Study Design and Methods to Investigate Inhalation and Dermal Exposure to Polycyclic Aromatic Compounds and Urinary Metabolites from Asphalt Paving Workers: Research Conducted through Partnership

Collection of polycyclic aromatic sulfur heterocycles from asphalt fumes and quantification by an HPLC-DAD method

A chromatographic method is described for the separation and quantification of polycyclic aromatic sulfur heterocycles (PASHs) using liquid chromatography coupled with diode array detection (DAD). The PASHs that were investigated in this study were chosen based on their similarity in molecular weight, volatility and polarity of their PAH analogues. The chromatographic separation of the compounds was optimized, and their analytical characteristics were evaluated. The limits of detection and quantification ranged from 0.05 for 2,3,4,7-tetramethylbenzothiophene to 2.16 μg L-1 for thieno[2,3-b]thiophene and from 0.16 for 2,3,4,7-tetramethylbenzothiophene to 6.53 μg L-1 for thieno[2,3-b]thiophene, respectively. Recoveries ranged from 84.9 for benzo[b]benzo[4,5]thieno[2,3-d]thiophene to 110% for dinaphtho[2,1-b:1',2'-d]thiophene. Intermediate precisions and repeatabilities lie between 1.4 and 3.0%, and 0.3 and 1.7%, respectively. The chromatographic method was applied for determination of PASHs directly in asphalt fumes, which were obtained by heating asphalt samples in a homemade closed system. The mutual interference of PAH analogues was also discussed. The method was successfully used for PASH determination in asphalt samples obtained from three different oil refineries in Brazil.

Effects of asphalt source and mixing temperature on the generated asphalt fumes

Asphalt fumes generated in pavement construction have been extensively studied from the perspective of occupational health. In this paper, they are examined from the perspective of material and construction. Asphalt binders from different sources were used to create standard mixtures. An asphalt fume generation and collection system was designed and built for generating fumes at simulated construction conditions and collecting fumes similar to the procedure used in field exposure studies. Total particulates (TP) in the fume samples were analyzed gravimetrically, and the chemical components of the samples were identified by using GC/MS. Results indicate that the TP concentration and chemical component of asphalt fumes are dependent on asphalt source and temperature. The concentration from one asphalt can be several times higher than that from another. With a temperature rise in 20 °C, the concentration increases about 3-7 times. At 140 °C, the total number of detected PAHs ranges from 4 to 9; at 160 °C, the number ranges from 4 to 12. The hazardous potentials of asphalt fumes vary with asphalt source and mixing temperature. Therefore, standardized laboratory test procedures are needed for risk assessment, based on which proper material selection and construction strategies may be chosen for hazard mitigation.

A review of the current state of the art of physiologically-based tests for measuring human dermal in vitro bioavailability of polycyclic aromatic hydrocarbons (PAH) in soil

Polycyclic Aromatic Hydrocarbons are classed as Persistent Organic Pollutants, a large group of compounds that share similar characteristics. They are lipophilic, resistant to degradation in the environment and harmful to human and environmental health. Soil has been identified as the primary reservoir for Polycyclic Aromatic Hydrocarbons in the United Kingdom. This study reviews the literature associated with, or is relevant to, the measurement and modelling of dermal absorption of Polycyclic Aromatic Hydrocarbons from soils. The literature illustrates the use of in vivo, in vitro and in silico methods from a wide variety of scientific disciplines including occupational and environmental exposure, medical, pharmaceutical and cosmetic research and associated mathematical modelling. The review identifies a number of practical shortcomings which must be addressed if dermal bioavailability tests are to be applied to laboratory analysis of contaminated soils for human health risk assessment.

Alternatives for Benzene in the Extraction of Bitumen Fume from Exposure Sample Media

Benzene is frequently used to extract collected bitumen fumes from personal sampler substrates. However, this solvent is particularly dangerous because of its carcinogenicity (group 1 of the International Agency for Research on Cancer classification). Therefore, to prevent the exposure of laboratory technicians to benzene during the fume extraction step from samplers, a compromise had to be found to identify a less toxic solvent with the same extraction capacity. To compare the extraction capacities of selected solvents, bitumen fumes were generated in the laboratory from three different batches of road surfacing bitumen collected on dedicated bitumen fume samplers. The samplers were then extracted by benzene and the solvents tested. Of 11 selected solvents less toxic than benzene and used in studies on bitumen and bitumen fume analyses, n-hexane and n-heptane were identified as alternatives to benzene. In particular, the results demonstrated that n-heptane was the best candidate solvent for benzene replacement, due to its extraction efficiency comparable to benzene for the three bitumen fumes tested and its low toxicity, which is highly compatible with benzene replacement.

