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Study finds danger in blacktop sealants
Dec 06, 2010 3:20 pm
WASHINGTON — McClatchy Newspapers is reporting today that a black sealant sprayed on parking lots, driveways and playgrounds turns out to be the largest contributor to the rise of a toxic pollutant in urban lakes and reservoirs across America... all according to a just-released U.S. Geological Survey study.
"Scientists saw concentrations of polycyclic aromatic hydrocarbons (PAHs) going up rapidly in the 1990s in areas of urban sprawl. PAHs have been known as a probable human carcinogen since the 19th century, when cancer struck chimney sweeps, said Peter Van Metre, a USGS scientist and a principal author of the report. PAHs also are toxic to fish and other aquatic plant and animal life," runs the story. "The research was based on sampling of sediments from the bottom of 40 lakes and reservoirs in commercial and residential areas in cities and suburbs typical of where most Americans live — not near old industrial sites.
"The scientists found that coal-tar-based sealants contribute, on average, about half of the PAHs in U.S. urban lakes," the story continues. "Vehicles account for about a quarter, on average. Coal combustion, the next highest source, is about 20 percent, but varies greatly because of different levels of coal use around the nation.
The study was published in the current issue of the journal Science of The Total Environment. The story adds that Austin, TX, Washington, D.C., and several other cities and towns have banned coal-tar-based pavement sealants and are using an alternative sealant, an asphalt-emulsion-based one, which has PAH levels about 1,000 times lower. Home Depot stopped carrying coal-tar-based sealant about five years ago. The USGS, however, said that coal-tar-based sealants are still widely used commercially and by homeowners.
For the full story click HERE.
"Scientists saw concentrations of polycyclic aromatic hydrocarbons (PAHs) going up rapidly in the 1990s in areas of urban sprawl. PAHs have been known as a probable human carcinogen since the 19th century, when cancer struck chimney sweeps, said Peter Van Metre, a USGS scientist and a principal author of the report. PAHs also are toxic to fish and other aquatic plant and animal life," runs the story. "The research was based on sampling of sediments from the bottom of 40 lakes and reservoirs in commercial and residential areas in cities and suburbs typical of where most Americans live — not near old industrial sites.
"The scientists found that coal-tar-based sealants contribute, on average, about half of the PAHs in U.S. urban lakes," the story continues. "Vehicles account for about a quarter, on average. Coal combustion, the next highest source, is about 20 percent, but varies greatly because of different levels of coal use around the nation.
The study was published in the current issue of the journal Science of The Total Environment. The story adds that Austin, TX, Washington, D.C., and several other cities and towns have banned coal-tar-based pavement sealants and are using an alternative sealant, an asphalt-emulsion-based one, which has PAH levels about 1,000 times lower. Home Depot stopped carrying coal-tar-based sealant about five years ago. The USGS, however, said that coal-tar-based sealants are still widely used commercially and by homeowners.
For the full story click HERE.