The influence of complex matrices on method performance in extracting and monitoring for microplastics.

Previous studies have evaluated method performance for quantifying and characterizing microplastics in clean water, but little is known about the efficacy of procedures used to extract microplastics from complex matrices. Here we provided 15 laboratories with samples representing four matrices (i.e., drinking water, fish tissue, sediment, and surface water) each spiked with a known number of microplastic particles spanning a variety of polymers, morphologies, colors, and sizes. Percent recovery (i.e., accuracy) in complex matrices was particle size dependent, with ∼60-70% recovery for particles >212 µm, but as little as 2% recovery for particles <20 µm. Extraction from sediment was most problematic, with recoveries reduced by at least one-third relative to drinking water. Though accuracy was low, the extraction procedures had no observed effect on precision or chemical identification using spectroscopy. Extraction procedures greatly increased sample processing times for all matrices with the extraction of sediment, tissue, and surface water taking approximately 16, 9, and 4 times longer than drinking water, respectively. Overall, our findings indicate that increasing accuracy and reducing sample processing times present the greatest opportunities for method improvement rather than particle identification and characterization.

What determines accuracy of chemical identification when using microspectroscopy for the analysis of microplastics?

Fourier transform infrared (FTIR) and Raman microspectroscopy are methods applied in microplastics research to determine the chemical identity of microplastics. These techniques enable quantification of microplastic particles across various matrices. Previous work has highlighted the benefits and limitations of each method and found these to be complimentary. Within this work, metadata collected within an interlaboratory method validation study was used to determine which variables most influenced successful chemical identification of un-weathered microplastics in simulated drinking water samples using FTIR and Raman microspectroscopy. No variables tested had a strong correlation with the accuracy of chemical identification (r = ≤0.63). The variables most correlated with accuracy differed between the two methods, and include both physical characteristics of particles (color, morphology, size, polymer type), and instrumental parameters (spectral collection mode, spectral range). Based on these results, we provide technical recommendations to improve capabilities of both methods for measuring microplastics in drinking water and highlight priorities for further research. For FTIR microspectroscopy, recommendations include considering the type of particle in question to inform sample presentation and spectral collection mode for sample analysis. Instrumental parameters should be adjusted for certain particle types when using Raman microspectroscopy. For both instruments, the study highlighted the need for harmonization of spectral reference libraries among research groups, including the use of libraries containing reference materials of both weathered plastic and natural materials that are commonly found in environmental samples.

Quantitative assessment of visual microscopy as a tool for microplastic research: Recommendations for improving methods and reporting.

Microscopy is often the first step in microplastic analysis and is generally followed by spectroscopy to confirm material type. The value of microscopy lies in its ability to provide count, size, color, and morphological information to inform toxicity and source apportionment. To assess the accuracy and precision of microscopy, we conducted a method evaluation study. Twenty-two laboratories from six countries were provided three blind spiked clean water samples and asked to follow a standard operating procedure. The samples contained a known number of microplastics with different morphologies (fiber, fragment, sphere), colors (clear, white, green, blue, red, and orange), polymer types (PE, PS, PVC, and PET), and sizes (ranging from roughly 3-2000 µm), and natural materials (natural hair, fibers, and shells; 100-7000 µm) that could be mistaken for microplastics (i.e., false positives). Particle recovery was poor for the smallest size fraction (3-20 µm). Average recovery (±StDev) for all reported particles >50 µm was 94.5 ± 56.3%. After quality checks, recovery for >50 µm spiked particles was 51.3 ± 21.7%. Recovery varied based on morphology and color, with poorest recovery for fibers and the largest deviations for clear and white particles. Experience mattered; less experienced laboratories tended to report higher concentration and had a higher variance among replicates. Participants identified opportunity for increased accuracy and precision through training, improved color and morphology keys, and method alterations relevant to size fractionation. The resulting data informs future work, constraining and highlighting the value of microscopy for microplastics.

Evaluation of Closed-system Transfer Devices in Reducing Potential Risk for Surface Contamination Following Simulated Hazardous-drug Preparation and Compounding.

