Annals of Occupational Hygiene Advance Access originally published online on July 13, 2006
Annals of Occupational Hygiene 2006 50(8):789-804; doi:10.1093/annhyg/mel047
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Collection, Validation and Generation of Bitumen Fumes for Inhalation Studies in Rats Part 1: Workplace Samples and Validation Criteria
Fraunhofer Institute Toxicology und Experimental Medicine Nikolai-Fuchs-Strasse 1, 30625 Hannover, Germany
*Author to whom correspondence should be addressed. Tel: +(49) 511 5350 116; fax: +(49) 511 5350 155; e-mail: pohlmann{at}item.fhg.dc
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONSUMMARY AND CONCLUSIONSACKNOWLEDGEMENTSREFERENCES |
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Objectives: Undertaking a chronic inhalation study on bitumen fume presents a challenge in terms of generating large amounts of representative fume. The objective of the study described in this and the following contributions was to collect sufficient fume and develop a laboratory-generated exposure atmosphere that resembles, as closely as possible, personal exposures seen in workers during road paving operations, for use in chronic inhalation toxicity studies in rats.
Methods: To achieve this goal, atmospheric workplace samples were collected at road paving work sites both by Shell Global Solutions, Int. (Shell) and by the ‘Berufsgenossenschaftliches Institut für Arbeitssicherheit’ (BIA, Germany) and compared with bitumen fume condensate samples collected from the head space of hot bitumen storage tanks. Part 1 describes the collection and analysis of personal and static workplace samples. Different sampling methods were also used to allow a comparison of the standard German sampling method with the most common industry method used. Samples were analyzed by Shell, BIA and by the Fraunhofer Institute of Toxicology and Experimental Medicine (Fh-ITEM, Germany) using different methods. Parameters determined were: total particulate matter (TPM), benzene soluble matter (BSM), semi-volatiles (SV), total organic matter (TOM), boiling point distribution (BPD), polycyclic aromatic hydrocarbons (PAHs) and UV fluorescence (UVF).
Results: The BPD of personal and static samples had almost identical start and end points, but static samples show a tendency towards an increase in amounts of higher boiling point compounds. Personal samples generally show higher PAH concentrations than comparable static samples. The results of the analysis of personal workplace samples were used to establish validation/acceptance criteria for the bitumen fume condensate sampled from storage tanks for the inhalation study, which is described in a further publication.
Conclusions: The criteria involve a range of parameters that can be analyzed in both workplace samples and samples of tank fume condensate: BPD, UVF and content of individual PAHs were selected as parameters.
Keywords: asphalt • bitumen • fume • workplace • chemical analysis • sampling methods • polycyclic aromatic hydrocarbons
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONSUMMARY AND CONCLUSIONSACKNOWLEDGEMENTSREFERENCES |
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Bitumen is a complex mixture of a large number of high molecular weight organic compounds made by processing of petroleum crude oils (Corbett and Urban, 1985). Depending on the type of application various grades of bitumen are used. The profile of volatile components (either as gases or aerosols) produced depends on the type of bitumen and its working temperature. Bitumen fumes were characterized by Thayer et al., 1983, Belinsky et al., 1986, Brandt et al. 1985, Knecht et al. 1997 and Kriech et al. 2002. The difficulty is to decide whether these compositional data are representative for typical working conditions. It is known that bitumen and bitumen fumes contain small amounts (p.p.m. quantities) of polycyclic aromatic hydrocarbons (PAHs) and sulfur analogs of PAHs (SPAHs), some of which have the potential to cause cancer. The concentrations of PAH in bitumen are several orders of magnitude lower than that in coal tar. (Binet et al., 2002).
Skin painting studies with bitumen fume condensates have been criticized, because the laboratory derived condensates used were not thought to be representative chemically of the fumes to which humans are exposed in the workplace (CONCAWE, 1992). Sivak et al. (1997) reported that condensed roofing bitumen (asphalt) fumes, generated at 316°C with stirring and under vacuum, produced statistically significant increased tumor yields of papillomas and carcinomas of the skin in mice as compared with that of the respective vehicle controls. The fume collection procedure used in the current study, as well as the heating temperature (
170°C compared with 316°C) are very different from those used in the Sivak study (Sivak et al., 1997). Furthermore, the main target organ under investigation for potential carcinogenic effect of bitumen fumes is the respiratory tract and not the skin.
