282
PARTICLE BOUNCE AND ENDOTOXIN LEVELS IN A MARPLE CASCADE SAMPLER WITH PVC
FILTERS.
S. Kirychuk, N. Koehncke, University of Saskatchewan, Saskatoon, SK, Canada; S. Reynolds, J. Nakatsu, J. Mehaffy, Colorado State University, Fort Collins, CO.
Several studies indicate distortion related to particle bounce when utilizing cascade impactors with certain filter media. To reduce the effect of particle bounce and the related effect on size distribution, it is often recommended to utilize impaction grease on filter media in cascade impactors. The effect of particle bounce with polyvinyl chloride (PVC) filters in a Marple® cascade impactor were unknown as was the effect of impaction grease on endotoxin levels. A pilot study was undertaken utilizing six-stage Marple cascade impactors and 5.0 µm PH-PVC 34-mm filters with radial slits. Poultry dust was run through a wind tunnel in which four six-stage samplers were stationed. For each of the three runs that were carried out, the filters of two of the samplers were treated with impaction grease and two of the samplers were not treated. Levels of total dust (mg/m3) and endotoxin (EU/m3 and EU/mg) were analyzed to determine if there was any effect from utilizing impaction grease. The results indicate that when utilizing the PVC filters in the Marple impactor running at 2.0 litres/minute there was no significant difference in total dust between filters treated with impaction grease (0.20 mg/m3) and those not treated (0.24 mg/m3) when controlling for the impaction stages. There was a significant difference (p = 0.01) in airborne endotoxin between filters treated with impaction grease (5.61 EU/m3) and those not treated (6.00 EU/m3), but no significant difference in endotoxin concentration (EU/mg). The results indicate that there is no difference in particle bounce utilizing impaction grease or no impaction grease on 5.0 µm PVC filters in a Marple impactor, but the impaction grease does appear to inhibit the endotoxin assay. Furthermore, utilizing impaction grease with PVC filters had some negative practical issues such as filter tearing and inaccurate impaction grease application rates.
283
DIFFERENCES IN DISSOLUTION BEHAVIOR IN A PHAGOLYSOSOMAL SIMULANT FLUID FOR
SINGLE-COMPONENT AND MULTICOMPONENT BERYLLIUM MATERIALS ASSOCIATED WITH
BERYLLIUM SENSITIZATION AND CHRONIC BERYLLIUM DISEASE.
A. Stefaniak, G. Day, M. Hoover, NIOSH, Morgantown, WV; P. Breysse, Johns Hopkins University, Baltimore, MD; R. Scripsick, Los Alamos National Laboratory, Los Alamos, NM.
Dissolved beryllium is the hypothesized input to the cell-mediated immune reaction associated with development of beryllium sensitization and chronic beryllium disease (CBD). Particle dissolution within the macrophage phagolysosome is thought to be an important source of dissolved beryllium. Using a phagolysosomal simulant fluid in a static dissolution technique, we measured dissolution rates for single- and multicomponent beryllium aerosol materials associated with elevated prevalence of beryllium sensitization and CBD. The observed dissolution rates were normalized to measured values of specific surface area (SSA) to calculate a chemical dissolution rate constant (k) for each material. The values of k, in g/(cm2·day), for single-component beryllium oxide released from a screener unit operation (1.3 ± 1.9 x 10-8) and for single-component finished product beryllium oxide powder (1.1 ± 0.5 x 10-8) were similar (p = 0.45). The value of k observed for single-component finished product beryllium metal powder (1.1 ± 1.4 x 10-7) was significantly greater than observed for the beryllium oxide materials (p < 0.0003). For multicomponent aerosol material collected from an arc furnace during processing of copper-beryllium alloy, k (1.6 ± 0.6 x 10-7) was significantly greater than observed for single-component beryllium oxide (p < 0.00001), despite the fact that the chemical form of beryllium in the aerosol was beryllium oxide. Thus, knowledge of the SSA of the particles and the k value of the chemical form of beryllium was not sufficient to characterize beryllium dissolution from the multicomponent material. Additional studies of the dissolution behavior of beryllium alloy materials, as well as beryllium minerals, metal, oxide, and composite materials in a variety of mixture configurations (uniform mixtures, nonhomogeneous mixtures, surface coatings, etc.) are needed to aid in developing exposure-response models to improve understanding of the risk of beryllium sensitization and CBD.
