Showing papers in "American Industrial Hygiene Association Journal in 1995"

The Strain Index: A Proposed Method to Analyze Jobs For Risk of Distal Upper Extremity Disorders

Abstract: Based on existing knowledge and theory of the physiology, biomechanics, and epidemiology of distal upper extremity disorders, a semiquantitative job analysis methodology was developed. The methodology involves the measurement or estimation of six task variables (intensity of exertion, duration of exertion per cycle, efforts per minute, wrist posture, speed of exertion, and duration of task per day); assignment of an ordinal rating for each variable according to exposure data; then assignment of a multiplier value for each variable. The Strain Index is the product of these six multipliers. Preliminary testing suggests that the methodology accurately identifies jobs associated with distal upper extremity disorders versus jobs that are not; however, large-scale studies are needed to validate and update the proposed methodology.

Permeability of Commercial Solvents Through Living Human Skin

Abstract: A procedure has been developed for measuring the steady state rate of permeation of commercial solvents through living human skin. To get the most consistent results, it was necessary with some solvents to normalize the solvent permeation rate of a given skin sample with its [3H] water permeation rate. For other solvents this was not necessary, so the un-normalized data were used. High [3H] water permeation rate also was used as a criterion for “efective” skin samples that gave erroneous permeability rates, especially for solvents having slow permeability. The linearity of the steady state data was characterized by calculation of the “percent error of the slope.” The following permeability rates (g/m2h) of single solvents were measured: dimethyl sulfoxide (DMSO), 176; N-methyl-2-pyrrolidone, 171; dimethyl acetamide, 107; methyl ethyl ketone, 53; methylene chloride, 24; [3H]water, 14.8; ethanol, 11.3; butyl acetate, 1.6; gamma-butyrolactone, 1.1; toluene, 0.8; propylene carbonate, 0.7; and sulfolane, 0.2. ...

Bioaerosol Concentrations in Noncomplaint, Complaint, and Intervention Homes in the Midwest

Abstract: Forty-one homes of conventional design were studied to investigate the relationship between bioaerosols, building parameters, and season, and to determine if differences existed across health-based home categories. The homes were categorized as: those for which no indoor air problems were known (noncomplaint homes), noncomplaint homes of allergy patients (intervention homes), and complaint “sick” homes (complaint homes). Carbon dioxide and relative humidity were measured in the basement and main floor areas. CO2 concentrations were elevated for complaint homes (mean 1190 ppm) but less than 1000 ppm for all noncomplaint homes (mean 550 ppm). Relative humidity was significantly lower for intervention homes than for complaint or noncomplaint homes. Viable and nonviable bioaerosol sampling was performed on the main floor, the basement, and outside. Outdoor viable fungi exhibited an 8.4-fold range when plotted by month, but respirable and nonrespirable indoor fungal concentrations did not differ significantly ...

Occupational exposure and indoor air quality monitoring in a composting facility.

Abstract: The objective of this study was to investigate indoor air quality in a completely covered enclosure used for the aerobic composting of organic wastes originating from vegetable, fruit, and garden refuse. Samples of gases and vapors were taken in the ventilation exhaust ducts. Volatile organic compounds (VOCs) were collected on Tenax® absorbent; after thermal desorption they were analyzed by gas chromatography/mass spectrometry. Hydrogen sulfide was determined using Drager test tubes. Microbial samplings were conducted on four sites inside the hall. Microbes were collected using a modified Anderson high-volume sampler, consisting of two impactor stages. Results indicate that the concentrations of VOCs were rather low; only the limonene level was elevated, but it was still well below the current Dutch provisional threshold limit value. Hydrogen sulfide levels found were also far less than the Dutch threshold limit value. Both total bacteria and gram-negative bacterial counts exceeded the provisional Dutch g...

Use of ozone generating devices to improve indoor air quality.

