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OUTLINE FOR AN EFFECTIVE INDUSTRIAL HYGIENE-MEDICAL INTERFACE.
J. Sherrill, Open Range Software, Crossville, TN.
The industrial hygienist’s role in support of the occupational physician is to capture the actual and anticipated exposure potential for workers, and to present this information to the physician in a meaningful way for making medical surveillance and health consequence decisions.
As simple as it sounds, the presentation of industrial hygiene data in a useful manner is quite complex, involving the standardization and establishment of worker exposure groups, the performance and documentation of worker risk assessments, the collection of personal monitoring data, and the creation of business rules for evaluating and presenting this information in a clear manner.
This presentation outlines a start-to-finish method for achieving an effective industrial hygiene-medical interface that will present industrial hygiene information to the physician in a meaningful way for making medical surveillance and health consequence decisions.
71
ENDOTOXIN IN EXHALED BREATH CONDENSATE (EBC).
T. Schoonover, L. Conroy, R. Malcolm, S. Erdal, S. Dorevitch, University of Illinois at Chicago, Chicago, IL.
The method of exhaled breath condensate (EBC) collection is rapidly becoming a less invasive and reliable substitute for biological monitoring in occupational settings. This research focused on optimizing collection and detection of gram negative bacterial endotoxin in EBC as a biomarker of exposure. EBC was collected from 12 subjects at a swine confinement facility and 10 controls. Personal endotoxin samples were collected concurrently at the swine confinement facility. Controls were sampled in a university classroom. Both groups were sampled pre- and post-workshift. The EBC collection device consisted of a one-way non-rebreather valve connected to a vertical Teflon tube. The valves and tubes were conditioned to be endotoxin-free and cooling packs were applied externally to facilitate condensation. Participants breathed at tidal volume for 20 minutes, consistently producing approximately two milliliters of condensate. Condensate was collected and handled avoiding endotoxin contamination and analyzed using the QCL-1000 LAL chromogenic assay. The median EBC endotoxin concentration for subjects at the swine confinement facility was 0.9 EU/ml (0.08 to 818 EU/ml) pre-workshift and 0.4 EU/ml (0.08 to 417 EU/ml) post-workshift. The median EBC endotoxin concentration for controls was 0.14 EU/ml (0.07 to 63 EU/ml) pre-workshift and 0.12 EU/ml (0.05 to 60 EU/ml) post-workshift. The median endotoxin concentration for personal samples collected at the swine confinement facility was 1294 EU/m3 (316 to 8435 EU/m3). The Wilcoxon rank sum test was applied and showed no significant difference between pre- and post-workshift EBC endotoxin concentrations among swine confinement facilty subjects. The same test was applied to the control group and showed no significant difference between pre- and post-workshift EBC endotoxin concentrations. There was a moderate correlation between personal endotoxin exposure and post-shift EBC endotoxin concentration among the swine confinement subjects. Conclusions are that EBC endotoxin may not be an effective biomarker of workshift exposure but may be of recent exposure.
72
POWER PLANT FIRE: WHAT IS IN THE SMOKE?
V. Feuerstein, Reclamation, Billings, MT.
The failure of a solid state transformer located inside a 30-year-old hydroelectric power plant resulted in the contamination of all 10 floors. The 40-minute melt-down of the resin insulated copper wound high voltage transformer generated temperatures in excess of 3500 degrees Fahrenheit releasing dense smoke, soot, and volatile gases. The chemical composition of the surface contamination throughout the plant was determined utilizing GSMS and AA-ICP analysis of parallel wipe samples to assess the hazards to clean up personnel and facilitate the selection of the appropriate personal protective equipment. The sample data revealed that the smoke and heat transported metals and chemical residue over a wide area throughout the plant.
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PERSONAL PASSIVE SAMPLERS USED TO MONITOR THE EXPOSURE OF MAINTENANCE WORKERS
(INDUSTRIAL PLUMBERS) TO ASBESTOS.
D. Bard, G. Burdett, Health and Safety Laboratory, Sheffield, United Kingdom.
Past industrial manufacture and use of asbestos-containing products has led to a high incidence of asbestos-related diseases and this accounts for a high proportion of all industrially-related cancers. The annual mortality rates due to past asbestos exposure are predicted to continue to rise over the next 15 years, regardless of any further controls that could be applied now. Although the UK and USA have taken measures to reduce the risk from asbestos exposure, there are a number of sources that have the potential for continuing exposure and future disease. Large amounts of asbestos are still in place in buildings and epidemiological data suggest that there has been and continues to be a significant risk to demolition and maintenance workers who may, through their work, use or disturb asbestos-containing materials.
