G. Whitney, R. Winkel, T. McCleskey, D. Ehler, E. Minogue, Los Alamos National Laboratory, Los Alamos, NM.
The DOE beryllium rule (10 CFR 850) and concerns over health hazards have lead to an increased demand for measuring beryllium surface contamination. Surface samples are typically analyzed by ICP-AES, which can involve significant costs and delays of days to obtain results. Seeking to reduce beryllium analytical costs and turn-around time, researchers in the Chemistry Division of Los Alamos National Laboratory have developed a method based on the fluorescence of 10-Hydroxybenzo[h]quinoline sulfonate. Initial tests with chemical standards and field-collected samples indicated that the method is very sensitive (14 ng/filter LOD) and not subject to interference from other metals (Al, Ca, Li, Pb, U, Zn).
Industrial hygienists at the laboratory field-tested the method for its practical application. It was determined by observation and analytical results that the nylon filter originally selected for sample collection left residual material on the surface sampled. Tests with multiple lots of filters indicated that our standard surface sampling medium (Whatman® 541, 47-mm circles) was acceptable for the new method. Materials likely to be encountered in the workplace (oils, cleaners, etc.) were added to filters spiked with a known amount of beryllium. Subsequent analysis showed no significant interference with the fluorometric method (mean recovery 99.5%). Six pairs of side-by-side samples collected on a surface known to be contaminated with beryllium were analyzed with ICP-AES and the new fluorometric method. Accounting for the variability expected on the contaminated surface, the two methods were very comparable, with a mean relative percent difference of 7.85%.
It was concluded that this method is very promising and practical for preliminary determination of beryllium surface contamination. Surface contamination can be determined rapidly (30 minutes), in a useful range (0.01 to 6 ug/filter), and at relatively low cost with a potentially field-portable system.
D. Weitzman, P. Wambach, J. Slawski, U.S. DOE, Washington, DC.
Chronic Beryllium Disease (CBD) is caused by an immune system response to beryllium particles embedded in lungs. This response can cause progressive damage to the lungs, which, in turn, can result in disability and shortening of life. It appears that 3–5% of the population is susceptible to this disease. The United States Department of Energy (DOE) has used large quantities of beryllium since its inception as the Atomic Energy Commission and anticipates continuing to use it well into the future. Unfortunately, some workers who worked with beryllium for DOE have contracted CBD and new cases still are occurring. DOE has aggressively addressed this disease but is concerned that gaps in beryllium health and safety technology may hinder further efforts.
DOE has categorized the technology gaps into exposures, controls, and health effects. The exposures category consists of improving sampling methods and using the improved methods to better characterize exposures. Controls consist of developing innovative controls and observing the impact of lower exposures on disease rates. Health effects consists of achieving better understanding of the disease process and improving diagnostics. Pursuing research in all three categories requires developing basic research tools and capabilities such as establishing a library of tissues samples taken from beryllium diseased individuals.
DOE has inventoried current research activities and will coordinate its efforts with other agencies and the private sector to assure that the highest priorities are addressed first and that redundancy is avoided.
Enlisting the participation of the research community in pursuing this research program presents challenges. Past government solicitations for research applications often were not responded to. DOE is addressing the reasons for this apparent lack of interest which it believes were primarily the lack of access to basic tools and materials needed to conduct the research and uncertainty over the stability of funding.
R. Baran, Los Alamos National Laboratory, Los Alamos, NM.
In 1959, Building 141 was constructed by the Los Alamos National Laboratory to be used as a metal powder research facility. Over an approximate 25-year period, experiments with a variety of metals, metal powders, and metal powder mixtures were conducted in support of the development of stronger, lighter, and more durable components for aircraft, satellite, and weapons mechanisms. Pre-renovation site characterization determined that these activities had left the building, its equipment, and its supplied air and exhaust ventilation systems contaminated with beryllium, copper, lead, nickel, thorium, uranium, and vanadium. This poster presents the industrial hygiene and safety practices employed by the contractor charged with the decontamination and partial demolition of portions of the facility necessary prior to planned renovations. These included: (1) identification and implementation of engineering controls to prevent airborne dispersion of the metal contaminants; (2) establishment of a transition zone between the controlled, contaminated work area and uncontrolled, clean spaces; and (3) identification of required personal protective equipment (PPE) designed to protect workers performing largely manual, hands-on labor involving close contact with equipment, ventilation systems, and building surfaces highly contaminated with a wide variety of toxic metals. Challenges included development of a company Chronic Beryllium Disease Prevention Program, as well as the development of an Industrial Hygiene Sampling and Monitoring Plan. Swipe sampling results confirm that the engineering controls used, and practices such as the doffing of PPE within the transition area, prevented the transfer of contamination to clean, uncontrolled areas. Sampling data is presented. Conclusions from sampling enabled management to verify their risk assessment approaches and confirm the adequacy of controls, such as negative air ventilation system strategies and wet work methods, to prevent airborne beryllium and lead from exceeding permissible exposure limits.