284
EMISSION CHARACTERISTICS OF SIDESTREAM CIGARETTE SMOKES.
C. Chen, F. Chiang, T. Yang, C. Hsu, Y. Lin, National Taiwan University, Taipei, Taiwan Republic of China.
Tobacco smoke is formed by a complex series of processes, including combustion, pyrolysis, evaporation, distillation, and condensation. This complex matrix is composed of several thousand constituents. Numerous studies have been conducted to investigate the health effect. Historically, smoking-control efforts have focused on smoking prevention and cessation through individual and group counseling efforts, reflecting a reliance on the individual-based medical model. Compared to the policy-oriented control, the technology-oriented control measures do not receive as much attention as they deserve. Therefore, the ultimate goal of this work was to develop or improve the current commercial air cleaners designed for removing sidestream cigarette smokes.
An experimental system, composed of a sidestream cigarette smoke generator, a mixing and test chamber, and a sampling train, was set up to investigate the chemical and physical characteristics of the sidestream cigarette smokes. Real time instruments, such as Q-Trak, were used to monitor the concentrations of CO and CO2; PID was used to measure the concentration of VOCs. Filter samples were collected for estimating the mass concentration. We also measured the particle size distribution (by using a scanning mobility particle sizer) and temperature of cigarette burning tip, by using a homemade thermocouple with 79-µm nickel-aluminum and chrome wires.
The results showed that cigarette combustion rate increased with decreasing packing density of cigarette due to less mass and therefore relatively higher oxygen transfer. The emission factors and emission rates of CO, CO2, aerosol mass concentration, VOCs, and the surface temperature of the smoldering cone all increased with increasing passing air flow. The thermal conductivity of the ashtray played an important role in both aerosol and gas emission. The design of the trench holding the cigarette was particularly critical. The cigarette smoldering rate decreased with increasing contact area, until the combustion ceased due to not enough heat generation.
285
INDUSTRY AND EXPOSURE PROFILES FOR INDUSTRIES AFFECTED BY THE PROPOSED OSHA
HEXAVALENT CHROMIUM STANDARD.
L. Verdier, R. Krishnan, D. Schupp, Shaw Environmental Inc., Cincinnati, OH.
The Occupational Safety and Health Administration (OSHA) published a proposed rule for occupational exposure to hexavalent chromium [Cr (VI)] in the October 4, 2004, edition of the Federal Register. Among other regulatory requirements, the proposed rule establishes a Permissible Exposure Limit (PEL) of 1 µg/m3. OSHA estimates there are 380,000 workers exposed to Cr (VI), of which 84,000 are estimated to be exposed above the proposed PEL. As a contractor to OSHA’s Office of Regulatory Analysis and OSHA’s Directorate of Standards and Guidance, Shaw Environmental Inc. (Shaw) provided technical support to OSHA in conducting research to identify the industries and industrial processes potentially affected by the proposed rule. Shaw identified a total of 32 industries or processes that are potentially affected, and developed an industry profile which describes these affected industries.
In addition to the industry profile, occupational exposure data for affected job categories in each industry was obtained from a variety of sources including: (1) site visits conducted by Shaw and NIOSH to selected establishments in the affected industries, (2) data provided by public and private employers, and (3) data obtained during research projects performed by universities, labor unions, and NIOSH. The eight-hour time-weighted average exposure data for each job category in each industry was sorted into an exposure profile consisting of eight exposure ranges from “less than 0.25 µg/m3” to “greater than 20 µg/m3.” The percentage of worker exposure concentrations in each group was calculated to estimate the overall percentage and number of workers in each job category for each industry who are exposed above the proposed PEL of 1 µg/m3.
286
TECHNOLOGICAL FEASIBILITY OF ACHIEVING COMPLIANCE WITH OSHA’S PROPOSED
HEXAVALENT CHROMIUM STANDARD IN WELDING AND PAINTING OPERATIONS.
