Industrial Hygiene Applications - Nanotechnology, Drugs, and Other Agents

​​​PO​108

​Tuesday, May 24, 2016, 10:30 AM - 12:30 PM

CS-108-​01

Methodology for the Assessment, Evaluation, and Control of Potential Exposure to Engineered Nanomaterials (ENM)

C. Penniall, S. Maberti, B. Janke, and A. Jachak, ExxonMobil, Spring, TX

Situation/Problem: Existing research and recommended worker protection guidance is focused on the manufacture of engineered nanoparticles and engineered nanomaterials (ENM). There is little to no guidance on how to protect researchers or other workers when they handle engineered nanomaterials or nano enabled products such as insulation, paints, cements, catalysts, process additives, etc.

Resolution: A methodology was developed to review, evaluate, and control the exposure during handling of free-form engineered nanomaterials or nano enabled products. The methodology involves a flowchart that assesses the release potential of engineered nanomaterials during work and the relative toxicity of the engineered nanomaterials. Based on these parameters and the feasibility of control implementation, a hierarchy of work controls has been established. Separate training programs were developed for line management, IH staff responsible for research and pilot plants, and IH staff responsible for operational sites.

Results: The results include a comprehensive approach to the identification of potential exposure scenarios, exposure pathways, risk and the minimum work controls to protect employees during both research activities and handling of nano enabled products in process operations and maintenance work.

Lessons learned: IH staff require basic training on: the unique chemical and physical properties of engineered nanomaterials, the factors that drive release potential of nano size particles, potential health effects associated with exposure to engineered nanomaterials, and effective work controls, including engineering and PPE. Further, the lack of a consensus definition and lack of unique CAS numbers compound the difficulties in identification of engineered nanomaterials before they arrive in a lab or work site.

 

SR-​108-02

Adsorption Efficiency Comparison of Fabricated Buckypapers (BPs) for Volatile Organic Compound (VOC) Sampling and Analysis

J. Oh and C. Lungu, Environmental Health Sciences, University of Alabama at Birmingham, Birmingham, AL; E. Floyd, University of Oklahoma, Oklahoma City, OK

Objective: To find the most adsorptive sorbent through the fabrication of different types of single-walled carbon nanotubes (SWNTs) for use in volatile organic compound (VOC) passive samplers.

Methods: Arc discharge (AD) SWNT solution (0.5 mg/mL) and high pressure carbon monoxide (HiPco) SWNT powder were fabricated into a buckypaper (BP), a self-standing form of carbon nanotubes. For the fabrication of AD SWNT BP, 100 mL (50 mg) of the SWNT solution was suspended in 400 mL of acetone, filtered through a membrane filter under vacuum. SWNT cake deposited onto the filter was delaminated to obtain a BP (non-cleaned BP). SWNT cake was cleaned with deionized water and acetone after SWNT solution was vacuum filtered (acetone cleaned BP). Also, methanol was used to suspend SWNTs and in the cleaning process (methanol cleaned BP). For HiPco SWNT BP, 50 mg SWNT powder was suspended in methanol and sonicated in a cold bath. The same filtration procedure was followed. The fabricated buckypapers (n=4) were examined for surface area (SA) and toluene adsorption isotherm. SA was measured with a Micromeritics® ASAP2020 physisorption analyzer. Adsorption isotherm was obtained through diffusive adsorption isotherm chamber system (lab designed) in which liquid toluene diffuses onto a sorbent at 30 degrees Celsius.

Results: AD BPs showed 211±61, 322±38, and 387±16 square meter/g Brunauer, Emmett and Teller (BET) SA for non-cleaned, acetone-cleaned, and methanol-cleaned BPs, respectively, while HiPco BPs exhibited 649±9 square meter/g BET SA. The toluene adsorption capacities were 24, 33, 43, and 101 mg (toluene)/g (BP) for non-cleaned, acetone cleaned, methanol cleaned AD BPs, and HiPco BP, respectively.

Conclusions: HiPco BP had the highest SA and toluene adsorption capacity and among AD BPs, methanol cleaned BP was the most adsorptive, indicating that the cleaning process with methanol was the most desirable to fabricate AD BPs. Overall, toluene adsorption capacity was proportional to the SA. The fabricated BPs will be further annealed to increase SA and investigated on desorption efficiency using photothermal desorption technique which can shorten the current analytical procedure and consequently, exposure assessment time.

