Asphalt fume dermal carcinogenicity potential: I. dermal carcinogenicity evaluation of asphalt (bitumen) fume condensates

Clark, Charles R.; Burnett, Donald M.; Parker, Craig M.; Arp, Earl W.; Swanson, Mark S.; Minsavage, Gary D.; Kriech, Anthony J.; Osborn, Linda V.; Freeman, James J.; Barter, R. A.; Newton, Paul E.; Beazley, Shelley L.; Stewart, Charles L.

doi:10.1016/j.yrtph.2011.04.003

Cited by 33 publications

(19 citation statements)

References 21 publications

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“…The results of well conducted and validated dermal studies by Clark et al 2011 andFreeman et al 2011, are consistent with IARC's conclusions -straight run paving bitumen condensate was not carcinogenic to mouse skin whereas oxidized roofing bitumen condensate was weakly carcinogenic and shown to be an initiator of dermal tumorigenesis. Moreover, these studies demonstrated that carcinogenic effects are correlated with composition, temperature at which emissions were generated, dermal irritation, duration and frequency of exposure.…”

Section: Discussionsupporting

confidence: 79%

“…To investigate the weak tumorigenic response observed by Clark et al 2011 with field-matched roofing fume condensate, a dermal initiation-promotion study was undertaken . Groups of male mice were exposed by skin application, to the same fume condensate tested by Clarke et al twice per week for either two weeks, during the initiation phase, or 26 weeks during the promotion phase.…”

Section: Case Study 1 -Evaluating Carcinogenic Potential Of Bitumen Ementioning

confidence: 99%

“…Results of mammalian studies vary broadly from benign (Fuhst et al 2007;Clark et al 2011) to carcinogenic (Sivak et al 1997). With studies showing such vastly different outcomes, it is often difficult to reach sound scientific conclusions on the health effects of a complex substance without an in-depth understanding of the material, how it behaves under different conditions and what factors can influence exposure.…”

mentioning

confidence: 99%

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Assessing cancer hazards of bitumen emissions – a case study for complex petroleum substances

Kriech¹,

Schreiner²,

Osborn³

et al. 2017

Critical Reviews in Toxicology

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When assessing cancer hazard and risk associated with a complex petroleum substance, like bitumen emissions, there are often conflicting results related to human, animal and mechanistic studies. Validation of the complex composition to assure that it matches real-world exposures and control of confounders are pivotal factors in study design to allow the necessary read-across during assessments. Several key studies on bitumen emissions in two-year dermal cancer assays reported variable outcomes ranging from high cancer incidence to no cancer incidence. Here, we synthesize findings from published studies to explain the differences and discuss critical factors in cancer hazard evaluation for complex petroleum substances. Using these critical factors, we reviewed relevant human genetic toxicity, mammalian toxicity and mechanistic studies with bitumen to understand the divergence in results. We assess the most reliable and scientifically supported information on the potential carcinogenic hazards of bitumen emissions and comment on quality and completeness of data. Human hazard data are typically considered highest priority because they eliminate the need for interspecies extrapolation and reduce the range of high -to low-dose extrapolation during the risk assessment process. Finally, two well-conducted comprehensive animal studies are discussed that have well-defined test material, exposure concentration and composition representative of worker exposure, evidence of systemic uptake, no confounding exposures and provide consistency across all elements within both studies. Studies that allow effective read-across from human, animal and mechanistic components, control for confounders and are well-validated analytically against workplace exposures, provide the strongest evidence base for evaluating cancer hazard. ARTICLE HISTORY

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Section: Discussionsupporting

confidence: 79%

Section: Case Study 1 -Evaluating Carcinogenic Potential Of Bitumen Ementioning

confidence: 99%

mentioning

confidence: 99%

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Assessing cancer hazards of bitumen emissions – a case study for complex petroleum substances

Kriech¹,

Schreiner²,

Osborn³

et al. 2017

Critical Reviews in Toxicology

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“…The decrease was largest in the first quarter of the oxidation reaction. These findings indicate that oxidation, by itself, was not a likely factor in the tumour induction seen in the Clark et al (2011) studies.…”

