Evaluation of Generic PAH Profiles Commonly Used in Receptor Models: Implications for Source Control Policy

New Journal piece - Asphalt Institute - Review of the impact of stormwater and leaching from pavements on the environmental

Complex Mixture Analysis of Emerging Contaminants Generated from Coal Tar- and Petroleum-Derived Pavement Sealants: Molecular Compositions and Correlations with Toxicity Revealed by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry | Environmental Science & Technology (

Austin Sediment Study Summary



Over the past several months, PCTC continued to work with the team at Exponent Labs as well as renowned attorney David Kanter to produce a brief outlining the outcome of this battle and celebrating what can only be considered as a victory for our industry. The full brief can be found below.

For years state and local governments have been restricting or banning the use of refined tar  sealants (commonly referred to as coal tar sealants) citing potential health risks to humans and  aquatic life from exposure. The primary basis for these restrictions and bans has been the  published work of two scientists affiliated with United States Geological Survey (USGS). This  work essentially concluded that run-off from parking lots and driveways sealed with coal-tar  sealants was a primary source of Polycyclic Aromatic Hydrocarbons (“PAH’s”) in lakes, rivers  and other waterways.  

Soon after the USGS funded article was published, the Pavement Coatings Technology  Counsel (an industry trade association) smelled a rat and questioned the methodology used by the  USGS scientists to support their conclusions. PCTC asked to see the underlying data relied on by  the USGS scientists to support their conclusion. In essence, PCTC requested what is asked of all  scientists and students – “show us your work; show us the support for your conclusion.” USGS  inexplicitly denied PCTC’s multiple Freedom of Information Act requests, refusing to provide the  data support for their conclusions and preventing PCTC from attempting to replicate USGS’s  hypothesis and methodology - a basic, yet critical element for testing a science-based conclusion.  

USGS’s refusal to show its work triggered the start of a long and expensive legal journey  which ultimately resulted in a Federal Court of Appeals ruling in PCTC’s favor – stating that  government scientists (like the authors of USGS’s paper fingering RTS) should not be immune to  peer review—that is, analysis of their conclusions by other scientists -- and that USGS must  provide PCTC with the underlying data used as support for the conclusions reached by USGS  scientists so that PCTC could attempt to replicate what USGS had done. 

And so, more than ten years [!] after PCTC filed its first Freedom of Information Act  request, USGS finally released its data allowing, for the first time, other scientists to fairly evaluate  the conclusions reached by the USGS scientists. Kirk O’Reilly, PhD. of Exponent has, in the  attached paper, looked behind the veil behind which USGS had previously hid and has concluded what PCTC has long suspected—the conclusions reached by the USGS scientists were deeply  flawed, were not reproducible and were not supported by sound scientific methodology. In short, Dr. O’Reilly has demonstrated that when put to a rigorous scientific analysis, the  conclusions of the USGS scientists -- that coal-tar sealants are a significant source of PAH’s in  lakes, rivers and waterways cannot legitimately used as a basis to restrict or ban the use of coal tar sealants. Dr. O’Reilly has exposed the USGS scientists’ decision to essentially put their thumb  on the scale to reach their desired, albeit flawed, conclusions.  

USGS Used Invalid Modeling to Evaluate Sources of PAHs in Urban Sediments Introduction 

In 2010, USGS published a paper describing the use of EPA’s Chemical Mass Balance (CMB)  model to assess their hypothesis that refined tar sealants (RTS) are an important source of  polycyclic aromatic hydrocarbons (PAHs) in urban sediments (Van Metre and Mahler 2010). As  the model was developed to evaluate sources of air pollution at one location and USGS used it  to evaluate sediment samples from 40 lakes from across the country, this application has been  the subject of an on-going debate. Resolution of the technical issues was impeded by the  refusal of USGS to release the outputs of the model runs. After a lengthy legal battle, many of  these outputs were released and evaluated in 2022. Additionally, a detailed investigation of the  model inputs was published in 2023 (O’Reilly et al. 2023). This document summarizes the  finding of these studies. 

The key findings are: 

USGS’s modeling approach has not been validated.

USGS used invalid model inputs. 

USGS’s study did not include appropriate controls. 

USGS’s conclusions are based on circular reasoning. 

The results do not support the hypothesis that RTS is an important source of PAHs in  urban sediments. 

