R. Kling, H. Davies, P. Demers, University of British Columbia, Vancouver, BC, Canada.
Noise-induced hearing loss is the most common health outcome associated with exposure to noise. However, studies show that occupational noise increases the risk of both fatal accidents and nonfatal workplace injury. The purpose of this study was to assess the effect of cumulative noise exposure on serious workplace accidents. The cohort was 5876 workers who were employed for at least one year, between 1989 and 1998, in one of 14 British Columbia sawmills. Cases were those who were hospitalized having a work-related injury as determined by the hospital discharge record noting an “E-code” and either (1) a fifth digit was added to the code, indicating work-relatedness, or (2) the Workers’ Compensation Board was indicated under the field “responsibility for payment.” Under this definition, 163 cases were identified. Work history data for each cohort participant was collected directly from the study sawmills, and cumulative noise exposure was retrospectively assessed using regression models based on full-shift personal noise dosimetry data collected by the researchers, the local regulatory agency, and the mill itself.
The NIOSH life table analysis system (LTAS) was used to stratify person-days at risk, and an internal comparison of cumulative noise exposure and accidents was conducted using Poisson regression. Cumulative exposure to noise was found to significantly reduce the risk for serious accidents at levels of 126-130 dBA-years (RR=0.59, 95% confidence interval [CI]= 0.36-9.97) and 131-135 dBA-years (RR= 0.50, 95% CI= 0.29-0.85). The characteristics of being of Caucasian race and working between 1995-1998 (compared to 1989) were found to significantly reduce the risk of injuries. The results do not support the original hypothesis. A person working longer in the industry surrounded by high levels of noise may have developed better methods over time of recognizing and communicating potential risks for injury. The effects of acute exposure to noise on accidents are currently being investigated.
K. Michael, doseBusters USA, State College, PA; A. Burks, doseBusters USA, Pittsburgh, PA; C. Dixon-Ernst, Alcoa, Pittsburgh, PA; R. Wilkinson, Alcoa Intalco Works, Ferndale, WA.
This study describes the results of a program to monitor the actual, protected noise exposure of a population of at-risk workers in an aluminum smelter over a 24-month period. A total of 130 workers was selected, based on recent shifts in hearing level, for enrollment in the continuous monitoring program, and approximately 30,000 daily exposure measurements have been gathered. Each worker was personally outfitted with a specially designed, dual-microphone dosimeter, which uses a microphone in real ear (MIRE) technique to measure the noise exposure dose when personal protection is worn. The workers chose to use either custom-molded protectors or a variety of insert-type ear tips or cap-mounted circum-aural protectors. Workers are active participants in the monitoring process and are provided quantitative, real-time exposure information each day so they can make good decisions about effective use of their personal protection. Overall, in spite of the normal 12-hr shift duration, 99.6% of the daily noise dose measurements were maintained below a time-weighted average (TWA) of 90 dBA while 97.8% were below a TWA of 85 dBA. It is concluded that the use of continuous monitoring of individual workers’ protected dose provides a practical solution to the long-standing and serious problems with the real-world use of personal protection, and this continuous monitoring is essential to the prevention of noise-induced hearing loss in most workplaces.
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An Evaluation of Concrete Saw Blades for Noise Reduction
S. Shepherd, S. Woskie, M. Virji, University of Massachusetts Lowell, Lowell, MA.
Noise is a serious hazard in construction. A proposed OSHA hearing conservation standard in the construction industry will require that more resources be allocated to limiting noise levels where possible to 85 dB. Concrete saw cutting is an extremely noisy operation. In the literature, saw cutting has been measured at 88-102 dB. These levels present a hearing loss hazard not only to the saw operators but to all tradespeople working in the area. In addition, studies have indicated that hearing protection devices (HPDs) are not completely effective as noise controls because they are not consistently worn. Therefore, other noise controls are needed in construction to reduce the noise at the source. It has been suggested that vibration damping in the core of the saw blade could reduce noise exposures. Another approach is to use saw blades with smaller gullets to limit the amount of air moved by the blade. This randomized field experiment evaluated five 14-in chop saw blades of varied configurations used on a hand-held, gas-powered chop saw that was cutting reinforced concrete pipe (RCP). Experienced volunteers cut the RCP while measurements were taken for personal noise exposure, area noise levels, and octave band analysis. Personal average noise measurements ranged from 97.6 dBA to 101.9 dBA over the sampling times. Sound levels were highest in the 4000 Hz and 8000 Hz frequencies.
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Air and Noise Certification Program Designed to Build Teamwork and Ensure Consistent Sampling Data
H. Harapan, 3M, St. Paul, MN.
Hygienists work hard to ensure that exposures are properly managed for all employees in companies around the world. To help in this important endeavor, monitoring certification programs can be implemented to ensure the consistency of monitoring data. In addition to achieving consistency, establishing a certification process can effectively build teamwork throughout an organization. An air and noise certification program was designed to establish a system that effectively promotes consistency of air and noise samples collected in a large Fortune 500 manufacturing company. The certification program includes online training, hands-on training, coaching, online tests, periodic program evaluation, and an added bonus of a stronger global industrial hygiene network. This presentation describes a process of creating an air and noise certification program as well as the challenges and important opportunities created for individuals, business, and the corporation.
