Personal Breathing Zone Samples Research Articles

Personal Exposure to Fine Particulate Air Pollution among Brick Workers in Nepal

Prior studies suggest brick workers in Nepal may be chronically exposed to hazardous levels of fine particulate matter (PM2.5) from ambient, occupational, and household sources. However, findings from these studies were based on stationary monitoring data, and thus may not reflect a worker’s individual exposures. In this study, we used RTI International’s MicroPEMs to collect 24 h PM2.5 personal breathing zone (PBZ) samples among brick workers (n = 48) to estimate daily exposures from ambient, occupational, and household air pollution sources. Participants were sampled from five job categories at one kiln. The geometric mean (GM) PM2.5 exposure across all participants was 116 µg/m3 (95% confidence interval [CI]: 94.03, 143.42). Job category was significantly (p < 0.001) associated with PBZ PM2.5 concentrations. There were significant pairwise differences in geometric mean (GM) PBZ PM2.5 concentrations among workers in administration (GM: 47.92, 95% CI: 29.81, 77.03 µg/m3) vs. firemen (GM: 163.46, 95 CI: 108.36, 246.58 µg/m3, p = 0.003), administration vs. green brick hand molder (GM: 163.35, 95% CI: 122.15, 218.46 µg/m3, p < 0.001), administration vs. top loader (GM: 158.94, 95% CI: 102.42, 246.66 µg/m3, p = 0.005), firemen vs. green brick machine molder (GM: 73.18, 95% CI: 51.54, 103.90 µg/m3, p = 0.03), and green brick hand molder vs. green brick machine molder (p = 0.008). Temporal exposure trends suggested workers had chronic exposure to hazardous levels of PM2.5 with little to no recovery period during non-working hours. Multi-faceted interventions should focus on the control of ambient and household air pollution and tailored job-specific exposure controls.

129 A task-Based Approach to Nanomaterials Exposure Assessment in the Construction Trades

Abstract While the critical task of evaluating the hazards of nanomaterials continues, exposure assessments can provide additional information to safeguard workers. The frequent exposure of construction workers to inhalation hazards underscores a pressing need to characterize and quantify nanomaterials in aerosols generated during construction activities. Research was conducted in partnership with affected building trades unions and in collaboration with NIOSH toxicologists to obtain occupationally relevant exposure data. Initial studies took place in a test chamber, in which a skilled tradesperson sprayed or sanded paints and coatings containing ZnO, TiO2, or Ag nanoparticles. The current study, conducted outdoors, investigated exposure to graphene nanoplatelets during cutting, grinding, and tuckpointing of cementitious composites. Personal breathing zone samples were analyzed for elemental carbon (EC) respirable mass concentration and by transmission electron microscopy (TEM) with energy-dispersive x-ray spectroscopy. Wet methods and local exhaust ventilation effectively reduced exposure to graphene; respirable EC was non-detectable when using exposure controls versus up to 3 mg m-3 without. A high proportion of graphene particles observed by TEM were free and not bound to the cement matrix. Compared to the unincorporated graphene, the dimensions of graphene particles observed in air samples were smaller, suggesting a potential physical transformation prior to release from the matrix. Given the dustiness of construction environments, analysis of filter loading prior to collection of TEM samples proved methodologically valuable. These results provide actionable information about exposure risks and controls and support further investigation of the extent to which graphene may alter the toxicity of cement dust.

Airborne concentrations of chrysotile asbestos during operation of industrial crane controls and maintenance of associated arc chutes

Some industrial crane control panels were historically equipped with chrysotile-containing arc chutes. Because of the paucity of data regarding potential exposure from such equipment, we used a simulation approach to quantify the release of chrysotile from arc chutes in two functional 1970s-era industrial crane control panels during operation and maintenance. Two experienced operators separately simulated operation of crane controls under load; one of these operators then simulated two arc chute maintenance protocols: sanding (protocol 1) and scraping, sanding, and blowing (protocol 2). The original arc chutes contained approximately 36% chrysotile. Personal breathing zone (PBZ) (n = 8) and area samples (n = 8) were collected and analyzed using phase contrast microscopy (PCM) and transmission electron microscopy. PCM-equivalent (PCME) concentrations were derived, from which 8-h time-weighted averages (TWA) were calculated. During operation, chrysotile was identified in one of the four PBZ samples, equivalent to a PCME concentration of 0.012 f/cm3 (8-h TWA: 0.011 f/cm3). During protocols 1 and 2, chrysotile was identified in all PBZ samples (n = 4); PCME concentrations (and corresponding 8-h TWA) were <0.013 and 0.021 f/cm3 (0.001 and 0.004 f/cm3) and 0.013 and 0.017 f/cm3 (0.003 f/cm3), respectively. Many of the airborne chrysotile fibers had matrix attached, supporting the low exposure potential during this work. These data indicate very low, if any, exposures to chrysotile asbestos during the simulated scenarios. In addition, these data could assist with refining assumptions in exposure reconstruction and inform the state-of-the science on low-level chrysotile exposure.

