NEXT MEETING: ST. LOUIS, MISSOURI - AUGUST 4-8 2025

There is growing number of cities and States banning and regulating the use of coal tar and other high-PAH sealcoating products used to enhance the look and longevity of pavement but pose a threat to human health and the environment. In 2022, a sealcoat certification program was established by a U.S. EPA funded grant to test and certify sealcoating products. The QC protocol developed requires laboratories perform EPA Method 8270 to report total PAHs as the sum of the 17 compounds. Manufacturers need to know if their products meet a 1,000 mg/Kg or 10,000 mg/Kg regulatory limit. Some coal tar brands can exceed 100,000 mg/Kg, which are highly toxic. Alternative, PAH friendly asphalt-based products exist. In some cases, these products are “juiced” illegally with coal tar or something else for better performance. 

This presentation features performance data analyzing sealcoat samples tested in the certification program. Graphing the percent PAH content and using double ratio plots helps identify what the sealcoat is made with and can be achieved when more advanced forensic tests are not performed. Data published by the U.S. Geological Survey (USGS) testing weathered coal tar scrapings, dust and sediments were also plotted and the signature in coal tar is easy to identify. Phenanthrene, fluoranthene and pyrene are always the most abundant and always in that order.

Hydrocarbon fingerprinting was also performed using Sitelab’s portable UVF-Trilogy analyzer. This fluorescence-based instrument is highly sensitive and selective to different types of aromatic hydrocarbons. Samples tested in methanol and hexane solvents were analyzed for PAHs and double ratio plots were applied. The concentrations and signatures exhibited correlate well to the laboratory GC/MS results. It cannot detect one compound from another and as such, is only used for screening purposes.