A City scientist collects a sample of paving sealant from a parking lot in Southwest Travis County. Tests showed it was not coal tar, which has a blacker, shinier look than the grey surface above.
by Tony Tucci
AUSTIN - Austin Independent School District will begin removing cancer-causing coal tar from its playgrounds and parking lots this summer, thus becoming what is reportedly the first entity in the country to tackle the problem.
The estimated cost of removing the coal tar sealant on seven playgrounds and replacing it with an asphalt surface is $115,500. Work will begin this summer. Work on the 60 parking lots and driveways will be considerably more, depending on the size of the surface.
While the city banned coal tar sealants in 2006, an estimated 15,000 paved surfaces sealed before that date still are covered with coal tar in amounts depending on the age of the sealant and how much has been washed away. As it ages, the coal tar flakes and crumbles and is blown into the air we breathe, washed into our waterways, and tracked on shoes into homes and cars.
Coal tar sealant contains polycyclic aromatic hydrocarbons (PAHs) known to cause cancer. Studies show that the coal tar is particularly dangerous to children, who play on their hands and knees and put their fingers into their mouth.
“Coal tar needs to be banned, and we feel strongly that we need to do our part,” said Curt Shaw, director of the Austin Independent School District’s Construction Management Department. He has been working with the city’s Watershed Protection Department for more than a year to identify the presence of coal tar on school grounds and develop a schedule for removal.
While a final report won’t be released for several weeks, Shaw said it will show that coal tar exists on playgrounds at seven schools and on parking lots at about 60 schools — about half of the district’s 130 schools. Shaw said the removal program would begin with the playgrounds, starting with the worst, which is Doss Elementary School. Other elementary schools with less amounts of coal tar are Williams, Summitt, Pleasant Hill, Linder, Hart and Campbell.
Evidence of the danger of coal tar continues to mount. Dr. E Spencer Williams, a human health risk assessment expert from Baylor University, said the probable risk to children exposed to coal tar soil and dust exceeds 1 in 10,000. According to federal law, that risk is “unacceptable” and is “sufficient basis” for action.
Trace amounts of PAHs exist in foods, including fish, grilled and fried foods, and vegetable oil, but Dr. Williams’ study showed that children who put their hands in their mouth most often are likely receiving nine times more exposure through house dust than through food.
More than 15 local governments and the state of Washington have taken action, following Austin’s lead in banning the sealant. Four other states — California, New York, Illinois and Maryland —are considering legislation to ban coal tar, and U.S. Rep. Lloyd Doggett (D-Austin) plans to introduce a bill calling for a nationwide ban. Illinois’ legislation would allow counties to adopt bans. Meanwhile, major retailers including Lowe’s and Home Depot, have pulled coal tar from their shelves.
Austin’s ban was prompted by research that showed tiny bits of coal tar were being washed by rain into waterways, sickening and even killing aquatic life. More recent studies have examined the effect on human health.
U.S Geological Survey researchers measured large amounts of PAHs vaporizing into the air off coal tar-sealed parking lots. The vapors from parking lots in suburban Austin were higher than in centers of heavy industry, including Jersey City and Camden, N.J.; Chicago; London and Manchester, England; and Guangzhou, China.
Concentrations measured four feet above the coal tar-sealed lots in some cases exceeded health-protection guidelines recommended by a European Union science panel to protect against cancer. The United States has no similar guidelines.
Using the 85 million gallons of coal tar sealants laid down annually and the out-gassing rates measured in Austin, Geological Survey researchers calculated that nationwide, more PAHs are getting into the air from coal tar-sealed parking lots, driveways and playgrounds than from all the auto and truck exhaust. This raised questions about the effect on children in those homes.
Dr.Williams said that “just one little fingerfull could be a relevant dose,” meaning a dose that worries health experts.
The city’s Watershed Protection Department said that since the 2006 ban the concentrations of PAHs in some watersheds have decreased, while others remain flat.
Mateo Scoggins, a senior environmental scientist with the city department, said it is estimated that the coal tar sealant wears off at a rate of 3% to 5% a year. Scoggins acknowledged that PAHs “persist” on paved surfaces sealed prior to the ban. He said these older lots continue to add PAHs to waterways, although the amount is relatively low compared to newly surfaced lots.
“We believe that by implementing the ban we have taken care of the most significant part of the problem and will continue to monitor how (older sealed surfaces) affect our water bodies over time,” he said.
In a written statement, the Austin/Travis County Health and Human Services said it supports continuing studies of PAHs in coal tar sealants, but added that “there is no evidence to suggest” that inhalation, skin contact or ingestion of PAHs in coal tar will affect human health.
However, the statement went on to say that concerned citizens can “minimize their risk” by washing their hands and face before eating or drinking and damp mopping their floors.
Asked about the health department’s comment, Spencer Williams said, “I wouldn’t be comfortable making that statement.”
A new paper in which the city of Austin participated along with Baylor University, the USGS, the Minnesota Pollution Control Agency and the University of New Hampshire states: “human health concerns are real.” Dr. Williams said cancer might not show up for 20, 30 or 40 years.
Austin schools were briefed by the health department and the Watershed Protection Department almost two years ago, and decided to hire an independent environmental science firm. The firm recommended that the schools develop a plan to reduce future releases of PAHs. The report said the “risk” of exposure to PAHs “depends on the concentration and the frequency and duration of the exposure.”
Shaw said that Doss was chosen as the first school in its coal tar removal plan because 50 percent of its playground is covered with coal tar.
About 20 to 30 percent of the coal tar remains at Pleasant Hill and Linder, and the other schools have only 5 percent remaining.
Once playgrounds are completed, the schools will move to parking lots and drives at about 60 schools. Since the schools have complied with the city ban, newer schools and surfaces sealed since 2006 do not contain coal tar.
Coal tar is readily identified by its shiny black appearance, unlike asphalt, which is gray. Asphalt-based sealants contain about 1/1000th the concentration of the cancer-causing chemicals in coal tar-based products.
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