Bitumen workers handling mastic versus rolled asphalt in a tunnel: assessment of exposure and biomarkers of irritation and genotoxicity.

Emission levels of vapours and aerosols of bitumen are different when processing rolled asphalt compared to mastic asphalt, with working temperatures up to 180 and 250°C, respectively. During the Human Bitumen Study, we examined six workers handling rolled asphalt and mastic asphalt in two consecutive weeks at the same construction site in a tunnel. In addition to the determination of exposure to bitumen and polycyclic aromatic hydrocarbons (PAH) during shift, we examined urinary PAH metabolites, irritative and genotoxic effects before and after shift. Median personal shift concentration of vapours and aerosols of bitumen was 1.8 (range 0.9-2.4) mg/m(3) during the application of rolled asphalt and 7.9 (range 4.9-11.9) mg/m(3) when mastic asphalt was applied. Area measurement of vapours and aerosols of bitumen revealed higher concentrations than the personal measurements for mastic asphalt (mastic asphalt: 34.9 mg/m(3); rolled asphalt: 1.8 mg/m(3)). Processing mastic asphalt was associated also with higher PAH concentrations. Urinary 1-hydroxypyrene and the sum of 1-, 2+ 9-, 3- and 4-hydroxyphenanthrene increased slightly during shift without clear difference between mastic and rolled asphalt application. However, the post-shift urinary PAH-metabolite concentrations did not reflect the different PAH exposure during mastic and rolled asphalt application. Individual workers could be identified by their spirometry results indicating that these data reflect more chronic than acute effects. In most cases, an increase of 8-oxodGuo adducts was observed during shift that was independent of the asphalt application. 8-oxodGuo and (+)-anti-BPDE-DNA adducts were higher than in exposed workers of the Human Bitumen Study independent of the asphalt application. The DNA-strand breaks were considerably higher pre-shift and decreased during shift. In this study, mastic asphalt application led to significantly higher exposure to vapours and aerosols of bitumen, as well as to airborne PAH, compared to rolled asphalt application. Nevertheless, no differences in the excretion of urinary PAH metabolites, lung function impairment and genotoxic markers were detected. However, higher levels of genotoxicity markers on both examination days compared with the results of the Human Bitumen Study may indicate a possible influence of the specific tunnel setting.

Air sampling and determination of vapours and aerosols of bitumen and polycyclic aromatic hydrocarbons in the Human Bitumen Study.

The chemical complexity of emissions from bitumen applications is a challenge in the assessment of exposure. Personal sampling of vapours and aerosols of bitumen was organized in 320 bitumen-exposed workers and 69 non-exposed construction workers during 2001-2008. Area sampling was conducted at 44 construction sites. Area and personal sampling of vapours and aerosols of bitumen showed similar concentrations between 5 and 10 mg/m(3), while area sampling yielded higher concentrations above the former occupational exposure limit (OEL) of 10 mg/m(3). The median concentration of personal bitumen exposure was 3.46 mg/m(3) (inter-quartile range 1.80-5.90 mg/m(3)). Only few workers were exposed above the former OEL. The specificity of the method measuring C-H stretch vibration is limited. This accounts for a median background level of 0.20 mg/m³ in non-exposed workers which is likely due to ubiquitous aliphatic hydrocarbons. Further, area measurements of polycyclic aromatic hydrocarbons (PAHs) were taken at 25 construction sites. U.S. EPA PAHs were determined with GC/MS, with the result of a median concentration of 2.47 µg/m(3) at 15 mastic asphalt worksites associated with vapours and aerosols of bitumen, with a Spearman correlation coefficient of 0.45 (95% CI -0.13 to 0.78). PAH exposure at mastic-asphalt works was higher than at reference worksites (median 0.21 µg/m(3)), but about one order of magnitude lower compared to coke-oven works. For a comparison of concentrations of vapours and aerosols of bitumen and PAHs in asphalt works, differences in sampling and analytical methods must to be taken into account.

Irritative effects of vapours and aerosols of bitumen on the airways assessed by non-invasive methods.

Irritative effects caused by vapours and aerosols of bitumen were assessed by non-invasive methods including spirometry, nasal lavage fluid (NALF) and induced sputum (IS) in a cross-shift study comparing 320 bitumen-exposed workers with 118 road construction workers as the reference group. Lung function parameters, forced vital capacity (FVC) and forced expiratory volume in one second (FEV(1)) were within normal ranges in both the reference and the bitumen-exposed groups pre- and post-shift with marginally lower values in smokers of both groups. During the shift, a slight decline in FEV(1) and FVC was observed in the bitumen-exposed group independent of their smoking habits, whereas in the non-smoking reference group, the decline in FEV(1) was not observed. No significant differences between bitumen-exposed workers and the reference group and no significant shift effect were observed on the upper airways using NALF analysis. The IS concentrations of interleukin (IL)-8, total protein and matrix metalloproteinase-9 were significantly higher in bitumen-exposed workers than in the reference group. However, the concentration of these three biomarkers in the IS samples, which are indicators of inflammatory effects on the lower airways of bitumen-exposed workers, was already higher in exposed workers before shift and did not show an increase during the shift. Therefore, the key finding of this aspect of the Human Bitumen Study is the detection of potentially (sub-) chronic irritative inflammatory effects in the lower airways of bitumen-exposed workers.