Section: Strategies For Continued Reduction Of Exposurementioning

confidence: 67%

Review and implications of IARC monograph 103 outcomes for the asphalt pavement industry

Kriech¹,

Osborn²

2014

Road Materials and Pavement Design

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On 18 October 2011, the International Agency for Research on Cancer (IARC) revealed its conclusions of an eight-day comprehensive review of bitumen (asphalt) and bitumen emissions (fumes). The working group concluded that occupational exposures to oxidized bitumens and their emissions during roofing are 'probably carcinogenic to humans' (Group 2A); occupational exposures to hard bitumens and their emissions during mastic asphalt work are 'possibly carcinogenic to humans' (Group 2B); and occupational exposures to straight-run bitumens and their emissions during road paving are 'possibly carcinogenic to humans' (Group 2B) These evaluations and supporting data have been published as Volume 103 of the IARC Monographs. The IARC process is described, as well as details of the conclusions, hazard versus risk, prominent human, animal and mechanistic studies, routes of exposures and ways to reduce exposures. Implications for the asphalt pavement industry include communication to workers and product users, and potential changes in safety data sheets. Implications with regulatory agencies as a result of this hazard communication are discussed. Results encourage continued occupational exposure reduction strategies within the industry to minimise risk of this potential hazard to workers.

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“…(4) Inhalation animal studies conducted by Fuhst et al, (5) on air-rectified paving bitumen showed no significant tumor formation in rats. Clark et al (6) summarized recent mouse skin painting study results which highlight that the paving fume condensate was not carcinogenic under their test conditions whereas field-matched Type III Build-Up Roofing Asphalt (BURA) (oxidized bitumen) fume condensate produced a weak tumorigenic response. Trumbore et al (7) showed that the oxidation process does not appear to increase the formation of biologically active.…”

Section: Introductionmentioning

confidence: 99%

Effect of Temperature and Process on Quantity and Composition of Laboratory-generated Bitumen Emissions

Bolliet

Kriech²,

Juery

et al. 2015

Journal of Occupational and Environmental Hygiene

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In this study we investigated the impact of temperature on emissions as related to various bitumen applications and processes used in commercial products. Bitumen emissions are very complex and can be influenced in quantity and composition by differences in crude source, refining processes, application temperature, and work practices. This study provided a controlled laboratory environment to study five bitumen test materials from three European refineries; three paving grade, one used for primarily roofing and some paving applications, and one oxidized industrial specialty bitumen. Emissions were generated at temperatures between 140°C and 230°C based on typical application temperatures of each product. Emissions were characterized by aerodynamic particle size, total organic matter (TOM), simulated distillation, 40 individual PACs, and fluorescence (FL-PACs) spectroscopy. Results showed that composition of bitumen emissions is influenced by temperature under studied experimental conditions. A distinction between the oxidized bitumen with flux oil (industrial specialty bitumen) and the remaining bitumens was observed. Under typical temperatures used for paving (150°C-170°C), the TOM and PAC concentrations in the emissions were low. However, bitumen with flux oil produced significantly higher emissions at 230°C, laden with high levels of PACs. Flux oil in this bitumen mixture enhanced release of higher boiling-ranged compounds during application conditions. At 200°C and below, concentrations of 4-6 ring PACs were ≤6.51 μg/m(3) for all test materials, even when flux oil was used. Trends learned about emission temperature-process relationships from this study can be used to guide industry decisions to reduce worker exposure during processing and application of hot bitumen.

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Asphalt fume dermal carcinogenicity potential: I. dermal carcinogenicity evaluation of asphalt (bitumen) fume condensates

Cited by 33 publications

References 21 publications

Assessing cancer hazards of bitumen emissions – a case study for complex petroleum substances

Assessing cancer hazards of bitumen emissions – a case study for complex petroleum substances

Review and implications of IARC monograph 103 outcomes for the asphalt pavement industry

Effect of Temperature and Process on Quantity and Composition of Laboratory-generated Bitumen Emissions

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