JA:2021-6. Effectiveness of a Low-cost Intervention: Changes to Cytokines and Microbiome among Bioaerosol Exposed Dairy Workers

ABSTRACT Purpose: Livestock workers experience an increased burden of bioaerosol-induced respiratory disease. We have previously demonstrated that dairy operations generate bioaerosols spanning the inhalable size fraction. These aerosols contained complex bacterial communities and inflammagens. Because those particles with an aerodynamic diameter between 10 and 100 μm are known to deposit in the nasopharyngeal region, we believe that exposure health outcomes in the upper respiratory tract are important and need consideration, especially in the context of the nasal microbiome (i.e., collection of bacterial communities suggested to play a key role in health and disease). Methods: We evaluated the effectiveness of a hypertonic saline nasal lavage in reducing inflammatory responses in dairy workers from a high-volume dairy operation. We collected inhalable personal breathing zone (PBZ) samples and pre-/post-shift nasal lavage samples from each participant over five consecutive days. The treatment group (n = 5) received hypertonic saline, while the control group (n = 5) received normotonic saline. PBZ samples were analyzed for particulate concentrations and endotoxin using gravimetric and enzymatic methods, respectively. Pro- and anti-inflammatory cytokines (i.e., IL-8, IL-10, and TNF-α) were measured from nasal lavage samples using a multiplex assay. To measure the air and nasal microbiomes, lavage and dust samples were analyzed using 16S rRNA sequencing. Results/Findings: Inhalable dust concentrations ranged from 0.15 to 1.9 mg/m3. Significant differences in pro-inflammatory cytokines were observed between treatment and control groups for IL-6. Contrary to the hypothesis, IL-6 concentrations were higher in the treatment group than the control group. However, the treatment group had significantly higher IL-10 (anti-inflammatory) concentrations than the control group. Distinct bacterial communities were observed in pre- and post-shift lavage samples, with post-shift communities more closely resembling those found in dust samples. Practical Implications: Based on pilot results, the intervention was successful in upregulating anti-inflammatory cytokines and promoting changes in the nasal microbiome. Therefore, more research is warranted to determine if a hypertonic nasal rinse is an effective intervention that does not cause adverse perturbations to the microbiome.

JA:2021-31. Does the Use of a Nasal Lavage Intervention Improve Pulmonary Function for Dairy Workers?

ABSTRACT Purpose: Dairy workers are at the frontline of exposure to bioaerosols, which typically contain bacteria and associated pro-inflammatory constituents (e.g., endotoxin). As such, dairy workers are at an increased risk for respiratory illness, most likely mediated through a strong proinflammatory response. Very few studies have systematically evaluated control strategies to reduce exposure and improve health. Given the challenges and limitations of implementing engineering controls, we propose the use of a low-cost and low-burden intervention. Hypertonic saline (HTS) was recently shown to attenuate inflammation in trauma patients. Here, we conducted an intervention to administer HTS in a nasal lavage to determine if the inflammatory response was mitigated and if the airway function improved among dairy workers. Methods: Ten participants were recruited from a large herd dairy and randomly assigned to treatment (n = 5) and control groups (n = 5). Each participant received normotonic saline (308 mOsm) nasal lavage (NL) before their shift over 5 consecutive days. After each shift, the treatment group received HTS, while the control group received normotonic saline. All samples were analyzed for 10 different cytokines using a multiplex assay. Spirometry was performed pre- and post-shift to examine forced expiratory volume in one second, forced vital capacity and the subsequent ratio, and peak expiratory flow rate (PEFR). Personal breathing zone samples for inhalable bioaerosols were collected across the work shift; mass concentrations and endotoxin abundance were determined by gravimetry and a fluorescent assay, respectively. Statistical analyses and models were performed using SAS. Results/Findings: Differences in pro-inflammatory cytokines were observed. There was an interaction effect on IL-10 between treatment, day, and time of day, indicating promotion of anti-inflammatory effect. The treatment group experienced an increase in PEFR change (0.76 L, p = 0.12) near statistical significance; no statistically significant differences were observed in the other spirometry measures. Both groups of dairy workers in this study experienced less of a decline in cross-shift pulmonary function when compared to other studies. Practical Application: The HTS nasal lavage is designed as a low-cost intervention that can be self-administered before and after every shift across other agricultural operations. This study was limited by small sample size and warrants further investigation.