The sampling and assessment of maintenance workers’ exposure is a particular problem because they may not know that they are working with asbestos-containing materials. A strategy to monitor their true exposure has been developed and applied to one group of workers.
The asbestos exposure of industrial plumbers was measured using personal passive samplers developed at the Health and Safety Laboratory. The lightweight samplers, which collect particles by electrostatic attraction, are simple to use and do not require prior knowledge that asbestos is to be disturbed as does conventional sampling. The samplers, along with activity logs, were issued by post and analysed, after return, using transmission electron microscopy. The activity logs were used to assess whether maintenance workers were knowingly or unknowingly exposed to airborne asbestos fibres during the course of a working week. The monitoring carried out in parallel with a questionnaire provided a detailed picture of workers’ awareness, assumptions, and responses to working with asbestos containing materials.
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THE INVESTIGATION OF THE IMPACT OF WORKER LOCATIONS, ORIENTATION, AND ACTIVITY
ON EXPOSURE.
E. Lee, C. Feigley, J. Khan, S. Tamanna, University of South Carolina, Columbia, SC; M. Ahmed, Hydek Inc., Atlanta, GA.
Worker exposure is a complex function of the many factors that affect contaminant transport to the worker’s breathing zone. Here the impact of worker position, orientation, and activity was studied in an experimental room. Simulated personal exposures to a tracer gas (propylene) were measured by monitoring the concentration in front of a worker’s respirator facepiece. For a stationary worker, simulated exposure was measured at 12 locations within the room, and for four orientations at each location. Simulated exposures of a moving worker were measured along two paths, one close to the source and the other farther from the source. All measurements were made for each of four factorial combinations of air inlet types (wall jet and ceiling diffuser) and air flowrates (5.5 m3/min and 3.3 m3/min).
Over the 12 worker locations, the breathing zone concentrations were significantly higher when the worker was facing the source than when not facing the source with ratio ranging from 1.15 to 1.25 (all p-values < 0.05). Exposure downwind of the source, and upwind but close to the source, was higher when the worker was facing the source than when facing away from the source. The TWA exposure of the worker walking along a path near the source was about 1.76 times greater than the exposure of the worker walking along the other path. Also, the exposure of the worker walking along the two paths within the room was significantly higher than the average exposure of the worker standing still at several points along these paths, possibly because worker movement prevents formation of a convective boundary layer found around a stationary worker.
These experiments clearly demonstrate the importance of basing exposure estimates on personal sampling when possible rather than area sampling as a result of the impact of worker orientation and movement on breathing zone concentration.
75
CHARACTERIZATION OF THE CUMMULATIVE ASBESTOS EXPOSURES OF U.S. AUTOMOBILE BRAKE
MECHANICS.
P. Sheehan, G. Brorby, R. Kalmes, Exponent, Oakland, CA; F. Mowat, Exponent, Menlo Park, CA; R. Richter, Exponent, Irvine, CA; B. Finley, Exponent, Santa Rosa, CA.
An analysis of the cumulative exposures of U.S. brake mechanics to asbestos during the period 1960 to 2000 was conducted. Cumulative exposures in fibers per cubic centimeter times years (f/cc*year) were estimated based on published data regarding typical airborne asbestos concentrations experienced by U.S. brake mechanics and their job tenure. Cumulative exposures were calculated using Monte Carlo methods based on three different distributions of eight-hour TWA exposure concentrations reported by NIOSH for brake mechanics and the distribution of job tenure for automobile mechanics working in repair garages. The median (50th percentile) and upper bound (95th percentile) estimated cumulative exposures for mechanics in garages with no dust control procedures ranged from 0.20 to 0.56 f/cc*year and 2.2 to 2.9 f/cc*year, respectively. The estimated median and upper bound cumulative exposures of mechanics in garages employing dust control procedures ranged from 0.01 to 0.02 f/cc*year and 0.08 to 0.11 f/cc*year, respectively. An evaluation of the trends in cumulative exposure based on the initial date of exposure indicate that those mechanics that started work in 1955 had an upper bound cumulative exposure of 2.5 f/cc*year while those that started in 1975 had an upper bound exposure of 1.2 f/cc*year. European brake mechanics have higher estimated upper bound cumulative exposures (ranging from 6.0 to 13 f/cc*year), likely the result of longer job tenure than U.S. mechanics and inclusion of higher concentration data for truck and bus mechanics, which were not considered in the evaluation of U.S. mechanics. Because epidemiological studies of automobile mechanics worldwide have consistently shown no association between occupational exposures and an increased risk of mesothelioma, the form of cancer most often associated with asbestos exposure, the upper bound cumulative exposure estimates for brake mechanics provide a conservative estimate of the cumulative exposure threshold for mesothelioma risk in workers exposed to short chrysotile fibers.
