1 / 30

What is the Evidence for Stopping All Monitoring? of the Vapor Intrusion Pathway

Explore the evidence and perspectives supporting the cessation of monitoring the vapor intrusion pathway, including stack effects, wind effects, mixing in indoor air, radon sources, and more. This presentation discusses changing toxicity levels, exposure durations, and concentrations for better assessment methods.

bergevin
Download Presentation

What is the Evidence for Stopping All Monitoring? of the Vapor Intrusion Pathway

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. What is the Evidence for Stopping All Monitoring? of the Vapor Intrusion Pathway A&WMA, Sept. 10-11, 2014 Philadelphia, PA/ Cherry Hill Area, NJ Presented by Henry Schuver, MS (Geology), DrPH(Epi) Personal perspective by (does not represent Agency policy): USEPA – Office of Resource Conservation & Recovery (ORCR) Wash. DC See: http://iavi.rti.org and http://epa.gov/oswer/vaporintrusion *Follows &evolved from: AWMA VI 2012 (MNA); AEHS EPA-Workshop 2014 (LTS as context); Battelle 2014 (LTS comparison to other pathways/policies); & today’s LTS in AM panel

  2. Does this (simplest) Conceptual Site Model [Outline:of variable categories 1-6] support Stopping All Monitoring (SAM)? 4 Stack effects Wind effects Mixing in indoor air and inhalation 3 Rn source Indoor Air Typical Samples: Outdoor Indoor Sub-slab Soil-Gas Groundwater Qsoil Cracks 3 Advection Building zone of influence Air streamlines Contamination 2c Convection Vadose zone 2b Diffusion LT Top of capillary zone Diffusion Contamination 2a Water Table Vapor Source Term Phase partitioning Dissolved Contamination Cgw to Csoil gas 1 Mod. from slide by M. Bolas, Ohio EPA, presented Jan. 2006 5Improving Assess. Methods. 6 Changing Tox., Exposure Durations & Conc.

  3. Introduction . • Why are we asking about SAM? • Most VI monitoring is for a: • Presumedone-time,limited-duration‘Assessment’ • i.e., That can be used to Predict the futureVI • Often making it complex, difficult, costly and lengthy, but • That is always seeking/Goalto: • ‘Stop All Monitoring’ i.e., ‘Screen-out’ based on Prediction • Relic of early/initial ‘triage’ era/period? (still desirable, but …) • We will see results from Time Series Analysis-based predictions • Does other evidence support the presumed goal of StoppingAll* Monitoring (while VI-source remains)? *Across allbuildings (space) and alltime

  4. Background • Some (small) _% VI is ~obviously unacceptable • So continuously high • Even single/few IA samples ‘catch’ unacceptable baseline conc. • Some _%VI is likely not-complete or ‘acceptable’(ALSR) • So precluded (e.g., under ‘clean’ aquifer)/continuously low • Any number of IA samples will never find it ’unacceptable’ • But Most VI is in the ‘Grey Zone’ • So the question becomes: • How long before Stopping All Monitoring, for most VI • [i.e., ‘Grey Zone’ sites] w/ ‘naturally varying conditions’ • Beginning w/ category #6 – Toxic./Exposure Durations IA = Indoor Air ALSR = As Long as [VI] Source Remains

  5. Do unavoidable Inhalation Exposure Factors supportStopping All [VI] Monitoring?(e.g. VI vs. Water Ingestion – per Day) • Air - 20 m3/day (20,000 liters/day) of air (inhalation) not easily avoided • Water - 2 liters/day of water (ingestion) ‘voluntary’ • Exposure factors 10:1 (in their units of 20 m3/d & 2 l/d) • For equalExposures per DAY: • Inhalation conc. (in m3/d) should be 1/10 of Ingestion (in l/d) • Comparing similar exposure Conc.: Exposure Daily • MCL = 5 ug/l (water) (x 2 l/d = 10 ug/d) • Similar exposure ~ 0.5 ug/m3 (air) (x 20 m3/d = 10 ug/d) • Example indoor air concentrations (VI levels measured to-date): • 1ug/m3 ~ exposures from an MCL of 10 ug/l • 2ug/m3 ~ exposures from an MCL of 20ug/l • 10 ug/m3 ~ exposures from an MCL of 100 ug/l • 100ug/m3 ~ exposures from an MCL of 1,000 ug/l • 1000ug/m3 ~exposures from an MCL of 10,000 ug/l MCL = US EPA’s Maximum Contaminant Level for drinking water.

