Something right under your feet could be deadly.
"My advice is not to use it at all anytime, by anyone, anywhere," Dr. Robert Lynch, of the OU College of Public Health, says.
Dr. Lynch is talking about PAH'S or Polycyclic Aromatic Hydrocarbons. They are found in coal-tar sealants often found in pavement sealants.
"These compounds have been widely tested for years. We know that they cause cancers in animals. There is no doubt about that," Dr. Lynch explains.
Pavement sealant is sprayed onto asphalt and marketed to increase asphalt life and improve appearance.
Edmond mom Reagan Akin knows her driveway is safe but worries about others.
"My kids play outside all the time. They're at school. So to hear there is any type of product that is used that would be harmful to my children scares me to death."
A decade ago, officials in Austin, Texas found high levels of PAH's in waterways.
David Mott from the United States Geological Survey says the culprit was coal tar-based sealants on pavement.
“The seal coat doesn't necessarily stay on the pavement once it's laid down on the parking lot. It dries out. It becomes weathered by the sun. People drive over it their tires abraid it. The rains can come and wash the seal coat off the parking lot into the waterways," Mott says.
Mott says USGS Research on the compounds show an increased lifetime cancer risk. They are especially dangerous for children.
"Folks that are living close to these products, the coal tar based sealants, [are] about 38 times higher," David Mott says.
You can't tell just by looking if the sealant is being used in Oklahoma, but Mott says chances are high.
"Another thing about the coal tar sealant is it's predominantly used East of the Continental Divide and we are east so that would indicate it is used here and we do know it's used extensively in Texas."
NewsChannel 4 tried to contact a number of pavement companies here in Oklahoma and not one of them would go on camera to talk about this.
But the Director of the Pavement Coatings Technology Council, Anne LeHuray, did respond.
So far Washington and Minnesota have outlawed coal-tar sealants. Some cities and counties in Texas, Illinois, New York and Maryland have also passed bans.
But in Oklahoma, Lynch said that is not the case.
"We should know better," Lynch says.
If you find out you do have a coal tar-based sealant on your driveway there are safe ways to cover it.
Stores such as Home Depot, Lowe’s and Ace Hardware have stopped selling coal tar sealants. The product gradually wears off and breaks down into particles that are washed off by rain into streams, blown elsewhere by wind or tracked into homes on the soles of shoes.
Some of its toxic compounds evaporate into the air, which is why sealed parking lots give off a strong odor.
USA Today did a report on the sealants and reported advice for avoiding coal tar: You can see that full article here.
Tom Ennis recommends these steps to avoid coal tar. He's an official in Austin, the first city to ban coal tar sealants, and oversees the Coal Tar Free America blog.
• Before sealing your driveway, hire only a contractor who provides a MSDS (material data safety sheet) for the intended product. Check to see if it contains this CAS number for coal tar: 65996-93-2. If doing the work yourself, buy only products with a "coal tar free" logo.
• You can't tell by looking at pavement if it contains coal tar, and definitive testing is costly, but there's an alternative for those careful to wear safety goggles and gloves: Scrape off a small amount of pavement sealant with a screwdriver or razor. Place it in a glass vial filled with mineral spirits. Seal and shake the vial. Allow it to sit for 30 minutes. If the liquid is dark and coffee-colored, the sealant is probably asphalt-based, but if it's like amber-colored tea, it's probably coal tar-based.
• If your sealant contains coal tar, you can hire contractors to remove it safely via shot blasting. You can also coat over it with an asphalt-based product to keep the coal tar from leaching out.