Measurement of area and personal breathing zone concentrations of diesel particulate matter (DPM) during oil and gas extraction operations, including hydraulic fracturing

ABSTRACTDiesel engines serve many purposes in modern oil and gas extraction activities. Diesel particulate matter (DPM) emitted from diesel engines is a complex aerosol that may cause adverse health effects depending on exposure dose and duration. This study reports on personal breathing zone (PBZ) and area measurements for DPM (expressed as elemental carbon) during oil and gas extraction operations including drilling, completions (which includes hydraulic fracturing), and servicing work.Researchers at the National Institute for Occupational Safety and Health (NIOSH) collected 104 full-shift air samples (49 PBZ and 55 area) in Colorado, North Dakota, Texas, and New Mexico during a four-year period from 2008–2012. The arithmetic mean (AM) of the full shift TWA PBZ samples was 10 µg/m3; measurements ranged from 0.1–52 µg/m3. The geometric mean (GM) for the PBZ samples was 7 µg/m3. The AM of the TWA area measurements was 17 µg/m3 and ranged from 0.1–68 µg/m3. The GM for the area measurements was 9.5 µg/m3. Differences between the GMs of the PBZ samples and area samples were not statistically different (P > 0.05).Neither the Occupational Safety and Health Administration (OSHA), NIOSH, nor the American Conference of Governmental Industrial Hygienists (ACGIH) have established occupational exposure limits (OEL) for DPM. However, the State of California, Department of Health Services lists a time-weighted average (TWA) OEL for DPM as elemental carbon (EC) exposure of 20 µg/m3. Five of 49 (10.2%) PBZ TWA measurements exceeded the 20 µg/m3 EC criterion. These measurements were collected on Sandmover and Transfer Belt (T-belt) Operators, Blender and Chemical Truck Operators, and Water Transfer Operators during hydraulic fracturing operations.Recommendations to minimize DPM exposures include elimination (locating diesel-driven pumps away from well sites), substitution, (use of alternative fuels), engineering controls using advanced emission control technologies, administrative controls (configuration of well sites), hazard communication, and worker training.

A case report of personal exposures to isoflurane during animal anesthesia procedures

ABSTRACTThe purpose of this study was to compare personal exposures to isoflurane from participants' breathing zone samples during animal anesthesia procedures by the method of anesthetic gas delivery and the waste anesthetic gas (WAG) control method utilized. WAG control methods included passive scavenging using charcoal canisters, active scavenging using a building vacuum system, and various local exhaust ventilation systems such as laboratory fume hoods and capture hoods. Methods of anesthesia delivery included induction chambers, face masks (also known as nose cones), and intubation. Personal breathing zone samples were collected using 3M 3520 Organic Vapor Diffusion Monitors and submitted to an International Organization for Standardization (ISO) 17025 accredited laboratory for analysis.When using face masks and induction chambers as the method of anesthesia delivery, local exhaust ventilation systems were found to be the best WAG control method to mitigate personal exposures to isoflurane. Personal exposures to isoflurane were well-controlled when animals were intubated, regardless of whether passive scavenging with an adsorptive charcoal canister or active scavenging with a building vacuum system was used. Personal exposures to isoflurane were highest when induction chambers and face masks were used for anesthesia delivery, and passive scavenging with adsorptive charcoal canisters were used as the control method. This study served to identify best practice WAG control methods for research and veterinary procedures that involve isoflurane anesthesia.

Nano-metal oxides: Exposure and engineering control assessment

ABSTRACTIn January 2007, the National Institute for Occupational Safety and Health (NIOSH) conducted a field study to evaluate process specific emissions during the production of ENMs. This study was performed using the nanoparticle emission assessment technique (NEAT). During this study, it was determined that ENMs were released during production and cleaning of the process reactor. Airborne concentrations of silver, nickel, and iron were found both in the employee's personal breathing zone and area samples during reactor cleaning. At the completion of this initial survey, it was suggested that a flanged attachment be added to the local exhaust ventilation system. NIOSH re-evaluated the facility in December 2011 to assess worker exposures following an increase in production rates. This study included a fully comprehensive emissions, exposure, and engineering control evaluation of the entire process. This study made use of the nanoparticle exposure assessment technique (NEAT 2.0). Data obtained from filter-based samples and direct reading instruments indicate that reactor cleanout increased the overall particle concentration in the immediate area. However, it does not appear that these concentrations affect areas outside of the production floor. As the distance between the reactor and the sample location increased, the observed particle number concentration decreased, creating a concentration gradient with respect to the reactor. The results of this study confirm that the flanged attachment on the local exhaust ventilation system served to decrease exposure potential. Given the available toxicological data of the metals evaluated, caution is warranted. One should always keep in mind that occupational exposure levels were not developed specifically for nanoscale particles. With data suggesting that certain nanoparticles may be more toxic than the larger counterparts of the same material; employers should attempt to control emissions of these particles at the source, to limit the potential for exposure.