To investigate the potential cancer risk for workers caused by inhalation of bitumen fume at paving workplaces in Germany, studies on bitumen fumes are being undertaken. Acute (single dose), 14 and 90 day inhalation studies have been already completed and a 2 year carcinogenicity bioassay is in progress. The work is being carried out by the Fraunhofer Institute of Toxicology and Experimental Medicine (Fh-ITEM) in Hannover, Germany.
For risk assessment it is important that the quality of the fumes generated in the laboratory be similar to typical exposures in the workplace during asphalt paving. To this end a series of validation studies to compare the laboratory fume with a number of workplace samples collected were carried out.
During the course of the validation work, there was concern that static workplace atmosphere samples, collected in a first sampling campaign, may not reflect personal exposures during paving operations and, therefore, additional workplace monitoring and validation work was arranged. In a second campaign, samples were taken at workplaces where a minimum of potential confounders could be expected, e.g. influence of traffic exhaust emissions. The chosen paving site was located at the construction site of the new Federal Motorway (BAB) A 20 between Strasburg and Pasewalk not far from the German–Polish border. Since it is a new motorway, no vehicles (especially diesel cars), except the trucks used on the construction site, influenced the samples. For comparison of sampling and analytical procedures, both personal and static samples were taken using two different sampling methods [most common industry method used by Shell Global Solutions, Int. (Shell) and ‘Berufsgenossenschaftliches Institut für Arbeitssicherheit’ (BIA, Germany)-method].
Finally validation criteria were derived to allow optimization of the bitumen fume condensate for the 2 year carcinogenicity study.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONSUMMARY AND CONCLUSIONSACKNOWLEDGEMENTSREFERENCES |
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Bitumen grade
Bitumen grade 50/70 was selected for this work as it represented the highest volume paving grade bitumen used in Germany and was considered to be representative of bitumens used in the road paving industry.
Sampling
Personal exposure and static workplace samples were taken by Shell using the following equipment: Closed-face (3-piece) 37 mm polystyrene cassettes (Millipore) containing pre-weighed PTFE filters (Gelman Zefluor), adsorbent tubes containing 100/50 mg XAD-2 resin (SKC Inc. Cat. no. 226-30-04) and Giliam Instruments (HFS 513A Hiflow) and MSA (Escort Elf, Cat No. 805558) personal sampling pumps at ca. 2 l/min.
In parallel, personal exposure and static samples were also taken by BIA using the following equipment: German PGP System, GGP sampler (closed-face sampler with cassette containing a 37 mm glass fiber filter and adsorbent cartridge with 3 g XAD-2 resin (size 0.5–0.9 mm)), Gilian Instruments pump (PP5 ex) at ca. 3.5 l/min.
Sampling was carried out over a period of 3 days, 25–27 September 2001. Sampling details are given in Tables 1 and 2.
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Weather conditions
The weather conditions during sample collection were monitored at intervals each day. Details are summarized in Table 3.
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Paving conditions
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The asphalt mixture was supplied in (covered) dump trucks, typical load 25 Mt. Asphalt supply was not continuous; there were intermittent periods of inactivity while waiting for the next truck. The asphalt was fed into the paver from the dump truck, which moved slowly in front of the paver.
Following sample collection, it was discovered that the asphalt used on 27 September was supplied by a different mixing plant, and it subsequently emerged that it contained an amount of reclaimed asphalt pavement (RAP). Detailed information on this asphalt was not available. As the RAP may contain other confounding materials the implications of this are discussed later in the relevant analytical result sections.
Analytical approach
Personal exposure samples taken by Shell were first analyzed by Shell with respect to the parameters total particulate matter (TPM), benzene soluble matter (BSM), semivolatiles (SV) and total organic matter (TOM), and later on by the Fh-ITEM with respect to boiling point distribution (BPD), polycyclic aromatic hydrocarbons (PAH) and UV fluorescence (UVF). The Fh-ITEM also analyzed the TOM of these samples in order to confirm sample identity. For static samples collected by Shell and BIA, the parameters BPD, PAH and UVF were determined by Fh-ITEM. Furthermore, additional personal and static samples were taken and analyzed by BIA according to the BIA method 6305.