  6. TCE toxicity in IRIS Sept. 2011*Changing Tox. help SAM? “Based on a weight-of-evidence evaluation … • Including • Human epidemiologic studies, • Animal dosing studies, and • Experimental mechanistic studies • The assessment concluded that TCE poses … • Non-cancer toxicity to the • Central nervous system, • Kidney, • Liver, • Immune system, • Male reproductive system, and the • Developing fetus, and is • “Carcinogenic to humans” by all routes of exposure.”* *Aug. 27, 2014; OSRTI Memo: Compilation of Information Relating to Early/Interim Actions at Superfund Sites and the TCE IRIS Assessment

  7. Disease Assoc.*Support SAM? . . “Conclusions: Maternal residence in both areas was associated with cardiac defects. Residence in the TCE area, but not the PCE area, was associated with low birth weight and fetal growth restriction.” • TCE plume (70 block) area: • ~2615 residents, 1090 births (‘78-02) • 117 Small for gestational age • RR = 1.23 (95% CI = 1.03-1.48) • 76 Low birth weight • RR = 1.36 (95% CI = 1.07-1.73) • 37 Term low birth weight • RR = 1.68 (95% CI = 1.20-2.34) • 15 Cardiac defects • RR = 2.15 (95% CI = 1.27-3.62) • 3Conotruncal** defects • RR = 4.91 (95% CI = 1.58-15.24) 3 mos. after TCE in IRIS * Also a similar paper on increases in adult cancers ** “abnormal formation of the outflow tracts of the heart” (RR) Rate Ratios relative to the rest of NY state (excluding NYC) http://ehp03.niehs.nih.gov/article/fetchArticle.action?articleURI=info%3Adoi%2F10.1289%2Fehp.1103884

  8. Who thinks EPA’s VI-db (GW) supports Stopping All Monitoring? >100,000x variability across both space (24 sites) & time* [*Using a few (short-term) Indoor Air samples per building, for up to ~year] https://iavi.rti.org/attachments/WorkshopsAndConferences/04_For_Web_Dawson2012_AEHSfinal%20v2.pdf

  9. Slide by Dr. Paul Johnson – presented in AEHS March 20, 2012 – blue text added Does variability in SS conc. in both: Space & Time (under ASUhouse) support SAM? Note, no SS conc.> 5 ppbv; (Some State’s SS matrix 5 level = No Further Action) See – https://iavi.rti.org/attachments/WorkshopsAndConferences

  10. Who thinks … >10,000x* Variation in SS-IA Attenuation … supports SAM? [*Using a few (short-term) Indoor Air samples per building, for up to ~year @ 12 sites] Figure 2-15. A. Box-and-whisker plot showing subslab soil gas CVOC attenuation factor distributions from EPA’s vapor intrusion database for individual sites with several buildings per site and subslab soil gas concentrations over 50 times “background” (U.S. EPA, 2012a)

  11. ~100x more atten. in building than in subsurface * Does this Support SAM ? (Lowry Air Force Base, Colo.) * Extended ‘medians’ analysis for rest of EPA VI db showed similar results (by Dr. Wertz) Red & blue added to original slide by Dr. Helen Dawson, from AEHS March 2011

  12. 3) Do differences & changes in Buildingssupport Stopping All Monitoring? • Design, incl: • Ground contact • Heating type, HVAC • Height, elevation, orientation … • Vegetation surrounding? • Construction • Condition • Occupants/Operation • Natural changes • Man-made changes

  13. House-to-house (simpler-)Radon conc. distribution in a typical small MN town Support SAM? Across space 1-yr samples? Figure from EPA’s draft “Lessons from Radon for Vapor Intrusion Research & Programs” by Dr. Steck Dashed lines show nearly equal probability that individual homes, likely overlying similar Rn sources (in small town), can have ~1 or ~5 pCi/L in indoor air.