A New Approach Combining Analytical Methods for Workplace Exposure Assessment of Inhalable Multi-Walled Carbon Nanotubes.

To date there is no consensus about the most appropriate analytical method for measuring carbon nanotubes (CNTs), hampering the assessment and limiting the comparison of data. The goal of this study is to develop an approach for the assessment of the level and nature of inhalable multi-wall CNTs (MWCNTs) in an actual workplace setting by optimizing and evaluating existing analytical methods. In a company commercially producing MWCNTs, personal breathing zone samples were collected for the inhalable size fraction with IOM samplers; which were analyzed with carbon analysis, inductively coupled plasma mass spectrometry (ICP-MS) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX). Analytical methods were optimized for carbon analysis and SEM/EDX. More specifically, methods were applied and evaluated for background correction using carbon analyses and SEM/EDX, CNT structure count with SEM/EDX and subsequent mass conversion based on both carbon analyses and SEM/EDX. A moderate-to-high concordance correlation coefficient (RC) between carbon analyses and SEM/EDX was observed [RC = 0.81, 95% confidence interval (CI): 0.59-0.92] with an absolute mean difference of 59 µg m-3. A low RC between carbon analyses and ICP-MS (RC = 0.41, 95% CI: 0.07-0.67) with an absolute mean difference of 570 µg m-3 was observed. The large absolute difference between EC and metals is due to the presence of non-embedded inhalable catalyst particles, as a result of which MWCNT concentrations were overestimated. Combining carbon analysis and SEM/EDX is the most suitable for quantitative exposure assessment of MWCNTs in an actual workplace situation.

Exposure assessment to engineered nanoparticles handled in industrial workplaces: The case of alloying nano-TiO2 in new steel formulations

This experimental study addresses the occupational exposure assessment to nano-TiO2 (AEROXIDE ® TiO2 P 25, EVONIK GmbH) along the processing steps of ingot steelmaking at three sites, whose characteristics range from conditioned room to multi-source industrial environments (MSIS). In Site A, which is a MSIS of multiproduct flexible production, the alloying tablets are manufactured through compression of bulk nano-powder at room temperature. Tablets are then assembled in Site B, which is a lab room equipped with local exhaust ventilation (LEV). The alloying of steel takes place in Site C, which is a full-scale casting hall where substantial amounts of material per batch (3000kg steel/batch) are processed in open-face molds and severe working conditions prevail.A comprehensive experimental strategy based on simultaneous measurements using direct reading instruments (DRI) and time integrated filter-based sampling has been set up. The main goal of this unusual campaign at an industrial site was to determine the suitability of the various options within the decision frame of the current methodological approaches, mainly chemical- and site-dependent.In Site A the DRI were of limited applicability for the quantification of exposure, because of a high-variability of the background and a characteristic low but unstable counting in the coarse size range where agglomerates of nano-TiO2 are present. In Site B, under controlled environmental conditions no interferences were relevant. Therefore, real-time devices showed no change in the total particle concentration suggesting that tasks performed did not result in any detectable release of the nano-powder. Readings in the size range>0.3µm showed low-signals, in the order of the device accuracy, that could not be linked to any potential release. However, the mass concentration of TiO2, as obtained by the off-line analysis of personal breathing zone (PBZ) samples, spans from 0.021 to 0.296mg/m3 in both Sites, which seems to be due to big agglomerates observed by scanning electron microcopy (SEM). In Site C (steel foundry) the on-line instruments could not be used due to access restrictions and severe working conditions. Therefore, only personal sampling approach was used, including the comparative study with and without nanomaterial, which indicates no additional or TiO2 specific workers exposure.This work highlights how, in this particular case, occupational exposure to engineered nanoparticles (ENP) is better assessed through off-line analysis of personal filter samples. The DRI, however, are of unquestionable applicability as real-time monitors to quantify engineering controls efficiency and, thus, for risk management activities and decision making. The need for a scientific consensus in performing such an exposure assessment in industrial contexts is stressed.