L. Verdier, R. Krishnan, D. Schupp, Shaw Environmental Inc., Cincinnati, OH.
The Occupational Safety and Health Administration (OSHA) published a proposed rule for occupational exposure to hexavalent chromium in the October 4, 2004, edition of the Federal Register. As a contractor to OSHA’s Office of Regulatory Analysis and OSHA’s Directorate of Standards and Guidance, Shaw Environmental Inc. (Shaw) provided technical support to OSHA in conducting research to identify the technical feasibility of reducing worker exposures to achieve compliance with the proposed PEL. Two industrial operations involving a significant number of workers potentially exposed to hexavalent chromium include: (1) welding stainless steel or chromium-containing alloys, and (2) spraying paints and coatings that include hexavalant chromium-containing ingredients.
Existing processes and engineering controls for welding and painting operations were identified in the shipbuilding, construction, and general industry through a combination of site visits to selected establishments, NIOSH health hazard evaluations, and industrial hygiene surveys reported in the literature. The need for additional controls for welding was found to be dependent on (1) the type of welding operation, e.g., shielded metal arc welding, gas metal arc welding, (2) the chromium content of the metal alloy, and (3) the welding environment, e.g., dilution or mechanical ventilation, percentage of time striking the welding arc, etc. The research identified additional controls for welding and painting operations necessary to achieve exposures below 1 µg/m3, including effective use of local exhaust ventilation, welding process modification, and use of spray painting equipment with higher paint transfer efficiency. The effectiveness of these additional controls was determined by surveys performed in field-use conditions. A summary of additional controls for welding and painting operations are presented.
287
A COMPARISON OF NIOSH 7600 AND OSHA ID-215 USING A SINGLE EXTRACTION METHOD FOR
THE ANALYSIS OF HEXAVALENT CHROMIUM.
D. MacDuff, M. Hermann, F. Posey, Galson Laboratories, E. Syracuse, NY.
Hexavalent chromium may be analyzed by industrial hygiene laboratories using one of two methods: NIOSH 7600, which is a spectrophotometric technique, and by OSHA ID-215, which uses ion chromatography. OSHA ID-215 was published in 1998 and offers an extraction method which yields results as total hexavalent chromium. NIOSH 7600 was first published in 1989, and can provide results as either soluble or total hexavalent chromium. In order to compare analytical results for total hexavalent chromium obtained from the same sample filter, the OSHA ID-215 extraction method was modified. The modified method allows analysis of a single filter using both OSHA ID-215 and NIOSH 7600 analytical methods. Bias, sensitivity, and precision of both methods using the single extraction method were measured. Analytical data was collected from a large number of “real-world” samples using the single extraction method. Improved percent recoveries were demonstrated on spiked filters using the modified extraction method, with subsequent analysis by NIOSH 7600. Results generated from “real-world” samples yielded a strong correlation when analyzed by both NIOSH 7600 and OSHA ID-215. Sample storage requirements of the two methods were also compared.
288
QUANTITATIVE FIELD SCREENING METHOD AND DEVICE FOR DERMAL EXPOSURE TO HEXAVALENT
CHROMIUM.
T. Tekleab, G. Mihaylov, K. Kirollos, Microteq LLC, Virginia Beach, VA.
Dermal exposure to Cr(VI) is one of the main environmental and occupational concerns that may cause adverse health effects. Sources for dermal exposure to Cr(VI) include liquids, gases, vapors, aerosols, and solids containing chromate compounds which can deposit on skin and either interact with the skin directly or permeate through the skin to blood. Conventional methods for the assessment of dermal exposure to Cr(VI) require sending samples to the laboratory for analysis. These methods are expensive and require several days to obtain the result. To our knowledge there is no method available to asses Cr(VI) dermal exposures on site.
A quantitative, on-site, direct-read system has been developed to detect and measure exposure of skin, hair, and clothing to Cr(VI). The system consists of three main components: a clean swab free of any chemical reagent to swipe skin, hair, or clothing; a sensor that can be activated to produce color with the treated swab; and a color comparator to match the color produced and determine the Cr(VI) concentration. The comparator is capable of compensating color interferences due to dirt or any dark substances that might be collected on the swab.
The device is highly sensitive and selective to Cr(VI). It is calibrated and validated to Cr(VI) concentrations ranging from 0.1 to 12 µg and it operates properly at temperatures ranging from 4 to 50oC. Within the concentration range tested, the device shows a mean CV of ± 6.0% and a mean bias of 4.1%.
