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Polycyclic Aromatic (PAHs) in Urban

Purpose of this document Recent studies by the US Geological Survey (USGS) and several universities indicate that PAHs are an important emerging contaminant in urban waterways, including the rapidly growing metro areas of North Carolina. This document offers an overview of recent studies of potential sources for PAHs in urban waterways and provides information on management strategies for reducing the risks of PAH impacts on aquatic ecosystems.

What are PAHs? weight PAHs tend to be more stable, persist in the PAHs, or Polycyclic Aromatic Hydrocarbons, environment longer, are less soluble, and consist of hundreds of separate chemicals that are more toxic. Exposure to UV light can increase occur together as . PAHs are naturally of PAH compounds and increase toxicity occurring and are concentrated by the - to some aquatic species. (Garrett 2004) ing of and the incomplete burning Scientific studies have documented detri- of -containing materials (such as , mental impacts from PAHs on aquatic organ- , and ). PAHs are a wide and varied isms. Examples include: group of compounds whose sources include tire • In Austin, Texas biological studies revealed particles, leaking motor , vehicle exhaust, a loss of species and decreased number of crumbling , atmospheric , in streams with PAHs present coal , and parking lot sealants, as (Van Metre 2005) as sources inside the home (such as tobacco , wood smoke, grilling or - ring ). PAHs are also commonly found in particulate of . PAHs tend to adhere to , attaching readily to sedi- ment particles and leading to elevated con- centrations in sediments. PAHs have complex chemical structures (see figure 1), so they do not break down easily and are persistent in the environment.

Why should we be concerned about PAHs? Some PAHs are known to be toxic to aquatic Figure 1. The chemical structure of Benzo[a]- , a carcinogenic PAH. animals and . Generally, higher molecular Urban Waterways

• In Puget Sound, Washington’s and immunity. PAHs generally have their tendency to attach to particles Ambient Monitoring Program a low degree of acute toxicity to rather than dissolve in water. USEPA (WA DFW) found PAHs were humans, meaning harmful effects has a maximum contaminant level associated with: through a single or short-term (MCL) for PAH in water of – Liver lesions and tumors in fish, exposure are minimal. Mammals 0.2 ppb of . – Liver problems leading to repro- absorb PAHs through inhalation, risks from consuming fish ductive impairment, contact with skin, and ingestion (EPA are thought to be low because PAHs – Malformations in fish embryos Ecological Toxicity). Recent research do not readily bioaccumulate within and embryonic cardiac by USGS raises concerns about expo- vertebrates. Bivalve mollusks read- dysfunction, sure of children through inhalation ily accumulate PAHs in their tissues, – Reduction in aquatic (eel- and ingestion of house dust con- however. (Garrett 2004). The U.S. grass) that provide fish habitat. taminated by PAHs that have abraded and Drug Administration (FDA) • Benzo(a)pyrene was lethal to newt from nearby parking lots sealed with has not established standards govern- larvae at low levels (50 parts per coal sealant (Mahler 2010).The ing the PAH content of foodstuffs billion) (Fernandez and Lharidon International Agency for Research on (USDHHS 2009), with the excep- 1994) Cancer (IARC) classifies two PAHs tion of issuing levels of concerns for • A 2006 study showed develop- as probable human and PAHs in fish and shellfish following mental delays and deformities three as possible human carcinogens. the . The in with exposure to The US EPA classifies seven PAHs as European Union has set a maximum pavement sealants (which probable human carcinogens, while allowable level of benzo(a)pyrene for contain PAHs), with larger levels the state of California classifies 25 bivalve mollusks on the market (EU of sealant causing greater devel- PAHs as carcinogenic PAHs (cPAHs). Commission 2006). opmental problems and death. The IARC and EPA both classify (Bryer 2006) benzo(a)pyrene and benz(a)anthra- How do PAHs get into streams, • Brown bullhead catfish and cene as probable human carcinogens. lakes, , and the ? English sole have been docu- Benzo(a)pyrene is often used as an PAHs enter water bodies through mented as among the more environmental indicator for PAHs. atmospheric deposition and direct sensitive bottom-dwelling fish to PAHs in streams and lakes are releases of substances through petro- the carcinogenic effects of PAHs thought to rarely pose a human health leum spills and use, municipal - (Garrett 2004). risk via drinking water because of plants, industrial • Crustaceans and fish metabolize PAH compounds more efficiently than do bivalve species such as mussels, clams, and oysters, which readily accumulate PAHs (Garrett 2004). • Interactions between aquatic organisms and PAHs in sediment are complex, depending on many factors including—but not limited to—sensitivity of species, stage of development, bioavailability of PAHs, and exposure to (Garrett 2004).