Methods used by Shell
TPM and BSM. Gravimetric determination was carried out according to NIOSH method 5042 with the following modifications:
A total of six field blanks were taken on Day 1 and 7, on Day 2 and 5, and on Day 3. Only three field blanks per day were analyzed for both TPM and BSM by Shell. Three field blanks per day (Days 1 and 2) were supplied to the Fraunhofer Institute Fh-ITEM along with static samples.
Particulate matter was collected on a pre-weighed 37 mm filter in a closed-face cassette. TPM was determined by weight difference after sampling. Filter extraction was carried out in a 4 ml vial with screw cap using 2 x 3 ml benzene for 20 min (1st extraction) and 5 min (2nd extraction). Extracts were filtered (sequentially) using a syringe driven PTFE (polytetrafluoroethylene), 13 mm 0.45 µm frit and transferred to weighing cup. Solvent was first evaporated in a sample concentrator at ca. 60°C using nitrogen, then in a vacuum oven at 40°C and 5–7 kPa for 2 h. The residue (BSM) was determined gravimetrically.
SV. The SV fraction is defined as the extractable hydrocarbons collected on the adsorbant (XAD-2) situated after the particulate filter. The front and back sections of the XAD-2 tubes were extracted using dichloromethane (DCM), typically 1.5 ml DCM per section for personal samples. Front and back sections were extracted separately to check for breakthrough.
Analysis and quantification were performed by means of gas chromatography (GC) with flame ionization detection (FID). The FID response was calibrated using a suitable reference material (bitumen fume standard Shell, 2 mg ml–1 in dichloromethane), a material with a composition/boiling range as similar as possible to that of the SV. Samples of SV, BSM and TOM have comparable FID response/mass.
Conditions used for the analyses of SVs (and also BSM, and hence TOM) were: column, 30 m *0.32 mm id, DB-5MS, film thickness, 0.25 µm; pre-column (retention gap), deactivated fused silica 1.5 m *0.54 mm id; carrier gas, helium at constant pressure (ca. 75 kPa); initial temperature, (i) 10°C min–1 to 250°C and (ii) 5°C min–1 to 350°C; final temperature, 350°C for 10 min; injection, on column injection of 2 µl; FID, 375°C.
TOM. Determination was carried out by summation of SV and BSM. The latter was determined both gravimetrically and by GC.
Combination of BSM and SV samples sent to Fh-ITEM. Extracts of SV were transferred by a syringe, and by filtration, into 14 ml Vari-Clean vials (Pierce 13514). Extracts of BSM were dissolved in 0.5 ml DCM in 1.5 ml vials. Then, the content was quantitatively transferred by a syringe into the 14 ml Vari-Clean vials already containing the SV.
Methods used by Fh-ITEM
Sample preparation. For the analysis of static workplace samples provided by Shell and BIA, the filters and XAD cartridges were extracted separately. While the filters were extracted in a soxhlet apparatus with DCM for 2 h, the XAD resin was extracted with 4 *5 ml DCM for 5 min in an ultrasonic bath. The extracts were combined and reduced in a gentle nitrogen stream to a final volume of 1.0 ml. A small aliquot (usually 0.1 ml) was used for the determination of the BPD. The residual solution was analyzed for PAH.
PAH. The analysis of the workplace samples includes the 16 priority PAH defined in the EPA method 610 and benzo(e)pyrene. Quantitation of PAH was achieved by GC coupled to mass spectrometry (GC/MS) using deuterated isotopomers as internal standards. Benzo(e)pyrene was quantified using benzo(a)pyrene-d12, as the deuterated isotopomer was not available.