CMB – A brief tutorial 

As stated in its user’s manual (Coulter 2004), CMB is an air quality model used to estimate the  relative contribution of various sources of air pollution. Its inputs are the chemical make-up or  “profiles” of potential site-specific sources and chemical profiles of the environmental samples being evaluated. The model mathematically mixes the potential sources and identifies which  combination results in a mixture that is most similar to each environmental sample. Key  assumptions are that all important sources are known, relatively stable, and different enough  that they can be distinguished by the model. Meeting these assumptions can be challenging  when investigating sources of air pollution, but even more so when focused on sediments. 

USGS’s use of CMB 

USGS used CMB to evaluate the source of PAHs in sediments collected from 40 lakes situated  across America (Van Metre and Mahler 2010). Instead of selecting realistic source inputs from  the areas where the lakes were located, they used generic profiles taken from the literature. A detailed study demonstrates that these profiles do not represent any actual sources (O’Reilly et  al. 2023). USGS did not use samples of RTS to generate RTS source profiles, but used samples of  parking lot dust even though the profile of dust collected from sealed and unsealed lots are  indistinguishable. USGS claimed they ran the model about 200 times, but only presented the  results of four runs.  

Our Evaluation 

The technical approaches used to evaluate USGS’s work are described in a series of peer  reviewed publications (See Appendix 1). 


The use of CMB to evaluate environmental sources of PAHs in sediment has not been  validated.

     o CMB was developed to evaluate sources of diverse contaminants in air, not a  single class of contaminants in sediments. 

     o The model has strict assumptions that were violated when evaluating PAHs in  sediment. 

     o While others have used CMB to investigate the link between combustion sources  and PAHs in sediments, the results have never been confirmed. 

     o USGS is the first to use CMB to evaluate the contribution of both combustion  sources and a specific product. 

The source profiles used by the USGS as model inputs are invalid. 

     o CMB requires appropriate site-specific source inputs, not generic inputs.  o There was no site-specific evaluation of probable sources. 

     o Real world sources are too many and variable to be represented by a few generic  profiles. 

     o The variability of real sources is so great the model cannot distinguish among  different types of sources. USGS improperly lowered the variability factor inputs  to get the model to run. 

     o The combustion source profiles were artificially constructed from inconsistent  data and do not represent any real sources. 

     o The source profiles claimed as RTS, do not represent RTS. They are based on samples of parking lot dust, not RTS. Profiles from samples collected at sealed  and unsealed parking lots are indistinguishable. 

USGS’s study did not include appropriate controls. 

     o Controlled experiments are required to test a hypothesis.  

     o A negative control would be comparing model outputs with RTS as a source input  to runs without RTS as a source input. A positive control would be running  samples of RTS as a source input. 

     o A review of USGS output files indicates a few negative controls were run. The  model was able to successfully identify potential sources in the absence of RTS.  This is inconsistent with the hypothesis that RTS is an important source.

     o We ran negative controls replacing RTS sealed parking lot dust with unsealed  parking lot dust and the calculated contributions were similar. This is inconsistent  with the hypothesis that RTS is an important source. 

     o There is no evidence USGS ran positive controls. We ran the model with actual  RTS profiles and RTS was not identified as a source. 

USGS’s conclusions are based on circular reasoning. 

     o Urban dusts, soils, and sediments contain PAHs derived from many sources. o Since they have the same sources, dusts, soils, and sediments have similar and  overlapping PAH profiles that are typically called urban background. 

     o CMB assigns greater contribution to sources that are most similar to  

environmental samples. 

     o Because USGS labeled parking lot dust derived urban background profiles as  RTS, the model assigned dust a higher contribution, 


USGS modeling effort does not support the hypothesis that RTS is a source of PAHs in urban  sediments. 


Coulter, C. T. 2004. EPA-CMB8.2 Users Manual. In. Research Triangle Park, NC 27711: US.  Environmental Protection Agency, Office of Air Quality Planning & Standards. O’Reilly KT, Athanasiou D, Edwards M. Evaluation of Generic PAH Profiles Commonly Used in  Receptor Models: Implications for Source Control Policy. Environmental Forensics. 2023: DOI:10.1080/15275922.2023.2172094 

Van Metre, P. C., and B. J. Mahler. 2010. Contribution of PAHs from coal–tar pavement sealcoat  and other sources to 40 U.S. lakes. Science of The Total Environment 409 (2):334–44. Appendix 1 

O’Reilly KT, Athanasiou D, Edwards M. Evaluation of Generic PAH Profiles Commonly Used in  Receptor Models: Implications for Source Control Policy. Environmental Forensics. 2023: DOI:10.1080/15275922.2023.2172094 

O’Reilly, KT, Edwards, M. Comment on Norris and Henry (2019). Science of the Total  Environment. 2020; 704:135248. 

