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Opposition to Proposed Ordinance: Technical/Scientific Elements

PCTC disputes Austin's ban on coal tar sealants, citing incomplete studies and disputing PAH sources. The PCTC action plan includes acquiring data, toxicological research, and challenging USGS findings.

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Opposition to Proposed Ordinance: Technical/Scientific Elements

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  1. Opposition to Proposed Ordinance: Technical/Scientific Elements On Behalf of – Pavement Coatings Technology Center Robert P. DeMott, Ph.D., DABT Environmental Toxicologist rdemott@environcorp.com Addendum (slides 2-7) G.C. Dubey, STAR, INC.

  2. CITY OF AUSTIN (COA) passed a ban on the use of coal tar sealants, effective Jan. 1, 2006 COA reached the following conclusions: • High concentrations of Polycyclic aromatic hydrocarbons (PAH’s) are present in sediments within the Austin waterways. • Primary source being the parking lots sealed with coal tar sealers. • Ban on coal tar sealers will significantly change water quality and protect organisms in the streams.

  3. PCTC STRONGLY DISPUTES COA’s FINDINGS:REASONS • The COA Study is incomplete. It did not conclusively prove that PAH,s found in the sediments. • Current publications on urban sources of PAH’s (including USGS’s publications) do not support COA’s conclusions. • Overall PAH’s levels in sediments in Austin are NOT high relative to other cities- USGS stated after the ban.

  4. PCTC STRONGLY DISPUTES COA’s FINDINGS 4.All PAH’s sources and contribution should be quantitatively examined for COA’s claim. • 2800 lbs. (1300 kg) of PAH are produced by COA traffic is 130 times greater than PAH’s from water run off from parking lots. – EPA & Texas transportation Institute. • Risks are greater for alternative sealer i.e. asphalt based sealer (A/E) will abrade and deteriorate faster.

  5. PCTC STRONGLY DISPUTES COA’s FINDINGS 7. COA did not consider asphalt based sealers as a source of PAH’s. 8. Adverse Economic Impact, using a less durable product (A/E) was not considered by COA.

  6. PCTC’s RESPONSE & ACTION PLAN 1. GET ALL THE DATA ON AUSTIN STUDIES (under Texas Open records Act.) 2. Article in Feb/March issue of Pavement magazine- PCTC’s position, and critique on Austin’s FUZZY science. 3. PCTC’s own PAH studies on Sediment sampling & Source characterization, and national publication & presentation.

  7. PCTC’s RESPONSE & ACTION PLAN 4. Toxicological research- Bio-availability of coal tar sealer particles and the specific effects on sediment dwelling amphibians and invertebrates. 5. Challenge USGS’s findings (“formal request for corrections” procedure. 6. Keep a tab on the PAH noise in Washington- a consultant will monitor. 7. Tell our side of the story- Hire a Public Relations (PR) firm.

  8. Overview • Scientific evaluation incomplete • Current publications contradict anticipated benefit of ordinance • Specific comparison sources and PCTC sediment study should be considered • Substitution risk should be specified quantitatively

  9. CITY OF AUSTIN (COA) passed a ban on the use of coal tar sealants, effective Jan. 1, 2006 Based on studies by: • COA’s Watershed protection & Development Review dept. (WPDRD) • United Sates geological Survey (USGS)

  10. Background -- PAHs Are Everyday Urban Constituents • From all combustion processes • Vehicle exhaust and power generation unchallenged predominant urban sources overall • Present in construction materials • Asphalt pavement; roofing; pavement sealers • Used in consumer products • Shampoos; dyes; medicines; plastics; mothballs • All chemicals are toxic –managing exposure differentiates “pollution” from dandruff control

  11. “The presence and distribution of PAHs in the environment are largely a product of the incomplete combustion of petroleum, oil, coal, and wood. Anthropogenic sources such as vehicles, heating and power plants, industrial processes, and refuse and open burning are considered to be the principal sources to the environment.” Van Metre, Mahler and Furlong, 2000. Urban Sprawl Leaves its PAH Signature. ES&T 34: 4064.

  12. Vehicles in Austin Emit More Than A Ton of PAHs/Year • USEPA -- PAHs in vehicle exhaust 3.7 x 10-7 pounds/mile • Texas Transportation Institute -- 20.8 million miles traveled per day in Austin • Exhaust contributes 2800 pounds (1300 kg) per year of PAHs U.S. EPA. 1998. Locating and Estimating Air Emissions from Sources of Polycyclic Organic Matter Texas Transportation Report. 2005. The 2005 Urban Mobility Report.

  13. Shampoos and Topical Gels • Denorex Shampoo • 12.5% coal tar solution for dandruff control • Each bottle contains 5400 mg of PAH • Product contains “percent levels” of PAHs, yet environ-mental loading managed, not perceived to pollute

  14. Austin Waterbody PAH Levels Not Extraordinary Sediment measurements typical – sources:Van Metre et al., 2000. ES&T 34:4064; Geismer report. COA unpubl. results.