Best practices for health and safety technology transfer in construction

BACKGROUND

Construction continues to be a dangerous industry, yet solutions that would prevent injury and illness do exist. Prevention of injury and illness among construction workers requires dissemination, adoption, and implementation of these effective interventions, or "research to practice" (r2p).

METHODS

CPWR recruited participants with experience and insight into effective methods for diffusion of health and safety technologies in this industry for a symposium with 3 group sessions and 3 breakout groups. The organizers reviewed session notes and identified 141 recommendations, which were then assigned to 13 over-arching themes.

RESULTS

Recommendations included a guide for researchers on patenting and licensing, a business case model, and in-depth case studies including development, testing, manufacturing, marketing, and diffusion.

CONCLUSIONS

A more comprehensive understanding of the health and safety technology transfer landscape, the various actors, and their motivators and goals will help to foster the successful commercialization and diffusion of health and safety innovations.

Airborne Exposures to Polycyclic Aromatic Compounds Among Workers in Asphalt Roofing Manufacturing Facilities

We studied exposure of 151 workers to polycyclic aromatic compounds and asphalt emissions during the manufacturing of asphalt roofing products-including 64 workers from 10 asphalt plants producing oxidized, straight-run, cutback, and wax- or polymer-modified asphalts, and 87 workers from 11 roofing plants producing asphalt shingles and granulated roll roofing. The facilities were located throughout the United States and used asphalt from many refiners and crude oils. This article helps fill a gap in exposure data for asphalt roofing manufacturing workers by using a fluorescence technique that targets biologically active 4-6 ring polycyclic aromatic compounds and is strongly correlated with carcinogenic activity in animal studies. Worker exposures to polycyclic aromatic compounds were compared between manufacturing plants, at different temperatures and using different raw materials, and to important external benchmarks. High levels of fine limestone particulate in the plant air during roofing manufacturing increased polycyclic aromatic compound exposure, resulting in the hypothesis that the particulate brought adsorbed polycyclic aromatic compounds to the worker breathing zone. Elevated asphalt temperatures increased exposures during the pouring of asphalt. Co-exposures in these workplaces which act as confounders for both the measurement of total organic matter and fluorescence were detected and their influence discussed. Exposures to polycyclic aromatic compounds in asphalt roofing manufacturing facilities were lower than or similar to those reported in hot-mix paving application studies, and much below those reported in studies of hot application of built-up roofing asphalt. These relatively low exposures in manufacturing are primarily attributed to air emission controls in the facilities, and the relatively moderate temperatures, compared to built-up roofing, used in these facilities for oxidized asphalt. The exposure to polycyclic aromatic compounds was a very small part of the overall worker exposure to asphalt fume, on average less than 0.07% of the benzene-soluble fraction. Measurements of benzene-soluble fraction were uniformly below the American Conference of Governmental Industrial Hygienists' Threshold Limit Value for asphalt fume.

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.

Using urinary biomarkers of polycyclic aromatic compound exposure to guide exposure-reduction strategies among asphalt paving workers

INTRODUCTION

Paving workers are exposed to polycyclic aromatic compounds (PACs) while working with hot-mix asphalt (HMA). Further characterization of the source and route of these exposures is necessary to guide exposure-reduction strategies.

METHODS

Personal air (n=144), hand-wash (n=144), and urine (n=480) samples were collected from 12 paving workers over 3 workdays during 4 workweeks. Urine samples were collected at preshift, postshift, and bedtime and analyzed for 10 hydroxylated PACs (1-OH-pyrene; 1-, 2-, 3-, 4-OH-phenanthrene; 1-, 2-OH-naphthalene; 2-, 3-, 9-OH-fluorene) by an immunochemical quantification of PACs (I-PACs). The air and hand-wash samples were analyzed for the parent compounds corresponding to the urinary analytes. Using a crossover study design, each of the 4 weeks represented a different exposure scenario: a baseline week (normal conditions), a dermal protection week (protective clothing), a powered air-purifying respirator (PAPR) week, and a biodiesel substitution week (100% biodiesel provided to replace the diesel oil normally used by workers to clean tools and equipment). The urinary analytes were analyzed using linear mixed-effects models.

