Abstract
Coal tar (CT) is a thick black liquid produced as a by‐product of coal carbonization to produce coke or manufactured gas. 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. CT is used in some pavement sealants (also known as sealcoat), which are applied to pavement in order to seal and beautify the surface. 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. In this study we examined the genotoxicity of an extract of a commercially available CT‐based sealcoat in the transgenic Muta™Mouse model. Mice were orally exposed to 3 doses of sealcoat extract daily for 28 days. 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. Significant increases were seen for each endpoint and in all tissues. 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. The results of this study are the first demonstration of mammalian genotoxicity following exposure to CT‐containing pavement sealcoat. 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. Environ. Mol. Mutagen. 57:535–545, 2016. © 2016 Her Majesty the Queen in Right of Canada
Highlights
Such as light and medium oils from crude coal tar (CT)
Concentrations in the sealcoat extract are expressed in terms of sealcoat equivalents, which were calculated based on the amount of crude sealcoat that was extracted and submitted for chemical analysis
The results indicate that a 15-L pail contains more than 750 g of priority polycyclic aromatic hydrocarbons (PAHs) and 147 g of B2 carcinogenic PAHs, including 32 g of BaP (Table I)
Summary
Such as light and medium oils from crude CT. RT-12 is the most viscous of 12 refined products derived from Driveway sealants (i.e., sealcoats) are widely used high-temperature CT pitch. across North America by homeowners and commercial property owners to beautify and protect asphalt and concrete surfaces. CT is well recognized as a multi-organ carcinogen in experimental animals [Robinson et al, 1987; Culp et al, 1998; Goldstein et al, 1998], and CT and CT pitch are both known human carcinogens [IARC, 1985; IARC, 2010a,b] 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 [IARC, 1983, 2010b]. PAH concentrations in water runoff from CT-sealed lots were shown to be 65-fold higher than in runoff from asphalt-sealed lots, and a study of 40 US lakes determined that CT sealcoat was likely the greatest contributor to elevated levels of sediment PAHs [Mahler et al, 2005; Van Metre and Mahler, 2010]. In an effort to reduce PAH loading to local waterways via storm water discharge, other municipalities (e.g., Washington, DC) have implemented similar bans [District of Columbia, 2013]
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