In response to O'Reilly et al. (2014)
Coal‐tar‐based pavement sealant, a black liquid that is sprayed or painted on asphalt pavement, typically is 15 to 35% by weight coal tar or low‐ or high‐temperature coal‐tar pitch. USGS, other governmental, and academic research that has concluded that coal‐tar‐based pavement sealants are a major source of urban PAHs have relied on a wide array of forensic methods. Published academic and government research on effects of coal‐tar‐based pavement sealants has produced results consistent with those of the USGS. PAH contamination concerns associated with coal‐tar‐based sealcoat are not limited to stream and lake sediments; coal‐tar‐based sealcoat is a major source of PAHs to many environmental compartments.