W. May, E. Ligus, Draeger Safety Inc., Pittsburgh, PA.
From an industrial hygiene point of view it is very important to check portable gas detectors for their proper temperature class and overall ingress protection (IP) rating before use. The temperature class describes the maximum level to which any component of an instrument can heat up in the event of an electrical short circuit in the PCB or in the power supply. The temperature class is important because all combustible chemicals have an ignition temperature in air if the lower explosion level is exceeded. In refineries, for example, it is often not sufficient to have an instrument with a temperature class T3, as some hydrocarbons, especially those with a higher molecular weight, have ignition temperatures significantly lower than 200°C, so that a temperature class of T4 would be required. Another critical point is the ingress protection or IP rating, which consists of two numbers. The first number represents for the protection level against particles or dust ingress and the second number represents the protection level against water ingress. The greater the number, the higher the protection level for dust and water ingress. However, we now have to check whether the IP-rating describes the whole instrument, i.e. case and sensor inlet or if it only describes the protection level for the case, where the sensor inlet is somehow neglected.
There is the tendency of having modern instruments with a temperature class of at least T4 and an ingress protection-rating of ideally IP 67, where the whole instrument could be submerged in water down to a depth of 1.5 m without any impact to have a very universal instrument for the different ambient conditions.
E. Kennedy, M. Woebkenberg, P. Schlecht, D. Bartley (retired), S. Shulman, H. Feng, NIOSH, Cincinnati, OH; R. Song, NCHSTP, Atlanta, GA; C. Cowherd, M. Grelinger, K. Bauer, Midwest Research Institute, Kansas City, MO.
As part of a NIOSH program for the development of monitoring methods, we have produced guideline information to help others with the evaluation of sampling and analysis technology. The first publication in this series was “Guidelines for Air Sampling and Analytical Method Development and Evaluation,” published in 1995. It was developed primarily for methods relying on sampling media requiring sampling pumps. A similar approach to method evaluation has been taken for direct-reading gas and vapor monitors. A document entitled “Guidelines for the Evaluation of Direct-Reading Monitors” has been produced along with an Addendum that specifically addresses the needs of the first responder community for direct-reading monitors. The new guidelines provide a summary description of the available types of direct-reading monitors and discuss the experimental work necessary for their evaluation in assessing occupational exposures. The experimentation includes evaluation of physical and operational characteristics, response time, calibration, linearity, drift, environmental effects, interferences, limit of measurement, and bias and precision. The guidelines document includes recommendations on data interpretation for accuracy, measurement uncertainty, bias and precision, and suggestions for the treatment of data from alarm-only monitors. The addendum further addresses special needs of the first responder community such as monitor ease-of-use in harsh environments. The addendum describes an ease-of-use test program for hands-on monitor evaluation by qualified first responder participants. These guidance documents will be made available on the NIOSH website in 2006.
K. Gunderson, C. Thoraval, JDSU, Santa Rosa, CA.
Very fine grained abrasive powders known as rouges are used to polish glass in industrial applications. These rouges primarily consist of oxides of rare earth elements (REE) such as lanthanum, cerium, neodymium, samarium, and praseodymium. Significant concentrations of arsenic (As) were detected in bulk, water, and air samples of a glass polishing rouge using EPA Methods 3050B/6010B and 3050/6020, as well as NIOSH Method 7300, despite the manufacturer’s insistence that the material was As-free. No As was detected in the rouge when analyzed by furnace atomic absorption (EPA 3051/7060). The manufacturer claimed that false As detections were due to REE interferences when using Inductively Coupled Plasma (ICP) analytical techniques. An investigation was conducted to evaluate these potential interferences and to determine an appropriate technique to quantitate As in a REE-rich matrix. Standard samples of REE were analyzed via ICP/Atomic Emission Spectroscopy (AES) and ICP/Mass Spectroscopy (MS) to determine REE interferences. In addition, a sample of the rouge spiked with As oxide was analyzed by atomic absorption (AA) to determine if As would be detected in the REE oxide matrix. The 1000 ppm lanthanum standard was reported to contain 49 ppm arsenic via ICP/AES. The 1000 ppm neodymium standard was reported to contain 7.3 ppm arsenic via ICP/MS. The AA method did not detect arsenic (< 5 ppm) in a rouge sample spiked with 380 ppm arsenic (as As203). It was concluded that some REE oxides cause interferences that can be reported as As when using standard EPA and NIOSH ICP methods. It was also concluded that AA is an unreliable alternative because known quantities of arsenic were not detected when REE oxides were present. Alternate methods have been explored and to date we have found no reliable method for quantifying As in this REE oxide matrix.