Environmental characterization of a coffee processing workplace with obliterative bronchiolitis in former workers

ABSTRACTObliterative bronchiolitis in five former coffee processing employees at a single workplace prompted an exposure study of current workers. Exposure characterization was performed by observing processes, assessing the ventilation system and pressure relationships, analyzing headspace of flavoring samples, and collecting and analyzing personal breathing zone and area air samples for diacetyl and 2,3-pentanedione vapors and total inhalable dust by work area and job title. Mean airborne concentrations were calculated using the minimum variance unbiased estimator of the arithmetic mean.Workers in the grinding/packaging area for unflavored coffee had the highest mean diacetyl exposures, with personal concentrations averaging 93 parts per billion (ppb). This area was under positive pressure with respect to flavored coffee production (mean personal diacetyl levels of 80 ppb). The 2,3-pentanedione exposures were highest in the flavoring room with mean personal exposures of 122 ppb, followed by exposures in the unflavored coffee grinding/packaging area (53 ppb). Peak 15-min airborne concentrations of 14,300 ppb diacetyl and 13,800 ppb 2,3-pentanedione were measured at a small open hatch in the lid of a hopper containing ground unflavored coffee on the mezzanine over the grinding/packaging area. Three out of the four bulk coffee flavorings tested had at least a factor of two higher 2,3-pentanedione than diacetyl headspace measurements.At a coffee processing facility producing both unflavored and flavored coffee, we found the grinding and packaging of unflavored coffee generate simultaneous exposures to diacetyl and 2,3-pentanedione that were well in excess of the NIOSH proposed RELs and similar in magnitude to those in the areas using a flavoring substitute for diacetyl. These findings require physicians to be alert for obliterative bronchiolitis and employers, government, and public health consultants to assess the similarities and differences across the industry to motivate preventive intervention where indicated by exposures above the proposed RELs for diacetyl and 2,3-pentanedione.

A Cross-Sectional Study of the Cardiovascular Effects of Welding Fumes.

ObjectivesOccupational exposure to particulate air pollution has been associated with an increased risk of cardiovascular disease. However, the risk to welders working today remains unclear. We aimed to elucidate the cardiovascular effects of exposure to welding fumes.MethodsIn a cross-sectional study, structured interviews and biological sampling were conducted for 101 welders and 127 controls (all non-smoking males) from southern Sweden. Personal breathing zone sampling of respirable dust was performed. Blood pressure (BP) and endothelial function (using peripheral arterial tonometry) were measured. Plasma and serum samples were collected from peripheral blood for measurement of C-reactive protein, low-density lipoprotein, homocysteine, serum amyloid A, and cytokines.ResultsWelders were exposed to 10-fold higher levels of particles than controls. Welders had significantly higher BP compared to controls, an average of 5 mm Hg higher systolic and diastolic BP (P≤0.001). IL-8 was 3.4 ng/L higher in welders (P=0.010). Years working as a welder were significantly associated with increased BP (β=0.35, 95%CI 0.13 – 0.58, P=0.0024 for systolic BP; β=0.32, 95%CI 0.16 – 0.48, P<0.001 for diastolic BP, adjusted for BMI) but exposure to respirable dust was not associated with BP. No clear associations occurred between welding and endothelial function, or other effect markers.ConclusionsA modest increase in BP was found among welders compared to controls suggesting that low-to-moderate exposure to welding fumes remains a risk factor for cardiovascular disease.

Quantification of Total Particulate Matter and Benzene-Soluble Fraction Inhalation Exposures in Roofing Workers Performing Tear-off Activities

Asphalt shingle removal (tear-off) from roofs is a major job task for an estimated 174,000 roofers in the United States. However, a literature search showed that there are no published studies that characterize worker inhalation exposures to asphalt particulates during shingle tear-off. To begin to fill this gap, the present study of inhalation exposures of roofers performing asphalt shingle tear-off was undertaken. The airborne agents of interest were total particulate matter (TP) and organic particulates measured as the benzene-soluble fraction (BSF) of total particulate. The study's objectives were to measure the personal breathing zone (PBZ) exposures of roofing tear-off workers to BSF and TP; and to assess whether these PBZ exposures are different from ambient levels.Task-based PBZ samples (typical duration 1–5 hours) were collected during asphalt shingle tear-off from roofs near Houston, Texas and Denver, Colorado. Samples were analyzed for TP and BSF using National Institute of Occupational Safety and Health (NIOSH) Method 5042. As controls, area samples (typical duration 3–6 hours) were collected on the ground near the perimeter of the tear-off project Because of the presence of significant sources of inorganic particulates in the work environment, emphasis was placed on the BSF data. No BSF exposure higher than 0.25 mg/m3 was observed, and 69% of the PBZ samples were below the limit of detection (LOD). Due to unforeseen confounding, however, statistical comparisons of on-the-roof PBZ samples with on-the-ground area samples posed some special challenges. This confounding grew out of the interaction of three factors: statistical censoring from the left; the strong inverse correlation between LOD concentration and sampling duration; and variation in sampling durations between on-the-ground area samples and on-the-roof PBZ samples.A general linear model analysis of variance (GLM-ANOVA) was applied to help address the confounding. The results of this analysis indicate that personal sample BSF results were not statistically significantly different from the background/area samples.