289
COMPARISON OF THE GRIMM PDM 1108 OPTICAL PARTICLE COUNTER TO THE TSI AERODYNAMIC
PARTICLE SIZER.
T. Peters, D. Ott, P. O’Shaughnessy, University of Iowa, Iowa City, IA.
The Grimm PDM 1108 optical particle counter measures particle number concentration in 15 channels from 0.3 to 20 µm. This instrument is suited for industrial hygiene applications because it is compact, battery powered, direct reading, and capable of operating in dusty environments (up to 100 mg/m3). The aerodynamic particle sizer (APS) model 3321 (TSI Inc., St. Paul, Minn.) provides similar information over the same size range, but it is substantially more expensive than the PDM-1108, powered by AC current, and limited to particle concentrations below 1000 particles/cm3. Whereas considerable work has aimed to document the response of the APS 3321 and earlier APS models, little has been done to document that of the PDM 1108.
This study compared the response of the PDM 1108 to that of the APS 3321 as a function of particle size (0.3 to 10 µm), particle type (liquid or solid), and aerosol mass concentration (0.1 to 5 mg/m3). Aerosols were generated with a Collison nebulizer: (1) polydisperse liquid droplets of oleic acid; (2) polydisperse solid sodium chloride particles; and (3) monodisperse polystyrene latex spheres. Clean, compressed air was used to dilute the aerosol to the intended mass concentration. The test aerosol was passed through a flow splitter and sampled concurrently by an APS 3321 and a PDM 1108. Our results will help industrial hygienists in interpreting data from the PDM 1108 instrument.
290
A COMPARATIVE STUDY OF COMMONLY USED INSTRUMENTS FOR ASSESSMENT OF INDOOR
ENVIRONMENTAL QUALITY.
R. Lawrence, S. Martin, M. Duling, C. Calvert, J. Hudnall, C. Coffey, NIOSH, Morgantown, WV.
Direct-reading instruments are used to characterize the indoor air environment. During field surveys these instruments can provide different results, even when placed side-by-side. A pilot study was developed to assess and evaluate the performance of direct-reading instruments to the manufacturers’ specifications under varying environmental factors. This study consisted of three each of the most commonly used direct-reading instruments: TSI P-Traks, DustTraks, and Q-Traks, and GRIMMs with temperature and humidity probes. Testing was done for 18 days in two different environments, regulated air circulation (RAC) and minimal air circulation (MAC). Instruments were calibrated per the manufacturers’ instructions and placed one foot apart in random order inside each environment. In the RAC environment, the location of the instruments was changed daily to offset any bias. Rotation of instruments was not required in the MAC environment. For each instrument type, the difference or percent difference was calculated between the instruments and compared to the manufacturers’ specifications. For the MAC scenario, the Q-Traks provided CO2 (70.8%) and humidity (8.1%) values which were much greater than the manufacturer’s specifications (± 10.1% and ± 3%, respectively). The temperature difference (0.8%) was within TSI’s specification (± 1.0şF). The total count difference from the GRIMMS (11.6%) was over five times higher than the manufacturer’s specification (± 2%). Since the P-Traks, DustTraks, and GRIMMS (humidity and temperature) do not have published accuracy ranges, the National Institute for Occupational Safety and Health (NIOSH) method comparison accuracy criterion (± 25%) was used. Only the DustTrak results were greater than the NIOSH criterion, at 69.5%. Similar results were seen in the RAC environment. This study indicates that direct-reading instruments may not perform according to published specifications. This would greatly impact the characterization of indoor environmental air quality. NIOSH is currently conducting further research to determine the extent of this potential problem.
291
EVALUATION OF GAS MONITORS.
G. Alkire, U.S. DOL/OSHA, Cincinnati, OH.
There are no nationally or internationally accepted performance standards for gas monitors. Determining which instrument is best to use for evaluating a workplace can be just as important to industrial hygienists and safety professionals as is the actual gathering of the data. With so many makes and models of instruments available with many features and options, the decision to select the proper equipment which best fits the user’s requirements can be overwhelming. Even when the desired instrument has all the features needed for the survey, do we really know that the selected instrument will do what it needs to do, in the environment being surveyed?