The reference compounds (PAH and deuterated PAH) were purchased from Promochem (Wesel, Germany). Instrumental conditions applied were as follows: GC, HP 5890 Series II Plus; injector, split/splitless, 300°C; injector purge off time, 1.0 min; carrier gas, helium; column, 60 m (0.32 mm i.d., DB 5 (J & W Scientific), df = 0.32 µm; initial temperature, 60°C; temperature program, (i) 4°C min–1 to 280°C, 5 min at 280°C and (ii) 20°C min–1 to 300°C; final temperature, 300°C for 15 min; injection, 1 µl; detector, MSD 5972; transfer line, 280°C; data acquisition, SIM with 1 mass per component.
BPD. The method used is based on the ASTM standard method D2887-97. The Boiling Point Distribution determined by distillation is simulated by the use of GC with FID. For the GC-analysis, the bitumen fume condensate is diluted adequately with carbon disulfide.
The following GC conditions were used: GC, HP 5890; detector, FID, 330°C; injector, split/splitless, 290°C; carrier gas, helium; column, DB 5 (J & W Scientific), 30 m, 0.53 mm i.d., df = 0.5 µm; initial temperature, 40°C for 3 min; rate, 10°C min–1; final temperature, 305°C for 12 min; injection 1 µl, chemicals: carbon disulfide, CS2 (Rathburn), n-alkane standard mixture (C5–C40, 100 µg per component in 1 ml CS2) (Promochem).
UVF. The UVF intensities of the samples were measured in dichloromethane without cyanopropyl cleanup because personal workplace samples were provided by Shell as DCM solutions. Measurements were carried out in a 1 ml cuvette using a Shimadzu RF 1501 spectrometer (high sensitivity range, excitation wavelength 380 nm, emission wavelength 410 nm, bandwidth 10 nm). All UVF values were corrected for solvent blanks.
TOM. Analysis and quantification were carried out by means of GC/FID. The FID response was calibrated using a suitable reference material (bitumen fume standard Shell, 2 mg ml–1 in dichloromethane), provided by Shell.
The following experimental conditions were used: GC, HP 5890; detector, FID, 350°C; injector, on column; carrier gas, helium; column, 30 m (0.25 mm i.d., HP-5MS, film thickness 0.25 µm; pre-column (retention gap), deactivated fused silica 0.5 m *0.54 mm i.d., initial temperature, 45°C for 5 min; temperature program, 10°C min–1 to 350°C; final temperature, 350°C for 10 min; injection, 2 µl.
Methods used by BIA
Quantification of aerosol and total hydrocarbon fume. The method (BIA method 6305) is based on an infrared (IR) determination of aliphatic hydrocarbons and does not allow for a differentiation according to compound classes. Data are calculated relative to a standard BIA-reference oil (CAS [8042-47-5]), which differs significantly in its composition to that of the bitumen fume condensate itself. Results are presented as aerosol and total hydrocarbon fume including aerosol phase in µg m–3. It should be noted, however, that the BIA method underestimates actual THC exposure owing to the method and the calibration material used. A correction factor thus needs to be applied to BIA measurements.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONSUMMARY AND CONCLUSIONSACKNOWLEDGEMENTSREFERENCES |
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Locations of the different sampling devices (personal and static) around the paving machine and the sampling details are shown in Fig. 1.
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Personal samples
Data determined by Shell global solutions. A summary of personal exposures, reported as TPM, BSM, SV and TOM is given in Table 4. All data are corrected for field blanks. The comparison of BSM and TOM indicates that the BSM in the samples of the first 2 days captures on average 9.4% of the total organic exposure. This is in agreement with values reported in the literature (Kriech et al., 2002). On the third day, however, the value is almost twice as high (18.2%). Asphalt used on this day was supplied by a different mixing plant and was later found to contain RAP (refer also to UVF and PAH profile).
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Data determined by the Fh-ITEM. TOM: For the personal exposure samples 6–9, 21–24, 40–42 and 45, as well as for the static upwind samples 12, 32 and 44, TOM was first calculated by Shell (as sum of GC-BSM and GC-SV) before dispatching the combined (BSM+SV) solutions to the Fh-ITEM. After reception, TOM was determined again by the Fh-ITEM in order to confirm the state and the identity of the samples. TOM values calculated by Shell were confirmed by the Fh-ITEM. Data are included in the last column of Table 4.
