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Coal tar sealant is applied at a study site at the University of Texas in Austin.
When you think of pollution, you might picture an industrial center like Camden, N.J., or Jersey City. But new research shows that when it comes to a potent class of cancer-causing toxic chemicals, many American parking lots are a lot worse.
New studies paint an increasingly alarming picture – particularly for young children – about how these chemicals are being spread across big swaths of American cities and suburbs by what may seem an unlikely source – a type of asphalt sealer. These sealants are derived from an industrial waste, coal tar.
Four new studies (links are at the end of this article) announced this week further implicate coal tar-based asphalt sealants as likely health risks. The creosote-like material typically is sprayed onto parking lots and driveways in an effort to preserve the asphalt. It also gives the pavement a dark black coloring that many people find attractive.
Coal tar is a byproduct of the steelmaking industry. In 1992, the U.S. Environmental Protection Agency declared that it would not be classified as a hazardous waste, even though it met the characteristics of one, because it could be recycled for uses that include coating asphalt. That meant steel mills didn’t have to pay for costly landfilling or incineration of the waste.
Only in recent years have scientists discovered the ill effects of this practice.
Coal tar sealants are used most heavily in the eastern United States, but were applied in all 50 states until Washington state banned the products last year. More than a dozen local governments, including Washington, D.C., and Austin, Texas, also have banned the coal tar sealants in favor of the other major type of sealant, which is asphalt-based.
Asphalt-based sealants contain about 1/1000th the concentration of the cancer-causing chemicals that coal tar-based products do. Home Depot and Lowe’s stores have dropped the coal tar sealants from their product lines, but still some 85 million gallons of the coal tar-based sealants are applied annually in the United States.
The new research, published in peer-reviewed science journals, focuses on a class of chemicals found in coal tar and known as “polycyclic aromatic hydrocarbons,” or PAHs. Previously, researchers believed that people’s exposure to PAHs came primarily through food, which contains trace amounts produced primarily from smoking food or cooking it at high temperatures in practices such as grilling, roasting, and frying. PAHS are produced when any organic matter burns.
The new research shows:
- It appears that children – especially those from 3 to 5 years old – living by coal tar-sealed parking lots and driveways are getting a bigger dose of PAHs from house dust than from their food. The kids who put their hands in their mouth most often are likely receiving 9 ½ times more exposure through house dust than through food, according to research led by E. Spencer Williams, a Baylor University human health risk assessment expert. That’s just from the house dust. When the kids are outside in the yard or playing on coal tar-sealed pavement, they likely are picking up much larger doses.
- While researchers previously theorized that airborne PAHs come mostly from power plants, factories and cars’ and trucks’ tailpipe emissions, U.S. Geological Survey researchers measured large amounts vaporizing into the air off coal tar-sealed parking lots. The concentrations coming off parking lots in suburban Austin, where the researchers are based, were higher than in centers of heavy industry, including Jersey City and Camden, N.J.; Chicago; London and Manchester, England; and Guangzhou, China. The Austin parking lots tested were three to eight years old. Much more off-gassing occurs in the first few years after the sealants are applied, researchers said.
- 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.
- Extrapolating from 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.
“That’s a lot,” said Barbara Mahler, a USGS scientist involved in the research.
Researchers previously had shown that coal tar-sealed parking lots were shedding tiny bits of the material, which was washed by rain into nearby waterways – killing, sickening and maiming aquatic creatures such as salamanders, minnows and, importantly, bugs at the base of the food chain. The chemicals kill tadpoles, cause tumors on fish, stunt growth of aquatic creatures and reduce the number of species able to live in a waterway.
As a result of being washed into waterways by stormwater, these chemicals’ concentrations have been rising over the last two decades, even as levels of most contaminants are headed down, Geological Survey researchers showed.
The chemicals are getting into the house dust, researchers think, when small bits are eroded off pavement and tracked into nearby homes.
Scientists also had previously demonstrated that toxic constituents of coal tar were showing up in the dust of homes adjacent to parking lots and driveways, raising questions about health effects on children in those homes, especially toddlers who frequently put their hands in their mouths. Coal tar is known to cause cancer in humans, as well as genetic mutations in lab animals.
One of the new studies helps quantify that risk. Kids who are average in terms of how often they put their hands into their mouths are getting 2 ½ times as many PAHs from house dust as from food, while those in the 95th percentile of hand-to-mouth behavior – they do it more than 94 percent of other kids – get 9 ½ times as much from the dust.
Researchers still would like to know how much of a toxic dose those same kids are getting when they play outside in yards next to coal tar-sealed asphalt, or on the asphalt itself. The level of cancer-causing chemicals in the dust on the asphalt itself has been measured at about 37 times the levels found in house dust.
“Those concentrations are a good bit higher and this study doesn’t include that at all,” said Williams, the Baylor researcher. “That may be important because just one little fingerful could be a relevant dose,” meaning one that worries health experts.
While researchers have known about contamination of water and dust, the findings about air pollution are new. Significant amounts of PAHs continue to vaporize off coal tar-sealed lots even years after the sealant is put down.