Abstract: Room ozonization has been in widespread use to “freshen” indoor air for more than 100 years. This use is sometimes promoted with the claim that ozone can oxidize airborne gases, and even particulates, to simple carbon dioxide and water vapor. Aside from whether ozone can improve indoor air quality, the potentially deleterious consequences to public health of overexposure to ozone are of concern. The literature on both allegations is reviewed. It indicates that ozone is not a practical and effective means of improving indoor air quality, especially in light of its potentially serious risk to health.

Characteristics of Blood-Containing Aerosols Generated by Common Powered Dental Instruments

Abstract: Powered dental instruments applied to whole-blood in a typodont field of operation generated aerosols of red blood cell and hemoglobin-tinged plasma at rates ranging from 0.003 to 2.2 µL of plasma per minute with particle sizes ranging from 0.06 to 13 µm and half-lives of 35 minutes to 17 hours. Particles 0.06 to 0.38 µm were plasma spheroids that contained no detectable hemoglobin or red blood cell fragments. Particles 0.66 to 13 µm were mostly plasma spheroids, only a small fraction of which contained whole and fragmented red blood cells. All the recovered particles physically could contain the 0.042 µm hepatitis B virus, could be inhaled, and 20 to 100% of them could be retained in the human respiratory system. Of 0.06 to 2.5 µm plasma aerosol particles, 15–83% passed through the filter media of nine makes of surgical masks used by dentists for protection from occupational infection. These findings lend support to the hypothesis of an airborne route for the hepatitis B infections reported for dental pr...

Dust Generation from Handling Powders in Industry

Abstract: This article explores the hypothesis that the amount of dust generated by an industrial process that handles granular material depends on (a) the size distribution of the granules and (b) the ratio of impaction to cohesion Here, impaction characterizes particle separation forces caused by energy input from the process, and cohesion characterizes interparticle binding forces within the material itself A mathematical model based on this hypothesis is presented and evaluated using 441 data sets from an industrial-scale apparatus designed to measure dust generation Dust generation was characterized in experiments using titanium dioxide, limestone, glass beads, and lactose with moisture contents ranging from 0% to 6% and size distributions of d 25 µm in aerodynamic diameter, dropped from heights of 025, 07, and 125 m at material flows of 01, 03, and 06 kg/sec Results are presented in equations for impaction, cohesion, and dust generation as a function of particle size The equa

The particle size distribution, density, and specific surface area of welding fumes from SMAW and GMAW mild and stainless steel consumables

Abstract: Particle size distributions were measured for fumes from mild steel (MS) and stainless steel (SS); shielded metal arc welding (SMAW)and gas metal arc welding (GMAW) consumables. Up to six samples of each type of fume were collected in a test chamber using a micro-orifice uniform deposit (cascade) impactor. Bulk samples were collected for bulk fume density and specific surface area analysis. Additional impactor samples were collected using polycarbonate substrates and analyzed for elemental content. The parameters of the underlying mass distributions were estimated using a nonlinear least squares analysis method that fits a smooth curve to the mass fraction distribution histograms of all samples for each type of fume. The mass distributions for all four consumables were unimodal and well described by a lognormal distribution; with the exception of the GMAW-MS and GMAW-SS comparison, they were statistically different. The estimated mass distribution geometric means for the SMAW-MS and SMAW-SS consumables we...

TVOC and CO2 Concentrations as Indicators in Indoor Air Quality Studies

Abstract: This article reviews the sources, levels, and interpretation of CO2 and VOC concentrations in buildings. The use of an enrichment factor to identify emission sources and potential IAQ problems is suggested. The indicator is evaluated by collecting concentration data in two office buildings and by reviewing recent air-quality studies in the literature. Results show that bioeffluent and occupant-related emissions often account for a large share of VOC emissions; the suggested indicator clearly shows when other sources are significant. Several issues that influence the interpretation of IAQ indicators are discussed, including the use of pollutant surrogates, temporal and spatial variability in large buildings, VOC measurement technique, and outdoor pollutant levels.