BPD: Because of the small amount of material, in most cases it was not possible to determine BPD curves. Figures 2a–c show the results of the measurements where an evaluation of the BPD was possible.
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PAH: The results of the PAH analysis of the personal exposure samples of 25–27 September 2001 are given in Table 5. Data are presented as concentration percentage, relative to the sum of the 17 analyzed PAH in ng m–3, which is given in the last line of this table. All data are corrected for field blanks.
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On 25 September the sample ‘4th Person’ shows the highest concentration of PAH while the sample ‘Screedman left’ shows a higher concentration than that of ‘Screedman right’. The lowest concentration was found for the sample ‘Driver’. The naphthalene values of the samples are between 26 and 40% of the total PAH measured. It must be taken into account that the concentrations for the higher boiling PAH were often close to the detection limit and, therefore, uncertain.
For samples on the 26th a similar picture arises with one exception: On this day the sample ‘Screedman right’ shows a higher concentration of PAH than that of sample ‘Screedman left’. Naphthalene values are between 27 and 41%.
In the samples of the third day (27 September 2001), the highest concentration of PAH was found for the sample ‘Screedman right’ and the lowest for the sample ‘Screedman left’. The samples from this day showed higher percentages for naphthalene (between 55 and 67%) and, therefore, correspondingly lower percentages for most of the other PAH. This further confirms the assumption that the asphalt used on this day was ‘contaminated’, probably with RAP (refer also to Table 4: BSM percentage of TOM).
UVF: The UVF intensity of a bitumen fume condensate is usually related to the PAH content of the sample (Osborn et al., 2001). In the case of workplace samples, however, the bitumen fume is collected on filters and adsorbent tubes. Therefore, the only possibility to compare the UVF of workplace samples with those of the bitumen fume condensate samples is to relate the UVF intensity of the workplace samples to TOM (Kriech et al., 2002). The corresponding values are listed in Table 6. The samples of the third day (27 September 2001) show significantly higher UVF intensities than the samples of the first two days. The conclusion, derived from the BSM percentages of TOM and the PAH profiles, that RAP was probably incorporated into the bitumen used on the third day is, thus, further confirmed by the UVF values. This was subsequently confirmed from mixing plant records.
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For this reason analytical data for samples taken on the third day are not included in the comparative discussion.
Data determined by BIA. Aerosol and total hydrocarbon fume: The values for the aerosol and the total hydrocarbon fume (gas including aerosol phase) as determined at the BIA, St Augustin, according to the BIA 6305 method are presented in Table 7. Direct comparison of the personal exposure measurements by Shell and BIA is not possible since the samples were collected by different samplers, i.e. the NIOSH and BIA personal samplers, generally for different sampling periods, and characterized by different parameters (Shell: TPM, BSM, SV and TOM; BIA: aerosol and total hydrocarbon fume). Further details of the BIA measurements are given in BIA report 2001 3577 (26 October 2001).
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Static samples
Data determined by the Fh-ITEM. BPD: Because of the small amount of material, in most cases it was not possible to record BPD. Figure 3 shows the results of the measurements where an evaluation of the BPD was possible.
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PAH: PAH concentrations of static samples collected on 25 September 2001 are listed in Table 8, typical PAH-profiles are shown in Fig. 4 and comprehensive data can be found in the online data appendix. All data are corrected for field blanks. The total PAH concentrations of the two ‘upwind’ samples are 90 and 188 ng m–3. For the ‘Screed LHS’ samples the Shell samples 3 and 13 show higher total concentrations of PAHs (704 and 798 ng m–3) than BIA samples MP 57, MP 58, MP 59 and MP 60 (219–365 ng m–3). Both types of samplers found very low total PAH concentrations for ‘Screed RHS’ (72–206 ng m–3) and ‘by Driver’ samples (69–158 ng m–3), which are in the concentration range of the ‘upwind’ samples.
