Submitted by Jeff Buster on Mon, 10/01/2007 - 14:30.

That annual mopping of asphalt sealer all over your driveway or parking lot  leaves a question hanging…


Where is the coat you had splashed on last year?


Well I can tell you  that the last coat didn’t climb back into the five gallon buckets from Home Depot.  And it didn’t go back up the hose into the tank on the itinerant sealer man’s truck.


Where is it?


Some of it’s in the local creek and some is in Lake Erie. 


That brings up another good question. 


Do fish like asphalt  (and who knows what else is in it)? 

We humans don't have to worry too much about the fact that Lake Erie is the source of our drinking water though, cuz don't our municipal water filtration systems take out all the carcinogens?

asphalt seal coat.jpg112.28 KB


Every chemical product must have one of these,
I had a person come at me once about using round up to kill weeds, telling me it was a hazard to the environment.  They asked me if I knew what was in it, I said why yes I do, citric acid and salt!  
It is tough these days, you have to research products, and make intelligent choices.   If you have an asphalt drive, it requires sealer or it will degrade.   People should take the time to research. 
Do not assume it is dangerous it may not be, and do not assume it is safe it also may not be.    
The product is biodegradable and non-toxic. 
If you are like me you question that, it contains asphalt, usually an acrylic or vinyl and water and an emulsion.  Emulsions are chemicals that keep a product from congealing.   If independently they offer no threat then collectively, they should not. 
Is it bad for the environment? 

Tell me, if it is and what my alternatives are. 


Oengus,  Funny, none of



Funny, none of these Material Safety Data Sheets mention "citric acid and salt"...


...however, they do list: up to 41% Glyphosate, isopropylamine salt, CAS#38641-94-0


...and if you are interested in some more information on this hazardous chemical you can find it



Also, about asphalt being "biodegradable", it is a petroleum product, as are both acrylic and vinyl compounds. Just because someone writes in their marketing literature that a product is "biodegradable" doesn't mean that it is true.

As per the "non-toxic" claim, your friends at Enviroseal Corporation say that their product contains "coal tar emulsions"....  Here is the OSHA page on Coal Tar Pitches (from which the emulsions are made). 

Coal Tar Pitches are listed by the National Toxicology Program (11th Report) as "Known to Be Human Carcinogens"

Just thought you might be interested.

polycyclic aromatic hydrocarbons (PAHs) in house dust

New research finds that apartments with adjacent parking lots treated with the coal-tar based sealcoat contained house dust with much higher concentrations of PAHs than apartments next to other types of parking lots.   Science Daily reports what your nose already tells you: when you are around asphalt emultions with coal tar in them, you get your fair share - in the dust in your living spaces, and in your lungs too!

If these poisonous sealers are really necessary for residential driveway and parking lot mainenance - why is it that we don't see them used en mass on the New York State Throughway and on CalTrans highways?

The entire "asphalt sealing" trade is bogus.  


coal tar in your carpets

Contaminated House Dust Linked to Parking Lots With Coal Tar Sealant

Coal-tar-based pavement sealants therefore have very high levels of PAHs compared to other PAH sources (e.g., soot, vehicle emissions, used motor oil). PAHs are an environmental health issue because several are probable human carcinogens and they are toxic to fish and other aquatic life.

Two kinds of sealcoat products are widely used: coal-tar-emulsion based products and asphalt-emulsion based products. National use numbers are not available; however, previous research suggests that asphalt-based sealcoat is more commonly used on the West Coast, and coal-tar based sealcoat is more commonly used in the Midwest, the South, and on the East Coast.

Previous research by the same group of USGS scientists, published earlier in 2009, demonstrated that dust from sealcoated parking lots in cities east of the Continental Divide had concentrations of PAHs that were about 1,000 times higher than in dust from sealcoated parking lots in cities west of the Continental Divide.

Oh and somebody picked up this post: National Pavement Contractors Association

There's a guy named Don Turner there - boasts to know all about pavement and sealing. When this news hit MSNBC a couple days ago it popped up on the forum. In the thread where Jeff's post was linked Don refuted the accusation that coal tar in sealant might be harmful. When the MSNBC link was posted one participant writes, "We can't deny the fact that coal tar has a lot of PAHs. And we all must do our part to help prevent cancer. Properly or improperly applied sealer doesn't matter. It all wears off eventually. If sealer never worn off, "we" wouldn't be in business like we are now. Drive Smooth Big or Small We Pave'em All"

The next give a shout out to Don: "yeah, a customer of mine sent that link to me yesterday...and then it was on my local evening news...i know similiar stuff/articles and talk etc..happens often over the years about coal tar, for sure makes you think and wonder, where you at don? clear this up brother, i know you are the one to put this into perspective."

