Is your driveway toxic?
Protecting your home and property from the elements seems like a fail-safe goal, but recent research says your good sense of maintenance could actually be harming you.
Protecting your pavement from the harsh effects of winter ice and summer heat can be smart home maintenance — if you're not coating your driveway with carcinogens. Scientists at the U.S. Geological Survey found that coal-tar pavement sealant, typically used east of the Continental Divide, contains 1,000 times more polycyclic aromatic hydrocarbons (PAHs), which are byproducts of fuel burning, than its asphalt-based counterpart used throughout the West. What's more, these known cancer-causing compounds might be tracked indoors.
After sweeping up samples of pavement dust from across the U.S., a USGS team discovered much higher levels of PAHs in the dust from pavement coated with coal-tar sealant than from pavement coated with asphalt-based sealant or no sealant at all.
"We thought that concentrations of PAHs were so high in parking lots that they may be affecting house dust," says Barbara Mahler, a hydrologist involved in the research, which was published in Environmental Science & Technology in November 2008.
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Her hunch was right. For a follow-up study published this month in the same journal, the team found that PAH concentrations are 25 times higher in homes next to parking lots with coal-tar sealant because people naturally ferry road dust inside on their shoes and clothes. Based on human toxicology data, Mahler says the level of PAHs detected in these homes translates, minimally, to an increased cancer risk for preschoolers, who often crawl around and ingest things on floors and whose young bodies are still developing.
Another team of researchers, working for Austin, Texas, began studying PAHs several years ago; they quickly determined that the compounds are also an environmental health problem because they drain into aqueous environments as runoff. Members of that team began talking to the Environmental Protection Agency about their findings in 2005, but say it took the agency five years to take their warning seriously. "Coal-tar seal coat needs to be phased out," team member Nancy McClintock says. "It's a nationwide problem."
Austin, Washington, D.C., and Dane County, Wis., meanwhile, have banned its use, and Minnesota has banned the purchase of coal-tar seal-coat products by state agencies by July 1.
Such phase-outs don't come easily, but there is precedent for them. Back in the 1940s, manufacturers began chemically treating lumber used in playgrounds and decks with a preservative called chromated copper arsenate to protect against rot and insect damage. CCA contains chromium and arsenic, toxic compounds that leach out of the wood and into soil — as with PAHs, putting children who crawl in the contaminated area at risk. After an EPA assessment, manufacturers phased out the use of CCA for virtually all residential wood products by the end of 2003. (Existing nonresidential uses include utility poles and crossties.) It has been replaced successfully by new water-based preservatives and composites such as recycled plastic lumber.
According to McClintock's team in Texas, asphalt-based seal coat is currently the only widely available, affordable alternative to coal tar. A product from Carbon Plex, made from a blend of asphalt-based seal coat and recycled tires, appears promising, but a gallon is about 15 times more expensive than a similar amount of coal tar — and, the researchers say, it's not commercially available, especially to smaller cities like Austin. Ushering in a viable alternative is a manufacturing and investment hurdle, compounded by a bad economy, they say.
|Is asphalt-based seal coating safer?|
The Austin team isn't certain that an alternative to seal coat is even needed. Manufacturers claim that coal tar-based sealants preserve the appearance of pavement, as well as protect it from water, salt, gas and oil penetration, extending its life span. But scientific studies about seal coat's efficacy have thus far been minimal. "We're not convinced seal coat is a terribly important product," Austin research team member Mateo Scoggins says. "But the PAHs in it are a serious problem."
This is not a yes-no? good-bad? question. Avoid chemicals, drive on dirt or gravel - opps, got dust in the air. Lookie, our body is composed whatever 87% (guess) of water. We need water, get too much water - ya drown and die. Okay, maybe I'm messing with yo mind. Point is, ya gotta use whatever you got righteously. "Sealing" is an inexpensive way(comparatively), to maintain and extend the life of asphalt. Sometimes, a lot of times, it's not justified to add 1 1/2 or 2 inches lift of asphalt on a driveway. "Sealing" of and by itself is not bad, although some products or services can be a total rip off. Nah, you ain't gonna die from it, and your plants beside the driveway shouldn't die, which should reassure you somewhat. OF COURSE it's not healthy! It doesn't allow plants to grow thru it, use native gravel or rock and post a "drive slow" sign if that's what you want. And then you may want to spray deadly chemicals on said gravel to keep your gravelway passable. Right!- ?
I spent 27 years in a public works street department. None of this stuff is without risk. Getting out of bed isn't without risk. Well, shucks, staying in bed isn't risk free either. This is much ado about nothing, unless you are unusually sensitive. That is the price of civilization.