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PAH concentrations of static samples for 26 September 2001 are summarized in Table 9. The total PAH concentrations of the ‘upwind’ samples were between 53 and 90 ng m–3. Unlike the day before, the highest total PAH concentrations were determined on this day for the ‘Screed RHS’ samples (836–1081 ng m–3) and the lowest for the ‘Screed LHS’ samples (120–176 ng m–3), while moderate values were found for the ‘by Driver’ samples (192–343 ng m–3).
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Data determined by BIA. Aerosol and total hydrocarbon fume (BIA): The values for the aerosol and the total hydrocarbon fume (gas plus aerosol phase) as determined for static samples by the BIA according to BIA method 6305 are presented in Table 10. A direct comparison with the static samples collected by Shell/BIA and analyzed by the Fh-ITEM is not possible since the samples were characterized by different parameters (Fh-ITEM: BPD, PAH; BIA: aerosol and total hydrocarbon fume). Further details of the BIA measurements are given in BIA report 2001 3577 (26 October 2001).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONSUMMARY AND CONCLUSIONSACKNOWLEDGEMENTSREFERENCES |
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Comparison between different sampling devices and strategies
Comparison between Shell and BIA procedures. Personal samples: The results obtained from Shell personal samples cannot be compared directly with the results of the BIA personal samples since different parameters and different methodologies were used. Among the Shell personal monitoring data, the ‘4th Person’ samples showed the highest value of the sum of the concentrations of the 17 PAH, of all samples collected on the first 2 days, whereas the highest PAH concentration on the third day was found for the ‘Screedman right’ sample (Table 5). These PAH concentrations correlate with the TOM values determined (Table 4). Nevertheless, it should be mentioned that the BIA samples also showed the highest values of total hydrocarbon fume on the first two days for the ‘4th person’ sample (Table 7).
Static samples: Regarding the relative PAH concentrations within the Shell and BIA series (analyzed by Fh-ITEM), the samplers provide comparable trends. Both samplers showed the highest relative PAH concentration on the first day for the sample Screed LHS (although the absolute concentration in the BIA sample was much lower than that in the Shell sample, Table 5) and on the second day for the sample Screed RHS (Table 9). The absolute PAH concentrations in the other samples (Screed RHS, By Driver) on the first day were in the range of the upwind samples for both sampling procedures. On the second day, this was the case for the sample Screed LHS only, whereas both sampler types found higher, but comparable, concentrations for the ‘By Driver’ sample.
For comparison of the PAH profiles, only samples collected at the same position are considered. Because the concentrations of the higher boiling PAH were often close to (or below) the limit of quantification (LOD), only samples with the highest PAH concentrations are taken into account. The comparison is difficult since the Shell and BIA samplers were operated with different flow rates (2 and 3.5 l min–1, respectively) and thus the collection times reflect different periods. Furthermore, the limit of quantification depends on the sampled volumes, which also differed for the selected samples (Shell: 1069–1217 l, BIA: 777–903 l). Despite these restrictions, averaged PAH profiles of selected samples are compared in Fig. 4. The averaged PAH concentrations and standard deviations are listed in Table 11.
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Significantly higher values are observed in the BIA samples for fluoranthene, pyrene, benzo(b)fluoranthene, indeno(1,2,3-cd)pyrene and benzo-(g,h,i)perylene.
It is open to discussion whether these results can be explained by the different characteristics of the samplers, by partly different sampling periods or by different sample preparation procedures.
Comparison between personal monitoring and static samples. BPD: Compared with the Shell personal samples, the BPDs of the Shell and BIA static samples have almost identical start and end points (Figure 5). The static samples, however, show a tendency towards a relatively stronger increase in higher boiling compounds. This tendency is particularly pronounced in the BIA samples. The Shell static sample (only one sample could be evaluated) shows a slight increase. The more pronounced difference in the BIA samples might also be due to differences in the sampling procedure.
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PAHs: Regarding PAH, only the Shell personal samples (Table 5) can be compared with corresponding Shell and BIA static samples (Tables 8 and 9). Shell personal samples in all cases show higher PAH concentrations than comparable static samples (e.g. Screedman right in comparison to Screed RHS). This is true for both Shell and BIA static samples.