76
AIRBORNE ASBESTOS FIBER EXPOSURE ASSESSMENT OF HEAVY EQUIPMENT MECHANICS.
F. Boelter, C. Simmons, Boelter & Yates Inc., Park Ridge, IL; J. Spencer, Environmental Profiles Inc., Baltimore, MD.
The purpose of this study was to determine the concentration of airborne fibers during maintenance and repair activities involving asbestos-containing friction products and gaskets on heavy equipment. Both personal and area air samples were collected inside a heavy equipment repair facility over a period of nine days during removal and replacement of asbestos-containing friction products and gaskets from four different pieces of heavy equipment. Samples were collected while four mechanics, experienced in heavy equipment repair and maintenance, removed and replaced asbestos-containing friction and gasket materials. Samples were analyzed using NIOSH Method 7400 for phase contrast microscopy (PCM) and NIOSH Method 7402 transmission electron microscopy (TEM). Statistical methods were used to calculate likely upper limits during full-shift and short-term exposures. Full-shift personal samples ranged from 0.005 to 0.049 f/cc by PCM and 0.002 to 0.041 asbestos f/cc TEM. Personal excursion limit (short-term exposure limit) exposures ranged from 0.043 to 0.56 f/cc by both PCM and TEM. Statistical analysis determined with 95% confidence that 95% of eight-hour TWA exposures were below 0.061 f/cc by PCM and below 0.057 asbestos f/cc by TEM. Statistical analysis indicated with 95% confidence that 95% of short-term (30-minute) exposures were below 0.19 f/cc by PCM and 0.13 asbestos f/cc by TEM. Repair and maintenance of asbestos-containing friction products and gaskets in heavy equipment results in exposures well below both OSHA’s standard for an eight-hour TWA and the 30-minute excursion limit.
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HEALTH AND ENVIRONMENTAL ENGINEERING FLIGHT TEST AT THE AIR FORCE FLIGHT TEST
CENTER.
S. Neumann, U.S. Air Force, Edwards AFB, CA.
This presentation will show how the new capability of the 412 TW Health and Environmental Engineering Test and Evaluation Branch merged health and environmental engineering considerations throughout flight test activities and optimized sustainment. Some examples include the F/A-22 Raptor, the Joint Strike Fighter (F-35), and Airborne Laser (ABL) test programs at the Air Force Flight Test Center, Edwards AFB, Calif.
This presentation will show tailored strategies for capturing health and environmental data, test outcomes, and lessons learned for fielding weapon systems with the least impact to the human and the environment. As a result, logistics footprint and total operating costs are minimized. The F/A-22, the F-35, and the ABL are at varying stages of flight and ground test within the acquisition cycle. Some examples within the F/A-22 Raptor flight test program associated with stealth maintenance, copper beryllium testing, and repair maintenance for the F119 engine are presented. The F-35 flight test activities example will show how early involvement in preparation to receive the aircraft can minimize facility contamination and maximize logistics testing. Finally, the ABL ground and flight test activities require emphasis on environmental and health planning to ensure success for total operation. When health and environmental engineering considerations are incorporated prior to the start of the flight test and throughout flight test activities, weapon system sustainment improves the readiness of the warfighter at lower total operating costs.
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DERMAL EXPOSURE MEASUREMENT OF EPOXY COMPOUNDS.
R. Lindahl, M. Rhen, A. Hagenbjörk-Gustavsson, National Institute for Working Life, Umeå, Sweden.
Epoxy compounds, such as diglycidylether of bisphenol A (DGEBA), may cause allergic contact dermatitis. The aim of this study was to develop and test two methods, patch sampling and tape stripping, for the determination of dermal epoxy exposure. The adhesive used for both tape stripping and patch sampling was Fixomull®, a self-adhesive gauze with woven polyester backing and a polyacrylate adhesive. The adhesive was, immediately after sampling, put into dimethyl formamide (DMF) to stop curing and other reactions with DGEBA. For the analysis, liquid chromatography with fluorescence or mass spectrometric detection was used. Laboratory tests showed no stability or recovery problem after dissolving in DMF.