The most significant effect of PAH toxicity to humans is cancer. Increased incidences of , skin, and bladder cancers are associated with occupational exposure to PAHs (USDHHS 2009). Other non-cancer effects are not well understood, though they may include adverse effects on reproduction, development, Figure 2. Bivalves, including oysters, readily accumulate PAHs in their tissues.

2 Polycyclic Aromatic Hydrocarbons (PAHs) in Urban Waters discharges, runoff, landfill leachate, and runoff. Many studies have been conducted recently regarding runoff sources of PAHs. Rainfall runs off parking lot and surfaces, transporting PAHs that originate from tire particles, leaking , vehicle exhaust, crumbling asphalt, atmospheric deposition, , and parking lot seal- . PAHs attach readily to sediment particles, leading to high concentra- tions in bottom sediments of water bodies. A literature review on tire wear particles in the environment indicates that the high aromatic (HA) generally used in tires contain PAHs. Zinc, PAHs, and a suite of other organic compounds (including phthalates, benzothiazole derivatives, Geological Survey phenolic derivatives, and fatty ) found in tires are noted to likely cause Figure 3. Sealant is applied to a parking lot. toxicity in aquatic organisms. Because of this toxicity, the European Union Austin study, parking lots with coal curing of the test plots at UNH con- has banned sales of tires that contain tar sealcoat yielded an average PAH tributed to the high concentrations HA oils. This is estimated to reduce concentration of 3,500 mg/kg on of PAHs found in runoff (LeHuray future PAH emissions from tires by particles in runoff, 65 times more 2009). The results of analyzing sources 98 percent. (Wik & Goran 2009) It is than from unsealed lots in simulated of PAHs in sediment cores from 40 unclear whether tire manufacturers events. The average concentra- lakes across the U.S. has led some will continue to sell tires containing tion of PAHs in particles washed off USGS researchers to conclude that HA oils in the United States. asphalt-based sealants was 620 mg/kg, coal tar sealcoat likely is the primary about 10 times higher than the aver- cause of upward trends in PAHs in Coal tar-based sealants age concentration from the unsealed response to urban sprawl in much of Research from the USGS in the parking lots. The other sources of the United States. (Van Metre 2010) of Austin, Texas (Van Metre et al PAHs previously mentioned, besides 2005), nine other (Van Metre sealants, can account for the PAH Attributing sources of PAHs et al 2009)), and from the University concentrations found off the to uses of New Hampshire (Mahler et al unsealed parking lots (Van Metre Determining the sources of PAHs in 2012) indicates that coal tar-based 2005). A recent UNH study compared streams is a complex process and is sealants (also called sealcoats) on runoff from lots they sealed with both usually done by evaluating the ratios parking lots likely contribute sig- types of sealants to an unsealed lot. of individual compounds found nificant amounts of PAHs to water- They found both types of sealcoat led in stream sediment. USGS is cur- ways via stormwater runoff. These to a rapid increase in PAH concentra- rently conducting research in North sealants (CTS) are made of coal tar, tions in the initial runoff—up to 5,000 Carolina to examine PAH concentra- a product created during the cok- parts per billion (ppb), compared to tions in bridge deck runoff. Research ing of coal. This type of sealant and 10 ppb released from the unsealed on metals and PAHs in Santa Monica, another sealant made from asphalt lot. Concentrations decreased after California, found that both com- are used to prevent damage to asphalt several rainstorms. The PAH concen- mercial and industrial land uses and surfaces. Friction from automobile trations in the sediments immediately provided higher concentrations tires causes the sealcoat to flake off. downstream of the coal tar sealed of both metals and PAHs than single- These flakes are then scrubbed from lot increased by nearly two orders of family residential land uses (Lau & the surface during a rain event and magnitude within the first year (14). Strenstrom 2005). A study of the rela- into storm-drain networks, and then The Pavement Coating Technology tive importance of individual source flow into lakes and streams. In the Council maintains that improper areas in contributing to contaminants

