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John Nephew

Maplewood City Council Policy & Politics


Coal Tar Sealant Ban

This past Monday we approved the first reading of Maplewood's revised stormwater ordinance.

One thing new in the ordinance is a ban on the use of coal tar-based driveway and road sealants in the city of Maplewood. You may have read about the problems with coal tar sealcoating in the news recently. It's been a hot topic around the nation; the city of White Bear Lake was the first in Minnesota to ban them, and the legislature has been considering a state-wide ban. The MPCA has a handy fact sheet about the products. PAHs (polycyclic aromatic hydrocarbons) found in coal tar sealcoats easily wear off the pavement, and from there work their way into homes and are washed down into the stormwater system (where they can result in major expenses for cities that have to eventually dredge and dispose of contaminated sediment from stormwater ponds).

Coal tar has been known as a carcinogen since the 18th century, so the presence of these toxins in house dust is especially worrisome for small children — having two crawling around my house right now, I can tell you that anything on the floor is going to make it into a mouth sooner or later. In our outside environment, the chemicals that run off of coal tar "kill tadpoles, cause tumors on fish and eliminate whole species of tiny aquatic creatures near the base of the food chain," to quote a lengthy and well-worth-reading article on MSBNC.com.

Banning coal tar sealants is good for the health of our families, our environment, and our city's pocketbook — as eliminating these chemicals from stormwater runoff will avoid big future bills in cleaning and maintaining our storm sewer infrastructure.

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It would seem that the city engineer was pretty through in covering the people who favor the ban. How about if council actually speaks with the industry group-PCTC? I know that the city engineer mentions the group in their report date May 3. Did you know that PCTC had an independent scientist perform an environmental forensics analysis on the PAH studies in MN. Would you believe that sealer in not the source of PAHs in MN ponds. You could also asking Mr. Ennis from Austin that how much did their PAH levels drop since 2006? Another study that was done was that PAH levels were compared before and almost three years after the ban and PAH levels did not drop. Unlike the the USGS studies, an environmental forensics analysis was run before and after and the composition did not change and the major source of PAHs were combustion sources. You could ask Mr. Ennis if their ban was on a precautionary basis.

I am sure you do not want to hurt local and regional business based on an incorrect theory. I thought you would want to know those facts so that you can make an informed decision.

Your friend,


Hi, Rod, and thanks for commenting.

A USGS study (http://pubs.acs.org/doi/pdfplus/10.1021/es802119h) compared the PAHs levels in regions where coal-tar sealants are commonly used (the East and Central US), versus the West. Not using coal tar sealants correlates to lower levels of PAHs in the environment. To quote, "The elevated concentrations of PAHs in dust from sealcoated pavement in central and eastern cities cannot be attributed to urban sources of PAHs invoked in the past, such as used motor oil; burning of wood, coal, and oil; tirewear particles; and vehicle exhaust (6-8). As all of these sources are expected to affect both sealcoated and unsealcoated pavement, they cannot explain the large difference (80×) in concentrations from sealcoated and unsealcoated pavements in the central and eastern cities." (p. 4)

While there are obviously other sources of PAHs, I am persuaded that the weight of scientific evidence identifies coal tar sealants as a major source -- and one that we can do something about, given that there is a readily available alternative product (asphalt-based sealant). Indeed, the home improvement retailers in Maplewood that sell sealants have already voluntarily stopped selling the coal tar-based ones.

I should add, for anyone interested in the coal tar industry's response to these various studies and regulations, they have a website called "The Truth About Coal Tar" (http://www.truthaboutcoaltar.com/). It argues that the MSNBC online story that I linked to above is one-sided and filled with errors, and takes issue with other articles and studies. The site's basic message is that published studies "have overstated the link between Refined Tar-Based Pavement Sealers and environmental PAHs" (to quote their front page).

Here's another interesting article, which explains how Austin's ban came into being and gives voice to people on both sides of the issue: http://pubs.acs.org/cen/government/85/8507gov1.html

Obviously there's a great deal of technical information and debate, as often happens at the intersection of science and public policy. But the science and policy consensus is moving toward coal tar sealant bans. Minnesota state agencies will be prohibited from buying these products after July 1 this year. State law also has created an incentive for local regulations, since cities without such restrictions "are not eligible for state financial assistance to clean up PAH-contaminated stormwater ponds" (to quote an LMC document: http://www.lmc.org/page/1/coaltarbill.jsp).


Let's address the first study that you mention, chemical fingerprinting never established the true source of PAHs. That is pretty much the same problem with all of the USGS studies. They run a EPA PP PAH 16 test and claim that it is a chemical fingerprint, which it is not. At best it is only a screening tool. You need to run a minimum of PAH 50 to get a true fingerprint, not to mention all the other tools of environmental forensics that USGS and MPCA did not utilize.

What I am wondering is if you are even willing to look at the industry information and get their side? I honestly don't see the harm in getting the complete story, wouldn't you agree?

I did think that was really nice of the state legislation to basically reward local governments to ban something that the science if very far from settled. Not to mention, there was zero interaction with government and industry. I thought this was the business friendly state? To me that doesn't seem very friendly.


Even though retailers in the city have voluntarily agreed not to sell tar sealer, has the city thought of the economic implications regionally? If so, how was this addressed?

Also, would city council agree to meet with industry to get their side.

Hopefully you are not taking this the wrong way. I do not like to see business get pushed around by the government because of some precautionary measure.