O'Reilly KT, Ahn S, Pietari J, Boehm P. Use of receptor models to evaluate sources of PAHs in  sediments. Polycyclic Aromatic Compounds 2015; 35:41-56

Mesard PM, Sparacio T, O’Reilly KT. Criteria for allocation of responsibility under state law.  Environmental Claims Journal 2015; 27:40–49. 

O’Reilly KT, Pietari J, Boehm P. Parsing Pyrogenic PAHs: Forensic Chemistry, Receptor  Models, and Source Control Policy. Integrated Environmental Assessment and Management  2014; 10, 279–285. 

O'Reilly K, Ahn S. Letter commenting on "Primary sources and toxicity of PAHs in Milwaukee area streambed sediment"-To the editor. Environ Toxicol Chem. 2017 36:1978-1980.  

O’Reilly KT, Pietari J, Boehm P. Parsing Pyrogenic PAHs: Forensic Chemistry, Receptor  Models, and Source Control Policy. Integrated Environmental Assessment and Management  2014; 10, 279–285. 

O’Reilly KT. Article title misstates the role of pavement sealers. Environmental Pollution 2014;  191:260–261.

Letter to NY Governor Requesting Veto

Dear Mr. Shah:

On behalf of the Pavement Coatings Technology Council (PCTC), we note that Assembly bill 518/Senate bill 4095 has been delivered to the Governor for executive action. On behalf of PCTC, we urge the Governor, based on the below, to veto the above-referenced bill.

The bill, if signed into law, would prohibit the use of refined coal tar-based sealers in New York. As way of background, there are two common types of pavement sealers, one uses an asphalt base and the other a refined coal tar base. These sealers are routinely used by many businesses, colleges and universities, school districts, municipalities and residential consumers to seal asphalt parking lots and driveways to protect against the environmental degradation and promote longevity of the underlying pavement. Use of sealants in a protective maintenance program has been demonstrated to significantly reduce costs of pavement upkeep. Enactment of this bill will not only increase costs of parking lot maintenance, it will significantly impact employers. For instance, the bill is an threatens both the direct employees of Cosmicoat of Western New York at its manufacturing facility in Gasport and the many independent businesses in Buffalo and throughout the region that distribute and use Cosmicoat’s products. It is notable that, in the decades in which sealant products have been used throughout New York State, there have been few health or environmental complaints, demonstrating PCTC’s contention the bill is a solution in search of a problem.

Refined coal tar-based sealers last longer, provide more effective protection of paved surfaces, and have a lower life cycle costs than the alternative asphalt-based sealer. With respect to claims regarding human health concerns, it is instructive to look at other products consumers use that contain the chemicals of a similar quality. For instance, the Food and Drug Administration (FDA) has approved coal tar for decades as a base ingredient for skin creams and shampoos that fight certain skin conditions. Coal tar is designated as “Generally Regarded as Safe and Effective” by FDA, which has received only 82 case reports (less than 2 per year) of adverse effects related to exposure to coal tar from 1975 to June 30, 2021. The most common reported effect has been itching (11 of 82 reports) followed by ineffectiveness (8 of 82), hypersensitivity (6 of 82), and a variety of diverse reactions with 5 or fewer reports, No death cases have been reported. For context, compare those data with an ubiquitous “Generally Regarded as Safe and Effective” substance, dextrose – a simple sugar. From 1969 to June 30, 2021, FDA has received 4,304 case reports (over 82 per year) of adverse effects related to exposure, including 501 death cases. faers.

While this alone should eliminate any concern that coal tar-based sealer is harmful, this product has been used for over six decades and there has not been a single study, properly researched, that has found any harmful impact to humans or animal life attributed to coal tar sealer. In fact, coal tar sealer has never been classified as a hazardous material by the Environmental Protection Agency (“EPA”) or as a known human carcinogen by the United State Department of Health and Human Services. In short, to date, there is no objective evidence that this product poses a danger to human health. To the contrary, consumer products have been used on the human skin and have not been proven to have a negative health impact.