3 Urban Waterways in an urban watershed in Marquette, Michigan, found parking lots to be a major contributor (~64 percent) of PAH compounds (Steuer et al 1997). The USGS study of bridge decks may be the first North Carolina study evaluating land-use contributions to PAH concentrations in water- ways. Future research in N.C. could seek to attribute sources of PAHs to land uses, including commercial and industrial land uses, roads, and parking lots. Estimating PAHs from various land uses could be calculated using methods used in the Marquette, Michigan, study.

At what concentration do PAHs affect in-stream aquatic organisms? Figure 4. Burnt Mill Creek is an urban stream in NC that is impaired by PAHs.

The sediment quality guideline, known as the Probable Effect echo studies from around the UNC-Wilmington/NC State Concentra­tion (PEC), represents world (Garrett 2004). University research project found the concentration of a contami- • Levels of PAHs have been indi- high levels of PAHs through- nant in bed sediment expected cated by NCDWQ as the lead out the creek at six sites for four to adversely affect bottom- impairment of Burnt Mill yearly sampling events. Zinc dwelling organisms. The PEC Creek, an urban stream in levels, which can be used as indi- for PAHs is 22.8 mg/kg. Wilmington, N.C. A subsequent cators of tire-wear particles, were

How do PAHs affect streams in North Carolina? The North Carolina Division of (NCDWQ) does not moni- tor the presence of PAHs in streams. Laboratory analysis for PAHs is much more expensive than for commonly measured pollutants like and , and North Carolina has no official standard for PAHs. Special studies do sometimes include PAH analysis, such as: • The USGS National Water Quality Assessment found a strong cor- relation between PAHs and urban intensity across the country, including 30 watersheds of the Raleigh-Durham metro area. The highest concentrations of PAHs in sediments at the bottom of water bodies were found in watersheds with increasing development and motor vehicle traffic. These results Figure 5. This bioretention cell reduced PAHs in runoff flowing through it.

4 Polycyclic Aromatic Hydrocarbons (PAHs) in Urban Waters

low at these same sampling sites, indicating that tire-wear particles from parking lots may be ruled out as major contributors to this watershed’s PAH toxicity prob- lems. (Perrin et al 2008)