Closed-system transfer devices mitigate occupational exposure risks associated with hazardous-drug handling. This study was conducted in a controlled laboratory to evaluate the effectiveness of a needle-free and a needle-based closed-system transfer device in minimizing surface contamination during simulated compounding, preparation, and administration. A needle-based and a needle-free closed-system transfer device underwent three trials per system. Each trial included reconstituting cyclophosphamide in a vial, withdrawing cyclophosphamide from the vial, and pushing cyclophosphamide into an intravenous bag. After every trial, wipe samples were collected from five sources: biological safety cabinet workbench (left and right sides), biological safety cabinet grill, biological safety cabinet airfoil, and technicians' gloves. Wipe samples were then analyzed using high-performance liquid chromatography with dual-mass spectrometry to measure cyclophosphamide concentrations. Surface contamination levels from 30 post-trial tests (15 per device) are reported, representing five different surface wipe samples from three trials for each device. Pre-trial samples of precleaned vials and work surfaces were obtained to ensure no cyclophosphamide contamination. Field blank samples were analyzed for quality-control purposes. Post-trial wipe sample analyses following each of the three needle- free trials did not detect cyclophosphamide on the biological safety cabinet workbench (both left/right), biological safety cabinet grill, biological safety cabinet airfoil, or the technician's gloves. For the needle-based closed-system transfer device, the wipe sample analyses after the first trial showed no contamination; however, cyclophosphamide was detected on the right biological safety cabinet workbench at concentrations of 0.223 ng/cm2 and 0.021 ng/cm2, respectively, following the second and third trials. No cyclophosphamide was found on the technician's gloves after any of the three needle- based closed-system transfer device trials. Based on surface contamination analyses, this study verified the ability of a needle-free closed-system transfer device in preventing the escape of cyclophosphamide during simulated compounding and preparation. Needle-free closed-system transfer devices warrant consideration for the handling of hazardous drugs.

Evaluation of Closed-system Transfer Devices in Reducing Potential Risk for Surface Contamination Following Simulated Hazardous-drug Preparation and Compounding.

Closed-system transfer devices mitigate occupational exposure risks associated with hazardous-drug handling. This study was conducted in a controlled laboratory to evaluate the effectiveness of a needle-free and a needle-based closed-system transfer device in minimizing surface contamination during simulated compounding, preparation, and administration. A needle-based and a needle-free closed-system transfer device underwent three trials per system. Each trial included reconstituting cyclophosphamide in a vial, withdrawing cyclophosphamide from the vial, and pushing cyclophosphamide into an intravenous bag. After every trial, wipe samples were collected from five sources: biological safety cabinet workbench (left and right sides), biological safety cabinet grill, biological safety cabinet airfoil, and technicians' gloves. Wipe samples were then analyzed using high-performance liquid chromatography with dual-mass spectrometry to measure cyclophosphamide concentrations. Surface contamination levels from 30 post-trial tests (15 per device) are reported, representing five different surface wipe samples from three trials for each device. Pre-trial samples of precleaned vials and work surfaces were obtained to ensure no cyclophosphamide contamination. Field blank samples were analyzed for quality-control purposes. Post-trial wipe sample analyses following each of the three needle- free trials did not detect cyclophosphamide on the biological safety cabinet workbench (both left/right), biological safety cabinet grill, biological safety cabinet airfoil, or the technician's gloves. For the needle-based closed-system transfer device, the wipe sample analyses after the first trial showed no contamination; however, cyclophosphamide was detected on the right biological safety cabinet workbench at concentrations of 0.223 ng/cm2 and 0.021 ng/cm2, respectively, following the second and third trials. No cyclophosphamide was found on the technician's gloves after any of the three needle- based closed-system transfer device trials. Based on surface contamination analyses, this study verified the ability of a needle-free closed-system transfer device in preventing the escape of cyclophosphamide during simulated compounding and preparation. Needle-free closed-system transfer devices warrant consideration for the handling of hazardous drugs.