Carbon Nanotube and Nanofiber Exposure Assessments: An Analysis of 14 Site Visits.

Recent evidence has suggested the potential for wide-ranging health effects that could result from exposure to carbon nanotubes (CNT) and carbon nanofibers (CNF). In response, the National Institute for Occupational Safety and Health (NIOSH) set a recommended exposure limit (REL) for CNT and CNF: 1 µg m(-3) as an 8-h time weighted average (TWA) of elemental carbon (EC) for the respirable size fraction. The purpose of this study was to conduct an industrywide exposure assessment among US CNT and CNF manufacturers and users. Fourteen total sites were visited to assess exposures to CNT (13 sites) and CNF (1 site). Personal breathing zone (PBZ) and area samples were collected for both the inhalable and respirable mass concentration of EC, using NIOSH Method 5040. Inhalable PBZ samples were collected at nine sites while at the remaining five sites both respirable and inhalable PBZ samples were collected side-by-side. Transmission electron microscopy (TEM) PBZ and area samples were also collected at the inhalable size fraction and analyzed to quantify and size CNT and CNF agglomerate and fibrous exposures. Respirable EC PBZ concentrations ranged from 0.02 to 2.94 µg m(-3) with a geometric mean (GM) of 0.34 µg m(-3) and an 8-h TWA of 0.16 µg m(-3). PBZ samples at the inhalable size fraction for EC ranged from 0.01 to 79.57 µg m(-3) with a GM of 1.21 µg m(-3). PBZ samples analyzed by TEM showed concentrations ranging from 0.0001 to 1.613 CNT or CNF-structures per cm(3) with a GM of 0.008 and an 8-h TWA concentration of 0.003. The most common CNT structure sizes were found to be larger agglomerates in the 2-5 µm range as well as agglomerates >5 µm. A statistically significant correlation was observed between the inhalable samples for the mass of EC and structure counts by TEM (Spearman ρ = 0.39, P < 0.0001). Overall, EC PBZ and area TWA samples were below the NIOSH REL (96% were <1 μg m(-3) at the respirable size fraction), while 30% of the inhalable PBZ EC samples were found to be >1 μg m(-3). Until more information is known about health effects associated with larger agglomerates, it seems prudent to assess worker exposure to airborne CNT and CNF materials by monitoring EC at both the respirable and inhalable size fractions. Concurrent TEM samples should be collected to confirm the presence of CNT and CNF.

Hydraulic Fracturing Industry Response to the Publication of Study Regarding Excessive Occupational Exposure to Respirable Crystalline Silica

Hydraulic Fracturing Industry Response to the Publication of Study Regarding Excessive Occupational Exposure to Respirable Crystalline SilicaAbstract Number:2203 Dana Drecksel*, David F. Goldsmith Dana Drecksel* Georgetown University, United States, E-mail Address: [email protected] Search for more papers by this author and David F. Goldsmith Georgetown University, United States, E-mail Address: [email protected] Search for more papers by this author AbstractBackground: Inhalation of crystalline silica dust causes silicosis, lung cancer, autoimmune disorders, kidney diseases, and an increased risk of TB. In 2010 NIOSH commenced a study on silica dust exposure in the hydraulic fracturing industry, publishing their results in 2013: Esswein, et. al JOEH, 10: 347-356. The study gathered personal breathing zone samples for employees at fracking sites, found that a majority exceeded NIOSH and OSHA exposure limits for respirable SiO2 dust, and suggested procedures for decreasing occupational exposure.*Aims*: Our purpose was to assess the response of the fracking industry to Esswein et al.’s findings. Via direct industry queries we analyzed and documented changes that have taken place to improve monitoring and control of SiO2 hazards in the fracturing industry.*Methodology*: We interviewed Esswein and others in the fracking industry regarding changes since 2013. We are gathering additional data from representatives of oil companies, completions contractors, companies engaged in controlling the dust, State based oil and gas commissions, and hydraulic fracturing equipment manufacturers.*Findings*: In response to the study, industry organizations formed focus groups to examine potential engineering controls, seek input from industrial hygienists, and improve communications regarding occupational risks. Completions contractors report that their oil and gas clients are requiring improved monitoring and control, though most dust control measures remain in the development stage. Others report improved PPE and ‘do not enter’ areas at fracking sites. There is a claim that controlling SiO2 during fracking fluid mixing will cost $6+ billion.*Why this Matters*: Until the NIOSH publication, no study demonstrated that workers engaged in hydraulic fracturing were subject to high silica dust levels. Given these findings, documenting industry changes to the monitoring/controlling of such hazards is timely and significant.