Reducing risk of PAH contamination from stormwater runoff Use asphalt sealants or latex modi- fied asphalt sealants if sealing an asphalt surface is necessary. Asphalt or latex modified asphalt sealants contain PAH concentrations of about 5 percent, whereas coal tar based- sealants contain between 20 to 35 percent PAHs. Homeowners should read and follow directions closely for applying and curing the sealant, or consider hiring a trained professional. professionals note that coal Figure 6. A parking lot with interlocking pavers in Swansboro, N.C. tar-based sealants perform better than asphalt sealants at protecting parking concentration of PAHs from parking Recommenda­tions for disposing of lots from and UV degrada- lot runoff after treatment by a veg- sediments from BMP maintenance tion and wear, and they are focusing etated bioretention cell (Wright et al are included in the NCDENR research and development on creating 2009). A University of Maryland Stormwater Best Management­ higher-performing asphalt sealants study indicates that a shallow biore- Practice Manual. (WECO 2009). tention cell design is adequate for Create parking lots with surfaces A number of national home- removing PAHs, with mitigation other than asphalt, such as improvement and hardware stores focused on the top surface layer near or permeable pavement. The upfront have discontinued coal tar-based seal- the inlet where sediment accumula- costs for installing concrete are higher ants (Hogue 2007), so homeowners tion occurs. PAHs were found to be than those for installing asphalt park- who purchase sealant at these stores degraded through indirect ing lots. Long-term maintenance is are using asphalt or latex modified processing of microbial-- likely lower, however, since concrete asphalt sealants. That said, coal tar- interactions with the rhizosphere parking lots do not require sealants based sealants are readily avail- (the area of soil 1 mm from the plant and have a longer lifespan. The lighter able for purchase online and through root). (Diblasi, et al 2009). Since surface of concrete also provides a ben- wholesale and commercial suppliers, PAHs are often sediment-bound, efit of reducing the urban heat and they are produced and used in stormwater practices that reduce effect by absorbing less solar North Carolina (WECO 2009). sediment (such as bioretention, than darker surfaces (EPA 2008). Intercept and manage stormwa- stormwater , wet ponds, Pervious pavement, including inter- ter runoff from all parking lots and swales, and filter strips) may be locking pavers and permeable concrete, roads. PAH compounds can be important for reducing PAH concen- are alternatives to concrete and asphalt removed from aquatic systems or trations. Some proprietary stormwa- that reduce stormwater runoff and pol- transformed to new compounds by ter management devices, such as inlet lution (see AG-588-14). Although per- volatilization (of low molecular filtration devices, are marketed as vious pavement is the most expensive weight PAHs), photo oxidation, and reducing organic toxins, including of the paving options when consider- (Garrett 2004). PAHs. Regular maintenance of these ing only construction cost, regulatory Installing bioretention cells (also and all stormwater management credit from NCDENR for reducing called rain gardens) to treat parking devices is integral for continued imperviousness and attenuating peak lot runoff reduces PAHs in stormwa- pollutant removal (see AG-588-7 for runoff with appropriate design can off- ter, likely through biodegradation. further discussion on maintenance). set the cost. This may allow permeable An NC State study in Wilmington, Proper disposal of contaminated pavement to replace or reduce the size N.C., found a reduction in the sediment is a concern. of other stormwater practices.