“When we look at a seal-coated parking lots, in any direction we look we see these really strongly elevated concentrations,” said Peter Van Metre, a U.S. Geological Survey scientist based in Austin. Of the dust on the coal tar-sealed pavement, he said: “It would just take a tiny amount of that to be a large enough dose for it to be significant.”
Companies that sell and use the coal tar sealants have previously disputed the growing body of evidence of the coal tar sealants’ danger being amassed by scientists from the Geological Survey, the University of New Hampshire, Baylor and other institutions.
Repeated attempts this week to reach an industry representative, Anne LeHuray, executive director of the Pavement Coatings Technology Council, for comment on the new studies were unsuccessful. In an email on Thursday, LeHuray said she was tied up at a meeting of the pavement council in Memphis.
Generally, the pavement council has attacked previous coal tar research on technical grounds.
Read previous articles on coal tar sealants:
Study sees parking lot dust as a cancer risk
State bans coal tar sealants in big win for foes
The pavement council has fought bans – sometimes successfully – when they have been proposed by local and state governments. In addition to the local governments that have forbidden use of the coal tar sealants, some governments have placed restrictions on their use, including the state of Minnesota and the California Department of Transportation. Restrictions also are in effect in more than 40 Illinois municipalities.
U.S. Rep. Lloyd Doggett, a Democratic congressman from the Austin area, has previously filed legislation calling for a nationwide ban on coal tar sealants. He plans to refile the legislation, a Doggett spokeswoman said, but is currently embroiled in a redistricting fight.
Tom Ennis, an Austin city official who helped get coal tar sealants banned there, has now launched a campaign to support a nationwide ban.
“You’re looking at a big urban air quality” problem, Ennis said. “It’s completely unacceptable and something needs to be done.”
The studies announced this week appeared in the science journals Environmental Science and Technology, Chemosphere, Atmospheric Environment, and Environmental Pollution.
InvestigateWest is a non-profit journalism center based in Seattle. If you value this kind of in-depth, independent news reporting, please consider making a tax-deductible donation to support further work of this kind.
Leave a Comment:
Blah, blah, blah, blah. This is dangerous, that is dangerous. Just live your lives people. We are all going to die of something.
blahblahblah
my kids dead from tar
and thats the real problem here
adults can die any time they like
but kids deserve a lil more than a childhood of cancer treatments
High EMFs in home wiring are dangerous too. Should we outlaw electricity?
Mean Girl
It seems to me you prefer being in the dark!
what the hell did one think?
quik money making schemes are a hazard to ones health
im pretty sure the original test were
spray it on and see if it stops leaks
oh ya later we will see if it causes cancer
by checking survivors
why not just tax the hell out of it and put a little warning label on the can and pay some retired capitol hill members outrageous pension.
You have to wonder why it is that Europe has all of these regulations against dangerous chemicals BUT WE DONT. We must show our papers however, so I feel a lot better now.
SHOW ME YOUR PAPERS!
.....if everything that COULD / CAN cause cancer....DID cause cancer...we'd all be dead by now. I also NEVER..(in my 50 yrs on earth)...contracted mercury poisoning from canned tuna....of course...I also never ate 60 cans of tuna a day for 40 years.
....relax....take it easy...sit back have a tall scotch and a cigar.
Well... don't eat the pavement...!
Everyone knows coal tar is a cancer causing agent. Certain people just don't care the collateral damage caused by all types of manufacturing and production. It'snot about a spotted owl, or a few moose in the Arctic - it's about how methods such as fracking are polluting huge areas of ground water, etc. It's not so much the oil or gas, it's the entire process from exploration to final use. If left to the multi-national conglomerates this country would be one big pool of oil and waste, and they wouldn't think twice about doing it in a National Park or in your backtard. But you won't see any of the executives exposing their families to all this filth, no sir!
Sad that the price of our technology is frequently cancer.
I've been consulting in the materials industry for 30+ years, with much of that time spent on paving, dust control, & storm water runoff (seems like an odd combination but works out in the end). Odd that the article doesn't mention that California and a few other States banned use of coal tar sealer for all public works over 15 years ago. Wonder why....
Twenty odd years ago I was working on a project to use asphalt as a coating to encapsulate hazardous waste, some of it radioactive. Worked great as long as the coating was not abraded or otherwise destroyed. We had the sense to back off that project for obvious reasons, so what was so not-obvious about coal tar products having the same issues? This isn't rocket science, for pete's sake....
OK.. what detrimental study is next on the agenda? 20~30 years ago we learned that the purging of Freon gas into the air caused a big hole in the ozone layer and skin cancers to increase. Yesterday it was elevated arsenic levels in organic baby foods. Today we have asphalt sealant troubles. The bad guys in the world don't have to attack us...we apparently are doing a good job of doing it to ourselves.
Whoops!
Well, I guess recycling was bad for the enviornment in this case.
how about studying the people who work in the industry. I've been an asphalt sealcoating contractor for over 20 yrs now using only coal tar sealer.
coal tar sealer is made with; water, clay, mineral fillers. 1-3% coal tar
let's get some more facts out there, my health has been great for 20yrs. but what if what I've worked with does end up giving me some form of cancer specific to those products, i would like to know and for others in the future, such as the asbestos industry or something as simple as microwave popcorn butter dust.