Industrial hygiene and safety professionals should periodically evaluate the instruments available to them, whether it is their own equipment or potential items to purchase or rent. Many factors need to be considered. OSHA is continually evaluating instruments considered for purchase and use by the OSHA compliance officers in the field. Factors of concern involve accuracy, safety approvals, functionality, desirable optional features, environmental effects on the instrument, and serviceability.
Applied to a simple item as a gas monitor, this evaluation translates into examining whether there is an intrinsic safety rating, ease of operation, environmental effects, possible radio-interference on the gas monitor reading, and serviceability.
Without consensus standards, it behooves the user to evaluate instruments which they intend to purchase. It is not sufficient to rely solely on the instrument manufacturers to provide the needed information.
292
AN AUTOMATED AIR SAMPLER FOR ANALYSIS OF VOLATILE AND SEMIVOLATILE CHEMICALS IN
INDOOR AIR.
T. Robinson, D. Cardin, C. Casteel, Entech Instruments Inc., Simi Valley, CA.
The use of fused silica lined and SUMMA passivated stainless steel canisters for air analysis has been previously limited to the more volatile constituents, such as solvents and other chemicals with high vapor pressures. This has precluded their use for detection of compounds with greater polarity and those compounds classified as “semivolatiles” with boiling points over 200°C. The introduction of heated GC autosamplers in the past two years has allowed these less volatile compounds to be recovered from fused silica-lined canisters, but losses were occurring in the flow regulating inlets used to perform time-weighted canister sampling in the field. An automated system for integrated sampling of air into canisters has been developed which allows recovery of both volatile and semivolatile compounds. Flow is controlled into the canisters using a novel “pulsed sampling” approach which minimizes inlet surface area to allow compounds up to C25 to be introduced quantitatively into the canister. The system allows up to eight canisters to be sampled under a user-specified schedule, or can wait for sampling to commence after receiving an external start signal. The canister pressure is monitored during the filling process in order to validate proper sampling fill rates during time-weighted averaging. A small critical orifice inlet can be easily exchanged to completely eliminate any chance of cross contamination, making cleanliness validation of the main sampler unnecessary. This is significant in that sampling professionals will not have to utilize GCMS equipment to validate the cleanliness of this sampler before use. Data will be presented showing the improved recovery of a wide range of chemicals, including microbial VOCs for mold detection, chemical warfare agent simulants, and heavier polar organics such as glutaraldehyde.
293
EXPRESS ANALYSIS OF SIX ELEMENTS BY ICP-MS.
P. Giles, U.S. DOL/OSHA, Sandy, UT.
A significant amount of time is saved by digesting air samples in plastic centrifuge tubes using microwave energy at atmospheric pressure, hence the term “express.” The method currently permits analysis of six elements: arsenic, cadmium, cobalt, copper, lead, and nickel. Detection limits for these elements show improvements ranging from three-fold for arsenic (as compared to its analysis by GFAAS) to 1000-fold for lead (as compared to its analysis by FAAS or ICP-AES).
Air samples are collected on mixed cellulose ester (MCE) membrane filters with accompanying cellulose backup pads (BUP). When sampling for volatile arsenic compounds, the BUP must be impregnated with a sodium carbonate solution. The MCE filters are oxidized and digested with the aid of concentrated nitric acid, hydrogen peroxide, and microwave heating to 106şC. After cooling, concentrated hydrochloric acid is added to the sample and it is reheated in the microwave to 86şC. Internal standards are added to correct for ICP-MS drift. The disadvantage of this technique is not being able to use the high pressure which occurs in a closed-vessel microwave oven, which has been shown to aid in the digestion of certain refractory elements and compounds.
Microwave digestion was compared with hot plate digestion in the analysis of SRM 1648 (Urban Particulate Material). SRM 1648 was used in this test because it is the nearest characterized material that could be found to simulate an urban, industrialized particulate. SRM 1648 contains certifiable values for five out of the six elements in this analysis (cobalt lacks a certifiable value). The analytical recoveries of the five elements were quite comparable, indicating that the two digestion techniques are similar with regard to the elements and compounds found in this material.
294
ACTIVE/PASSIVE AIR SAMPLERS MADE FROM ACTIVATED CARBON FOAM.