Evaluation of Airborne Particulates and Fungi During Hospital Renovation

Abstract: This study was conducted over 30 weeks on a hospital floor undergoing partial renovation. Some patients housed on the floor were immunosuppressed, including bone marrow transplant recipients. The construction zone was placed under negative pressure and was separated from patient rooms by existing hospital walls and via erection of a temporary barrier. Other control measures minimized patient exposure to airborne materials. Air sampling was done for 3 weeks prior to construction, 24 weeks during construction, and 3 weeks after renovation was completed. Airborne particulate concentrations, total spore counts, particle size, and fungal species were assessed. At the beginning of the renovation there were increases in airborne particulates (from 0.2 to 2.0 mg/m3) and fungal spores (from 3.5 to 350 colony forming units (CFU)/m3), but only in the construction zone. Throughout the remainder of the renovation, particulate and fungal spore levels fluctuated inside the construction zone but remained close to baselin...

Critical Review of Methods of Sampling, Analysis, and Monitoring for TDI and MDI

Abstract: This article is a critical review of certain methods that have been used for the sampling, analysis, and monitoring of toluene diisocyanate (TDI) and methylene bisphenyl diisocyanate (MDI). Only those methods that have received relatively widespread application are addressed. The review includes a “tutorial style” discussion of basic definitions, and basic principles and procedures of quality control and metrology for sampling, analysis, and monitoring. Recommendations are given for future work in this area. Proper exposure assessment is critical in the risk analysis process, since both exposure and effect measurements are required.

The Effect of Size and Fabric Weight of Protective Coveralls on Range of Gross Body Motions

Abstract: This study evaluated the effects of garment size and fabric weight on range-of-motion (ROM). Ten male subjects performed a series of twelve gross body movements while wearing each of nine similarly styled coveralls. The coveralls were undersized, appropriately sized, and oversized, and were constructed from three different weights of poly/cotton fabric. A balanced 3×3 repeated measures experimental design was used, along with a seminude control condition. ROM was measured with a two-arm manual goniometer. Garment size significantly affected (p<.05) ROM for all movements except shoulder extension and trunk lateral flexion. Compared to seminude ROM, undersized garments reduced the mean ROM by as much as 24% in the case of hip flexion. Fabric weights on ROM were significant for shoulder extension and elbow, hip, knee, and shoulder horizontal flexion. Fabric weight affected ROM less than garment size. Interaction effects between fabric weight and size generally were not significant. These results demonstrate ...

Exposure to Air Contaminants in Chicken Catching

Abstract: A cross-sectional study of chicken catchers was carried out by personal sampling of air contaminants. The catchers used either the drawer method (DM) or truck method (TM) for loading chickens into cages. DM catchers were exposed to higher concentrations of hazardous substances than TM catchers, except for ammonia. In terms of geometric means total dust concentrations were 11.3 mg/m3 (DM catchers) and 8.1 mg/m3 (TM catchers). Full-shift dust exposure exceeded the Danish occupational exposure limit (OEL) of 3 mg/m3 for organic dust by at least a factor of 2. From paired personal sampling data the concentration of respirable dust ranged from 18% to 28% of the total dust concentration. The average exposure level to bacterial endotoxin in total dust at 82 ng/m3 for DM catchers and 42 ng/m3 for TM catchers exceeded a limit of 10 ng/m3 recommended for poultry processing industry workers in the United States. Endotoxin content of airborne dust averaged 6.5±4.9 ng/mg. Exposure to microorganisms was determined by m...

Control of Paint Overspray in Autobody Repair Shops

Abstract: Commercially available controls for reducing worker exposure to paint overspray were evaluated in six autobody shops and a spray-painting equipment manufacturer's test facility. Engineering control measures included spray-painting booths, vehicle preparation stations, and spray-painting guns. The controls were evaluated by measuring particulate overspray concentrations in the worker's breathing zone, visualizing the airflow in spray-painting booths and vehicle preparation stations, and measuring airflow volumes and velocities. In addition, respirator usage observations were collected at five of the autobody repair shops, and quantitative fit tests were conducted on existing respirators at three shops. Several conclusions were drawn from this study. Downdraft spray-painting booths provide lower particulate overspray concentrations measured on the worker than crossdraft and semidowndraft spray-painting booths. In the latter two booths, the spray-painting gun can disperse as much as half the paint overspray ...

