Coal-Tar-Based Pavement Sealcoat: Health and Environmental Overview

Barbara MahlerforOhio Environmental Council30 September 2014

2

NAWQA: Contaminant Trends in Lake Sediment

http://tx.usgs.gov/coring/index.html

Van Metre et al., 2005, Environ. Sci. & Tech.

PAHs >1,500 mg/kg in some small drainages in residential areas

Probable Effect Concentration (PEC) is 23 mg/kg

The first clue: City of Austin measures high PAH in stream sediment

4

5

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the urban environment

Benzo(a)pyrene

PyreneNaphthalene

6

PAHs in urban sources

• Fresh asphalt 1.5• Weathered asphalt 3• Fresh motor oil 4• Brake particles 16• Road dust 24• Tire particles 86• Diesel engine 102• Gasoline engine 370• Used motor oil 440

All concentrations in mg/kg (means of as many as 6 studies)

Pavement Sealcoat

• Asphalt Based ~ 50

•Coal-tar-based

~70,000

Coal-tar sealcoatCoal-tar sealcoat

Used motor oilUsed motor oil

=

Coal-tar-based sealcoat use

• 85 million gallons per year (per industry)

• 170 mi2, or 110,000 ac covered

9

Contaminants in sealcoat are mobile

10

Sealcoat PAH transport pathways

Mahler et al., ES&T, 2012

11

5.2<13

2.1

3,000

570

3,2003,400

3,200

1,300

Sealed pavement dustTotal PAH (mg/kg)

Unsealed pavement dust

Asphalt Coal tar

8.5<8.6

0.83

54

24

2147 30

Van Metre et al., 2009, Environ. Sci. & Tech.

Decker Lake2,090 people/km

SPAH 0.76 mg/kg

Lake Anne2,095 people/km

SPAH 17.0 mg/kg

13

3 ring 4 ring 5-6 ring

0

0.05

0.1

0.15

0.2

0.25

CT dust

Lake Anne

12 PAHs

Fra

ctio

n

0

0.05

0.1

0.15

0.2

0.25Gas vehicle

Lake Anne

12 PAHs

Fra

ctio

n

0

0.05

0.1

0.15

0.2

0.25 Coal

Lake Anne

12 PAHs

Fra

ctio

nEnvironmental Forensics: PAH fingerprints

r=0.60

r=0.68

r=0.94

Phe

Ant

h

Flu

Pyr

BaA

Chr

y

BbF

BkF

BeP

BaP

IP

BgP

Phe

Ant

h

Flu

Pyr

BaA

Chr

y

BbF

BkF

BeP

BaP

IP

BgP

Phe

Ant

h

Flu

Pyr

BaA

Chr

y

BbF

BkF

BeP

BaP

IP

BgP

14

PAH sources to U.S. urban lakes

Probable Effect Concentration

Van Metre and Mahler, 2010, STOTEN

PAH Trends in New Urban Lakes

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Effects on aquatic biota

Bommarito et al., 2010, EcotoxicologyBommarito et al., 2010, ChemosphereBryer et al., 2010, Environ. Poll.Bryer et al., 2006, EcotoxicologyScoggins et al., 2007, J. NABS

Fish kill, 17 July 2010Hodge’s Creek, North Carolina

Photos from Jupiter Images and Corbis Images, Inc.

23 ground-floor apartments

5.15.1

9.09.0

129129

4,7604,760

Median total PAH [mg/kg]

n=12 n=11

Mahler et al., 2010, Environ. Sci. Technol.

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Sealcoat and pre-school ingestion of PAHs

Photo courtesy of CLEARCorps Durham, NC

Williams et al., Environ. Poll., 2012

0

50

100

150

200

250B2-PAH dose (ng B2-PAH/kg body weight/

day)

Dietary ingestion

Non-dietary ingestion, low house-dust

ingestion (0.027 g/d)

Non-dietary ingestion, high house-dust

ingestion (0.101 g/d)

CT sealcoat

no sealcoat

CT sealcoat

no sealcoat

Baby aspirin =0.081 g

National Institute of Environmental Health Sciences, USA

“Coal tars and coal tar pitches are known to be human carcinogens…”

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Coal-tar sealcoat contribution to excess lifetime cancer risk (central tendency)

Williams et al., Env. Sci. Technol., 2012

Urban background CT sealed0.00E+00

2.00E-05

4.00E-05

6.00E-05

8.00E-05

1.00E-04

1.20E-04

soilhouse dust

Excess Lifetime Cancer Risk

1:10,000

38x increase in cancer risk

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What are effects onair quality?