G. Day, C. Schuler, CDC/NIOSH, Morgantown, WV; M. Berakis, M. Kent, Brush Wellman Inc., Elmore, OH; M. McCawley, McCawley Consulting LLC, Morgantown, WV.
Efforts to prevent beryllium sensitization and chronic beryllium disease have historically focused on controlling inhalation exposures. Epidemiologic studies suggest that mass airborne beryllium exposure is not a good predictor of risk. The lack of a clear relationship between airborne exposure and sensitization suggests that other exposure pathways, such as dermal exposure, may be more relevant.
A dermal protection program, including use of gloves in production areas, was recently instituted at a beryllium ceramics production facility with a history of beryllium sensitization and chronic beryllium disease in workers. The purpose of this study was to assess the total amount of beryllium on workers’ hands following implementation of this program. Wipe samples were collected from the skin (2 hands) of 122 workers (87 production, 35 production support), following at least 1 hour performing their regular work. Additional information was collected on work area, work activity, and glove use. Samples were analyzed for mass beryllium by inductively-coupled plasma atomic emission spectrometry, and normalized to workers’ estimated hand size.
All participants reported wearing gloves when working in production areas, including production support workers entering or passing through production areas. Analytical results, although highly variable, indicated measurable levels of beryllium in 99% (121/122) of samples, ranging from less than the limit of detection (LOD = 0.01) to 46 µg. The overall geometric mean, normalized to hand surface area, was 0.27±5.3 µg/100 cm2. Levels of beryllium were higher on the hands of production workers, compared to production support workers (0.49±3.6 versus 0.06±4.9 µg/100 cm2, p<0.05).These results provide information regarding the relative mass of beryllium found on the hands of glove-wearing beryllium ceramics workers. Subsequent evaluations of work practices, both programmatic and individual, are being used to refine and improve personal protection practices.
J. Snyder, A. Weston, E. Demchuk, NIOSH, Morgantown, WV.
Chronic beryllium disease (CBD) represents a possible threat to approximately 800,000 workers and other individuals potentially exposed to beryllium. The pathobiology of chronic beryllium disease involves the major histocompatibility complex class II human leukocyte antigen (HLA). Molecular epidemiological studies suggest that inheritance of specific HLA-DPB1 alleles may be a factor contributing to disease susceptibility. We have studied three-dimensional structural models of HLA-DP proteins encoded by these genes. The extracellular domains of proteins encoded by HLA-DPA1*01031/B1*1701, *1901, *02012, and *0401, and HLA-DPA1*02011/B1*1701, *1901, *02012, *0401 were modeled from the X-ray coordinates of an HLA-DR template. Using these models the electrostatic potentials at the molecular surface of HLA-DP were calculated and compared. These comparisons show specific characteristics in the vicinity of the antigen-binding pocket that distinguish the different HLA-DP allotypes. The differences in electrostatics originate from the shape, specific disposition, and variation in the negatively charged groups around the pocket. The more negative the pocket potential, the greater the odds of CBD estimated from reported molecular epidemiologic studies. The impact is caused by substitutions in the beta-chain at positions B55, B56, B69, B84, and B85. Interestingly, these are the same loci that have been identified as genetic markers conferring susceptibility to CBD and other hard metal lung disease through epidemiological studies. These findings suggest that these substitutions may eventually promote an involuntary cation-binding site within the otherwise metal-free peptide-binding pocket, consequently demoting the innate function of HLA by changing the specificity of antigen recognition. Occupational risk assessment pertaining to beryllium exposures may benefit from consideration of the electrostatic characteristics of HLA-DP isotypes.