The environmental “claim” is that the coal tar-based sealer releases Polycyclic Aromatic Hydrocarbons (PAHs) into the water and presents a contamination concern. PAHs are naturally occurring and are derived from many natural sources such as forest fires and decaying organic matter (such as leaves) to name a few. PAHs are also present in the environment from many human activities, some of which may include vehicle exhaust, heating of motor oils that occurs in internal combustion engines, electric power generation, wood fireplaces and stoves, asphalt pavement, roofing, grilling meat, shampoos, cosmetics and dyes. The New York Academy of Science studied sources of PAHs in New York-New Jersey harbor sediments, concluding that more than 1/3 of the PAHs present came from fireplaces, wood stoves, and other wood-burning sources. They concluded that less than 1% of PAHs in the harbor were possibly attributable to pavement sealers. PAHs in the environment is simply not significant from the application of a coal tar-based sealer.

While there is an alternative product, an asphalt-based sealer, the product is inferior in terms of effectiveness, especially in the Northeast. The differences between coal tar-based sealer and asphalt emulsion sealers is significant and, as a business owner, the use of the asphalt based product, can present significant customer dissatisfaction and, with the weather in the Northeast, simply does not last as long. Coal tar sealer has been around for over six decades, and coal tar was chosen over asphalt emulsion as a better raw material based on its ability to prevent the penetration from gas, oil, and other petroleum products from damaging the pavement, and the very hard film that coal tar forms over the pavement, making it very durable to heavy traffic. The performance of asphalt emulsions, on the other hand, are inconsistent for use as a raw material in sealer and are generally only as a substitute in areas where the coal tar-based product is not available. Asphalt emulsion sealers only last a couple of years, only one coat can be applied in a day, and wash out areas are very common. Coal tar-based sealers last longer, dry faster, even in colder weather, and prevent erosion and decay of the product. The fact that application of asphalt emulsion sealers requires warmer temperatures means that all New York businesses will be forced to limit the months in which they operate, with more severe impacts to revenue and employment opportunities for businesses the farther north in the state the business is located. 

When you are sealing large areas, like college campuses, government and supermarket parking lots and the like, continued sealing with asphalt sealer is costly because it must be done more often. Asphalt sealer simply does not provide that level of protection that a coal tar based sealer does. 

For these reasons, we urge the Governor to veto this legislation.

Very truly yours,

Kevin P. Quinn


View the official document HERE.

Legislation (S.2936a/A.5029a) Prohibits Use of Grade 6 Heating Oil Fuel in Buildings and Facilities in New York State  

Legislation (S.4095b/A.518a) Prohibits the Use and Sale of Pavement Products That Contain Coal Tar  

Governor Kathy Hochul today signed a package of legislation to protect public health and the environment and address harmful pollutants in New York State. Legislation S.2936a/A.5029a prohibits the burning of grade 6 fuel oil in buildings. Legislation S.4095b/A.518a bans the use and sale of pavement products that contain coal tar.    

"The harmful effects of climate change and pollution have only heightened the importance of protecting the well-being of New Yorkers and the preservation of our state's environment," Governor Hochul said. "This legislation takes important steps to ensure that New Yorkers have access to clean water and a breathable environment free of harmful pollutants." 

Legislation S.2936a/A.5029a will reduce the level of toxic air pollutants that are a result of burning grade 6 fuel oil in buildings. Grade 6 fuel oil contains high concentrations of contaminants, such as polycyclic aromatic hydrocarbons (PAHs), heavy metals, nitric oxide, sulfur dioxide, nickel, and black carbon that are released into the air when it is used to heat buildings. PAHs are proven human carcinogens, and sulfur dioxide and nitric oxide are known respiratory irritants. Studies show combustion of grade 6 fuel oil forms soot that when conveyed into the atmosphere create a source of air pollution and contribute to respiratory illness. Cost-effective alternatives for building heating are available in the market today to both reduce emissions and lower energy costs for building owners. The prohibition on the use of grade 6 fuel oil in buildings for heating goes into effect on July 1, 2023. 