Don has yet to reply.

sealcoat in Austin OUTLAWED


The Material Data sheet you link says, "CAUTION - Keep out of waterways, drains, sewers by diking. Keep spectators away. Floor may be slippery. Use care to avoid falling.
Waste Disposal Method: Place contaminated material in suitable sealed metal containers for disposal. Do not incinerate closed containers. Use non leaking containers, seal tightly and label properly. Do not pour contaminated paint back into unused paint. Do not throw liquid paint into the trash. Where allowed by local laws (check with local regulatory agencies) allow liquid waste materials to dry out before disposing into trash containers. Take all liquid unused paint that cannot be used to approved recycling centers, paint roundups, or county facilities that are approved to take unused paint at collection sites. Contact state, county, city health services or fire departments to find nearest collection centers. Do not dispose of waste into water streams or storm water sewers. Do not mix with other kinds of waste. Dispose all waste in accordance with local, state and federal regulations.
RCRA Classification: As produced, this product is not a waste. If discarded as is, it is not classified a “Hazardous” waste under RCRA. This product is not ignitable, corrosive, reactive, or toxic; therefore is not defined as hazardous by the EPA.
Environmental Hazards: None known."

But there are hazards known, just not federally regulated, yet.

From a study in Austin Texas:

"The study of parking lot surfaces by the USGS and the City of Austin show that abraded sealcoat could be a major source of PAHs to urban and suburban water bodies in watersheds across the Nation where sealcoat is used. Such findings have implications that extend beyond Texas as sealcoat is used nationwide; further studies would help to evaluate the potential impacts of sealcoat on the aquatic environment in other parts of the country. Identification of this source may influence future strategies for controlling PAHs in urban environments. In the past, sources of PAHs in urban watersheds were thought to be dominated by numerous nonpoint sources, such as leaking motor oil, tire wear, vehicular exhaust, and atmospheric deposition. Such sources are difficult to quantify or control because of their diffuse nature. In contrast, sealcoated parking lots are specific areas that contribute directly to urban stormwater runoff (see photo below), and the use of sealcoat is voluntary and controllable. To address PAH contamination in streams, the City of Austin Council banned the use of coal-tar based sealcoat, effective January 2006 (Nancy McClintock, written communication, City of Austin, November 2005). Possible alternatives to coal-tar based sealcoating of parking lots and driveways include the use of concrete and unsealed asphalt pavement, and the use of asphalt-based sealcoat that contains lower levels of PAHs. Currently, the use of coal-tar based sealcoat is not federally regulated. In 1992, the U.S. Environmental Protection Agency excluded coke product residues, including coal tar, from classification as hazardous wastes if they are recycled. Under the Resource Conservation and Recovery Act, coal-tar based pavement sealants are products that contain recycled coal tar and, therefore, are not regulated."

Read More:

Not unlike mercury in dental amalgam, I didin't know this was a toxic substance; I didin't think that someone who pledged an oath to do no harm would affix poison in my mouth, I didn't think a sealcoating company would kill my stream and lake.

(Per the mercury amalgam issue- I found out that a guy I have sat next to at soccer games for the last 20 years is the president of an organization to get dentists to stop using dental amalgam. And yes, he has been at it for almost this long and yes, my friend reported to me last night that she had no idea and our dentist had filled one of her teeth with amalgam (what they call "silver") just last week.)

If they banned it then why

If they banned it then why are they doing it?



Austin streets receive sealcoat in annual program

We live in complicated society,

Thank You, for the

Thank You, for the information, the first link is to a standard seal coating product and the second is to an alternative product they are different.  


Polycyclic Aromatic Hydrocarbons are coal tar and petroleum.      


Yes, the seal coating wears off (abraded), but there are product choices. 


Neither of these contains coal tar, the first contain asphalt emulsion the second product does not. 


Sealing with the enviroseal the second material data sheet, actually could seal PAH’s and prevent them from abrading.  


If the product contains coal tar, it is the worst, if it contains asphalt emulsion it is less bad, and if it does not contain either it is the best choice, that or you could have an crushed aggregate drive or parking lot. 


NOTICE THE ENVIROSEAL PRODUCT CONTAINS: Polymeric Inorganic Acrylic Co-Polymers, (proprietary)


That could be derived from sodium chloride, much like PVC pipe. 


Big problem is propriety,

Asphalt gardening

We  need  to rethink  our lives.  Your post led me to the Brad Masi's New Agrarian Center article at Cool Cleveland.
I have one of those old fashioned drives--with the grass median center.  No asphalt and no cavities for me.  Thank god!

The information on

The information on enviroseal web site related to coal tar emulsion is for that…informational purpose, to explain why their product is a more environmentally safe product.  It does not contain coal tar; it does not contain asphalt emulsion either.   Simply put the people at enviroseal are selling a product that does not contain PHA’s, which are coal tar and asphalt emulsions. 


Biodegradable mean that it breaks down into it elemental compounds in the environment, it does not mean that those compounds are natural occurring in the environment they eventually end up in, that determination requires indulging into those compounds or elements.  

I was absolutely wrong to say Round Up contains citric acid, it does not, it does contain Glyphosate is an aminophosphonic analogue of the natural amino acid glycine
I am not going to get into complex chemistry, it contains a salt acid.  If a salt acid comes in contact with water then hydronium is produced,  the prodcut does not work if it rains, it breaks down in water…but is it harmfull?  Haha really funny nobody really knows that yet, however the EPA has found it best to limit its use in agricultrure, but not me in my yard. 
It is complex, I avoid most chemicals, but sometimes we are required to use them realted to employement, so I have to be well informed and find the best alternatives.   