 

CS-108​-03

Investigation of Airborne Particulate Matter on the International Space Station (ISS) Using a Thermophoretic Sampler

K. Rickabaugh, G. Casuccio, and K. Bunker, RJ Lee Group, Inc., Monroeville, PA; M. Meyer, NASA, Cleveland, OH

Situation/Problem: It is important to maintain excellent air quality and to minimize deposition of particulates on surfaces in the International Space Station (ISS) environment. A significant challenge arises as there is a fixed volume of air on ISS and there is no dilution, venting or gravitation settling of debris or particulates. As a result, the potential release of particulates and other contaminants from on board activities needs to be well understood to adequately recognize, evaluate and control any potential emissions that may occur during operation. NASA has down-selected a thermophoretic sampler (TPS) as a means to sample airborne particulates on the ISS.

Resolution: Studies are underway to adapt the TPS for outer space applications for a sampling experiment on the ISS. One of the studies performed demonstrating the use of the TPS has been the preliminary testing of particulate releases from the use of 3D printers on Earth. Initial test measurements have been obtained using direct-reading instrumentation to evaluate both the number abundance and size distributions of particulates associated with a variety of different printing activities. Sampling of particulates has also been performed in order to characterize the emissions using electron microscopy techniques. The use of a miniaturized thermophoretic sampler (TPS) was implemented to sample the air because, in part, it is easy to use and particles are deposited directly onto a TEM grid for examination. This use of the TPS direct deposition technique is also preferred to minimize the likelihood that particulates could be disaggregated or dissolved in the sample preparation stages involved with filter based techniques.

Results: The results from the use of the direct-reading instruments often indicate the presence of airborne particulates from study related activities with particles detected being in the nano-size (< 100 nm) range. In the case of 3D printing testing, early results indicate that there are differences in particle emissions from different printing scenarios. In this instance and during other tests performed, the use of the TPS has been demonstrated to be a useful technique in obtaining samples suitable for electron microscopy examination in order to characterize particulates.

Lessons learned: Additional study and planning is desired in order to understand the air quality implications involved with human and other operational activities performed in the ISS environment. The TPS has already been chosen for a flight technology demonstration. One of the challenges that has been uncovered is the need to modify the TPS design so that heat will be appropriately dissipated in a low gravity environment. A low gravity version is being fabricated and space flight hardware acceptance testing is underway. A customized version of the TPS is scheduled to be deployed on the ISS in 2016. An update on the engineering solutions and preliminary testing results from use of the TPS will be presented.

 

SR-10​8-04

A Standardized Approach for the Generation and Characterization of Aerosols Released from Composite Nanomaterials in Industrial Scenarios

L. Cena, D. Farcas, and A. Erdely, CDC/NIOSH, Morgantown, WV; J. Kang, West Virginia University, Morgantown, WV

Objective: Develop and test a standardized method for generation and characterization of particles released from composite nanomaterials undergoing mechanical stress.

Methods: An adaptable system was developed to accommodate life-cycle events (e.g., sanding, sawing) for test materials and consumer products. The system consisted of a sand-blasting cabinet with HEPA-filtered air intakes. An electrical motor was exteriorized and connected to a pulley through a v-belt. Inside the cabinet, the pulley was connected to a shaft that could accommodate various types of equipment such as a belt sander, a saw blade or a drill chuck. A material feeder with constant force was constructed. The system was tested with a belt sander by sanding: 1) glass fiber/epoxy resin, 2) glass fiber/epoxy resin containing post-coated multi-walled carbon nanotubes (MWCNTs), 3) epoxy resin, 4) epoxy resin containing MWCNTs, 5) epoxy resin containing glass-fiber-infused MWCNTs, 6) epoxy resin containing carbon black, and 7) epoxy resin containing carbon black and MWCNTs. Total number concentrations, respirable mass concentrations, and particle size number/mass distributions of the emitted particles were measured using a scanning mobility particle sizer, an optical particle counter and a condensation particle counter. Additionally, samples for electron microscopy analysis were collected with a thermophoretic sampler and filter samples. Measurements were taken in triplicate for each material with coarse (150 grit) and fine (320 grit) sandpaper.

Results: The highest number concentrations (arithmetic mean = 2670 particle/cm3) were produced with coarse sandpaper, epoxy resin containing carbon black and MWCNTs. The lowest number concentrations (arithmetic mean = 600 particles/cm3) were produced with fine sandpaper, epoxy resin containing MWCNTs. The highest respirable mass concentrations (arithmetic mean = 1.01 mg/m3) were measured for fine sandpaper, epoxy resin containing MWCNTs and lowest (0.2 mg/m3) for coarse sandpaper, glass fiber/epoxy resin. Airborne particles were primarily micrometer sized with CNT protrusions.