A. Dufresne, M. Boutin, McGill University, Montréal, PQ, Canada; C. Ostiguy, J. Lesage, IRSST, Montréal, PQ, Canada.
Polyurethanes are widely used in car paint formulations. During thermal degradation, such polymeric systems can generate powerful asthmatic sensitizing agents named isocyanates. In body repair shops, the thermal degradation of car paint can occur during abrasive processes that generate enough heat to involve isocyanates release in air. An environmental monitoring study was performed in two body repair training schools and in a body repair shop to evaluate the workers’ exposure to isocyanates during cutting, grinding and orbital sanding operations. Cassettes containing two 1-(2-methoxyphenyl)piperazine (MOPIP)-coated glass fibre filters (MFs) (≈5 mg of MOPIP per filter) and bubblers containing 15 mL of MOPIP solution in toluene (1.0 mg mL-1) backed at the outlet with cassettes containing two MFs were used. Tandem mass spectrometry was used to analyse the MOPIP derivatives of isocyanic acid (HNCO), all the linear aliphatic isocyanates ranging from methyl isocyanate (Me-i) to hexyl isocyanate (Hex-i), all the alkenyl isocyanates ranging from propylene isocyanate (Propylene-i) to hexylene isocyanate (Hexylene-i), 1,6-hexamethylene diisocyanate (HDI), trans- and cis-isophorone diisocyanate (IPDI), 2,4- and 2,6-toluene diisocyanate (TDI), 2,4’-; 2,2’- and 4,4’- methylenediphenyl diisocyanate (MDI), phenyl isocyanate (Ph-i), and p-toluene isocyanate (p-Tol-i). The instrumental detection limits (LOD) were in the 0.13–0.75 µg(NCO) m-3 range for 15 L air samples converted into 3 mL liquid samples. The isocyanate concentrations detected in the workers’ breathing zone during a 15-minute sampling period were in the 1.07–9.80 µg(NCO) m-3 range for cutting, 0.63–3.62 µg(NCO) m-3 range for grinding, and 0–1.29 µg(NCO) m-3 range for orbital sanding. Among the isocyanates detected the most abundant were the monomers (MDI, HDI, TDI, and IPDI) and Me-i. The highest isocyanate concentration measured in the worker’s breathing zone corresponds approximately to half the HSE’s MEL set at 20 µg(NCO) m-3.
R. DiRienzo, R. Wade, J. Reynolds, DataChem Laboratories, Inc., Salt Lake City, UT.
Newsweek magazine (August 8, 2005) calls methamphetamine America’s most dangerous drug. “It creates a potent, long-lasting high until the user crashes and too often, literally burns.” Newsweek calls attention to the dramatic surge in methamphetamine use which is no longer geographically isolated to the West but is used all across the United States. Methamphetamine use has also spread across the socioeconomic ladder and is no longer used primarily by the poor. Health and safety concerns for illicit drug labs extend beyond methamphetamine. Contamination and exposure may be from a number of other drugs, precursors, contaminants or adulterants. Identification and analysis of these compounds may be important depending on the information needed for the sampling site. It may be desirable to identify precursors used for the process of drug synthesis. As various drugs become harder to manufacture from certain precursors due to tighter restrictions, new synthetic procedures, new precursors, and new drugs appear in order to meet demand. Adulterants are substances intentionally or unintentionally added to illicit drugs in the process of production or distribution. Adulterants may exist as “impurities” which are unintentional by-products from manufacture or from impure starting material. Such impurities may help identify the nature or source of the starting material or the process being used to create the illicit drug. The identification of starting material may be important in obtaining convictions and in shutting down such sources.To protect human health and safety, and to assist the industrial hygienist to identify contamination and monitor cleanup of clandestine drug labs, methods for analysis of methamphetamine and other illicit drugs have been developed for this rapidly growing concern.
S. Seethapathy, T. Gorecki, University of Waterloo, Waterloo, ON, Canada; B. Zabiegala, J. Namiesnik, Gdansk University of Technology, Gdansk, Poland.
Passive samplers are increasingly often used for indoor and outdoor exposure monitoring owing to the simplicity of operation and low unit sample cost. The devices are based on either diffusion (diffusive passive sampling) or permeation of the analytes through a membrane (permeation passive sampling). Even though permeation passive samplers are advantageous because of their insensitivity to humidity and temperature variations, the major disadvantage thus far has been the requirement for the permeation passive samplers to be calibrated for each individual analyte prior to field deployment. This, in turn, requires the identity of the compounds to be known at the time of deployment. However, this is often not the case. In the research presented, attempts were made to estimate the uptake rates of permeation passive samplers equipped with polydimethyl siloxane (PDMS) membranes from the physico-chemical properties of the analytes rather than determine them by the time consuming laboratory method. Linear temperature-programmed retention indices (LTPRI) of the analytes determined in gas chromatographic columns coated with pure PDMS stationary phases were thought to have a potential application for the estimation of the calibration constants. This is because LTPRIs determined using such columns depend on the partitioning coefficients of the analyte molecules between the carrier gas and the stationary phase, just as the calibration constants of the PDMS-based passive samplers do. Apart from greatly simplifying the calibration of the samplers for target analytes, the method proposed makes it possible to quantify pollutants whose identity is unknown at the time of the exposure. The results of the study along with the application for the determination of Total Petroleum Hydrocarbons (TPH) in the air will be presented.
