Comparisons were made between exposures measured using the Occupational Safety and Health Administration (OSHA) exposure metric and the 1996 draft National Institute for Occupational Safety and Health/International Organization for Standardization (NIOSH/ISO) metric to examine the effects of differing exchange rates and instrument response times on construction noise exposures. The mean OSHA TWA for 338 samples was 82.8 dBA +/- 6.8 dBA, whereas the mean NIOSH/ISO TWA for 174 samples was 89.7 dBA +/- 6.0 dBA. Forty percent of OSHA TWAs exceeded 85 dBA, and 13% exceeded 90 dBA, the OSHA permissible exposure limit. The tasks and tools associated with the highest exposure levels were those involving pneumatically operated tools and heavy equipment. Trade was a poor predictor of noise exposure; construction method, stage of construction, and work tasks and tools used were found to be better exposure predictors. An internal validation substudy indicated excellent agreement between worker self-reporting and researcher observation. These data provide substantial documentation that construction workers in several key trades are frequently exposed to noise levels that have been associated with hearing loss, and demonstrate the need for targeted noise reduction efforts and comprehensive hearing conservation programs in the industry.     

Occupational burns from oxygen resuscitator fires: the hazard of aluminum regulators

BACKGROUND: There have been over 30 incidents of oxygen resuscitator fires over the last 6 years, causing severe burns to a number of fire fighters, emergency medical service personnel, health care workers, and patients. The National Institute for Occupational Safety and Health (NIOSH) was requested to investigate three such incidents. METHODS: NIOSH conducted site investigations of the incidents, and the requesters also sent the involved oxygen resuscitators to a forensic engineering company for a causal analysis. RESULTS: The investigated fires were associated with aluminum regulators, all from one manufacturer, on compressed pure oxygen cylinders. The investigations indicated that the cause of the fires was an initial small ignition in the high-pressure area of the aluminum regulator, which then consumed itself in a massive burnout. CONCLUSIONS: Aluminum regulators used with high-pressure oxygen systems are subject to rare, but potentially catastrophic combustion in normal use. Replacement of such regulators with those made of more fire-resistant materials or designs, as well as education and improved safety practices are needed to reduce this hazard.     

Surveillance of hearing loss among older construction and trade workers at Department of Energy nuclear sites

BACKGROUND: Medical screening programs at three Departments of Energy (DOE) nuclear weapons facilities (Hanford Nuclear Reservation, Oak Ridge, and the Savannah River Site) have included audiometric testing since approximately 1996. This report summarizes hearing evaluations through March 31, 2003. METHODS: Occupational examinations included a medical history, limited physical examination, and tests for medical effects from specific hazards, including audiometric testing. Hearing thresholds by frequency for DOE workers were compared to age-standardized thresholds among an external comparison population of industrial workers with noise exposures <80 dBA. Multivariate analyses were used to explore the risk of hearing impairment by duration of construction trade work and self-reported noise exposure, while controlling for potential confounders such as age, race, sex, smoking, elevated serum cholesterol, hypertension, solvent exposures, and recreational noise exposures. RESULTS: Hearing thresholds among DOE workers were much higher than observed in a comparison population of industrial workers with low noise exposures. Overall, 59.7% of workers examined were found to have material hearing impairment by NIOSH criteria. Age, duration of construction work, smoking, and self-reported noise exposure increased the risk of hearing loss. The risk of material hearing impairment was significantly elevated for construction trade workers compared to the external comparison population (odds-ratio = 1.6, 95% CI = 1.3-2.1) and increased with the duration of trade work. CONCLUSIONS: These medical screening programs confirm worker concerns about risks for hearing loss and the need for hearing conservation programs for construction workers, with emphasis on the prevention of noise exposures.     

