![]() In addition, according to IARC's 2011 evaluation, there is only limited evidence that bitumens are animal carcinogens. ![]() ![]() In contrast, asphalt (‘bitumen’ in Europe), which is similar in appearance to CT, is a by‐product of petroleum refining and contains only low concentrations of genotoxic and carcinogenic PAHs. They contain a complex mixture of polycyclic aromatic compounds (PACs), including a wide range of polycyclic aromatic hydrocarbons (PAHs), many of which have the ability to damage DNA (i.e., are genotoxic), as well as cause mutations and cancer. RT‐12 is the most viscous of 12 refined products derived from high‐temperature CT pitch.ĬT is well recognized as a multi‐organ carcinogen in experimental animals, and CT and CT pitch are both known human carcinogens. CT‐based sealcoats generally contain a refined material known as RT‐12 (i.e., ASTM D490, Road Tar 12), which is derived from high‐temperature CT pitch, the material that remains after removal of distillation products such as light and medium oils from crude CT. Crude CT used in the production of the former is a thick black liquid, generated as a by‐product of coal carbonization to produce coke or manufactured gas. There are two main formulations of sealcoat products used in North America: aqueous emulsions containing 10‐35% coal tar (CT) and aqueous emulsions containing a similar level of asphalt (i.e., bitumen). © 2016 Her Majesty the Queen in Right of Canadaĭriveway sealants (i.e., sealcoats) are widely used across North America by homeowners and commercial property owners to beautify and protect asphalt and concrete surfaces. This work provides in vivo evidence to support the contention that there may be adverse health effects in mammals, and potentially in humans, from exposure to coal tar. The results of this study are the first demonstration of mammalian genotoxicity following exposure to CT‐containing pavement sealcoat. The potency of the response differed across tissues, with the highest frequency of adducts occurring in liver and lung, and the highest frequency of mutations occurring in small intestine. Significant increases were seen for each endpoint and in all tissues. We evaluated genotoxicity by examining: (1) stable DNA adducts and (2) lacZ mutations in bone marrow, liver, lung, small intestine, and glandular stomach, as well as (3) micronucleated red blood cells. Mice were orally exposed to 3 doses of sealcoat extract daily for 28 days. In this study we examined the genotoxicity of an extract of a commercially available CT‐based sealcoat in the transgenic Muta™Mouse model. Human exposure is known to occur not only during application, but also as a result of the weathering process, as elevated levels of PAHs have been found in settled house dust in residences adjacent to CT‐sealed surfaces. CT is used in some pavement sealants (also known as sealcoat), which are applied to pavement in order to seal and beautify the surface. It is comprised a complex mixture of polycyclic aromatic compounds, including a wide range of polycyclic aromatic hydrocarbons (PAHs), many of which are genotoxic and carcinogenic. Coal tar (CT) is a thick black liquid produced as a by‐product of coal carbonization to produce coke or manufactured gas.
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