Assemblymember Amy Paulin said, "The climate crisis is rapidly accelerating, and so must our response. This legislation takes aim at one of the prime causes of climate change and extreme weather:  air pollution. Fuel oil grade number 6 releases extremely harmful pollutants into our air. We must take every step possible to make sure that the air we breathe is clean and contributes to life.  This law is a positive step in that direction. I thank Governor Hochul for signing this important legislation into law and for her commitment to protecting our health and the health of our environment."   

Legislation S.4095b/A.518a prohibits the use and sale of coal tar-based pavement sealants that contain benzo(a)pyrene and other similar carcinogenic PAHs which are harmful to wildlife and have been classified by the U.S. Environmental Protection Agency to increase cancer risks, particularly in children. Recent studies conducted by the U.S. Geological Survey have shown that while levels of most common environmental pollutants in waterways are consistently declining, levels of pollutants found in coal tar sealants are increasing. These carcinogens leach into soils and waterways through runoff, posing a toxic threat to these waterways and aquatic life. Chemicals associated with coal tar-based sealants that are known carcinogens, such as PAHs, have also been identified in house dust at alarming levels. Safer and more environmentally friendly pavement products, like asphalt-based pavement sealants, that contain PAHs in substantially lower concentrations (typically 50 ppm total PAH) are on the market and readily available. The prohibition on the sale of these products will begin Nov. 8, 2022. The ban on the use of pavement products containing coal tar starts Nov. 8, 2023. 

Senator James Sanders Jr. said, "This new law will protect residents of Southeast Queens and all New Yorkers, especially children, and wildlife from the toxic effects of coal tar."   

Assemblymember Linda Rosenthal said, "After 10 long years of fighting, I am thrilled that my bill to ban coal tar-based sealants is finally law. Coal tar is bad for our health and our environment. It poses a grave danger to fish and aquatic wildlife, as well as children and pets, who are more likely to be exposed to chemicals in coal tar that settle near the ground. It's beyond time that New York follow the lead of other municipalities that have already abandoned coal tar in favor of safer alternatives, such as asphalt-based sealants. Thank you to the environmental organizations that fought alongside me for years to see this bill finally become law."   

Senior Manager of Government Affairs for Riverkeeper Jeremy Cherson said, "Thank you Governor Hochul for signing legislation championed by Assemblymember Rosenthal and Senator Sanders to ban the toxic and carcinogenic coal tar based pavement sealants. This harmful fossil-fuel based product is applied to driveways, parking lots, and even playgrounds across the state. These sealants enter our waterways, poisoning wildlife and tracking into people's homes, putting children at an elevated risk of toxic exposure. I thank our elected leaders for prioritizing clean water and public health by finally banning this toxic product and transitioning New York to less toxic, readily available alternatives."

Coal Tar Free America's Thomas Ennis said, "I am grateful for the persistence of the bill's sponsors and advocates. This bill represents the real, annual reduction of millions of pounds of toxins which affect our children and the environment. It truly is a benefit to all!"

Director of Clean and Healthy New York Bobbi Wilding said, "Coal tar is known to cause cancer. Coal tar sealants also release high amounts of toxic PAHs, which harm workers, and contaminate our environment. Simply put, these toxic chemicals don't belong on our driveways or roads. Thank you, Governor Hochul, for signing this bill into law, and thank you, bill sponsors Senator James Sanders, Jr. and Assemblywoman Linda Rosenthal for this important to step to eliminate harmful fossil-fuel based toxics from New York communities. This law will make New York cleaner and healthier." 

Conservation & Development Program Manager for the Sierra Club Atlantic Chapter Caitlin Ferrante said, "Dirty fossil fuels and their toxic byproducts disproportionately impact New York's most disadvantaged communities, as inferior fuels and materials contribute to greater rates of asthma, cancers and neuropathies. By phasing out the burning of grade 6 heating oil and banning the use of coal tar in paving sealants, Governor Hochul and the Legislature are keeping two of the most persistent sources of pollution out of neighborhoods that have historically struggled with finding affordable, less toxic alternatives. This is a good day for clean air and water, and a good day for New York's communities."

View the Word Document HERE.

DC Circ.'s Exploratory Data Ruling Is A Win For Transparency 

By Lawrence Ebner and David Kanter (October 5, 2021) 

When scientists employed by universities, nonprofit institutes or corporations publish scientific studies, they routinely make their underlying research data available to peer reviewers and anyone else who is interested.