C. Manning, S. Green, Assay Technology, Pleasanton, CA.
Activated carbon combines efficient adsorption and retention of volatile organic compounds (VOCs) with the ease of desorption for analysis. In NIOSH and OSHA test methods, granular charcoal has been the preferred form, however, other forms have found application. These forms include porous discs, tubes, fibers, and foams, each of which may have advantages in sampling and analysis.
Porous discs used in diffusive samplers have superior mass transport characteristics compared to granular carbon, and the discrete disc is handled more easily in the laboratory. Small-diameter carbon tubes, with attenuated inner surfaces, afford efficient sampling of vapors and aerosols. Carbon fibers can collect a tiny VOC sample and then be placed directly into the injector of a gas chromatograph.
Recently, we have acquired activated carbon foams which were used to make a single device capable of active or passive sampling. The carbon foams are discrete structures presenting an open-pore structure such that significant air flow is accomplished at minimal back pressure using a small sampling pump with high collection efficiencies afforded by the intimate contact achieved in foam. This material was also used as a reservoir in a diffusive sampler by capping the foam with a sampling grid.
Active/passive samplers in several configurations were prepared as follows. Carbon foam was cut into cylindrical forms and installed in an inert tube capped at either end. 25-mm, 37-mm tubes were prepared having depths of 3–9 mm. By removing the caps, the air sampling tubes were able to sample at rates from 5–500 ml/minute with breakthrough volumes exceeding 50 liters for many VOCs. The same air sampling tube, fitted with a diffusive sampling grid, was used for diffusive sampling at 5–50 ml/minute. Recoveries of 90–100% were found for most VOCs consistent with other activated carbons.
295
CHEMICAL CHARACTERIZATION OF LABORATORY SIMULATED ROAD PAVING-LIKE ASPHALT FUME
GENERATED BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY AND HIGH PERFORMANCE LIQUID
CHROMATOGRAPHY-FLUORESCENCE TECHNIQUES.
B. Law, S. Stone, D. Frazer, P. Siegel, NIOSH, Morgantown, WV.
Workers in the paving and roofing industry are potentially exposed to asphalt fumes. Asphalt fume composition varies dependent on source of asphalt and application temperature. Polyaromatic hydrocarbon (PAH) content is of particular interest due to potential carcinogenic effects. The characterization of asphalt fume poses technical analytical problems. First and foremost it is a complex mixture. It is very difficult to identify and measure the small quantities of specific PAHs in such complex mixtures. A degree of isolation/separation must be achieved to quantify individual compounds from asphalt fumes. Many methods have been used to evaluate asphalt fume composition, however, they have involved either multiple difficult steps and/or lack specificity to the point that a confident chemical identification is not possible. The method used in this study utilizes a polyvinyl dibenzyl (PVDB) high performance liquid chromatographic (HPLC) column to separate aliphatics from the PAHs with subsequent analysis using gas chromatography-mass spectrometry (GC-MS). The PVDB-HPLC method can also, potentially, be used to quantify the total amount of PAHs by differential fluorometric detection following class separation by the column. A significant reduction in background interferences of the laboratory-generated asphalt fume extracts has been achieved following simple HPLC-single fraction collection that allows GC-MS identification and quantification. Inline fluorescent analysis of the PAH fraction may also provide total PAH quantification, however, comparability to established, accepted total PAH fluorescent measurement following solid phase extraction has not yet been assessed. In conclusion, this HPLC preparatory method is simple and its utility for analysis of specific PAHs has been demonstrated using asphalt fume generated under simulated road paving conditions.
296
THE USE OF FIELD PORTABLE X-RAY FLUORESCENCE (XRF) TO EVALUATE LEAD IN SOIL
AROUND 1950S ERA RESIDENTIAL STRUCTURES.
