"Every year about 85 million gallons of a toxic waste that is known to promote cancer is carefully painted across about 170 square miles of American cities and suburbs, a swath as big as the city of New Orleans."
"As incredible as that may sound, that’s the conclusion squarely presented by a growing body of research that looks at a gooey black pitch made from a substance known as coal tar. It’s a kind of creosote, the stuff used to weatherproof telephone poles and railroad ties.
It’s also one of the two main ways Americans use to 'seal' asphalt parking lots and driveways. It makes the asphalt look blacker and is intended to keep the pavement from wearing away so fast. Researchers are most interested in a class of chemicals contained in asphalt sealers known as 'polycyclic aromatic hydrocarbons,' or PAHs. And coal tar-based sealers are dangerous enough in the opinion of some local and state governments that they have been banned. In 2011 Washington became the first state to forbid the use of this kind of sealant, followed by Minnesota last year."