javascript:; EPA Shows Toxicity of Coal Tar Sealants in Controlled Study | Coal Tar Free America
 


The much-anticipated EPA analysis of coal tar sealant runoff at Edison, New Jersey is now available.  Actually the preliminary results were presented last year at a conference sponsored by the American Society of Civil Engineers (ASCE).  It is available at this link.  A more thorough publication is expected in the future.

The researchers set up test plots of an asphalt parking lot coated in coal tar sealants, asphalt based sealants, and unsealed asphalt surfaces.  Interestingly the areas were closed to vehicular traffic.  For those of us who pay attention to parking lots and sealants, without traffic or snow plows, pavement sealant can last a very long time. These are the primary mechanisms for sealant loss.  The study, while valuable for comparative purposes, misses an opportunity to measure real world PAH loading from parking lots.

While there is some potential for PAH contamination from cars and tires, these sources would be consistent for all types of surfaces.  Nonetheless, EPA showed that runoff from a coal tar sealed surface is about 100 times more potent in PAHs than asphalt based sealant.

What is surprising is that there is not a whole lot of change between the PAH loading after 24 hours and 30 days.  For coal tar sealants it only reduces by about one-third, which probably is insufficient to claim that the problem with sealants is only soon after the application.

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