S. Czerczak, M. Kupczewska-Dobecka, Nofer Institute of Occupational Medicine, Lodz, Poland.
Interdepartmental Commission for Maximum Admissible Concentrations and Intensities for Agents Harmful to Health in the Working Environment includes representatives of health and labour administration, various sectors of industry, trade unions, and research institutes in the fields of occupational medicine and work safety. The Commission has appointed the Group of Experts for Chemical and Dust Agents and the Group for Physical Factors, consisting of independent experts in the fields of toxicology, occupational medicine, and occupational hygiene. The experts prepare health-based documentation for recommended exposure limits along with analytical procedures, recommendations with respect to pre-employment and periodical medical examinations, and contraindications to exposure. The proposed MAC and MAI values are then the subject for evaluation by the Interdepartmental Commission and acceptance by the Minister of Labour and Social Policy. The MAC’s lists are published in the Law Gazette. These are hygienic standards valid for all branches of the national economy.To 2002 there are 441 MAC values for chemical substances (The Ordinance of the Minister of Labour and Social Policy on the maximum admissible concentrations and intensities of harmful to health agents in the working environment, J. of Law 217, item 1833). In 2003, the Expert Group of Chemical Agents proposed 36 MAC values for chemical substances. According to the type of biological effects, the following categories of MAC values are used: NDS-MAC(TWA): maximum admissible concentration; NDSCh-MAC(STEL): maximum admissible short-term concentration; NDS-MAC(C): maximum admissible ceiling concentration. In the Polish system, the MAC and MAI values documentation are published quarterly in the publication of the Interdepartmental Commission “Principles and Methods of Assessing the Working Environment,” which makes it possible for occupational physicians and sanitary inspectors to become acquainted with the problem.
E. Koziel, W. Domanski, M. Posniak, Central Institute for Labour Protection-National Research Institute, Warsaw, Poland.
Rubber industry is a very important branch of the national economy. The products of this industry are widely used in many production sectors. Production of rubber products is characterized by the emission of pollutants which are hazardous and harmful for health. The aim of the studies was to identify nitrogen and sulfur organic compounds that are found in workplace air during production and processing of rubber and assessment of workers’ exposure. The studies were carried out in three rubber industry factories that produce rubber plates and forwarding tape. In order to identify pollutants, samples were taken in places where the highest concentrations of air pollutants was expected. Charcoal, silica gel, silica gel coated ascorbic acid, and a glass fibre filter with amberlite XAD-2 resin (flowrate 20–120 L/min) were used to sample sulphur and nitrogen compounds. Prior to sampling, the sorbents were extracted in carbon disulphide, methanol, acetonitrile, and dichloromethane. Samples were analysed with gas and liquid chromatography. The GC/MSD tests made it possible to identify over 15 compounds containing sulphur and nitrogen in the mixtures emitted at workstations with mixers, roll mills, calenders, and vulcanizing presses.
Six of the identified chemical compounds of sulphur and nitrogen were identified at all workstations. These substances were determined during a typical production cycle of rubber plates and forwarding tapes. The results of the measurements indicated that the concentration of benzothiazole ranged from 1.42 mgm-3 to 23.50 mgm-3, 2-ditio(bis)benzothiazole from 2.01mgm-3 to 26.11 mgm-3, carbon disulphide from 274.02 mgm-3 to 6519.50 mgm-3, cyclohexyl isotiocyanate from 1.81 mgm-3 to 70.5mgm-3, 2-imidazolidinethione from 0.013 mgm-3 to 1.22 mgm-3, and N-nitrosodimethylamine from 0.02 mgm-3 to 0.58 mgm-3. Assessment of occupational exposure to these compounds is very difficult because there are no maximum admissible concentration values for several compounds either in Poland or abroad.
I. Makhniashvili, M. Posniak, M. Szewczynska, Central Institute for Labour Protection-National Research Institute, Warsaw, Poland.