I'll be a Guinea pig here lets study my system and see if I'moverloaded with PAH's and what is the long term effects to the exposure, so far so good. I've been breathing this stuff EXCESSIVELY for 20 yrs i've sealed thousands and thousands of drives and parking lots.
Acetaminophen is a coal tar derivative so you don't have to lick your driveway to have issues here.
Many places in Europe have parking lots made from interlocking formed concrete blocks. The blocks are formed with a lattice patten and the open spaces in the blocks are filled with dirt and grass is planted. Solid pavers provide a smooth area for people to walk on. The parking areas look like a lawn from a distance, and only when you look down can you see the underlying concrete framework that supports the vehicles. They rotate the parking areas so that the grass gets plenty of light. These parking lots are so pleasant compared to the "assfault" we use, both esthetically and environmentally. They also don't turn into sticky, stinky heat radiators in the summer. Rainfall is absorbed to a great extent without the toxic runoff of petroleum based asphault that occurs here.
The EPA, the over-paid lapdogs of Big Industry -- sit! heel! fetch! Good mongrels, here's another paid vacation and some stock options! The impotence of the EPA has been well-noted for decades -- it's an agency that does little or nothing until there's a problem, typically a serious problem.
First, drop the word 'Protection' from the title because the only thing they appear to protect is a massive bureaucracy and thousands of no-work jobs. "Elective Pollution Agency" is more appropriate and they can keep the monograms. Then investigate the political and financial ties of all the EPA higher-ups who voted against public safety and in favorof Big Oil, King Coal and Agro-Giants.
The day such a investigation was announced the paper-shredders at the EPA headquarters would burst into flames from over-use, there'd be a tornado-like effect from exit doors moving so rapidly and couple large shuttle buses going non-stop to the nearest airport.
Ah, but this is America and Washington don't play that shiat, Homey. Gotta go along to get along, don't ask and don't tell, one hand fills the other... Investigate the EPA?!? Commie! Heretic!
Anything to save a buck. America is the land of byproducts.
Having worked in the Asphalt Pavement Maintenance field for 25+ years, I have sufficient knowledge to state these facts. Coal tar sealers were designed to seal and fuel proof airport fuel ramps. In the group of people who make and apply coal tar, it is known to be really nasty stuff. Skin barrier, cartridge full face mask, tyvek suit, nitril gloves, rubber boots are all needed to be in proximity to it. The people who don't , have terrible health problems. That said, there is no reason to use it any where else as there are many asphalt based sealers available. When asphalt sealer are properly fortified with latex, they work just as well if not better because they are a compatible substance with asphalt paving as coal tar is not. The base stock for coal tars has gone up in cost over the last few years because, wait for it .... the steel company's now burn more of it as fuel at their factories. Why? Because petroleum fuels have all gone up. Source of this info... the mfg. of coal tar sealers.
Finally some reason and intelligence on here.....Thank-you....
If it makes money, let it be!
A Democrat tries to stop it but the greedy Republican$ will stop the bill of course. Hopefully they get cancer instead of the rest of us. Shameful.
Another vivid example of excessive government interference with business. No wonder the economy is in the toilet. These meddlesome bureaucrats and so called scientists are going out of their way to eliminate jobs and bankrupt hardworking business people. The scientists are obviously bucking for grants for more research. There is always a cash motive with these things. It is time to put a stop to these unnecessary intrusions into the free market process. If people don't want to use a product, companies will stop making it. Let the market do it's job.
Worked on highways and bridges most my life.This sealant is not as dangerous as they would have you believe.Similar products are used to seal the outside of block walls of basements below ground level with no ill effects.In other words don't take it as gospel everything these socalled authorities tell you.It's the same with lead paint in homes,if it's sealed ,it's no threat.Asbestos is a different matter.To the people of the state of new york and surrounding areas.Asbestos is in the concrete of all your highways.I would worry more about that.
This guy in the photo is probably addicted to the fumes, of the Poly Aromatic Hydrocarbons. The people that hate scientists and studies are the same people that do not care about the ingredients in the labels. They just buy and assume everything is fine.
The Pavement Coatings Technology Council did not even comment on this report. Thats how strong the asphalt lobby is in this country. We know that an asphalt made from rubber aggregate is available and lasts much longer than this sealed asphalt gravel product. But the coatings industry and the asphalt lobby does not want you to think about this.
For the non-sheep, we have to agree that economic activity is the major reason this sealant is allowed to be used. We assume that a new parking lot or playground is not finished until it has that black finish. Clearly the poorer neighborhoods with rougher roads suffer less from that off-gas pollution. My driveway is worn down to the gravel and i am not going to reseal it because i grow plants on my property.
If the EPA and anyone else in our Government says Coal Tar is safe, then why have they banned it at our nations capitol?
Hmm....Do they know something we don't?
Or look at this article.... Seems if it can be banned at our Nations Capitol, then they can ban it across the "ENTIRE" nation?
Gee....REALLY? I guess thats because it isn't labeled "toxic" to make it sound more badass and marketable huh?