CLEVELAND -- During the summer, Patricia Barley's kids are outside for hours on end. "My kids spend a lot of time on the driveway," Barley says, estimating during warmer months their play can last several hours in the morning and several more in the afternoon.
The Barley family's driveway is asphalt, or "black-top," and due for seal-coating.
Patricia Barley had not heard about studies linking a particular type of sealant with a human carcinogen.
"I had no idea," Barley says. The sealant in question contains "coal tar pitch," a byproduct of the steel-making industry.
Michale Pemberton, owner of Unique Paving Materials, says you can tell coal tar by its smell.
"There's a very strong vapor that comes off the coal tar," explains Pemberton who stopped using the sealant two decades ago. "When you put coal tar down, it an really burn you if you get it on your skin," Pemberton adds.
That's not all.
Studies suggest that coal tar sealant is a major source of suspected carcinogens; polycyclic aromatic hydrocarbon or PAH. Exposure occurs when, over time, sealants are crumbled into dust. They can be inhaled or washed into waterways.
One study estimates the lifetime cancer risk for people who live adjacent to coal tar sealed pavement is 38 times higher than someone who doesn't.
Michael Pemberton is well aware of the study.
"I would say, based on some of the studies I've read and everything, I put a lot of tar sealer down when I was a young man," Pemberton says.
Unique Paving developed what they consider is a superior, and safer alternative for their customers several years ago.
"It's asphalt based. It has no tar in it," Pemberton says. Minnesota and Washington have banned coal tar sealants.
Cities and communities across the country have enacted their own bans or restrictions over the last several years as well. Home Depot, Lowe's and Ace Hardware no longer sell coal tar sealants.
But not everyone agrees with coal tar study findings.
The Pavement Coatings Technology Council has lobbied successfully against a number of proposed coal tar bans. A council spokesperson calls the findings "controversial science," and contends this type of sealant has been used safely for decades by applicators who follow industry guidelines.
The Cleveland Metroparks tackled the issue last year when doing maintenance on the parking lot outside the Big Met Golf Course.
"Our thought was, well, there's a product out there that pretty much everyone agrees does not have environmental impacts, so lets give it a shot and see how it goes," says Jim Rodstrom, of the Cleveland Metroparks.
While coal tar sealant is still an option in Ohio, consumers do have a choice.
"They should ask the contractor what they're using, whether it's coal tar-based or asphalt-based," says Pemberton.
If you are sealing your own driveway, check the sealant label carefully. Most products feature labels that declare if they are made with coal tar or not. The only definitive way to tell is by checking the CAS number on the product's material safety data sheet, usually available online or from contractors.
The CAS number for coal tar is 65996-93-2.
Tom Ennis oversees the Coal Tar Free America blog. He recommends these steps to deal with coal tar:
- 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.