5 Urban Waterways

Pollutants in Streams to Urbanization in Six Metropolitan Areas of the United States.” U.S. Department of the Interior, U.S. Geological Survey. Scientific Investigations Report 2007-5113. Bryer, P.J., J.N. Elliot, J.N., E.J. Willingham. 2006. “The effects of coal tar-based pavement sealer on amphib- ian development and metamorpho- sis.” Ecotoxicology, 15. New York: Springer Science+ Media. European Union. Commission Regulation No. 1881/2006 of 19 December 2006. (2006). “Setting maximum levels for certain contami- nants in foodstuffs.” DiBlasi, C.J., H. Li, A.P. Davis, U. Ghosh. 2009. “Removal Figure 7. A permeable pavement lot in Wilmington, N.C. and Fate of Polycyclic Aromatic Pollutants in an Urban Summary Management Trust Fund and the US Stormwater Bioretention Facility.” PAHS have been identified by USGS Environmental Protection Agency, Environmental Science & Technology, as an important emerging contami- CWA Section 319. 43(2) Washington, D.C.: American nant in the waterways of growing Early versions of the fact sheet Chemical Society Publications. metropolitan areas of the United were reviewed by Sharon Fitzgerald, Environmental Protection States, including those of North U.S. Geological Service, and David Agency. 5 Superfund. Carolina. Negative impacts from Mayes and Jennifer Butler, City of Ecological Toxicity Information. PAHs in waters have been well docu- Wilmington Stormwater Services Online at: http://www.epa.gov/ mented in fish, amphibians, bivalves, Division. R5Super/ecology/html/toxprofiles. and benthic macro-. Peer review of this fact sheet htm#pahs Human-health impacts from drink- was conducted by Bill Hunt, P.E., Fernandez, M. , J. Lharidon. ing water and short-term contact with Ph.D., associate professor, and Mike 1994. “Effects of light on the cytotox- contaminated waters are thought to Burchell, P.E., Ph.D., assistant profes- icity and Genotoxicity of Benzo(a) be minimal, though consumption of sor, Department of Biological and pyrene and an effluent contaminated bivalves is a concern. Agricultural , North in the newt.” Environmental and There are many potential sources Carolina State University; and Mitch Molecular Mutagenesis. Volume 24 of PAHs to urban waters, though a Renkow, Ph.D., professor, Department Issue 2. Wiley-Blackwell. growing body of research has high- of Agricultural and Garrett, C.L. 2004. Priority lighted the use of coal tar based park- Economics, North Carolina State substances of interest in the Georgia ing lot sealant as a major contributor. University. Basin: profiles and background Strategies for reducing the risks of information on toxics issues: PAHs to aquatic ecosystems include References Report of the Canadian Toxics Work eliminating the use of coal tar-based Ahrens, M.; C.Depree; Olsen. G. Group. GBAP Publication no. EC/ sealants on parking lots, intercepting “Environmental forensics: GB/04/79. Online at: georgia.basin@ and managing runoff from parking the case of the contaminated streams”. ec.gc.ca lots and roads, and creating parking 2007. Water & 15(1). Hogue, C. 2007. “Dustup Over lots with materials that don’t require Online at www.niwa.co.nz. Pavement Coatings.” Chemical sealing such as concrete or permeable Bryant, W.L., S.L. Goodbred, & Engineering News. Volume 85, pavement. T.L. Leiker, L. Inouye, B.T. Johnson. Number 7. pp. 61-66. Washington, 2007. “Use of Chemical Analysis and D.C.: American Chemistry Society Acknowledgments Assays of Semipermeable Membrane Publications. Funding for this fact sheet was Devices Extracts to Assess the Lau, S-L. , M.K.Stenstrom, 2005. provided by the NC Clean Water Responses of Bioavailable Organic “Metals and PAHs adsorbed to street