T. Zdeb, URS CORP, Vista, CA; D. Clark, PCR Laboratories, San Marcos, CA.
The use of field portable X-ray fluorescence (XRF) analyses (EPA Method 6200) is capable of providing essentially real-time information regarding the concentrations of many metals of potential environmental concern including lead in soil. Such information can allow investigations related to concentrations of metals in soils to be optimized since turnaround time typically associated with having samples analyzed by a stationary laboratory is effectively eliminated. In addition, because the results of properly conducted XRF analyses are accepted by many, if not most regulatory agencies, the need for further confirmatory laboratory analyses may be substantially reduced and/or eliminated. A case study is presented which includes the results of over 180 soil samples analyzed for lead to depths of 6, 12, and/or 18 inches around six homes built between 1940 and 1960 in Southern California. The soils surrounding each dwelling were investigated using a minimum of two samples collected at the dripline on each side with stepout samples collected at several locations 5 and 10 feet perpendicular to the face of the structure. The use of multidepth sample locations at multiple distances away from the structure allowed a three dimensional characterization of the lead concentrations in the soils around each dwelling to be completed. Per the State of California “School Site Testing Guidelines,” selected samples containing concentrations of lead above 255 mg/Kg were also sent to a stationary laboratory for confirmatory analyses by either EPA Method 6010B or 7421. The results of soils analyzed with the XRF compared favorably to the results of soil samples analyzed by the stationary laboratory showing an overall correlation coefficient of approximately 0.90.
297
DETERMINING THE MOST SIGNIFICANT PREPARATION PROCEDURE FOR THE CONSISTENT
ANALYSIS OF LEAD IN SOIL AND DUST.
S. Roda, S. Clark, P. Succop, J. Buchanan, S. Spalding, University of Cincinnati, Cincinnati, OH.
Today, laboratories prepare soil and bulk dust samples for analysis using various sample preparation procedures that may or may not include drying, homogenization, grinding, or particle size fractionation. A previous study clearly demonstrated that the Pb concentration of the sieved < 125-µm particle size fraction of the samples consistently yielded the highest Pb value except in several cases where the overall Pb value was above 1000 ppm. In addition, excess variability existed for the analysis of both soil and bulk dust when using fractions < 2 mm and < 500 µm in particle size.
Sieving a soil or bulk dust sample may be more indicative of present exposure and thus be the better correlate to present measures being obtained, whereas, grinding the larger particles produces a result indicating potential future contamination. In a second study, samples were ground and then placed through a < 125-µm sieve. A dilution affect of grinding was evident at Pb levels below approximately 1000 ppm. Above all federal levels of concern the concentration began to increase in the ground portion and often exceeded the sieved < 125-µm particle size fraction.
Due to lack of precision, the bioavailability of Pb from smaller particles, the bioaccessibility of smaller particles to children, and the significantly lower ground sample result at federal levels of concern, the preparation and analysis of the < 125-µm particle size fraction of soil and bulk dust samples is recommended. We have demonstrated in two studies that a number of various answers can be derived from soil and bulk dust samples depending on the choice of preparation method. A consistent and universal procedure is critical for both risk assessment and subsequent remediation of contaminated areas. In addition, conclusions from past and present studies may be affected and dependent on the preparation procedures used for both soil and bulk dust.
298
SAMPLING AND ANALYSIS OF GLUTARALDEHYDE USING EVACUATED CANISTERS.
T. Robinson, D. Cardin, C. Casteel, Entech Instruments Inc., Simi Valley, CA.
A higher sensitivity technique for sampling and analysis of glutaraldehyde by gas chromatography/mass spectrometry (GCMS) using small silonite coated canisters has been developed to meet the lower permissible exposure limit (PEL) of 0.015–0.05 ppmv proposed by OSHA and the California State Health Department. Older technology for sampling and analysis involved collecting an air sample onto a diphenylhydrazine derivitizing sorbent tube with the analysis performed using high performance liquid chromatography. This technique has limitations in the sampling protocol which does not allow for a rapid sample to be taken in the event of an accidental spill or for short-term exposure limit evaluations. The analysis has limitations in the limit of detection due to the dilution performed in sample preparation and cannot meet the proposed PEL of 0.015 ppmv. The whole air sampling approach using evacuated silonite coated canisters is a simplified sampling technique that can take an instant grab sample, a short-term sample, or an eight-hour time-weighted sample. The air sample can then be analyzed by heated canister and preconcentration combined with GCMS. Evacuated canister sampling along with concentrating several hundred milliliters of sample prior to injection into a GCMS has been performed for over 25 years with EPA method TO14 and more recently with silonite coated canisters by OSHA method PV2120. This time proven technology has now been enhanced by heating of silonite canisters prior to analysis to extend the range of compounds recovered allowing heavier polar compounds including glutaraldehyde to be included in the analysis. In this presentation we will discuss the advantages of whole air sampling and evaluate the recovery of glutaraldehyde in canisters. In addition, the operation of the analytical instrumentation used for glutaraldehyde analysis, including instrument calibration and detection limit, will be shown.