Assessment of the Accuracy of Material Safety Data Sheets

Abstract: This study evaluated 150 material safety data sheets (MSDSs) for the accuracy and completeness of five areas of information: (1) chemical identification of hazardous ingredients; (2) reported health effects; (3) suggested first aid procedures; (4) recommended personal protective equipment; and (5) exposure level regulations and guidelines. The material from each MSDS was reviewed by both an industrial hygienist and an occupational physician using standard (secondary) references (that were readily available at the time the MSDS was prepared) and a rating system for each area of information. Eighty-nine percent of the MSDSs provided identifiable chemical names. Thirty-seven percent were found to have accurate health effects data (with chronic health information the most inaccurate). The majority of MSDSs (76%) provided adequate first-aid information. Slightly less than half (47%) were judged to have an accurate rating for personal protective equipment information or a correct listing for applicable occupati...

Estimation of Pesticide Exposure to Greenhouse Application Using Video Imaging and Other Assessment Techniques

Abstract: Pesticide exposure in greenhouse applicators was measured using the video imaging technique to assess exposure (VITAE) along with dermal patches, air monitoring, and biological assessment techniques. The exposure of five males to pesticides during high- and low-volume application methods in commercial greenhouse operations was evaluated. Failure to use precautionary handling methods when using low-volume applications resulted in the highest level of dermal tracer deposition. Results demonstrated nonuniform deposition of tracer/pesticide mixtures on various body regions, supporting earlier work that questioned the assumption of uniform deposition when assessing exposure with the dermal patch technique. By combining the tracer with an oil-based concentrate, it remained uniformly suspended in the spray solution, and deposition ratios remained constant. Estimates of pirimicarb exposure using the VITAE method were highly correlated with excretion of urinary metabolites (r2=0.93). The immediate visual results p...

Influence of Anxiety Level on Work Performance With and Without a Respirator Mask

Abstract: Work performance of mask wearers has been shown to be less than performance of the same individuals without masks. How much this performance decrement is attributable to psychological factors was the subject of this study. This experiment was designed to give quantitative information about the effect of anxiety level on relative work performance while wearing a respirator mask. Twenty subjects were tested for trait anxiety levels and performed on a treadmill at 80–85% of their maximum heart rates until they reached voluntary end-point. Physiological, metabolic, and subjective measurements were taken every minute. While experimental variability precluded many of the results from achieving statistical significance, performance times with the mask averaged less than without the mask. Anxious subjects experience more discomfort, perform for shorter times, and accomplish less total work than their lower anxiety counterparts, even when rate of work can be adjusted.

VOC emission rates and emission factors for a sheetfed offset printing shop

Abstract: Emission rates were determined during production for a sheetfed offset printing shop by combining the measured concentrations and ventilation rates with mass balance models that characterized the printing space. Air samples were collected simultaneously on charcoal tubes for 12 separate 1-hour periods at 6 locations. Air samples and cleaning solvents were analyzed by gas chromatography for total volatile organic compounds (VOC) and 13 hydrocarbons. The average VOC emission rate was 470 g/hr with a range of 160-1100 g/hr. These values were in good agreement with the amounts of VOC, hexane, toluene, and aromatic C9s determined from estimated solvent usage and measured solvent compositions. Comparison of the emission rates with source activities indicated an emission factor of 30-51 g VOC/press cleaning. Based on the test observations it was estimated that this typical small printing facility was likely to release 1-2 T VOC/year. The methodology also may be useful for the surface coating industry, as emission rates in this study were determined without recourse to a temporary total enclosure and without interfering with worker activities, increasing worker exposure, or increasing safety and explosion hazards.