Metal founding, especially iron founding, is a branch of industry in which working conditions are very bad. During the whole process in casting production workers are exposed to dangerous, harmful, and strenuous factors that can cause occupational diseases, occupational accidents, and also fatal accidents. Chemical substances are emitted to the air at every stage of castings production, which create different degrees of hazards for human health. Identification studies of harmful chemical substances and metals were carried out at workstations for the preparation of cores and moulds, smelting and flooding of iron, striking and cleaning of castings. In order to identify pollutants, air samples were taken in places where the emission of chemical substances was highest. Samples were analysed by GC-MS, HPLC-FL, HPLC-UV, and AAS. The studies made it possible to identify tens of chemical compounds. Aliphatic hydrocarbons and aromatic hydrocarbons with carcinogenic benzene made up the predominant group of compounds. Polycyclic aromatic hydrocarbons, formaldehyde, acetaldehyde, phenol, cresol, furfurol , ethylene glycol, buthanol, isopropanol and iron, chrome, and nickel were also identified. Quantitative investigations made it possible to confirm that carcinogenic and probably carcinogenic compounds—benzene, formaldehyde, and PAHs—create the highest hazard. Time-weighed average concentrations of those compounds were as follows: benzene 0.002–1.56 mg m-3, formaldehyde 0.004–0.07 mg m-3, and PAHs 0.0008–0.15 mg m-3. Other organic compounds were presented in many times smaller quantities than the maximum admissible concentration values which are valid in Poland. Iron concentrations ranged 0.01–0.2 mg m-3. The International Agency for Research on Cancer has classified iron and steel founding as carcinogenic processes to humans (Group 1) and because of that, occupational exposure to benzene, formaldehyde, and PAHs should be made two times per year.
R. Patel, Safe Workplace Inc., Anand, Gujrat, India.
This study investigated farmer exposure due to toxic organophosphorus insecticide during manual hand pump spraying in the cotton farm in anand district in the western part of India. It was found that farmers were not using personal protective equipment such as masks, gloves, shoes, etc. Specific aims were to: (1) perform a clinical evaluation of the pump operating workers; (2) conduct a walkthrough survey; (3) measure exposure to fine particles of insecticide; and (4) investigate effective control measures to reduce the exposure. Personal airborne samples were taken in the breathing zone of an individual performing spraying activity in cotton farms. A total of 26 samples were collected in four cotton farms where manual spraying carried out by farmers simultaneously covers total 25 hector land. The samples were analyzed by using gas chromatography method in the analytical laboratory to find out insecticide which shows of irritation of the eyes, skin, and respiratory system. Exposure concentrations of organophosphorus were compared with the OSHA, NIOSH, and ACGIH permissible exposure limit for compliance and evaluation of the degree of worker exposure. Personal air sampling results showed the mean total fine particle concentration is more then the permissible limit. Symptoms included headache, nausea, vomiting, giddiness, loss of appetite, and fatigue. The study revealed that toxic particle exposure of these workers was excessive. It is expected that improved work practices, appropriate engineering controls, and usage of PPE, along with effective training to the workers, can reduce the toxic particles exposure significantly.
S. Byeon, Korea University, Seoul, Republic of Korea.
Bioaerosol monitoring was undertaken in nine engine plants. Bulk in-use metal working fluids (MWF) samples were collected at the machining sites and compared with air measurements at the same sites. Gravimetric concentration of oil mist averaged 0.33mg/m3. Endotoxin concentration ranged from 270 to 290,500 endotoxin unit(EU)/ml in the bulk MWF and from 14 to 790 EU/m3 in air. Airborn microbe concentrations were from 38 to 42,500 colony-forming units (CFU)/m3. Concentrations of endotoxin in the MWF were significantly correlated with airborne microbes(r = 0.64, p<0.0019) and the significant relationship between pH and airborne microbes(r = -0.50, p<0.001) and between pH and airborne endotoxins(r = -0.67, p<0.001) were also observed. The predominant bacteria species in MWF were Pseudomonas spp., Streptococcus spp., Staphylococcus spp., Serratia marcescens, and Providencia rettgeri, in order. Hazardous agents emitted by using water-soluble MWF seems to be correlated microbial growth. In order to minimize workers’ exposure to several hazardous agents by a water-soluble MWF, microbial growth must be controlled to the lowest level possible. Administrative control as well as engineering control must comprehensively be applied to control microbe’s growth in water-soluble MWF.