  15. State of Science • USGS/City team published report documenting coal tar constituents can be washed off coal tar-based pavement sealer • City presented unpublished results on: • aquarium testing of midges, scuds • General stream quality around parking lots • No specific analysis of proportionate input from various PAH sources

  16. USGS/City 2005 Study • Mahler, Van Metre, et al. 2005.Parking lot sealcoat: An unrecognized source of urban polycyclic aromatic hydrocarbons.ES&T 39:5560 • Determined PAH amount washed from coal tar pavement sealer • Identified PAHs in runoff from in-use parking lots • Could NOT detect different PAH input from coal tar sealer vs. asphalt sealer in-use lots

  17. Recent Study Results • Average PAH yield -- first 3 washings of freshly sealed pavement is 0.046 mg/m2 Mahler, Van Metre, et al., 2005 -- Table S-2 • For residential driveway (540 sf) = 2.3 mg • After three simulated rainfall events, average yield drops 10-fold to 0.004 mg/m2Mahler, Van Metre, et al., 2005 -- Table S-2 • City-wide, amounts to 9.8 kg of PAH per year85 rain events, 2% of area as freshly sealed lots

  18. Source: Mahler, Van Metre et al. 2005 Source: Van Metre & Mahler 2003 Eyedropper Drop Used Motor Oil 1800 sf Home Rooftop Runoff Sealer Washoff Driveway Auto Exhaust 15 mi. 3 Drops Denorex

  19. Sealer Washoff 1 acre lot 2 large Retail Rooftops Runoff 5 sec. - Austin Vehicle exhaust 1 tsp Used Motor Oil ½ oz. Denorex Source: Mahler, Van Metre et al. 2005 Source: Van Metre & Mahler 2003

  20. Limits of 2005 USGS Study • No comparison to: • previously measured PAH loading settling from air • rooftop runoff to drainage features • No specified proportions of overall PAH loading to waterways • Not challenging value/validity of study, these elements simply not included

  21. Beyond Study Findings • Following cited to substantiate pavement sealer releasing “majority” of PAHs to environment “The average yield of PAHs from sealed parking lots is 50 times greater than that from unsealed lots. PAH assemblages and estimated loads further suggest that sealed parking lots could be dominating PAH loading in watersheds with commercial and residential land use.” Mahler, Van Metre, et al., 2005. Parking Lot Sealcoat: An Unrecognized Source of Urban PAHs.ES&T 39:5560 • No mention of non-parking lot input • No data to support suggestion –“This issue needs a lot more research.”P. Van Metre, 16 November 2005, Society for Environ. Tox and Chem

  22. Unpublished Aquarium Tests • Selected doses well above known lethal levels – outcome pre-determined by design • Not yet meet scientific standards requiring description of materials used • Source of test material not disclosed • Verbal description of sealer “turning to powder” inconsistent with normal properties • Lack of full chemical characterization precludes repeat by others

  23. Unpublished Stream Surveys Parking lot/roadway drainage contains many chemicals besides PAHs • Example: Copper from brake linings highly toxicto stream life – subject of other research groups • Reductions in stream quality routinewith urban drainage • Drought/scour cycles wash outmany Austin creek stretches

  24. Urban Stream Impacts Already Established • USGS documented non-sealer PAH and metal runoff sufficient to impact stream quality “Concentrations of zinc, lead, pyrene, and chrysene on a mass per mass basis in a majority of rooftop samples exceeded the established sediment quality guidelines for probable toxicity of bed sediments to benthic biota…. Metal roofing was a source of cadmium and zinc and asphalt shingles a source of lead.” p.1741;Van Metre and Mahler 2003. Chemosphere 52: 1727.

  25. Benefit Projection Contradicted by Other Research “Based on the USGS (United States Geological Survey) study it's pretty apparent that these sealants, particularly the coal tar sealants, are dumping a large portion, probably the majority of the PAHs that we see in the Austin area” – News 8 report, 9 Nov 2005 • 2005 USGS study does not mention fallout from air and other PAH sources • Previous publications by same USGS research team, however, measured other contributions larger than projection from coal tar sealer

  26. Airborne Transport Measured • Van Metre & Mahler, 2003. The Contribution of Particles Washed from Rooftops to Contaminant Loading to Urban Streams. Chemosphere 52: 1727-1741. • Roofs receive 9.2 g/m2 PAH from air • Percentage of watershed covered by roofs measured from aerial photos • City-wide – 261 kg of PAHs wash off roofs per year • 26X more than washoff from freshly sealed pavement

  27. Airborne Contribution to Lots • Applying USGS airborne settling rate (9.2 g/m2) • Austin parking lot area = 39 kg/yr PAH from air 4X more than washoff of freshly sealed lots • Austin street/sidewalk area = 41 kg/yr PAH from air 4X more than washoff of freshly sealed lots

  28. Sealer Washoff Contributes Less Than 1% of PAH Loading • Major Sources Not Included: • Used Motor Oil • Gas station runoff • Pavement Debris • Paved banks/ drainage channels Preliminary, “on paper” analysis indicates need for direct measurement and follow-up.

  29. Traffic, Not Urbanization Drives PAH Levels • USGS study of Town Lake concluded: • “increases in PAHs are proportional to increases in vehicle traffic” • “The large increases in traffic offer an explanation for why PAHs more than doubled in Town Lake from 1975 to 1990 while percent urban land use only increased by 5%.” Source: Van Metre, P.C. et al., 2000. Urban Sprawl Leaves Its Signature. ES&T 34:4064.

  30. Total PAH Increases in Town Lake Coincide with Increase in Vehicle Miles Traveled Source: Van Metre, Mahler and Furlong. 2000. ES&T 34: 4064 – 4070.

  31. Substitution Risk Requires Analysis • “No Free Lunch…” • More asphalt sealer – • wears faster • USGS study did NOT detect a difference in PAH loading from in use asphalt-sealed lots vs. coal tar-sealed lots • No Sealer • more pavement debris • penetration of petroleum-soluble contaminants

  32. Urban Complexities – Environmental Reality

  33. Oil, Vehicle debris – Congress Ave. Drainage Bridge Drainage Staining

  34. High Expectations for Emerging Science… “… probably the majority of the PAHs that we see in the Austin area” – News 8 report, 9 Nov 2005

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