A recent U.S. Court of Appeals for the District of Columbia Circuit decision¸  Pavement Coatings Technology Council v. United States Geological Survey,[1] confirms that federal government scientists should be no different.

They cannot shield their published work from professional, industry or public criticism by invoking Freedom of Information Act Exemption 5 — the deliberative process privilege — as a reason for refusing to disclose their exploratory research data.


Exploratory Data

Federal departments and agencies employ tens of thousands of scientists.

Every one of them uses the centuries-old scientific method when engaged in scientific research.

According to the Encyclopedia Britannica, the scientific method "is the technique used in the construction and testing of a scientific hypothesis ... a researcher develops a hypothesis, tests it through various means, and then modifies the hypothesis on the basis of the outcome of the tests and experiments."[2] 

Computer modeling has become a common way that scientists use the scientific method. They test hypotheses by constructing complex computer models of physical, biological or other systems, and then repeatedly run the model with various combinations of inputs to see how they affect the model's outputs. 

The question of whether federal government scientists' computer model runs are exploratory data exempt from disclosure under the FOIA Exemption 5 deliberative process privilege was at the heart of the Pavement Coatings case. 

This seemingly esoteric question actually has far-reaching implications for all federal government scientists, and for any company whose products or services may be affected by federal government research. 


The USGS Urban Lakes Study 

In the Pavement Coatings case, U.S. Geological Survey, or USGS, scientists obtained the agency's authorization to publish a modeling study that they designed and conducted to determine whether refined tar sealant, also known as sealcoat —a coal tar-based product used to prolong the service lives of asphalt surfaces such as residential driveways, parking lots and airport runways — is the principal source of environmentally ubiquitous, polycyclic aromatic hydrocarbons, or PAHs, in urban lakes. 

The study, published in 2010 with the USGS imprimatur,[3] indicated that the study authors had performed more than 200 computer model runs. But based on what the authors claimed were their four best modeling scenarios, they concluded that refined tar sealant accounts for at least 90% of the PAHs in urban watersheds. 

Relying primarily on the USGS urban lakes study, and on USGS' thinly veiled regulatory advocacy,[4] an increasing number of state and local governments have banned use of refined tar sealant. 


FOIA Request and Response 

In 2011, the Pavement Coatings Technology Council, which represents the producers and distributors of refined tar sealant, filed a FOIA request seeking, among other documents, printouts of the input and output data for the 200 computer model runs that were not analyzed or discussed in the published urban lakes study.

PCTC needed these data to determine whether USGS scientists had manipulated their computer model until they found input combinations — what the published study describes as the four best modeling scenarios — that supported their preconceived identification of refined tar sealant as the predominant source of urban PAHs.

More specifically, PCTC required the data not only to attempt to replicate the study conducted by USGS — an essential element in the scientific method — but also to determine whether USGS had cherry-picked the model runs used in its study in order to reach a desired conclusion. 

In response, USGS dumped thousands of pages of useless raw data on PCTC, but refused to produce the 200 urban lakes computer model runs, claiming that they represent exploratory analysis of data and fall within FOIA Exemption 5's deliberative process privilege. 

According to USGS, the withheld model runs were covered by this privilege because releasing them "would inhibit the ability [of USGS scientists] to freely explore and analyze data without concern for external criticism," and would "confuse the public on the approach and conclusions of the final published study." 


FOIA Litigation

In 2014 PCTC sued USGS in the U.S. District Court for the District of Columbia. The parties filed cross motions for summary judgment. After sitting on the case for three years, U.S. District Judge Ketanji Brown Jackson, subsequently elevated to the D.C. Circuit, finally issued a ruling, granting summary judgment to USGS.[5] 

PCTC appealed to the D.C. Circuit. Following briefing and oral argument, the court of appeals issued its decision in May 2021. In pertinent part, the court agreed with PCTC and held that USGS has not sustained its burden of demonstrating that the 200 withheld model runs qualify for Exemption 5's deliberative process privilege. 

The opinion explains[6] that Exemption 5 "covers deliberative, pre-decisional communications within the Executive Branch ... and was intended to protect not simply deliberative material, but also the deliberative process of agencies."[7] "To qualify for withholding, information must be both pre-decisional and deliberative."[8] 

The D.C. Circuit's panel opinion, authored by U.S. Circuit Judge Robert L. Wilkins, holds that the withheld model runs are neither predecisional nor deliberative. 