Factors affecting microbiological colony count accuracy for bioaerosol sampling and analysis.

Abstract: The effects of the following variables on the occurrence of colony masking (the indistinguishable merging or overlap of sufficiently close colonies) were evaluated experimentally using the bacterium Bacillus subtilis: spore density on a collection surface, concentration of nutrients in the culture medium, sample incubation time, and ability of an observation system to distinguish overlapped colonies. Increasing spore surface density and incubation time increased colony masking, whereas lowering nutrient concentration decreased colony diameter and, therefore, masking but also limited spore germination and growth. Overall, full-strength medium was best for accurate counting of early microcolonies examined with the aid of a microscope, whereas half- or quarter-strength medium was better for counting older readily observable macrocolonies. Masking bias was determined for varying spore surface densities and colony diameters and was applied to two widely used slit-to-agar bioaerosol impactors. Appropriate colle...

Exposure of commercial pesticide applicators to the herbicide alachlor.

Abstract: Presented in this paper are the results of a pilot study to estimate the alachlor inhalation (2-chloro-2′,6′-diethyl-N-[methoxymethyl] acetanilide) and skin exposures of commercial pesticide applicators, who apply a variety of herbicides and insecticides to crop land. Twenty applicators and seven hauler-mixers participated in the study. Inhalation exposures ranged from 0.32 to 6.4 µg/m3, with a geometric mean of 1.6 µg/m3. Alachlor deposition on clothing patches was highly variable, ranging from <0.01 to 32.0 µg/cm2. The thigh patches generally received more deposition than patches in other areas. Surface-wipe and hand- and glove-wash samples also indicated that the hands frequently were exposed; alachlor concentrations in postshift handwash samples ranged from 3 to 324 µg/sample. The results of the study indicate that commercial pesticide applicators encounter substantial exposures to alachlor and that proper precautions for reducing exposures are not always followed. Practical steps, in particular the u...

Exposure While Applying Industrial Antimicrobial Pesticides

Abstract: Forty-three assessments were made of dermal and/or inhalation chemical exposure while applying industrial antimicrobial pesticide products, either by manually pouring or pumping liquids or by pouring a solid (powder or flake) product. Inhalation exposure was assessed via a personal air sample but was usually below the chemical limit of detection. Dermal exposure outside work clothing and dermal deposition inside the clothing was assessed via dermal gauze dosimeters. While dosimeters at discrete body locations often received exposures below the limit of detection, one or more dosimeters on individual applicators almost always showed measurable exposure. The median measured dose was between 30% and 70% of the maximum credible summed dose calculated by assuming that each dosimeter showed either the level of measurable deposition or one-half of the detection limit at locations where the chemical was unmeasurable. Because of differences in settings and the low level of control implicit in these application processes, measurable dermal doses were highly variable. Mean measurable dose rates were near 3, 8, and 10 mg product/hr, and daily total deposited doses were 2, 3.5, and 5 mg of product for pouring and pumping liquids and for pouring solids, respectively. Although the effect of gloves cannot be directly determined, wearers of gloves had geometric mean hand total doses 155- to 290-fold less than those not wearing gloves. Similar to the statistics for agricultural pesticides, the dermal route of exposure for these industrial pesticides exceeds the inhalation route by 5X to 100X, depending on assumptions regarding nondetectable values.

Respirator Mask Effects on Exercise Metabolic Measures

Abstract: To test effects of respirator masks on maximum oxygen uptake, ventilation threshold, and lactate threshold, 14 subjects underwent incremental bicycle exercise with and without masks. There was a statistically significant difference in final oxygen consumption between the two conditions, but other results suggest that the physiological measure of maximum oxygen uptake was not reached at termination for the full-mask condition. Lactate and ventilation thresholds were not affected by mask condition. Hypoventilation while wearing masks caused higher amounts of blood lactate accumulation. The resulting higher mask CO2 levels and lower O2 levels, normally attributed to mask dead volume, may instead be due to mask resistance.