299
DETERMINATION OF NON-DIETARY ARSENIC IN URINE BY INDUCTIVELY COUPLED PLASMA MASS
SPECTROMETRY (ICP-MS).
L. Blum, E. Bakowska, J. Vinosky, G. Moldavchuk, National Medical Services Inc., Willow Grove, PA.
Arsenic is a known occupational health hazard, and the determination of urinary arsenic is an important aspect for the overall evaluation of arsenic exposure. Occupational exposure to arsenic is common in the smelting industry and in the microelectronics industry. Low-level arsenic exposure occurs through the commercial use of inorganic arsenic compounds in common products such as wood preservatives, pesticides, herbicides, fungicides, and paints, among others.
The toxicity of an arsenic-containing compound depends on its valence state, its form (inorganic or organic), and the physical aspects governing its absorption and elimination. The normal intake of arsenic by adults occurs primarily through ingestion, mostly organic arsenic from seafood. The specific arsenic compounds obtained from these sources are arsenobetaine and arsenocholine, which are relatively nontoxic; however, these compounds are rapidly excreted unchanged and add to the total arsenic level in the urine. The measurement of total urinary arsenic concentrations for purposes of biomonitoring arsenic exposure can be misinterpreted, if dietary influences are not taken into consideration. Therefore, non-dietary arsenic consisting of trivalent and pentavalent arsenic plus their methylated metabolites, monomethylarsonic acid and dimethylarsinic acid, is measured.
Patient urine samples (n = 2138) with no known industrial arsenic exposure were extracted, and then analyzed by inductively coupled plasma mass spectrometry. From this population, 97% had non-dietary urine arsenic concentrations below 20 mcg/L and 99% had less than 35 mcg/L (ACGIH BEI). In two populations with suspected arsenic exposure (n = 394 and n = 188) 82 and 38%, respectively, had urinary non-dietary arsenic levels below 20 mcg/L, and 96 and 54%, respectively, had less than 35 mcg/L. The measurement of urinary non-dietary arsenic eliminates the contribution of organic arsenic compounds usually attributed to seafood consumption and results in a more accurate assessment of arsenic exposure.
300
AVAILABILITY OF TRANS, TRANS-MUCONIC ACID AS A BIOMARKER FOR EXPOSURE TO LOW
CONCENTRATIONS OF BENZENE.
J. Roh, J. Won, C. Kim, H. Kim, H. Kim, D. Koh, Yonsei University, Seoul, Republic of Korea.
The aim of this study was to assess the availability of urinary trans, trans-muconic acid (t,t-MA) as a biomarker for low level exposure to benzene. The airborne benzene concentration was measured using a personal air sampler and determined by GC/FID. The urinary t,t-MA was determined in 40 urine samples collected from 20 workers in a petrochemical factory and from 20 controls with no occupational exposure to benzene. In the exposed group, the urine samples were collected at the beginning and end of the work shift. The t,t-MA concentrations in the urine were determined by HPLC/UVD. The individual whole-shift concentrations of benzene in the exposed group ranged from undetectable to 0.99 ppm with an average of 0.16 ± 0.22 ppm (geometric mean, 0.046 ± 0.12). The average urinary t,t-MA levels for the control and exposed group were 19.67 ± 18.88 µg/g creatinine (geometric mean, 12.44 ± 2.90) and 199.01 ± 64.76 µg/g creatinine (geometric mean, 189.27 ± 1.39), respectively. Significantly higher urinary t,t-MA levels were observed in the exposed workers. A statistically significant correlation was found between the t,t-MA concentrations in the end-of-shift samples and the airborne benzene concentrations(r = 0.63, p < 0.01). According to multiple regression analysis, no significant correlation existed between the urinary t,t-MA level and the demographic characteristics. These results support the availability of urinary t,t-MA as a biomarker for low levels of benzene exposure (< 1 ppm).
Posted May 30, 2005