Conclusions: The system provides a replicable and adaptable method for characterizing the particles released during an industrial use scenario. In this example, the number concentration, mass concentration and number size distribution of airborne particles depended on the characteristics of the material being sanded and the sandpaper grit.

 

CS-1​08-05

Models—What Can They Tell Us?

A. Havics, PH2, LLC, Avon, IN

Situation/Problem: Models have been used for years and have come to form a central part of exposure assessment. They can range from simple one-box models to complex computational fluid dynamics. Often times they are used before working through the base reasons and outcomes desired, the philosophically aspects. This would include determining the purpose, the use and level of specificity and accuracy required.

Resolution: Using several examples the assumptions, limitations, and practical (in context) application of some models will be explored.

Results: These aspects can been seen in: a) box models for paint exposure estimation, b) industrial site downwind carbon monoxide concentrations using an EPA industrial source complex model, c) 3D Fluent modeling of asbestos particle fate & transport from an abatement containment breach, d) dispersion/plume modeling of fracking fluids in groundwater and emitted from soils, and e) mesothelioma risk estimate in jewelry making. Some of these examples include other data, such as similar situation sampling data, to corroborate the models veracity (or lack thereof). The quality of the models will be addressed in this regards.

Lessons learned: This will demonstrate the benefits of models in terms of estimating exposure, exposure range, what is/isn’t probable, key factors in exposure, limitations in estimating & control, reduced time, preplanning assistance, etc. On the downside, this talk will also look at the potential negatives, generally related to quality, such as variability, sensitivity, limitations in prediction or retrospective evaluation, overconfidence in results, etc.

 

CS-108​-06

The Use of Surrogate Sampling for Evaluating the Efficiency of Engineering Controls During Hazardous Drug Compounding

E. Higgins, Environmental Health & Engineering, Inc., Needham, MA

Situation/Problem: Many pharmacies have struggled to meet current USP 797 standards and the proposed USP 800 standards are more strict. Older infrastructure and mechanical systems, aging equipment, small spaces have prohibited compliance, and many healthcare systems lack the capital budget necessary for retrofitting pharmacies, in order to meet compliance. The most common issues regarding compliance focus on isolation of areas where hazardous drugs (HDs) are compounded and insufficient air exchange rates and relative pressurization of compounding rooms. Retrofitting the heating, ventilating, and air-conditioning (HVAC) systems and/or purchase of compliant equipment is cost prohibitive for most organizations. Many of the HDs that are compounded are not inhalation hazards, rather dermal or contact hazards. Therefore, it is necessary to find a way to evaluate current work practices and engineering controls in an efficient and cost-effective manner.

Resolution: We have designed alternative approaches to evaluating the effectiveness of existing engineering controls which involves the use of surrogate air and surface sampling. We conducted baseline monitoring, followed by air sampling for selected chemicals that are similar (chemical state, vapor pressure, particle size) to the hazardous drugs that are used during compounding. This was completed every six months following the replacement of filters (on a preventative maintenance schedule) Monitoring was conducted during typical activities using the surrogates, which includes preparing syringes for intramuscular administration, pills, and intravenous bags. Surface sampling for particulate phase surrogates were also collected on surfaces outside the primary engineering control. We also developed a strategy in which additional filtration (primarily high efficiency gas absorption filters) were used to address potential exposures of liquid phase HDs.

Results: Through surrogate air and surface sampling we have shown that the use of best work practices, and in some cases additional filtration, is successful in controlling potential exposures to HDs during compounding. Monitoring has also indicated that the most likely source of contamination is through direct contact. We detected surrogate on surfaces that were not adequately cleaned after compounding activities. This allowed us to work with the organization to evaluate and improve the current cleaning programs, increase awareness, and better train employees on proper cleaning methods in the pharmacy.

Lessons learned: As it is for many regulations, it is important to be able to interpret compliance standards, and at the same time meet the needs of clients. We have used science to quantitatively evaluate the effectiveness of the controls without breaking the bank for hospitals. The results supported data that shows the primary hazard for HDs is dermal exposures and not inhalation. The results gave us quantitative evidence that directed us to work with the pharmacies in evaluating and improving handling of products and cleaning of surfaces. We learned that you don't need to spend a lot of money retrofitting the pharmacies in order to meet compliance and keep employees safe from HD exposures.​