W. King, EG&G Technical Services, Inc., Pittsburgh, PA; P. Gao, M. Yeso, NIOSH, Pittsburgh, PA.
System-level evaluation of protective ensembles is increasingly being used to develop performance specifications. For example, the 2006 proposed revision of the NFPA 1994 standard requires particulate integrity tests for class 4 suits. While aerosol penetration tests exist, there is a continued need for better methods suitable for use with human subjects and capable of passively sampling trace levels of particulates at multiple body locations between the skin and the ensemble. Surveying aerosols with properties to facilitate passive sampling, we found iron (II,III) oxide, magnetite, attractive due to low toxicity and cost, availability in several particle sizes and sensitive analytical methods. Magnetite’s magnetic susceptibility allows several isolation and detection schemes; most simply, collection with permanent magnets. However, a coating isolating the iron-containing magnet from the collected aerosol is required to prevent confounding the analysis. In this work, various coatings were evaluated for their compatibility with magnetic sampling and the analytical method. Collected magnetite was dissolved in acid, oxidized, and quantified by spectrophotometry. Method blank was determined to be 1.0 µg. Coatings alone results were silicone (2 µg), epoxy A (81 µg), polyethylene A (2 µg), polyethylene B (3 µg), polyperfluoroethylene (2 µg), and silicone (2 µg). Single coating on iron or magnet results were epoxy A (1100 µg), epoxy B (> 3600 µg), gold (575 µg), polyethylene A (3 µg), polyethylene B (3 µg), polyperfluoroethylene (2 µg), and silicone (660 µg). Incomplete coverage and delamination appeared responsible for magnet dissolution, which caused the high iron content in the extract. Double coatings results were epoxy A (10 µg), silicone (1 µg). Polytetrafluoroethyl-ene, silicone and polyethylene A were selected for further analysis. Monitoring magnet strength and blanks after repeated use indicated that all of these coatings were acceptable. However, polyethylene A was selected for further development based on practical considerations.
S. Parsons, CSIR, Pretoria, South Africa; P. Jensen, C. Wells, CDC, Atlanta, GA; M. First, E. Nardell, Harvard University, Boston, MA; K. Weyer, L. Roberts, MRC, Pretoria, South Africa; E. Mathews, North-West University, Potchefstroom, South Africa.
The Airborne Infection Research (AIR) Facility, recently completed in South Africa, is a collaborative research project between the MRC, CSIR, CDC, and Harvard University. The facility (apparatus) will be used to answer questions about the infectiousness of MDR-TB by measuring the number of guinea pigs infected over time, linking guinea pig infections to individual patients using molecular techniques. The objectives, results, and conclusions of the validation of the apparatus are discussed. The effectiveness and air tightness (leakage factor) of the air distribution from the wards, the transporting capacity of Gram-positive and negative aerosolized bacteria, and the efficacy of the in-line UVGI units to the animal infection chambers were an important component of the validation process. The validation process started with testing and balancing of the ventilation systems, to patient and animal areas to ensure comfort and health criteria are satisfied, and the infected transfer air system including the safety filtration units and electronic control systems. Before conducting any biological testing, nonbiological aerosols (PSL) were generated in the patient ward and sampled at various locations from the wards through to the animal quarters with an optical particle counter. Biological aerosols (Serratia marcescens and endospores of Bacillus subtilis var. niger) were generated in the patient ward and sampled at various locations between the wards and animal quarters, using a six-stage impactor for bioaerosols. The results presented indicate that from the validated operational parameters of the apparatus the losses were less than 5% for nonbiological substances and less than 12% for endospores (Serratia marcescens). No significant losses were noted across the transfer axial fan. With respect to 100% efficacy was achieved across the in-line ultraviolet germicidal irradiation units, as no Serratia marcescens were detected in the animal room and less than 1 endospore (Bacillus subtilis) per cubic meter of air was detected.
S. Cali, P. Scheff, R. Sokas, University of Illinois at Chicago, Chicago, IL.
Sampling of beach sand for asbestos structures was undertaken in a state park on the south-western shore of Lake Michigan where asbestos debris had been found during the last seven years. The beaches are located in an erosion zone and park stewards wished to determine whether certain local sources of sand could be utilized to replenish the beaches without causing a hazard to beach visitors. No thresholds of concern or standards currently exist for asbestos content in soil or sand. The purpose of the sampling was to determine whether asbestos structures had been released into the sand in concentrations greater than in background areas and sources of replenishment sand. Twelve composite samples consisting of five sub-samples each were collected on two target beaches, three background beaches, and two potential lake-bottom sand sources. In order to obtain a sufficiently low limit of detection, sample preparation and analysis was performed using the current iteration of the technique known as the Superfund Method for the Determination of Releasable Asbestos in Soils and Bulk Materials (US EPA 540-R-97-028, 1997, authored by Berman and Crump, Aeolus, Inc.) and modified in subsequent publications. The method utilized aggressive agitation of samples and separation of the respirable fraction (PM10) for capture on a filter. Analysis was performed with TEM, and fibers were counted using NIOSH 7402 and a Protocol method. The sample preparation techniques were modified for this study because very low amounts of PM10 were present in the sand. The 95% UCL of the means ranged from 0.43 to 24.74 million fibers per gram of PM10 in the seven locations sampled. The study results provide information on environmental asbestos background concentrations, QA/QC for the method, and the method’s efficacy for specific applications.
Posted May 30, 2006