A comparison of the PAH profiles obtained by averaging the PAH concentrations of selected Shell personal samples as well as Shell and BIA static samples of the first two days is shown in Fig. 6. To emphasize differences Fig. 6 represents only data without naphthalene. The profiles of the Shell personal and Shell static samples are very similar (with the exception of fluoranthene and crysene), while the profile of the BIA static samples shows the already mentioned relative increase for the 4–6 ring PAH.
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Aerosol and total hydrocarbon fume (BIA): With regard to the BIA samples, where both the aerosol and the total hydrocarbon fume were determined using the BIA method, personal samples (Table 7) showed, in most cases, much higher concentrations of total hydrocarbon fume than static samples (Table 10). For the aerosol, the differences are smaller but difficult to assess since ‘< values’ (smaller than) are often given rather than absolute values.
Derived acceptance criteria for bitumen fume condensate
The results from the workplace samples were used to set up acceptance criteria for the collection of bitumen fume condensate from storage tanks. Since it is obvious that an absolute match of the parameters of the bitumen fume condensate is not feasible, it was agreed to use the following strategy for optimization of the bitumen fume condensate sampling:
As a very sensitive parameter, UVF should match the workplace samples as closely as possible (2.1 ± 1.0 Absorbance units, compare Table 6). Using this parameter the PAH-content of the condensate should be maximized, recognizing the requirement to minimize the difference between boiling point distribution of the condensate and workplace samples. Also the PAH-profile of the condensate should mimic the profile of the workplace samples as closely as possible. After trial samplings from the bitumen storage tank an expert group established quantitative acceptance criteria for the parameters mentioned above.
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SUMMARY AND CONCLUSIONS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONSUMMARY AND CONCLUSIONSACKNOWLEDGEMENTSREFERENCES |
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The aim of this work was to develop validation criteria for a laboratory-generated exposure atmosphere to be used for chronic inhalation toxicity studies in rats. To achieve this, three different laboratories (Shell, Fh-ITEM and BIA) analyzed personal and static samples taken at road paving worksites by different methods. Parameters determined were: TPM, BSM, SV and TOM, BPDs, PAHs, UVF, aerosol and total hydrocarbon fume. Different sampling methods were also used to allow comparison of the standard German sampling method with the most commonly used industrial methods.
The results of the analysis of the workplace samples enabled us to establish the validation criteria for bitumen fumes to be used in inhalation studies in rats. The criteria involve parameters that can be analyzed in both the workplace samples and the bitumen fume condensate collected from bitumen storage tanks: BPD, UVF and content of individual PAHs were selected as parameters.
From the parameters measured in the workplace, acceptance criteria to be used for comparison with bitumen fume condensate sampled from the headspace of hot bitumen storage tanks were derived.
The fume sampling and condensate regeneration for exposure atmosphere for the inhalation study is described in further papers.
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ACKNOWLEDGEMENTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONSUMMARY AND CONCLUSIONSACKNOWLEDGEMENTSREFERENCES |
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The authors would like to thank C. Bowen and her team at Shell for preparing the analysis mentioned in the text and for their helpful discussions. We would also like to thank Dr. Zoubek from the tiefbau berufsgenossenschaft who was responsible for the sampling of the so-called bia-samples and for the sample analysis accomplished by the Berufsgenossenschaft and Dr. Breuer from the Hauptverband der Deutschen Berufsgenossenschaft for his organizational work. Furthermore we would like to thank arbit and eurobitume for the financial funding of the study and all the members of the project steering committee for their participation.
Received January 25, 2006; in final form May 16, 2006
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REFERENCES |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONSUMMARY AND CONCLUSIONSACKNOWLEDGEMENTSREFERENCES |
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Belinsky BR, Cooper CV, Niemeier RW. (1986) Fractionation and analysis of asphalt fumes for carcinogenicity testing. Proceedings 4th NCI/EPA/NIOSH Collaborative Workshop: Progress on Joint Environmental and Occupational Cancer StudiesApril 22–23, 1986 NIH Publication No 88-2960.
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Kriech AJ, Kurek JT, Wissel HL, et al. (2002) Evaluation of worker exposure to asphalt paving fumes using traditional and nontraditional techniques. AIHA J 63:628–35.
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