Health risk assessment of exposures to a high molecular weight plasticizer present in automobile interiors.

This study provides an exposure and risk assessment of diundecyl phthalate (DUP), a high molecular weight phthalate plasticizer present in automobile interiors. Total daily intake of DUP was calculated from DUP measured in wipe samples from vehicle seats from six automobiles. Four of the vehicles exhibited atypical visible surface residue on the seats. Two vehicles with no visible surface residue were sampled as a comparison. DUP was the predominant organic compound identified in each of the wipes from all seats. A risk assessment of DUP via oral, dermal, and inhalation routes resulting from contact with automobile seats was conducted. The mean, standard deviation, and maximum DUP concentrations on the seats with visible surface residue were 6983 ± 7823 µg/100 cm2 and 38300 µg/100 cm2, respectively. The mean and 95th percentile of the mean for daily cumulative dose of DUP for all exposure routes for the seats with no visible surface residue ranged from 7 × 10-4 to 4 × 10-3 mg/kg-day and from 8 × 10-4 to 5 × 10-3 mg/kg-day, respectively. For seats with visible surface residue, cumulative doses ranged from 2 × 10-3 to 2 × 10-2 mg/kg-day and from 4 × 10-3 to 2 × 10-2 mg/kg-day, respectively. The estimated daily intake (contact or absorbed dose) of DUP from automobile seats were far lower than the NOAELs reported in and derived from animal studies, and are well below the reported Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) Derived No Effect Levels (DNELs) for the general population. Based on this analysis, using virtually any benchmark for evaluating safety, exposure to DUP via automobile seat covers did not pose a measureable increased health-risk in any population under any reasonably plausible exposure scenario.

A strategy for assessing workplace exposures to nanomaterials.

This article describes a highly tailorable exposure assessment strategy for nanomaterials that enables effective and efficient exposure management (i.e., a strategy that can identify jobs or tasks that have clearly unacceptable exposures), while simultaneously requiring only a modest level of resources to conduct. The strategy is based on strategy general framework from AIHA® that is adapted for nanomaterials and seeks to ensure that the risks to workers handling nanomaterials are being managed properly. The strategy relies on a general framework as the basic foundation while building and elaborating on elements essential to an effective and efficient strategy to arrive at decisions based on collecting and interpreting available information. This article provides useful guidance on conducting workplace characterization; understanding exposure potential to nanomaterials; accounting methods for background aerosols; constructing SEGs; and selecting appropriate instrumentation for monitoring, providing appropriate choice of exposure limits, and describing criteria by which exposure management decisions should be made. The article is intended to be a practical guide for industrial hygienists for managing engineered nanomaterial risks in their workplaces.

Evaluation of surface contamination with cyclophosphamide following simulated hazardous drug preparation activities using two closed-system products.

PURPOSE: A preliminary investigation was conducted to evaluate and compare the effectiveness of two closed-system products in preventing contamination of typical pharmacy workplace surfaces with cyclophosphamide during simulated hazardous drug preparation activities in a controlled laboratory setting. METHODS: Two separate trials simulating hazardous drug compounding using cyclophosphamide were performed with two different closed-system products. Prior to each trial, work area surfaces of the biological safety cabinet (BSC) workbench, the BSC airfoil and front grill, and the floor below the BSC were cleaned, and wipe samples were collected and analyzed to determine, if present, levels of cyclophosphamide. Following each trial, wipe samples were collected from the work area surfaces to determine the hazardous drug containment effectiveness of each closed-system product. RESULTS: Cyclophosphamide was not detected on work area surfaces prior to each trial. Low levels were detected on the BSC workbench surface following both trials. DISCUSSION: Based on the limited number of samples obtained during this preliminary study and the determination of the presence of the chemical of interest on the drug vials, no statistical evaluation was performed to compare the relative effectiveness of the two systems tested. Work practices and procedures regarding product operation may affect hazardous drug containment and worker safety. Further study and statistical analyses are needed.