RESULTS

Postshift and bedtime concentrations were significantly higher than preshift concentrations for most urinary biomarkers. Compared with baseline, urinary analytes were reduced during the dermal protection (29% for 1-OH-pyrene, 15% for I-PACs), the PAPR (24% for 1-OH-pyrene, 15% for I-PACs), and the biodiesel substitution (15% for 1-OH-pyrene) weeks. The effect of PACs in air was different by exposure scenario (biodiesel substitution>dermal protection>PAPR and baseline) and was still a significant predictor of most urinary analytes during the week of PAPR use, suggesting that PACs in air were dermally absorbed. The application temperature of HMA was positively associated with urinary measures, such that an increase from the lowest application temperature (121°C) to the highest (154°C) was associated with a 72% increase in ΣOH-fluorene and 1-OH-pyrene and an 82% increase in ΣOH-phenanthrene. Though PACs in hand-wash samples were not predictors of urinary analytes, the effects observed during the PAPR scenario and the week of increased dermal protection provide evidence of dermal absorption.

CONCLUSIONS

Our results provide evidence that PACs in air are dermally absorbed. Reducing the application temperature of asphalt mix appears to be a promising strategy for reducing PAC exposure among paving workers. Additional reductions may be achieved by requiring increased dermal coverage of workers and by substituting biodiesel for diesel oil as a cleaning agent.

Predictors of dermal exposures to polycyclic aromatic compounds among hot-mix asphalt paving workers

OBJECTIVES

The primary objective of this study was to identify the source and work practices that affect dermal exposure to polycyclic aromatic compounds (PACs) among hot-mix asphalt (HMA) paving workers.

METHODS

Four workers were recruited from each of three asphalt paving crews (12 workers) and were monitored for three consecutive days over 4 weeks for a total of 12 sampling days per worker (144 worker days). Two sampling weeks were conducted under standard conditions for dermal exposures. The third week included the substitution of biodiesel for diesel oil used to clean tools and equipment and the fourth week included dermal protection through the use of gloves, hat and neck cloth, clean pants, and long-sleeved shirts. Dermal exposure to PACs was quantified using two methods: a passive organic dermal (POD) sampler specifically developed for this study and a sunflower oil hand wash technique. Linear mixed-effects models were used to evaluate predictors of PAC exposures.

RESULTS

Dermal exposures measured under all conditions via POD and hand wash were low with most samples for each analyte being below the limit of the detection with the exception of phenanthrene and pyrene. The geometric mean (GM) concentrations of phenanthrene were 0.69 ng cm(-2) on the polypropylene layer of the POD sampler and 1.37 ng cm(-2) in the hand wash sample. The GM concentrations of pyrene were 0.30 ng cm(-2) on the polypropylene layer of the POD sampler and 0.29 ng cm(-2) in the hand wash sample. Both the biodiesel substitution and dermal protection scenarios were effective in reducing dermal exposures. Based on the results of multivariate linear mixed-effects models, increasing frequency of glove use was associated with significant (P < 0.0001) reductions for hand wash and POD phenanthrene and pyrene concentrations; percent reductions ranged from 40 to 90%. Similar reductions in hand wash concentrations of phenanthrene (P = 0.01) and pyrene (P = 0.003) were observed when biodiesel was substituted for diesel oil as a cleaning agent, although reductions were not significant for the POD sampler data. Although task was not a predictor of dermal exposure, job site characteristics such as HMA application temperature, asphalt grade, and asphalt application rate (tons per hour) were found to significantly affect exposure. Predictive models suggest that the combined effect of substituting biodiesel for diesel oil as a cleaning agent, frequent glove use, and reducing the HMA application temperature from 149°C (300°F) to 127°C (260°F) may reduce dermal exposures by 76-86%, varying by analyte and assessment method.

CONCLUSIONS

Promising strategies for reducing dermal exposure to PACs among asphalt paving workers include requiring the use of dermal coverage (e.g. wearing gloves and/or long sleeves), substituting biodiesel for diesel oil as a cleaning agent, and decreasing the HMA application temperature.