Not Pre-decisional

The court found that USGS "failed to introduce any evidence establishing what role the requested model runs played in its decision to publish the urban lakes study."[9]

Although USGS argued that the relevant decision for Exemption 5 deliberative process privilege purposes was USGS's decision on whether to authorize publication of the study, the court of appeals was "faced with a record devoid of evidence that any decision-maker at USGS considered the discarded model runs in determining whether and in what form to publish the urban lakes study."[10] 


Not Deliberative

The deliberative prong of the deliberative process privilege "focuse[s] on whether disclosure of the requested material would tend to discourage candid discussion within an agency."[11]

Based on the affidavits provided by USGS, the court found that "USGS failed to establish how or why disclosure of the model runs would chill scientists' use of exploratory model runs in the future or impact the accuracy or efficiency of the Survey's operations. The agency's affidavits contain no explicit statement that disclosure will harm the agency's decision-making."[12] 

As to "claims that releasing the model runs will enable criticism of USGS," the court emphasized that "criticism is not a recognized harm against which the deliberative process privilege is intended to protect."[13] Further, USGS "does not explain how, if these model runs are disclosed, scientists will cease to conduct model runs in the future or do them differently."[14] 



USGS, represented by the U.S. Department of Justice, contended that the working thoughts of a scientist, reflected by computer modeling exploratory analyses, fall within the deliberative process privilege.

As the D.C. Circuit confirmed in its Pavement Coatings decision, however, such intellectual exercises, i.e., the scientific method's trial-and-error process, are not legal or policy deliberations, which is what Congress intended to protect when it enacted Exemption 5.

Equally important, the Pavement Coatings decision makes it clear that federal government scientists are no different than nongovernmental scientists when it comes to making a published study's underlying data available to interested parties, including for the purpose of replicating a study to assess its validity and credibility.

Like every other published study, a federal agency's published studies should not be immune from criticism. Indeed, because government-sponsored studies often influence federal, state and local policies, as they have in the case of refined tar sealant, they should be subjected to heightened scrutiny. 

The Pavement Coatings decision advances this objective by precluding federal government scientists from hiding behind Exemption 5. Their ethical obligations should be no different from those of private or nonprofit sector scientists.

As a practical matter, the Pavement Coatings decision will deter government agencies from attempting to manipulate computer modeling in a way that supports individuals' preconceived results regulatory agendas.

Although the rigging of federal government studies is presumably rare, it can have undue influence on federal, state and local decision makers. This is exactly why FOIA was enacted — to shed light on Executive Branch activity and make government personnel, including government scientists, accountable. 

For this reason, when a lawyer is confronted with a federal government-conducted scientific study that is being used to disparage their client's products of services, they should not hesitate to file a FOIA request to obtain all relevant underlying data, including all computer model runs or other exploratory data.


Lawrence S. Ebner is the founder of Capital Appellate Advocacy PLLC.

David A. Kanter is a partner at Swanson Martin & Bell LLP.

Disclosure: Ebner and Kanter represented the Pavement Coatings Technology Council in the FOIA litigation discussed in this article.

The opinions expressed are those of the author(s) and do not necessarily reflect the views of the firm, its clients, or Portfolio Media Inc., or any of its or their respective affiliates. This article is for general information purposes and is not intended to be and should not be taken as legal advice.

[1] Pavement Coatings Technology Council v. United States Geological Survey, 995 F.3d 1014 (D.C. Cir. 2021)

[2] Encyclopedia Britannica, Scientific Method (Jan. 16, 2020), available at

[3] Van Metre, P.C., and Mahler, B.J. 2010, Contribution of PAHs from coal tar pavement sealcoat and other sources to 40 U.S. Lakes, Sci. Total Environ., 49: 334-344.

[4] See, e.g., USGS, Coal-Tar-Based Pavement Sealcoat, PAHs, and Environmental Health, available at; USGS Fact Sheet 2011–3011 (Feb. 2011), Coal-Tar-Based Pavement Sealcoat, Polycyclic Aromatic Hydrocarbons (PAHs), and Environmental Health, available at

[5] 436 F. Supp. 3rd 115 (D.D.C. 2019).

[6] 5 U.S.C. § 552(b)(5).

[7] 995 F.3d at 1021.

[8] Id.

[9] Id.

[10] Id.

[11] Id.

[12] Id.

[13] Id.

[14] Id. at 1023.