With all due respect, which ain't very stinking much, this is another fear-mongering bologna Internet article of no value. You may have a driveway of native dirt, local or imported gravel, brick or block, asphalt or concrete, solid gold if you can afford it (and if so, hey, I'm really in love with you); but there ain't no "healthy" driveway , nor even pathway. Man, even the native deer paths occasionally exhibit some animal excretions!
Where is the comparative study between old crumbling asphalt (okay, maybe not that bad, but in "need" of resealing) versus newly "sealed" surface. Let's be scientific, show me the study of floating carcinogens or whatever on an old, original untreated driveway versus a resurfaced driveway at two months, 6 months, 1 and 2 years. Well, either that don't validate any headlines, or our researcher didn't research squat, except how to push our "dumb" buttons. I've shoveled a lot of asphalt, not got the 'eye' to rake, but do have the eye to see this article shouldn't have been shoveled off the barn floor.
Everything is going to kill you someday anyways DAMN
why don't we all just go back and live in the dark ages with horses/buggys, no electric no anything you think then we make all those frickin idiots happy
I've owned an asphalt maintenance business for 18 years. A family member forwarded this story to me. It scared the crap out of me. I am no longer using T-Gel when washing my hair! Seriously though, I get the enviromental impact argument. For example, I have always recycled rinse water and reused it on the next load of sealer. When I read some other stories about the Austin study I was a bit concerned. Finding "flakes" from a sealed parking lot tells me there was a spill or poorly prepared surface. This stuff does not "run off" in sheets. "Sealing is not necessary." Neither is painting your house or washing your car. It's called maintenance. Asphalt has petroleum in it. When it dries out it starts to leave the area pebble by pebble. Sealer slows that down considerably. Only people making their fortune paving/cementing will tell you differently.
Also, to any of you who have pavement please do not wait 5 years to seal it. If it is new pavement simply take your garden hose out and spray it. If the water "beads" it is not cured enough. I tell people to wait at least 6 months. Sealer will NOT stop your pavement from cracking. It is what is under it that determines the structurual integrity. That's why we don't pave over grass. If your pavement does develop cracks (say, pencil size or so) do not neglect them! Get them filled with a RUBBERIZED filler. Cold crack fillers are junk. Period. Even better is to find a reputable contractor (me) and have them clean them out with a heat lance and then fill them with a hot rubber material.
If you are scared by the story from Austin you should Google the following and do a little reading:
Germs on shopping carts
VRE (Vancomycin-Resistant Enterococcus)
Once you read about this stuff you'll be too worried about whether there's an "**** gasket" in the bathroom at Home Depot to care about how dangerous it is to seal coat your driveway!
Something tells me this skullpuppy guy never took a chemistry course. Just because you know a few guys who have been in the asphalt business for years and who don't have cancer doesn't mean there is nothing to be concerned about; you're sample size is much too small to draw any conclusion from it. Also, the article mentions that children are at a much higher risk for cancer than adults.
Putting petroleum on the ground is basically a dumb idea to begin with.
Doubt it will happen in our lifetime, but will bet if we stop using all these toxic chemicals, birth defects, especially most intellectual disabilities with kids will diminish. It has always been big business, big govermnment that allows these products to make it to the production line, when clear dangerous evidence is ignored or hidden. Think asbestos and you'll get the picture. I don't need a scientific study to tell me the sealcoats on driveways is toxic. My nose tells me so. Humans can be so greedy and selfish, and pros at ignoring the truth.
These materials are hazardous. My husband died of Doyle's carcinoma (bowel cancer), and a colleague of his also got the same cancer. They both worked with creasote - a known carcinogen for this cancer - and other sealing materials for bridge construction. We are poisoning ourselves, our world and our waterways unnecessarily. Please view Frontline's poisonous water program. http://www.pbs.org/wgbh/pages/frontline/poisonedwaters/
The best thing for our world is not to use these hazardous impervious materials, decrease run-off and deal with the reality we are part of an ecosystem, not outside of it. You can't destroy the natural world to have plants without bugs etc. etc. To OldFashionedFy I say you are being self-centred and short-sighted. To save our water and environment for the next generation, we have to learn to live with nature, not dominate it. Forget about any chance of suing these people who make this stuff... they just come back again and again with arguments that it could have been caused by any known carcinogen in our environment etc. Wake up before it is too late. I am a widow, supporting three children. This is personal now. To Carrdog, look for another job. Your life isn't worth this. Agree also with