Ototoxic occupational exposures for a stock car racing team: II. chemical surveys

The National Institute for Occupational Safety and Health (NIOSH) conducted a series of surveys to evaluate occupational exposure to noise and potentially ototoxic chemical agents among members of a professional stock car racing team. Exposure assessments included site visits to the team's race shop and a worst-case scenario racetrack. During site visits to the race team's shop, area samples were collected to measure exposures to potentially ototoxic chemicals, including, organic compounds (typical of solvents), metals, and carbon monoxide (CO). Exposures to these chemicals were all below their corresponding Occupational Safety and Health Administration (OSHA) permissible exposure limits (PELs), NIOSH recommended exposure limits (RELs), and American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit values (TLVs). During site visits to the racetrack, area and personal samples were collected for organic compounds, lead, and CO in and around the "pit" area where the cars undergo race preparation and service during the race. Exposures to organic compounds and lead were either nondetectable or too low to quantify. Twenty-five percent of the CO time-weighted average concentrations exceeded the OSHA PEL, NIOSH REL, and ACGIH TLV after being adjusted for a 10-hour workday. Peak CO measurements exceeded the NIOSH recommended ceiling limit of 200 ppm. Based on these data, exposures to potentially ototoxic chemicals are probably not high enough to produce an adverse effect greater than that produced by the high sound pressure levels alone. However, carbon monoxide levels occasionally exceeded all evaluation criteria at the racetrack.     

Occupational exposures to air contaminants at the World Trade Center disaster site--New York,September-October, 2001

Amid concerns about the fires and suspected presence of toxic materials in the rubble pile following the collapse of the World Trade Center (WTC) buildings on September 11, 2001, the New York City Department of Health (NYCDOH) asked CDC for assistance in evaluating occupational exposures at the site. CDC's National Institute for Occupational Safety and Health (NIOSH) collected general area (GA) and personal breathing zone (PBZ) air samples for numerous potential air contaminants. This report summarizes the results of the assessment, which indicate that most exposures, including asbestos, did not exceed NIOSH recommended exposure limits (RELs) or Occupational Safety and Health Administration (OSHA) permissible exposure limits (PELs). One torch cutter was overexposed to cadmium; another worker was overexposed to carbon monoxide (CO) while cutting metal beams with an oxyacetylene torch or a gasoline-powered saw, and two more were possibly overexposed to CO. NIOSH recommended that workers ensure adequate on-site ventilation when using gas-powered equipment and use rechargeable, battery-powered equipment when possible.     

A task-based assessment of noise levels at a swine confinement

This study describes a task-based noise evaluation conducted at a community college that operated a small swine confinement for training and profit. Seven full-shift dosimeter samples and area noise data were collected during the evaluation. The time weighted average noise levels were all well below the Occupational Safety and Health Administration's (OSHA) Permissible Exposure Limit, but exceeded the National Institute for Occupational Safety and Health's Recommended Exposure Limit on three of seven occasions. The potential for high noise exposures is evidenced in the noise dose measured for specific activities such as power washing, ear clipping, and snout snaring. When the data were extrapolated to depict exposures where specific tasks were carried out over a full shift, tasks such as power washing and snout snaring would exceed the OSHA Action Level (AL). Employees who exceed the OSHA AL are required to be enrolled in a hearing conservation program.     

A Task-Based Assessment of Noise Levels at a Swine Confinement

Abstract

This study describes a task-based noise evaluation conducted at a community college that operated a small swine confinement for training and profit. Seven full-shift dosimeter samples and area noise data were collected during the evaluation. The time weighted average noise levels were all well below the Occupational Safety and Health Administration's (OSHA) Permissible Exposure Limit, but exceeded the National Institute for Occupational Safety and Health's Recommended Exposure Limit on three of seven occasions. The potential for high noise exposures is evidenced in the noise dose measured for specific activities such as power washing, ear clipping, and snout snaring. When the data were extrapolated to depict exposures where specific tasks were carried out over a full shift, tasks such as power washing and snout snaring would exceed the OSHA Action Level (AL). Employees who exceed the OSHA AL are required to be enrolled in a hearing conservation program.     