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Using Measurements of Cosmic Radiation Doses to Estimate Flight Crew Exposures
M. Waters, T. Bloom, B. Grajewski, NIOSH, Cincinnati, OH.
Flight crews are occupationally exposed to cosmic radiation at commercial aircraft altitudes. Exposure estimates are needed for epidemiologic studies of flight crews and must be obtained from exposure models, since direct exposure measurement is infeasible for historical exposures and large-scale prospective studies. We measured cosmic radiation ambient dose equivalent on 37 commercial flights using tissue-equivalent proportional counters equipped with data loggers for the purpose of comparing the measurements to an exposure model. Measured doses were compared to equivalent dose estimates for the same flights obtained from the U.S. Federal Aviation Administration computer model CARI version 4Q. Flight length times ranged from 49 to 851 min. No major solar particle events took place during data collection. The measured dose equivalents ranged from 0.69 to 65.4 uSv. CARI 4Q model estimates of equivalent dose ranged from 11% to 61% lower than TEPC measurements of dose equivalent. In general, less model bias was observed for low-latitude and transequatorial flights than for high-latitude flights. Differences in measured vs. modeled data should be considered when estimating doses using a model for epidemiologic studies and correction for bias made where possible. We also evaluated the magnitude of four potential sources of measurement error of ambient dose equivalent, which could result in 5% to 12% differences in the measured ambient dose equivalent. These data can be used to correct CARI model estimates for epidemiologic studies of flight crews.
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Evaluation And Control Of Hydrogen Fluoride Exposure From A Plasma Oven
B. Altemose, Johnson & Johnson, Somerville, NJ; T. Grubb, Johnson & Johnson, Cornelia, GA; K. Duffer, Johnson & Johnson, San Angelo, TX.
A concern for potential exposure to hydrogen fluoride arose from a plasma oven used to ablate oil residue from surgical needles. Investigating odor complaints in this process area, an industrial hygienist noted acidic odors when opening the plasma oven door and also discovered that the sight glass for the oven appeared to be etched. Subsequent air sampling revealed the process generated hydrogen fluoride. Concentrations from 268 to 2562 ppm of hydrogen fluoride were detected in the exhaust stream of the plasma oven. Fortunately, integrated personal samples were equal to or below 0.35 ppm, but the potential for short-term exposures and the corrosion observed on components downstream of the plasma chamber were a concern. Needles are cleaned in this process by creating plasma from a gas mixture of carbon tetrafluoride, oxygen, and helium at a low pressure (350 mTorr) with approximately 2500 W of radiofrequency energy applied. Approximately 3 mole percent of fluoride ions are formed in the plasma. Further diagnosis of the source of hydrogen fluoride revealed an accumulation of aluminum trifluoride on the inside of the plasma chamber. This finding, along with the sampling results and corrosion patterns observed, indicated that some fluoride ions were not recombining in the discharge and subsequently were reacting with moisture to form hydrogen fluoride, particularly at a vacuum pump downstream of the plasma chamber. The recommended corrective actions to eliminate the potential for hydrogen fluoride exposure in the short term included the addition of local exhaust ventilation at the oven door, changes to personal protective equipment requirements, and the removal of the aluminum trifluoride buildup. The long-term solution is to revalidate the cleaning process with a gas mixture that does not include carbon tetrafluoride.
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50 Things You Can Do: How to Invigorate the Industrial Hygiene Profession in an Evolving World
D. Brown, 3M, St. Paul, MN; S. Barnes, Chevron North American Exploration and Production Co., Bakersfield, CA.
Today’s workplace is changing in fundamental ways as the effects of globalization and technological innovation are realized. Multinational corporations are evolving into globally integrated enterprises. Revolutionary changes in information and communication technologies are being incorporated in ways not even imagined just a few years ago. The outsourcing trend as well as offshoring trials continue. This dynamic environment challenges our profession to adapt and evolve. Simultaneously, the industrial hygiene (IH) profession in the United States may face an impending skill shortage as many practitioners anticipate retirement. Rather than focus on past models, IHs should contemplate a fresh vision for the profession’s future as well as new approaches to growth, collaboration, knowledge transfer, innovation, and global influence. In an attempt to supply IHs with ideas as well as tested methods for promoting, preserving, invigorating, and advancing the profession, the author surveyed a sample of environmental health and safety (EHS) practitioners. Industrial and occupational hygienists from sectors including industry, government, academia, and consulting were surveyed. A number of EHS professionals living and working outside the United States also were included in the survey. A selection of their responses about what actions will make a difference for the future of industrial hygiene will be presented, ranging from simple things a hygienist can do to actions requiring substantial effort.