A member of the Ohio

A member of the Ohio citizen’s action league told me that the EPA was useless.  I responded with no they are actually the most useful, when they mandate regulations it has the most significant impact. 


My choices make a difference; even collective consumer behavior makes a difference.  It is all about convenience, most of the hazards have to do with that, simpler and easier. That is tough since we live in time is money world. 


It is always and will always be trade off, the EPA has to use time lines that phase out hazards and also review alternatives, they have to be careful not to destroy industry and also not allow alternative worse than the products they replace. 


It is not possible to eliminate all environmental hazards, that is why it is best as a consumer to avoid using chemicals, especially if you have no knowledge of chemistry.  


If you can convince in clear concise manner and offer alternatives, then present it to the EPA, you can also harass your neighbor, one could make huge difference the other will not.   


Either way we have to make sure, we are concise, misinformation serve none well.  In some instances, it can cause a loss of credibility. 


If a person addresses the EPA then realize they can actually validate or discount the claim, they have the knowledge and resources, and your neighbor may not. 


Biodegradable is just a word, glass is not biodegradable and it is not an environmental hazard it is inert, pollution can be inert.  If it breaks down in the environment that can be good or bad, what does it break into?   PVC is not biodegradable, it is inert, but its manufacturing process includes hazards. 


Then you get into known affects and unknown affects, did you know an ionic air purifier creates ozone gas?   That people put it in babies room and it actually generate a toxic gas. (Tongue in cheek) do not believe everything you read.   We are very good at recanting, but who is good at research?    


Do you want it to break down in the landfill?   I am indifferent to that, if it buried in a hole I believe stable is better.  However that depends, what does it become over time?


I have faith in most of my fellow humans, if they get off track then they need to be made aware of that, maybe some only respond to a stick, but some may go in the opposite direction in response to the stick.   Some feel compelled to do the opposite when addressed with adversity. 

Does the EPA need to do better, absolutely, we all do.  Find alternatives, and phase out the worst.  The economy has to keep driving we all depend on it.          


The American Asphalt Sealcoating company in the image, by the way, is not applying asphalt sealcoat.  They are applying sealcoat TO asphalt pavement.  According to their website (

) , "All asphalt surfaces are sealed using rubberized THERMOSEAL ( a coal-tar based sealer  ...)."  So they are applying a coal-tar based sealer, not an asphalt-based sealer. Turns out that asphalt is a much more benign substance than coal tar, so the difference is important.  In the northeastern U.S., coal-tar based sealants are far more common than asphalt-based sealants.


Most coal-tar based sealers contain 20-30% coal tar.  Coal tar is one of the few compounds listed by the EPA as a known carcinogen.  So the question, "where did last year's sealcoat [and the coal tar contained] go?" is an excellent one.


As for the comment "If you have an asphalt drive, it requires sealer or it will degrade", can anyone come up with any data from any study that shows that application of sealer makes a significant difference in the life of the underlying asphalt pavement?  I don't mean personal experience, I mean an objective study designed to determine this.




You are absolutely right, “asphalt” is an intentional advertising misnomer – and I got sucked in when I used it without comment in the image of the post, and in the body of the post. 


I should be talking about “coal tar” sealer, not “asphalt” sealer. 


So Readers, here’s a more complete viewpoint from me.


One  can tell it’s coal tar because it smells like creosote and makes your face sting when you get a whiff of air off of it. If you think it is benign, smear a little on your skin and its immediate burn will convince you otherwise.


I have friends whose family has been in the oil recycling business since the 1940’s.  Here’s what they tell me about driveway sealer:  It is a great place to lose hazardous waste – and the ignorant homeowner pays you instead of the owner of the waste having to pay to have it properly disposed. 


Think this doesn’t happen?


Born yesterday?


Ever heard of driveway sealer being tested for quality?


We all know that for years dirt roads all over the US had their dust controlled by being “oiled” with waste oil from automobiles, from factories, and from transformers.  The transformer oil often was pcb containing Askeral – great for keeping the dust down but also full of dioxin.      Nobody at the time thought twice about it. 


Putting coal tar on our driveways is JUST AS IGNORANT as oiling our farm county roads with Askeral.  It just hasn’t dawned on us yet.


Steel mills produce a lot of coal tar in their process of making coke from coal.  Steel mills need to get rid of this poison.  What better way than to sell it to the unsuspecting while at the same time making the buyer think it makes their property look better. 


And I can image what other expensive-to-legally-dispose-of haz wastes  could be blended into the coal tar and delivered to your driveway.   Paints, resins, plasticizers, thinners – anything that will flash off and dry hard enough to drive over is money in the tank.


You don’t think this is happening?

pavement seal coating - common sense

Why do we have to wait for the official word from science and the government before banning this stuff? As a lay person, when I walk by several driveways in my neighborhood that have been freshly coated, the amateur scientist and occasional non-water-based polyurethaner in me thinks, "this is one of the most powerful toxic-type smells; it is outdoors and it's that strong an odor with lots of fresh air around it; the driveways are really big and need a large volume of coating; and, lots of people are doing it."