The methods have been tested in three companies. In the first two there was only direct contact contamination and no air transport of DGEBA. The work tasks were application of seamless floors and liquid shim application. In the third company the main exposure occurred after air transportation of DGEBA in aerosols produced during spray painting. Blank levels were less than 1 ng/cm2. A comparison of the two methods during application of seamless floors showed about three times the amounts for the patch sampling compared to tape stripping, probably due to a too thin stripping layer compared to the permeation rate and sampling time.
Both tested methods, tape stripping and patch sampling, are sensitive enough and can be used for dermal exposure measurement of epoxy compounds such as DGEBA. The methods can be used in different work tasks and with different exposure situations.
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COMPUTERIZED STATISTICAL METHODS FOR ASSESSING OCCUPATIONAL EXPOSURES.
P. Wambach, U.S. DOE, Washington, DC; E. Frome, Oak Ridge National Laboratory, Oak Ridge, TN.
The statistical methods recommended in J.R. Mulhausen and J. Damiano’s A Strategy for Assessing and Managing Occupational Exposures, Second Edition (AIHA Press, Fairfax, Va., 1998) and some additional methods have been computerized. The free software provides lognormal and nonparametric estimates of means, upper tolerance limits, and percent exceedance metrics, for any size data set, with or without the presence of nondetected results. Industrial hygiene exposure measurements may be subject to left censoring, i.e., the measured value is less than a “limit of detection.” Occupational exposure monitoring typically focuses on the mean exposure level and/or the probability that any measurement exceeds a limit. Parametric methods, used to determine acceptable levels of exposure, are often based on a two parameter lognormal distribution. The mean exposure level, an upper percentile (e.g., the 95th percentile), and/or the percent exceeding the limit are used to characterize exposure levels and confidence limits are needed to describe the uncertainty in these estimates. Statistical methods for random samples (without nondetects) from the lognormal distribution are well known for each of these situations. In this presentation, methods for estimating these quantities based on the maximum likelihood method for randomly left censored lognormal data are described. If the lognormal model is in doubt, then nonparametric methods for left censored data are used. All of these methods are well known but computational complexity has limited their use in routine data analysis with left censored data. The recent development of the R environment for statistical data analysis and graphics has greatly enhanced the availability of high quality nonproprietary (open source) software that serves as the basis for implementing the methods in this presentation. Numerical examples are provided and the availability of R functions is described.
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THE EFFECT OF A WORKER’S PRESENCE IN A ROOM ON CONTAMINANT DISPERSION.
E. Lee, C. Feigley, J. Khan, S. Tamanna, University of South Carolina, Columbia, SC; M. Ahmed, Hydek Inc., Atlanta, GA.
Previous studies have shown that contaminant concentrations in the breathing zone strongly depended on the worker’s position relative to a contaminant source. However, most investigations were performed in a wind tunnel or in rooms with displacement ventilation—air flow patterns that are not typical of workrooms in the U.S. Here the effect of worker presence near a source was investigated in an experimental room (2.86 m(L) x 2.35 m(H) x 2.86 m(W)) to determine if one worker’s presence could influence contaminant dispersion patterns in a room, and thus potential exposure levels of others in the room. A heated mannequin was placed in four locations near a source for a wall jet (WJ) air inlet and one location for the ceiling diffuser (CD) inlet. Tracer gas (99.5% propylene) concentrations were monitored automatically at 144 sampling points with a photoionization detector. Two flowrates (5.5 and 3.3 m3/min) were employed.
The worker presence influenced the contaminant dispersion pattern in the occupied portion of the room for all conditions investigated, except for CD-5.5 m3/min; for WJ-5.5 m3/min, concentrations were higher near the source pedestal for all worker locations compared to those without a worker present. Relatively more variation of contaminant concentrations was observed in the occupied zone of WJ-5.5 m3/min (CVs = 0.42–0.58) than those of WJ-3.3 m3/min (CVs = 0.2–0.28). For the CD-3.3 m3/min, the worker present north of the source generated better mixing of room air (CV = 0.17) in the breathing zone compared to when the worker was absent (CV = 0.49). Perhaps, thermal convection from the heated worker promoted better mixing of room air.
These experimental results indicate that contaminant dispersion patterns depend upon the location of the worker and the worker’s interaction with the air velocity field. Also, they suggest that a greater understanding of concentration variability in workrooms is needed to develop more sophisticated methods of exposure estimation.
Posted May 30, 2005