6 Polycyclic Aromatic Hydrocarbons (PAHs) in Urban Waters particles.” Water Research. Volume Perrin, C.A.; Wright, J.; W.F. Van Metre, P.C., B.J. Mahler. 2010. 39, Issue 17, October, 4083-4092. Hunt, P.G. Beggs, M. Mallin, M. “Contribution of PAHs from coal–tar : IWA Publishing. Burchell. 2008. Restoring the Burnt pavement sealcoat and other sources LeHuray, Anne P. 2009. Pavement Mill Creek Watershed through to 40 U.S. lakes”. Science of the Total Coatings Technology Council. Letter Stormwater Management and Environment 409 (2010) 334–344. to author. October 20, 2009. Community Development. Final EPA Elsevier publications. MacDonald, D.D., C.G. Ingersoll, 319 Report to NC Division of Water Van Metre, P.C, B.J. Mahler, J.T. T.A. Berger. 2000. “Development Quality. Online www.ncsu.edu/ Wilson. 2009. “PAHs Underfoot: and evaluation of consensus-based WECO/burntmill Contaminated Dust from Coal tar sediment quality guidelines for Richardson DC. 2006. “Parking Sealcoated Pavement is Widespread freshwater ecosystems.” Archives lot sealants: on the trail of urban in the United States.” Environmental of Environmental Contamination PAHs.” Stormwater, The Journal for Science and Technology 43 (1), pp and Toxicology. 39:20-31. New York: Quality Professionals, 20–25. Washington, D.C.: American Springer Science+Business Media. 7 (4). Santa Barbara, CA: Forester Chemistry Society Publications. Mahler, B.J., P.C.Van Meter, J.T. Media Inc. Van Metre, P.C, B.J. Mahler, Wilson, M. Musgrove, T.L. Burbank, SeaGrant New Hampshire. M. Scoggins, P.A. Hamilton. 2005. T.E. Ennis, T.J. Bashara. “Coal tar- Pavement Sealcoat a Source of Toxins Parking lot sealcoat- A major source based parking lot sealcoat: An unrec- in Stormwater Runoff. Online at: of PAHs in urban and suburban ognized source of PAH to settled http://www.seagrant.unh.edu/news- environments: U.S. Geological Survey house dust.” Environmental Science sealcoat.htm Fact Sheet 2005-3147, 6 pp. and Technology. 2010. 44, Pp 894- Steuer, J.,W. Selbig, N. Washington Department of Fish 900. Washington, D.C.: American Hornewer, J. Prey. 1997 . “Sources of and , Puget Sound Ambient Chemistry Society Publications. Contamination in an Urban Basin in Monitoring Program. Online at http:// Mahler, B.J.; P.C. Van Metre, T.J. Marquette, Michigan, and an Analysis www.wdfw.wa.gov/fish/psamp/ Bashara, D.A. Johns. 2005. “Parking of Concentrations, Loads, and Data Wik, A.,G. Dave. January 2009. lot sealcoat- An unrecognized source Quality“. U.S. Geological Survey “Occurrence and effects of tire wear of urban PAHs“. Environmental Water Investigations particles in the environment – A criti- Science and Technology, V. 39, Report 97-4242; U.S. Geological cal review and an initial risk assess- p. 5560-5565. Washington, D.C.: Survey: Denver, CO,. ment.” Environmental Pollution, American Chemistry Society U.S. Department of Health Volume 157, Issue 1. Pages 1-11. Publications. and Human Services, Agency for Elsevier publications. North Carolina Department Toxic Substances and Disease Wright, J.D.; Hunt,W.F.;Burchell, of Environmental and Natural Registry (ATSDR). July 1,2009. M.R.; Perrin, C.A.;McCoy, E.R. Resources. 2007. Stormwater Best Toxicity of Polycyclic Aromatic Implementation and of Management Practices Manual. Hydrocarbons (PAHs). Case Studies stormwater best management prac- Raleigh, NC: Division of Water in Environmental Medicine. Online at tice retrofits in Wilmington, NC. Quality. http://portal.ncdenr.org/web/ http://www.atsdr.cdc.gov/csem/pah/ Proceedings of World Environmental wq/ws/su/bmp-manual pah_where-found.html and Congress 2009: North Carolina Department U.S. Department of Health and Great Rivers 2009;342():5293-530. of Environmental and Natural Human Services, Public Health Kansas City, MO. Resources. 2004. “Assessment Report: Service. Agency for Toxic Substances Environmental Protection Biological Impairment in the Burnt and Disease Registry (ATSDR) Agency. 2008. Reducing Heath : Mill Creek Watershed”. Division ToxFAQ for Polycyclic Aromatic Compendium of Strategies Cool of Water Quality, Collaborative Hydrocarbons (PAHs). Online at: Pavements. Available at: www.epa.gov/ Assessment of Watersheds and http://www.atsdr.cdc.gov/tfacts69. heatisld/mitigation/pavements.htm Streams (CAWS) Project. html WECO Focus group. Parking Food and Drug Agency. Protocol Lots and Water: A focus group for for Interpretation and Use of Sensory professionals in the business of Testing and Analytical Chemistry building and/or sealing parking lots. Results for Re-Opening Oil-Impacted August 17, 2009. Wilmington, NC. Areas Closed to Seafood Harvesting Sponsored by NC State University Due to The Deepwater Horizon Oil Cooperative Extension and City of Spill. June 2010, Updated November Wilmington. 2010.

7 Urban Waterways

Prepared by

Christy Perrin, Extension Associate, Program Manager of Watershed for Communities and Officials Department of Agricultural and Resource Economics North Carolina State University

Published by NORTH CAROLINA COOPERATIVE EXTENSION SERVICE

Distributed in furtherance of the acts of Congress of May 8 and June 30, 1914. North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, or disability. In addition, the two Universities welcome all persons without regard to sexual orientation. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.

10/12—VB/BW 13-CALS-3429 AG-588-25

NC STATE UNIVERSITY

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