Airborne asbestos exposures associated with gasket and packing replacement: A simulation study and meta-analysis

Exposures to airborne asbestos during the removal and installation of internal gaskets and packing associated with a valve overhaul were characterized and compared to published data according to different variables (e.g., product, equipment, task, tool, setting, duration). Personal breathing zone and area samples were collected during twelve events simulating gasket and packing replacement, clean-up and clothing handling. These samples were analyzed using PCM and TEM methods and PCM-equivalent (PCME) airborne asbestos concentrations were calculated. A meta-analysis was performed to compare these data with airborne asbestos concentrations measured in other studies involving gaskets and packing. Short-term mechanic and assistant airborne asbestos concentrations during valve work averaged 0.013f/cc and 0.008f/cc (PCME), respectively. Area samples averaged 0.008f/cc, 0.005f/cc, and 0.003f/cc (PCME) for center, bystander, and remote background, respectively. Assuming a tradesman conservatively performs 1–3 gasket and/or packing replacements daily, an average 8-h TWA was estimated to be 0.002–0.010f/cc (PCME). Combining these results in a meta-analysis of the published exposure data showed that the majority of airborne asbestos exposures during work with gaskets and packing fall within a consistent and low range. Significant differences in airborne concentrations were observed between power versus manual tools and removal versus installation tasks. Airborne asbestos concentrations resulting from gasket and packing work during a valve overhaul are consistent with historical exposure data on replacement of asbestos-containing gasket and packing materials involving multiple variables and, in nearly all plausible scenarios, result in average airborne asbestos concentrations below contemporaneous occupational exposure limits for asbestos.

Personal Breathing Zone Exposures among Hot-Mix Asphalt Paving Workers; Preliminary Analysis for Trends and Analysis of Work Practices That Resulted in the Highest Exposure Concentrations

An exposure assessment of hot-mix asphalt (HMA) paving workers was conducted to determine which of four exposure scenarios impacted worker exposure and dose. Goals of this report are to present the personal-breathing zone (PBZ) data, discuss the impact of substituting the releasing/cleaning agent, and discuss work practices that resulted in the highest exposure concentration for each analyte. One-hundred-seven PBZ samples were collected from HMA paving workers on days when diesel oil was used as a releasing/cleaning agent. An additional 36 PBZ samples were collected on days when B-100 (100% biodiesel, containing no petroleum-derived products) was used as a substitute releasing/cleaning agent. Twenty-four PBZ samples were collected from a reference group of concrete workers, who also worked in outdoor construction but had no exposure to asphalt emissions. Background and field blank samples were also collected daily. Total particulates and the benzene soluble fraction were determined gravimetrically. Total organic matter was determined using gas chromatography (GC) with flame ionization detection and provided qualitative information about other exposure sources contributing to worker exposure besides asphalt emissions. Thirty-three individual polycyclic aromatic compounds (PACs) were determined using GC with time-of-flight mass spectrometry; results were presented as either the concentration of an individual PAC or a summation of the individual PACs containing either 2- to 3-rings or 4- to 6-rings. Samples were also screened for PACs containing 4- to 6-rings using fluorescence spectroscopy. Arithmetic means, medians, and box plots of the PBZ data were used to evaluate trends in the data. Box plots illustrating the diesel oil results were more variable than the B-100. Also, the highest diesel oil results were much higher in concentration than the highest B-100 results. An analysis of the highest exposure results and field notes revealed a probable association between these exposures and the use of diesel oil, use of a diesel-powered screed, elevated HMA paving application temperatures, lubricating and working on broken-down equipment, and operation of a broom machine. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a file containing tables summarizing statistical data and individual analyte results.]

Occupational Exposures to Respirable Crystalline Silica During Hydraulic Fracturing

This report describes a previously uncharacterized occupational health hazard: work crew exposures to respirable crystalline silica during hydraulic fracturing. Hydraulic fracturing involves high pressure injection of large volumes of water and sand, and smaller quantities of well treatment chemicals, into a gas or oil well to fracture shale or other rock formations, allowing more efficient recovery of hydrocarbons from a petroleum-bearing reservoir. Crystalline silica (“frac sand”) is commonly used as a proppant to hold open cracks and fissures created by hydraulic pressure. Each stage of the process requires hundreds of thousands of pounds of quartz-containing sand; millions of pounds may be needed for all zones of a well. Mechanical handling of frac sand creates respirable crystalline silica dust, a potential exposure hazard for workers. Researchers at the National Institute for Occupational Safety and Health collected 111 personal breathing zone samples at 11 sites in five states to evaluate worker exposures to respirable crystalline silica during hydraulic fracturing. At each of the 11 sites, full-shift samples exceeded occupational health criteria (e.g., the Occupational Safety and Health Administration calculated permissible exposure limit, the NIOSH recommended exposure limit, or the ACGIH threshold limit value), in some cases, by 10 or more times the occupational health criteria. Based on these evaluations, an occupational health hazard was determined to exist for workplace exposures to crystalline silica. Seven points of dust generation were identified, including sand handling machinery and dust generated from the work site itself. Recommendations to control exposures include product substitution (when feasible), engineering controls or modifications to sand handling machinery, administrative controls, and use of personal protective equipment. To our knowledge, this represents the first systematic study of work crew exposures to crystalline silica during hydraulic fracturing. Companies that conduct hydraulic fracturing using silica sand should evaluate their operations to determine the potential for worker exposure to respirable crystalline silica and implement controls as necessary to protect workers. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a file containing controls and recommendations to limit worker exposures to respirable crystalline silica at hydraulic fracturing work sites.]