E. Locke, R. Jeffers, K&M Environmental Inc., Virginia Beach, VA; K. Kirollos, Virginia Beach, VA.
Homeland protection against potential terrorist activities has become paramount in recent times. The sensitive detection of chemical warfare agents in urban environments is an important aspect in the homeland defense arena. Hydrogen cyanide is classified as a blood agent by the military due to its mechanism of action. Given its extensive use in U.S. industry, it is considered to be a high risk toxic industrial material for potential terrorist activities and an extremely dangerous chemical warfare agent in confined areas. The NIOSH short term exposure limit (STEL) is 4.7 ppm with an Immediately Dangerous to Life or Health (IDLH) level of 50 ppm (55 mg per cubic meter). The objective of this research was to develop a passive, direct reading, colorimetric hydrogen cyanide detection badge capable of warning the user of the presence of this agent at concentrations well below acceptable limits.
The detection badge consists of a colorimetric sensing layer housed in a chemically resistant badge body. The sensing layer is capable of providing a visual warning of the presence of hydrogen cyanide in three minutes at the STEL concentration. A visible threshold color response was obtained within 12–18 seconds at the IDLH (50 ppm). The sensor undergoes a gradual color change from yellow to red upon continued exposure to the agent. This colorimetric response was shown to be linear with respect to time and concentration. Service life studies confirmed the mechanical and colorimetric stability of the detection badge under extreme environmental conditions.
K. Chapman, K&M Environmental Inc., Virginia Beach, VA; K. Kirollos, G. Mihaylov, Virginia Beach, VA.
Chlorine use is widespread and its applications are numerous, from plumbing pipes to X-ray film, medicines to seat belts, household bleach to rocket fuel, blood bags to computers, tap water to bullet-resistant vests. It is a cornerstone of modern medicine, with 85% of all pharmaceuticals made with chlorine. In addition, about 25% of all medical equipment is made from chlorine-based plastics. Unfortunately, chlorine is a potent respiratory system irritant, with mild exposures causing burning of the eyes, nose, and mouth. Exposure to concentrations of 1000 ppm or higher is likely to be fatal after only a few deep breathes. The NIOSH REL for chlorine is 0.5 ppm (ceiling) whereas the OSHA PEL is 1 ppm (ceiling).
A direct-read, colorimetric dosimeter has been developed and validated to measure exposure doses of chlorine in the workplace. This dosimeter provides a visual color change to indicate exposure doses ranging from 0.4 to 13 ppm•hr. For higher resolution, a color comparator was used to validate the system in the range from 0.2 to 20 ppm•hr. The dosimeter was tested at concentrations ranging from 0.098 to 6.01 ppm for periods ranging from 12 minutes to 8 hours. The dosimeter was tested at relative humidities ranging from 12 to 85% RH with no effect on the performance of the device. In addition, the dosimeter was exposed to temperatures ranging from 15 to 38°C. At 15°C, the dosimeter showed no significant deviation; however, at 38°C, the chlorine dosimeter showed a mean bias of +30%. At ambient conditions, the dosimeter showed a mean coefficient of variation of ±10.6 and a mean bias of 3.7%.
K. Lee, M. Yun, University of California, Davis, CA.
Passive samplers, or diffusive samplers, are devices that collect gaseous pollutants by molecular diffusion. Fluctuating air velocities on the surface of the sampler can change the sampling rate, a problem that is exacerbated in indoor environments and sedentary populations where the air velocity may be very low. According to literature review, the measurement error caused by this face velocity effect can be significant. We identified 150 manuscripts describing various types of passive sampler, published from 1973 to 2003, and identified 28 manuscripts reporting face velocity effects, 23 of which are on badge type and 5 of which are on tube type samplers. Among the 23 manuscripts reporting badge type sampler, all but one passive sampler reported significant underestimation, about 20–60%, in the wind velocity range encountered in indoor environment. One passive sampler showed 4% underestimation in narrow range of 0.017 to 0.25 m/s, however the sampler was not evaluated for face velocity effect over 0.25 m/s. Face velocity effect of five different passive samplers were experimentally evaluated. When the passive samplers were placed in an exposure chamber with different face velocities ranged from 0.02 to 1.15 m/s, face velocity effects of all passive samplers tested were significant. Since a significant portion of personal exposure time is spent in indoor environments where the air velocities are low, this error plays a significant role in reducing the accuracy of passive sampler measurements. Further studies are needed to develop a configuration to minimize the face velocity effect of passive sampler.