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Fluxes (releases) from in-use CT-sealed lots

Flux = 88 mg/m2 hFlux = 1.4 mg/m2 h

Unsealed asphalt

Coal-tarsealed

Van Metre et al., Chemosphere, 2012

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Air trends after application

0 50 100 150 200 250 300 350 4000

10,000

20,000

30,000

40,000

50,000

Flux

time (days)

8 (

/2

)SPAH

flux

ugm

h

0 2 4 6 8 10 12 14 16 180

5,00010,00015,00020,00025,00030,00035,00040,00045,00050,000

day-night

regression

measured flux

time (days)

8 (

/2

)SPAH

ugm

h

R2=0.95

Van Metre et al., Chemosphere, 2012

SPAH ~2.5 g/m2

Van Metre et al., Atm. Environ., 2012

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Total PAH emissions during drying

Annual coal-tar sealcoat use 85 million gal

Area covered ~440 km2

Total PAH emitted during drying 2.5 g/m2

SPAH8 emissions/yr ~1,000 MgSPAH16 vehicle emissions, 2010 840 Mg*

* Shen et al., 2011

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PAH concentrations in Lady Bird Lake: Before and after the ban

1998 2000 2002 2004 2006 2008 2010 2012 2014 20160

2,000

4,000

6,000

8,000

10,000

12,000

TWN.1LBL.4LBL.1LBL.2Surficial bottom sedimentSeries11

Estimated date of sediment deposition

16

(

)

SPAH

microgramsperkilogram

2006 ban on coal-tar-based sealcoat

58% decrease

Van Metre and Mahler, ES&T, 2014

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Estimated PAH contribution to Lady Bird Lake sediment by source type

mean 1998-2006 mean 2012-140

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

woodoilcoalvehicleCT sealcoat

Ma

ss

of

PA

H (

mg

/kg

)

USGS Research on PAHs and Coal-Tar-Based Pavement Sealant

http://tx.usgs.gov/sealcoat.html

Barbara Mahler, bjmahler@usgs.gov(512) 927-3566

Peter Van Metre, pcvanmet@usgs.gov(512) 927-3506

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References cited in this presentation

• Van Metre, P.C., Mahler, B.J., Wilson, J.T. 2009. PAHs underfoot: Contaminated dust from coal-tar sealcoated pavement is widespread in the United States. Env. Sci. Technol., 43:20-25.

• Mahler, B.J., Van Metre, P.C., Crane, J.L., Watts, A.W., Scoggins, M., Williams, E.S. 2012. Coal-tar-based pavement sealcoat and PAHs: Implications for the environment, human health, and stormwater management. Env. Sci. Technol., 56:3039-3045.

• Van Metre, P.C., Mahler, B.J. 2010. Contribution of PAHs from coal-tar pavement sealcoat and other sources to 40 U.S. lakes. Sci. Total Environ. 409:334-344.

• Bommarito, T., Sparling, D.W., Halbrook, R.S. 2010. Toxicity of coal-tar pavement sealants and ultraviolet radiation to Ambystoma maculatum. Ecotoxicol. 19: 1147-1156.

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References cont.• Bommarito, T., Sparling, D.W., Halbrook, R.S. 2010. Toxicity of coal–

tar and asphalt sealants to eastern newts, Notophthalmus viridescens. Chemosphere 81: 187-193.

• Bryer, P.J., Scoggins, M., McClintock, N.L. 2010. Coal-tar based pavement sealant toxicity to freshwater macroinvertebrates. Environ. Poll. 158: 1932-1937.

• Bryer, P.J., Elliott, J.N., Willingham, E.J. 2006. The effects of coal tar based pavement sealer on amphibian development and metamorphosis. Ecotoxicol. 15: 241-247.

• Scoggins, M., McClintock, N., Gosselink, L., Bryer, P. 2007. Occurrence of polycyclic aromatic hydrocarbons below coal-tar-sealed parking lots and effects on stream benthic macroinvertebrate communities. J. NABS 26: 694-707.

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References cont.• Mahler, B.J., Van Metre, P.C., Wilson, J.T., Musgrove, M., Burbank,

T.L., Ennis, T.E., Bashara, T.J. 2010. Coal-tar-based parking lot sealcoat: An unrecognized source of PAH to settled house dust. Environ. Sci. Technol. 44: 894-900.

• Williams, E.S., Mahler, B.J., Van Metre, P.C. 2012. Coal-tar pavement sealants may significantly increase children's PAH exposures. Environ. Poll. 164: 40-41.

• Williams, E.S., Mahler, B.J., Van Metre, P.C. 2012. Cancer risk from incidental ingestion exposures to PAHs associated with coal-tar-sealed pavement. Environ. Sci. Technol. 47:1101-1109.

• Van Metre, P.C., Majewski, M.S., Mahler, B.J., Foreman, W.T., Braun, C.L., Wilson, J.T., Burbank, T. 2012. PAH volatilization following application of coal-tar-based pavement sealant. Atmos. Environ. 51: 108-115.

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References cont.

• Shen, H., Tao, S., Wang, R., et al. 2011. Global time trends in PAH emissions from motor vehicles. Atmos. Environ. 45: 2067-2073.

• Van Metre, P.C., Majewski, M.S., Mahler, B.J., Foreman, W.T., Braun, C.L., Wilson, J.T., Burbank, T., 2012. Volatilization of polycyclic aromatic hydrocarbons from coal-tar-sealed pavement. Chemosphere 88: 1-7.

• Van Metre, P.C., Majewski, M.S., Mahler, B.J., Foreman, W.T., Braun, C.L., Wilson, J.T., Burbank, T., 2012. PAH volatilization following application of coal-tar-based pavement sealant. Atmos. Environ. 51: 108-115.

• Van Metre, P.C., and Mahler, B.J. PAH concentrations in lake sediment decline following ban on coal-tar-based pavement sealants in Austin, Texas. Env. Sci. Technol. http://dx.doi.org/10.1021/es405691q