An Analysis of Workplace Exposures to Benzene Over Four Decades at a Petrochemical Processing and Manufacturing Facility (1962–1999)

Benzene, a known carcinogen, can be generated as a by-product during the use of petroleum-based raw materials in chemical manufacturing. The aim of this study was to analyze a large data set of benzene air concentration measurements collected over nearly 40 years during routine employee exposure monitoring at a petrochemical manufacturing facility. The facility used ethane, propane, and natural gas as raw materials in the production of common commercial materials such as polyethylene, polypropylene, waxes, adhesives, alcohols, and aldehydes. In total, 3607 benzene air samples were collected at the facility from 1962 to 1999. Of these, in total 2359 long-term (>1 h) personal exposure samples for benzene were collected during routine operations at the facility between 1974 and 1999. These samples were analyzed by division, department, and job title to establish employee benzene exposures in different areas of the facility over time. Sampling data were also analyzed by key events over time, including changes in the occupational exposure limits (OELs) for benzene and key equipment process changes at the facility. Although mean benzene concentrations varied according to operation, in nearly all cases measured benzene quantities were below the OEL in place at the time for benzene (10 ppm for 1974–1986 and 1 ppm for 1987–1999). Decreases in mean benzene air concentrations were also found when data were evaluated according to 7- to 10-yr periods following key equipment process changes. Further, an evaluation of mortality rates for a retrospective employee cohort (n = 3938) demonstrated that the average personal benzene exposures at this facility (0.89 ppm for the period 1974–1986 and 0.125 ppm for the period 1987–1999) did not result in increased standardized mortality ratio (SMRs) for diseases or malignancies of the lymphatic system. The robust nature of this data set provides comprehensive exposure information that may be useful for assessing human benzene exposures at similar facilities. The data also provide a basis for comparable measured exposure levels and the potential for adverse health effects. These data may also prove beneficial for comparing relative exposure potential for production versus nonproduction operations and the relationship between area and personal breathing zone samples.

Carbon nanotube dosimetry: from workplace exposure assessment to inhalation toxicology

BackgroundDosimetry for toxicology studies involving carbon nanotubes (CNT) is challenging because of a lack of detailed occupational exposure assessments. Therefore, exposure assessment findings, measuring the mass concentration of elemental carbon from personal breathing zone (PBZ) samples, from 8 U.S.-based multi-walled CNT (MWCNT) manufacturers and users were extrapolated to results of an inhalation study in mice.ResultsUpon analysis, an inhalable elemental carbon mass concentration arithmetic mean of 10.6 μg/m3 (geometric mean 4.21 μg/m3) was found among workers exposed to MWCNT. The concentration equates to a deposited dose of approximately 4.07 μg/d in a human, equivalent to 2 ng/d in the mouse. For MWCNT inhalation, mice were exposed for 19 d with daily depositions of 1970 ng (equivalent to 1000 d of a human exposure; cumulative 76 yr), 197 ng (100 d; 7.6 yr), and 19.7 ng (10 d; 0.76 yr) and harvested at 0, 3, 28, and 84 d post-exposure to assess pulmonary toxicity. The high dose showed cytotoxicity and inflammation that persisted through 84 d after exposure. The middle dose had no polymorphonuclear cell influx with transient cytotoxicity. The low dose was associated with a low grade inflammatory response measured by changes in mRNA expression. Increased inflammatory proteins were present in the lavage fluid at the high and middle dose through 28 d post-exposure. Pathology, including epithelial hyperplasia and peribronchiolar inflammation, was only noted at the high dose.ConclusionThese findings showed a limited pulmonary inflammatory potential of MWCNT at levels corresponding to the average inhalable elemental carbon concentrations observed in U.S.-based CNT facilities and estimates suggest considerable years of exposure are necessary for significant pathology to occur at that level.