I'm willing to look at the industry's information (such as the website I mentioned above) — that doesn't mean I will agree with their conclusions. :)

How settled does the science need to be? It seems like science is "not settled" whenever environmental regulations are being considered — if only because the business interests that profit from the status quo can always find a scientist to play up the importance of the inevitable statistical outliers in any data set. Consider how long industry declared the science to be "very far from settled" (and in some cases still do) in the cases of asbestos, tobacco, phthalates, BPA, and climate change. There's probably some professional denialist out there who is still holding up an asbestos miner who hasn't yet died of mesothelioma as evidence that the jury is still out on whether asbestos is really so bad after all. To say that the science must be settled before government takes action is just about the same as saying government should never take action.

Policy in cases like this is inevitably a matter of weighing cost and benefit with a healthy dose of uncertainty. In this situation we have the cost to the businesses that manufacture this specific product, who would be losing a potential market; and we have the benefit of reducing PAHs in our environment by some amount. (It appears that industry does not claim that there is no PAH from the coal tar sealants, just that it's not as much as the studies indicate or not as big as other sources.) It does not seem that the loss of coal tar sealants is a big problem for the consumer, nor for the service providers/contractors who do the sealcoating work, since there are substitutes — and the industry's own literature in one place states that coal tar sealants are NOT used in all 50 states (rebutting an article's claim that they are), so implicitly they agree that their product is not irreplaceable. I imagine there is some capital expense in terms of different equipment that might be used to apply alternative materials, which would be a cost to local businesses who had to switch materials. Even in terms of total economic activity, it seems to be a zero sum game — the coal tar sealant suppliers' loss is the asphalt-based suppliers' gain.

So how much environmental and human health damage should the public risk, given what the scientific studies show us so far, for the benefit of helping these particular businesses avoid these costs? At this point my calculation is, not much, especially since failing to regulate means losing the chance at future state help with PAH clean-up in our stormwater ponds.

If industry is interested in presenting their views to the city council, I would welcome them to attend the second reading of this ordinance, and would encourage any other member of the public to do so as well.


It would appear to me that you of the opinion that would fall under the precautionary principle. I am not sure if you familiar with the term since it is more an implicit policy than a formalized written policy. The problem with this principle that people tend to replace it over a formal risk assessment.

If you subscribe to this line of thought, then you should state it instead of going through this exercise of "how long do we need to wait to do something". Perhaps I am not understanding you correctly.

It would seem that if sealer manufacturers need additional and lay out additional capital, that doesn't sound like a net zero proposition to me. Also since these suppliers are going to switch to asphalt sealer, how did you factor in asphalt shortages? I think that most people can see there aren't a lot of road construction projects going on right now (due to various reasons) but yet there are asphalt shortages in various areas of the country (given that there isn't a lot of road work going on). Since the council want to legislate these sealer manufacturers to make a particular product, is the council prepared to accept the fact that perhaps these businesses may not have raw material. Just think of what will happen once the economy turns around and road work starts up. I am sure that will prices will go up and there may be a shortage. True, a lot of ifs but very possible given the current situation in that market.

I am curious, did council inquire with the other cities that banned tar sealer how their bans worked out? Did their bans reduce PAHs?

I assume what you are saying that council will not gather information from industry but rather industry must approach council to provide them with information? Am I incorrect with my assumption?

New Study Shows that USGS and City of Austin Pavement Sealer
Studies are Flawed:
Parking Lot Sealer Ban had NO Effect on Types and
Amounts of PAHs in Austin’s Waterways.
No Change in Amount or Sources of PAHs in Austin, Texas Years After Product Ban

PAH Fingerprints Do Not Identify Pavement Sealants as Source

ALEXANDRIA, Va., Dec. 9, 2010 /PRNewswire-USNewswire/ -- More than two years after Austin, TX banned refined tar sealants, there has been no discernable change in either the amount or sources of polycyclic aromatic hydrocarbons in sediment in Austin's waterways. Austin's ban went into effect on January 1, 2006.
Results of a study of the ban's impact were just published in a paper titled Polycyclic Aromatic Hydrocarbons (PAHs) in Austin Sediments After A Ban on Pavement Sealers in Environmental Forensics, the journal of the International Society of Environmental Forensics. Samples were collected from Austin's streams before the ban, in October 2005, and again after the ban in April 2008. Total concentrations of PAHs in sediments before and after the ban did not change, as might be expected if sealants were the principal source of PAHs in sediments. According to the study's author, Dr. Robert DeMott, the variation in individual PAHs is expected because PAHs are so common in so many different products. PAHs in the Austin samples were also evaluated using environmental forensics techniques. PAH fingerprinting of sediments collected before and after the ban did not identify any marked changes.
PAHs are everywhere in the environment and are formed by burning organic matter.. PAHs are found in used motor oil, grilled meats and vegetables, exhaust from internal combustion engines and emissions from fossil fuel power plants, forest fires and volcanoes as well as products made from coal and petroleum. The follow-up study of sediments in Austin as well as the results of a PAH fingerprinting study presented at a recent meeting of the Society of Environmental Toxicology and Chemistry (SETAC) indicate that pavement sealants are not the principal source of PAHs in downstream sediments, as has been suggested by others. Both studies were sponsored by the Pavement Coatings Technology Council, which researches and promotes environmentally responsible practices by sealcoat applicators.
SOURCE Pavement Coatings Technology Council
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