Toxic chemicals from a substance used to seal pavement, driveways and parking lots across the United States get tracked into homes and may pose a potential health threat.
Coal tar sealant -- a waste product of steel manufacturing that's a known carcinogen -- slowly wears off and is carried into homes on the shoes of residents, say U.S. Geological Survey scientists, MSNBC reported.
The researchers found that house dust contained high levels of chemicals used in the sealant. They said their findings raise concerns about the use of coal tar as a sealant.
"This is the kind of thing where, when you give a presentation, people's eyes get big -- even scientists'," said Barbara Mahler, a hydrologist who directed the research, MSNBC said.
The study was published Monday in the journal Environmental Science & Technology.