Occupational and environmental exposure of automobile mechanics and nonautomotive workers to airborne manganese arising from the combustion of methylcyclopentadienyl manganese tricarbonyl (MMT).

Abstract: Inhalation exposure to manganese (Mn) was measured for a group of garage mechanics and a control group of nonautomotive workers. The airborne Mn exposure of 35 garage mechanics suspected of being relatively highly exposed to Mn from MMT was measured at the workplace over a one-week period. It also was measured for 30 nonautomotive workers at the University of Montreal. The environmental exposure also was measured for the two groups, as was the exposure to three other metals, aluminum (Al), iron (Fe), and zinc (Zn). At work the mechanics were exposed to Mn concentrations varying from 0.010 to 6.673 µg m−3 with a mean of 0.45 µg m−3, while the control group was exposed to concentrations varying from 0.011 to 1.862 µg m−3 with a mean of 0.04 µg m−3. The mean environmental exposure for the two groups was similar to the Mn concentrations gathered in Montreal in 1992. Workplace concentrations of Al, Fe, and Zn also were higher for the garage mechanics. The results suggest that less than 10% of the Mn exposure o...

Rapid determination of metal particles on air sampling filters using laser-induced breakdown spectroscopy

Abstract: A preliminary investigation of an alternative method of analysis for metal particles is presented. The mass of thallium (TI) particles on filters was determined in less than 1 minute using the technique of laser-induced breakdown spectroscopy (LIBS).Thallium was collected by passing contaminated air through a filter or by wiping a TI-contaminated surface with a filter. The particles (<20 µm diameter) were in the form of thallic oxide used in the manufacture of superconducting metals. Thallium was detected by forming a series of laser sparks across the filter surface. The sparks vaporized the particles and excited the resulting atoms. Thallium was detected by temporally and spectrally resolving the spark light. The detection limit for TI was 40 ng/cm2 on a filter surface. The useful dynamic range extends from 0.2 to 40 µg/filter using the strong 535.05 nm neutral TI emission line. The LIBS method of detection is intended to supplement (rather than replace) conventional analytical methods such as atomic abs...

The effect of relative humidity on mouse allergen levels in an environmentally controlled mouse room.

Abstract: To determine the effect of humidity on the levels of the mouse allergen Mus m 1, an experimental animal room was constructed to control environmental variables. The sex, strain, age, and number of mice was constant in the room, so that the average daily production of Mus m 1 would not vary greatly. Six different levels of relative humidity from 15% to 65% were maintained for a minimum of a week each. Daily collections of airborne particulates were eluted from filters and Mus m 1 content measured by immunological assay. Increasing relative humidity caused a decrease in Mus m 1 levels from a high of 3 ng/m3 at 15% humidity to a low of 0.5 ng/m3 at 65% humidity. Thus, reduction of airborne allergen levels can be achieved by careful attention to humidity control, especially during the winter heating season when humidity levels may be low. This experimental room can be used to measure the effect of other variables such as ventilation rate, caging, bedding, and work practices on the levels of mouse allergen in ...

Sampling and Analysis of Isocyanates in Spray-Painting Operations

Abstract: Several methods were used for the sampling and analysis of airborne 1,6-hexamethylene diisocyanate (HDI) and polyisocyanates during spray-painting operations. National Institute for Occupational Safety and Health (NIOSH)Method 5521 uses an impinger filled with 1-(2methoxyphenyl)piperazine in toluene for collection and derivatization, HPLC separation, and simultaneous UV and EC detection. This method was compared directly to Occupational Safety and Health Administration (OSHA) Method 42, which is based on sample collection on a fiber filter coated with 1-(2-pyridyl)piperazine, HPLC separation, then UV detection. NIOSH Method 5521, modified so that polyisocyanate concentrations were determined based on polyisocyanate standards, also was compared with NIOSH Method 0500, which is a gravimetric assay for total particulates. The results for HDI monomer demonstrate that NIOSH Method 5521 appears to give higher results than those obtained using OSHA Method 42, especially when the total particulate concentration i...