A. Bejan, M. Morgan, L. Monteith, G. van Belle, University of Washington, Seattle, WA.
Passive monitors are an attractive choice for sampling volatile chemicals in a variety of industrial settings where active sampling is impeded. SKC 575-002 and Radiello 3310 monitors were used to sample MEK, TCE, and o-xylene delivered in a fluctuating time pattern (1 hour at 2 TLV® at the beginning or the end of a 4h sampling session) with or without continuous presence of an interferant (4 hours at TLV®). Hypotheses: monitors’ performance depends on the specific nature of the sampled solvents; polar solvents are more likely to be displaced by the non-polar solvents; more volatile compounds are more likely to have reduced sampling accuracies.
An exposure chamber was designed to allow simultaneous use of four passive monitors of each type. Solvent concentration in the airstream (RH 80%) was continuously monitored using MIRAN 1A infrared analyzers. The performance of each monitor was evaluated based on “sampling accuracy,” the ratio of the solvent concentration as obtained by desorption to the mean solvent concentration recorded by MIRAN 1A.
Sampling accuracy of each solvent sampled at 2 TLV® was significantly influenced by the type of monitor (p<0.05), interferent presence (p<0.0001), time of peak occurrence (p<0.005), and the interaction between time of peak occurrence and interferant presence (p<0.05). The 95% CI for MEK, TCE, and o-xylene sampling accuracies of SKC 575-002 monitor were [1.317; 1.374], [1.306; 1.333], and [0.982; 1.029]. Radiello 3310 monitor yielded [1.114; 1.171], [1.140; 1.170], and [0.940; 0.987], respectively. For MEK and TCE, the bias of SKC monitor is outside the permissible +/- 25% range allowed by the NIOSH validation protocol. For all solvents, both monitors had precisions within 10.5%. A correction for the TCE sampling rate was proposed for SKC 575-002 monitor. An extension of the NIOSH validation protocol regarding the concentration-time profile and use of interfering compounds was proposed.
H. Kim, The Catholic University of Korea, Seoul, Republic of Korea; K. Jung, Korean Industrial Health Association, Seoul, Republic of Korea.
Mixed organic solvents are being assessed routinely by charcoal tubes. To measure effects of polarity of mixed organic solvents collected on charcoal tubes on the accuracy of exposure assessment, two desorbents—carbon disulfide (CS2) and CS2 with 5% dimethyl formamide (DMF), called 5% DMF—were compared using samples from 111 workplaces that included auto-manufacturing, machinery assembly, printing shops, and hospitals.
The results showed that desorption efficiencies of the 5% DMF to such polar substances as alcohols, ketones, and esters were statistically significantly higher than those of using CS2 only. For nonpolar substances, no significant improvement was detected except styrene, which showed a slight reduction of the desorption efficiency. The desorption efficiency of CS2 only was statistically significantly reduced at low concentration levels of methanol, ethanol, and styrene, suggesting the effects of mass loading on charcoal tubes. However, with 5% DMF, no significant effect was detected regardless of polarity of substances tested.
With 5% DMF, concentrations for polar organic solvents increased to an average of 112.92% compared with those of nonpolar organic solvents by CS2 alone. Concentration ratios for alcohols, ketones, and esters increased to 136.6, 108.8, and 103.6%, respectively, when 5% DMF was added. For nonpolar organic solvents, however, no significant difference of concentration ratios, with an average of 100.34%, was found. For each group of nonpolar organic solvents such as aliphatic hydrocarbons, chlorinated hydrocarbons, and aromatic hydrocarbons, no significant difference was detected.
The results of this study showed that the desorption efficiency of CS2 only for mixed organic solvents which were collected on charcoal was very low, particularly for polar organic solvents, and can be significantly improved by adding 5% DMF to the CS2 solution. This study suggests that current exposure levels to mixed organic solvents could have been far underestimated, up to 37%, for some polar solvents.