DNA adducts and strand breaks in workers exposed to vapours and aerosols of bitumen: associations between exposure and effect.

To study the associations between exposure to vapours and aerosols of bitumen and genotoxic effects, a cross-sectional and cross-shift study was conducted in 320 exposed workers and 118 non-exposed construction workers. Ambient air measurements were carried out to assess external exposure to vapours and aerosols of bitumen. Hydroxylated metabolites of naphthalene, phenanthrene and pyrene were measured in urine, whereas (+)-anti-benzo[a]pyrene-7,8-diol-9,10-epoxide ((+)-anti-BPDE), 8-oxo-7,8-dihydro-2'-deoxyguanosine (8oxodGuo) and DNA strand breaks were determined in blood. Significantly higher levels of 8-oxodGuo adducts and DNA strand breaks were found in both pre- and post-shift blood samples of exposed workers compared to those of the referents. No differences between exposed workers and referents were observed for (+)-anti-BPDE. Moreover, no positive associations between DNA damage and magnitude of airborne exposure to vapours and aerosols of bitumen could be observed in our study. Additionally, no relevant association between the urinary metabolites of PAH and the DNA damage in blood was observed. Overall, our results indicate increased oxidative DNA damage in workers exposed to vapours and aerosols of bitumen compared to non-exposed referents at the group level. However, increased DNA strand breaks in bitumen workers were still within the range of those found in non-exposed and healthy persons as reported earlier. Due to the lack of an association between oxidative DNA damage and exposure levels at the workplaces under study, the observed increase in genotoxic effects in bitumen workers cannot be attributed to vapours and aerosols of bitumen.

Levels and determinants of exposure to vapours and aerosols of bitumen.

Bitumen (referred to as asphalt in the United States) is a widely used construction material, and emissions from hot bitumen applications have been a long-standing health concern. One objective of the Human Bitumen Study was to identify potential determinants of the exposure to bitumen. The study population analysed comprised 259 male mastic asphalt workers recruited between 2003 and 2008. Personal air sampling in the workers' breathing zone was carried out during the shift to measure exposure to vapours and aerosols of bitumen. The majority of workers were engaged in building construction, where exposure levels were lower than in tunnels but higher than at road construction sites. At building construction sites, exposure levels were influenced by the room size, the processing temperature of the mastic asphalt and the job task. The results show that protective measures should include a reduction in the processing temperature.

Stereotactic linear accelerater-based radiosurgery for the treatment of patients with glomus jugulare tumors.

BACKGROUND: The optimal treatment for patients with glomus jugulare tumor (GJT) of the skull base remains controversial. Surgical excision is associated with a high incidence of cranial nerve injury, decreased quality of life, and high mortality. Fractionated radiotherapy is used to control the majority of these tumors, but disadvantages are a prolonged therapy interval and exposition of adjacent brain tissue to irradiation. The authors present the results of a study on 12 of 14 consecutively admitted patients who were treated using linear accelerator-based radiosurgery (LINAC-RS), an innovative method for the treatment of GJT. METHODS: From May 1991 to March 2001, 14 patients with GJT were treated with stereotactic LINAC-RS for continued growth of tumor or of remaining tumor after surgery. Twelve patients (9 women and 3 men; age range, 28-71 years; median age, 59 years) with a median follow-up of 4 years (range, 0.8-9,0 years), were selected for retrospective analysis. A median single dose of 15 grays (Gy; range, 11-20 Gy) was applied to the surface of the tumor. RESULTS: After undergoing LINAC-RS, 8 of 12 patients (67%) reported partial or complete subjective improvement, whereas complaints remained unchanged in 4 patients (33%). Neurologic status improved in 3 patients (25%) and remained unchanged in 8 patients (67%). Magnetic resonance images showed tumor shrinkage in 8 patients (67%) and no further progression in 4 patients (33%). CONCLUSIONS: LINAC-RS is an effective and safe therapy for patients with GJT and may be used as an alternative to surgical resection. Compared with fractionated radiotherapy, LINAC-RS has some advantages. However, to clarify the question of long-term tumor control, longer observation times are required.