Historically, coal-tar-based sealants have been applied to asphalt surfaces to enhance and protect the appearance of asphalt pavements. Coal tar sealants are a prominent source of polycyclic aromatic hydrocarbon (PAH) contamination in a number of rural and urban areas that feature sealed asphalt.
A Breakdown of Coal-Tar-Based Sealants
According to the United States Geological Survey (USGS), most sealcoat products are either coal tar or asphalt emulsion. Classified as known human carcinogens, coal-tar-based sealants contain extremely high concentrations of PAHs, which makes them a concern for both human and aquatic life. Coal tar sealants typically contain 35,000 to 200,000 mg/kg parts per million (ppm) PAHS, about 1,000 times more PAH than asphalt-based sealants, and 100 times more than motor oil.
Where Do Coal-Tar-Based Sealants Go as They Wear Off?
Dried particles of sealcoat can be transported a number of ways – through rain, wind, tires, and even our feet. PAH concentrations from coal-tar-based sealants are much higher than runoff from concrete pavement, unsealed asphalt, and asphalt-based sealants.
PAH from coal tar sealants contaminates house dust which in turn leads to direct human exposure. According to the United States Geological Survey, in a study of 23 ground floor apartments, PAH levels in apartments with lots sealed with coal-tar-based sealants were 25 times higher than those sealed with asphalt-emulsion-based sealants.
After testing 40 urban lakes across the nation, USGS found that coal-tar-based sealants were responsible for nearly half of the PAHs in the lakes. Exposure to PAH will inevitably lead to elevated cancer risks.
Coal tar sealant runoff is also toxic to marine life. In data collected up to 42 days after coal-tar-based sealant application, there was a 100% mortality rate in day-old fathead minnows and water fleas. When the same organisms were exposed to runoff from unsealed pavement, there was only a 10% mortality rate.
Coal Tar Sealant Alternatives
For more than 60 years, UNIQUE Paving Materials has delivered asphalt repair products with durability, adaptability, and environmental impact in mind. As part of these efforts, we created our INTEGRA-SEAL® Rejuvenating Asphalt Sealer, which is a professional-grade pavement sealer designed to protect asphalt without harming the environment.
We understand how much of an impact PAH has on the environment, humans, and marine life and we’ve made it our environmental mission to create asphalt emulsion sealants that have minimal environmental impact.
Why We Don’t Create Coal-Tar-Based Sealants
U.S. field trials do not recommend coal-tar-based sealants for asphalt sealing due to the environmental harm they pose. In 2013, states began to ban tar-based sealants. Minnesota and Washington have both banned coal-tar-based sealants and there are city-wide bans against coal-tar-based sealants across the United States. Several major retailers have also stopped carrying coal tar sealants and have turned their focus to more environmental alternatives.
At UNIQUE Paving Materials, we are dedicated to providing reliable and environmentally friendly solutions to your asphalt sealing needs. Our asphalt emulsion sealants are tried, true, and trusted.
Ready to Try Our Asphalt-Emulsion-Based Sealant?
Are you ready to evaluate an asphalt-emulsion-based sealant that’s not harmful for the environment? Contact us today! We’re here to answer any questions and to help you find the asphalt sealing product that’s right for you and the environment.