Exposure assessment of polycyclic aromatic hydrocarbons in refined coal tar sealant applications.

BACKGROUND: Refined coal tar sealant (RCTS) emulsions are used to seal the surface of asphalt pavement. Nine of the 22 polycyclic aromatic hydrocarbons (PAHs) evaluated in this study are classified as known, probable, or possible human carcinogens. Exposure assessment research for RCTS workers has not been published previously. OBJECTIVES: The overall objective of this study was to develop a representative occupational exposure assessment of PAH exposure for RCTS workers based on worksite surveys. The specific aims were to: 1) quantify full-shift airborne occupational exposures to PAHs among RCTS workers; 2) quantify workers' dermal exposures to PAHs; 3) quantify biomarkers of PAH exposure in workers' urine; 4) identify specific job titles associated with RCTS exposure; and 5) apply these results to a biological exposure index to assess risk of potential genotoxicity from occupational exposures. METHODS: A total of twenty-one RCTS workers were recruited from three companies. Personal and area air samples were collected using a modification of NIOSH Method 5515. Dermal exposure was assessed by hand and neck wipes before and after shifts. Twenty-two PAHs were quantified via gas chromatography-mass spectrometry selected ion monitoring. Internal dose was estimated by quantifying select PAH metabolites in pre- and post-shift urine samples using on-line solid phase extraction-high performance liquid chromatography-tandem mass spectrometry. RESULTS: PAH levels in the worker breathing zones were highest for naphthalene, acenaphthene, and phenanthrene, with geometric means of 52.1, 11.4, and 9.8 µg/m3, respectively. Hand wipe levels of phenanthrene, fluoranthene and pyrene were the highest among the 22 PAHs with geometric means of 7.9, 7.7, and 5.5 µg/cm2, respectively. Urinary PAH biomarkers for naphthalene, fluorene, phenanthrene, and pyrene were detected in all workers and were higher for post-shift samples than those collected pre-shift. Urinary concentrations of the metabolite 1-hydroxypyrene were greater than the American Conference of Governmental Industrial Hygienists (ACGIH) Biological Exposure Index (BEI) for this metabolite in 89 percent of post-shift samples collected on the final day of the work week or field survey. Statistically significances were found between concentrations of fluorene, naphthalene, and phenanthrene in the breathing zone of workers and their corresponding urinary PAH biomarkers. Workers were placed in two work place exposure groups: applicators and non-applicators. Applicators had higher total PAH concentrations in personal breathing zone (PBZ) air samples than non-applicators and were more likely to have post-shift hand wipe concentrations significantly higher than pre-shift concentrations. Concentrations of post-shift urinary biomarkers were higher, albeit not significantly, for applicators than non-applicators. CONCLUSIONS: The exposure results from RCTS worker samples cannot be explained by proximal factors such as nearby restaurants or construction. Air and skin concentration levels were substantially higher for RCTS workers than previously published levels among asphalt workers for all PAHs. PAH profiles on skin wipes were more consistent with RCTS sealant product than air samples. Last day post-shift urinary concentrations of 1-hydroxypyrene greatly exceeded the ACGIH BEI benchmark of 2.5 µg/L in 25 of 26 samples, which suggests occupational exposure and risk of genotoxicity. When pyrene and benzo[a]pyrene were both detected, concentration ratios from personal exposure samples were used to calculate the adjusted BEI. Concentrations of 1-hydroxypyrene exceeded the adjusted BEIs for air, hand wipes, and neck wipes in most cases. These results indicate the need to increase safety controls and exposure mitigation for RCTS workers.

Occupational Exposures to Engineered Nanomaterials: a Review of Workplace Exposure Assessment Methods.

PURPOSE OF REVIEW: The purpose of this review is to consolidate exposure assessment methods for occupational research on engineered nanomaterials (ENMs) published within the past 5 years (2015-2020). RECENT FINDINGS: The three ENMs that generated the highest volume of new research include titanium dioxide, graphene, and aluminum oxide. A multi-metric approach, using both online and offline instruments and analyses, has been found to be a useful method to characterize ENM workplace exposures and was commonly used in the recently published literature. Particle number concentration was the most common online exposure metric used, followed by the metrics of mass and surface area. There are currently no consensus methods for offline analyses of most ENMs. Researchers generally used gravimetric or elemental analyses for carbonaceous nanomaterials, titanium dioxide, and other nanometals, but there was little overlap between other ENM materials reviewed. Using biological markers of exposure, such as urinary oxidative stress biomarkers, as an indication of chronic exposure may also be useful for some ENMs and should be further researched. Generally, similar online instrumentation and offline electron microscopy methods were used for all ENMs. However, this consistency was not observed for offline mass analysis methods within specific ENMs. Consolidation of the most recent methods and results of exposure assessments within this broad material category can guide researchers toward future areas of study. Establishing consensus methods of exposure assessment for each individual ENM is crucial to characterizing workplace exposures, pooling data to fully understand their associated risks, and developing useful occupational exposure limits.

Flame retardants, dioxins, and furans in air and on firefighters' protective ensembles during controlled residential firefighting.

INTRODUCTION: Structure fires that involve modern furnishings may emit brominated flame retardants (BFRs) and organophosphate flame retardants (OPFRs), as well as brominated and chlorinated dioxins and furans, into the environment. OBJECTIVES: The goal of this study was to quantify the airborne and personal protective equipment (PPE) contamination levels of these compounds during controlled residential fires in the U.S., and to evaluate gross-decontamination measures. METHODS: Bulk-sampling was done to confirm the presence of flame retardants (FRs) in the furnishings used in 12 controlled residential structure fires. Area air samples were collected during the fires and PPE wipe samples were collected from the firefighters' turnout jackets and gloves after firefighting. For each fire, half of the jackets were decontaminated and the other half were not. RESULTS: Of the BFRs and OPFRs measured in air during the fire period, decabromodiphenyl ether (BDE-209) and triphenyl phosphate (TPP) were the most abundant, with medians of 15.6 and 408 µg/m3, respectively, and were also detected during overhaul. These and several other BFRs and OPFRs were measured on PPE. Some gloves had contaminant levels exceeding 100 ng/cm2 and were generally more contaminated than jackets. Air and surface levels of the brominated furans appeared to be higher than the chlorinated dioxins and furans. Routine gross decontamination appeared to reduce many of the BFR contaminants, but results for the OPFRs were mixed. CONCLUSIONS: Structure fires are likely to result in a variety of FRs, dioxins, and furans into the environment, leading to PPE contamination for those working on the fireground. Firefighters should wear self-contained breathing apparatus during all phases of the response and launder or decontaminate their PPE (including gloves) after fire events.