J. Roh, S. Lee, C. Kim, H. Kim, Yonsei University College of Medicine, Seoul, Republic of Korea.
Technical analytic problems were occurred frequently by complicated methods analyzing ethylene oxide with OSHA method 50. The objective of this study is to suggest the optimal pre-treatment method based on the OSHA analytical method. The limit of detection, pooled coefficient of variation, desorption efficiency, and stability by pre-treatments were evaluated for analyzing the ethylene oxide adsorbed on HBr-coated charcoal tube. The pre-treatment Method I used benzene:CS2 (99:1) as desorption solvent. The Method II used n,n-dimethylformamide as desorption solvent and Method III used derivatization after desorbed to DMF.
The limit of detection and desorption efficiency of ethylene oxide were 2.483 ug/sample and 92.13% in Method I. Method II was 1.919 ug/sample and 102.75%. Method III was 1.301 ug/sample and 96.47%. The pooled coefficient of variation (precision) of Methods I, II, and III were 0.00503, 0.00329, and 0.00514, respectively. The analytical sample by Method I was more stable than by Method II and III. These stabilities of desorbed samples were in accordance with the less than 5% given by OSHA method 50. In conclusion, the Method I is more simple, precise, stable, and efficient than other methods for analyzing the ethylene oxide in the HBr-coated charcoal tube.
J. Scawin, Scawin Consultancy, Epsom, Surrey, United Kingdom.
The International Standardisation Organisation (ISO) technical committee 158 “Analysis of Gas” has provided standards for the preparation of calibration gas mixtures. These standards are used by national bodies to provide primary gas mixtures to calibrate traceable environmental instrumentation. The ISO 6145 series are methods for the preparation of a continuous flow of a corrosive or reactive calibration gas mixture at low concentration values. Such mixtures are not stable within a high pressure cylinder and will deteriorate either suddenly or slowly over time. Present standards include permeation, saturation, diffusion, and other methods. These methods have the disadvantage that they depend on stable temperature environments, continuous flow operation, and long time periods to establish and maintain equilibrium conditions. A method which overcomes these requirements is now in preparation. DIS 6145-11 provides an electrochemical method for the generation of a stable calibration gas mixture almost immediately. The method can be easily transferred from one laboratory to another for comparison purposes or used in the field. Alteration of the gas flow through the cell electrolyte, or the current supplied to the electrodes, will change the composition of the generated gas and can then be used as a single point or extended to obtain a complete calibration curve for an environmental analyser. Gas flow through the cell is achieved with a thermal mass flow controller. Gases that can be produced by electrochemical generation are oxygen, hydrogen, hydrogen cyanide, hydrogen sulphide, chlorine, bromine, nitric oxide, carbon dioxide, arsine, and ozone. The chosen complementary gas should not react with any generated component. The relative expanded uncertainty of measurement, U, obtained by multiplying the relative combined standard uncertainties for this method by a coverage factor, 2, is not greater than 5%.
F. Stones, S. Edwards, G. Schultz, U.S. DOL/OSHA, Salt Lake City, UT.
Samples used to evaluate personal exposures to metals are typically collected on mixed cellulose filters housed in 37-mm polystyrene cassettes. Ideally, all of the material that is drawn into the filter cassette is collected and deposited on the filter. In the past, when the inside of the cassette was found to be visibly contaminated, the material found in the cassette was wiped out and analyzed with the filter. This practice was recently reevaluated. A selected number of sampled cassettes were wiped out and analyzed separately from the filter. For some samples, the amount of analyte found on the cassette walls was significant, even when the cassette wall had no visible dust. As a result of this finding, the insides of all cassettes where fumes and dusts are collected are now cleaned and analyzed with the sample filters.
S. Srinivasan, U.S. DOL/OSHA, Cincinnati, OH.
There are no national or international performance standards for air sampling instruments. Determining which instrument is best to use for evaluating a workplace industrial hygiene and safety issue can be just as taxing on the industrial hygienists 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 fits one’s needs 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 they be on hand or potential items to purchase. Many factors need to be considered. The OSHA Cincinnati Technical Center is continually evaluating instruments considered for purchase for 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 an air sampling pump, this evaluation translates into examining whether there is an intrinsic safety rating, ease of operation and setting the flow rate, flow compensation tests, loading tests, temperature and humidity tests, fault sensing, current drain, battery/charger reliability, effects of radio-interference on the flow rate, accuracy of the elapsed time indicator, compatibility with the various pump flow calibrator types, 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.
Posted May 30, 2004