Surveillance of occupational noise exposures using OSHA's Integrated Management Information System

BACKGROUND: Exposure to noise has long been known to cause hearing loss, and is an ubiquitous problem in workplaces. Occupational noise exposures for industries stored in the Occupational Safety and Health Administration's (OSHA) Integrated Management Information System (IMIS) can be used to identify temporal and industrial trends of noise exposure to anticipate changes in rates of hearing loss. METHODS: The noise records in OSHA's IMIS database for 1979-1999 were extracted by major industry division and measurement criteria. The noise exposures were summarized by year, industry, and employment size. RESULTS: The majority of records are from Manufacturing and Services. Exposures in Manufacturing and Services have decreased during the period, except that PEL exposures measured by federal enforcement increased from 1995 to 1999. CONCLUSIONS: Noise exposures in manufacturing have been reduced since the late 1970s, except those documented by federal enforcement. Noise exposure data outside manufacturing is not well represented in IMIS.     

Measurement of impulse peak insertion loss from two acoustic test fixtures and four hearing protector conditions with an acoustic shock tube

Impulse peak insertion loss (IPIL) was studied with two acoustic test fixtures and four hearing protector conditions at the E-A-RCAL Laboratory. IPIL is the difference between the maximum estimated pressure for the open-ear condition and the maximum pressure measured when a hearing protector is placed on an acoustic test fixture (ATF). Two models of an ATF manufactured by the French-German Research Institute of Saint-Louis (ISL) were evaluated with high-level acoustic impulses created by an acoustic shock tube at levels of 134 decibels (dB), 150 dB, and 168 dB. The fixtures were identical except that the E-A-RCAL ISL fixture had ear canals that were 3 mm longer than the National Institute for Occupational Safety and Health (NIOSH) ISL fixture. Four hearing protection conditions were tested: Combat Arms earplug with the valve open, ETYPlugs^® earplug, TacticalPro headset, and a dual-protector ETYPlugs earplug with TacticalPro earmuff. The IPILs measured for the E-A-RCAL fixture were 1.4 dB greater than the National Institute for Occupational Safety and Health (NIOSH) ISL ATF. For the E-A-RCAL ISL ATF, the left ear IPIL was 2.0 dB greater than the right ear IPIL. For the NIOSH ATF, the right ear IPIL was 0.3 dB greater than the left ear IPIL.     

The high, medium, and low method--a better noise reduction rating?

This paper compares hearing protector attenuations calculated using National Institute for Occupational Safety and Health (NIOSH) method No. 1 ("long method") and the HML method. The study was done on 144 combinations of 12 noises and 12 protectors. In each case, the attenuation was calculated using each of the above methods. The difference between attenuations was used to define the accuracy of the high, medium, and low (HML) method. It was found that the attenuations calculated using the HML method are almost always lower than those calculated using the NIOSH method. However, the differences between both attenuations are well within the field noise level measurement errors. Consequently, the HML method appears to be an acceptable approximation of the NIOSH method, offering the additional advantage of being easier to apply. The higher accuracy of the HML method, when compared to the Noise Reduction Rating (NRR), makes is preferable for applications in industrial hearing conservation programs.     

The global burden of occupational noise-induced hearing loss

BACKGROUND: Excessive noise is a global occupational health hazard with considerable social and physiological impacts, including noise-induced hearing loss (NIHL). This paper describes the worldwide morbidity of occupational NIHL in the year 2000. METHODS: The proportion of the population exposed to occupational noise was estimated using noise exposure data from the US National Institute for Occupational Safety and Health (NIOSH), adjusted by data on the distribution of the work force by occupational category and economic sector, and economic activity rates in each WHO subregion. These values for the exposed population and risk measures for NIHL were used to develop estimates of the attributable fraction (AF) of adult-onset hearing loss resulting from occupational noise exposure. The AFs were applied to WHO estimates of total disability-adjusted life years (DALYs) from adult-onset hearing loss to estimate the DALYs due to occupational noise. RESULTS: Worldwide, 16% of the disabling hearing loss in adults (over 4 million DALYs) is attributed to occupational noise, ranging from 7% to 21% in the various subregions. The effects of the exposure to occupational noise are larger for males than females in all subregions and higher in the developing regions. CONCLUSIONS: Occupational noise is a significant cause of adult-onset hearing loss. The majority of this NIHL burden can be minimized by the use of engineering controls to reduce the generation of noise at its source.