Development of a New Qualitative Test for Fit Testing Respirators

Abstract: A new qualitative fit test was developed using Bitrex™ (Macfarland Smith Limited) as the test agent. It was validated by running a series of paired qualitative and quantitative fit tests. Quantitative tests were conducted with a small corn oil aerosol, using a condensation nucleus counter as a detector. Qualitative fit tests were run with Bitrex and saccharin, following the established protocol for the saccharin fit test. Four models of National Institute for Occupational Safety and Health—approved replaceable filter respirators were used in the study. All were half mask models equipped with high efficiency filters. In some cases, respirators expected to be the correct size for test subjects were tested. In other cases, respirators expected to be too small or too large for the subjects were tested. Test results were analyzed using fit test method validation criteria recommended in the American National Standards Institute draft standard on fit testing (ANSI Z88.10). The Bitrex and saccharin tests were fou...

Arsenic Levels in Hair of Workers in a Semiconductor Fabrication Facility

Abstract: This study examined the relationship between total arsenic levels in hair of employees in a semiconductor fabrication facility and job responsibility, a surrogate variable for arsenic exposure potential. Maintenance personnel who regularly worked in equipment cleaning areas were assumed to have higher potential for occupational exposure than other employees. Occipital scalp hair samples were collected from 30 maintenance personnel, supervisors, and equipment engineers with high, medium, and low potential for exposure and from 26 administrative employees. Total arsenic in hair was measured by atomic absorption spectroscopy with hydride generation. Workplace air and wipe samples were analyzed to verify differing exposure potential in fabrication and administrative areas. Subjects completed written questionnaires to identify possible nonoccupational sources of arsenic. Mean hair arsenic in two of the three groups working in or near fabrication areas was slightly higher but not statistically different from th...

Adsorption Capacity and Thermal Desorption Efficiency of Selected Adsorbents

Abstract: Four solid adsorbents (Tenax GR, Carbotrap, Carboxen 569, and Carbosieve S-III) were evaluated for possible use in a long-term, personal chemical-exposure monitor. Adsorption/thermal desorption and breakthrough experiments were performed to determine the efficiencies and the adsorption capacity of these adsorbent/organic vapor pairs. Different amounts of organic vapors (toluene, n-hexane, methylene chloride, and methyl ethyl ketone) were collected on adsorbent tubes at various flow rates, followed by thermal desorption and analysis using gas chromatography. The concentrations sampled ranged from 0.01 to 0.1 µg/mL, and the flow rate through the tubes ranged from 20 to 117 mL/min. The adsorbent tubes were spiked with 2 mL of a solvent solution containing 5mg/L of deuterated benzene, which served as an internal standard. The average recoveries for n-hexane, methylene chloride, and methyl ethyl ketone ranged from 95 to 107%; the recovery for toluene was about 85%. In the breakthrough experiments, known concen...

Pulmonary retention of ceramic fibers in silicon carbide (SiC) workers.

Abstract: The fibrous inorganic content of post-mortem lung material obtained from 15 men who worked in the primary silicon carbide (SiC) industry was evaluated. Five men had neither lung fibrosis nor lung cancer (NFNC), six had lung fibrosis (LF), and four had lung fibrosis and lung cancer (LFLC). The workers had 23 to 32 years of exposure. Mean duration of exposure was 23.4 (SD 6.9) years in the NFNC group, 28.8 (SD 5.5) in the LF, and 32.3 (SD 9.0) in the LFLC group. Concentrations of SiC ceramic fibers and other fibrous minerals and angular particles were determined by transmission electron microscopy and energy dispersive spectroscopy. The geometric mean and geometric standard deviation lung concentrations of SiC ceramic fibers 0.1). Pulmonary retention of SiC fibers ≥ 5 µ showed an excess in LF and LFLC cases combined versus NFNC that approached statistical significance (Mann-Whitney, p=0.06). There was a somewhat greater difference ...