  14. Occupant-OperationsHourly Rn Variation Does this Support SAM? Windows: Closed, Open ~5x factor Rn testing procedures use Closed-house conditions – How many CVI investigations/datasets do? Fig. from Lessons from Radon Studies …

  15. Do Radon Studiesillustrating effects of changes inbuilding-structural factors – Support SAM? Both man-made + natural changes: Earthquakes, Settling, Drying soils, Burrowing … 1-yr samples ~ 1/4xchange for Stairwell ~ 5xchange for both locations Note, the difficulty of estimating changes in heating or air condition or adding porches; and also impacts to VI. Steck 2007, see: http://www.aarst.org/proceedings/2007/8-SteckYTYRnvariation07.pdf

  16. Episodic Peaks Drive Exposure – Support SAM?25 days (3.5%) present more exposure than the other 698 days Chemical VI (TCE) at ASU’s ‘Sun Devil Manor’ Dr. Paul Johnson’s slide 20/48 - Note audio recording of presentation also available at: https://iavi.rti.org/attachments/WorkshopsAndConferences/05_Johnson_03-19-13.pdf

  17. Some data from USEPA-ORD’s VI Research Housewith ~similarly Episodic behavior support SAM? Heated side of duplex Slide 7 of 22, audio also available at: https://iavi.rti.org/attachments/WorkshopsAndConferences/06_Truesdale_03-19-13.pdf

  18. Do studies of ‘conventional’ Sample vs. True mean*(at ASU’s house) support SAM? • 32% probability 4-Qtr samplemean<0.3x true • 60% probability 4-Qtr samplemeanwithin** • Order of magnitude(from 0.3x to 3x) of truemean • 8% probability 4-Qtr samplemean>3x true • Some regulators may Note: • 4x more likely to under-estimate truemean by >3x • 32/8 = 4x • * Holton et al. 2013; Fig. 9; w/ 5000 ‘conventional’ randomly-selected 4-Qtr sampling realizations from real data **’Not bad’ for ‘chronic’ mean? If we use std/3?

  19. Who thinks ‘conventional’ Screening methods* (at ASU’s house) support SAM? • With True (actual) mean conc. 5x ‘std’ • 6% probability all 4Qtr sample results <‘std’ (FN)** • 36% prob. of finding 3 Qtr<‘std’ -If need 2 ‘hits’ 2b sure (FN) • With True (actual) mean conc. 2x ‘std’ • 20% probability all 4Qtr sample results <‘std’ (FN) • 66% prob. of finding 3 Qtr<‘std’-If need 2 ‘hits’ 2b sure (FN) • With True (actual) mean conc. 1x (=) ‘std’ • 40% probability all 4Qtr sample results <‘std’ (FN) • If ‘normal’ distribution, should be ~0.54 = 6% [not ~40:60] • *From Holton et al., 2013; Table 1 [w/ False Negative (FN) screening result here] • ** Still not >95% Confident with actual mean 5x times (screening level) ‘std’

  20. Is all VI Episodic?Are ASU & ORD studies representative? • 2/2 (100%) of data-rich studies indicate - ~Yes • To show these two sites are anomalies: • Need ~45 data-rich studies indicating notepisodic? • To have >95% confidence that (most) VI is not episodic • One research house is ~modern sub-urban • One research house is older & ~urban • Together they can represent a high % of US housing • Both have Low/dilute source concentrations • We’re Not worried about sites with ‘high’ baseline conc. (easy)

  21. Is (simpler-)* Radon Intrusion Episodic?Looks to be in this Swedish home w/ unusual 1-day samples * w/ a more constant & closer source, than most Chemical VI (e.g. ASU & ORD) Note, highest often not in winter Do these daily samples support SAM?

  22. Is (simpler-)* Radon Intrusion Episodic?Looks to be in this USA-MNhome w/ calculated 1-day samples* * w/ a more constant & closer source, than most Chemical VI) Do these daily samples (of Radon*) support SAM? Fig. from Steck in draft Lessons from Radon Studies …

  23. Is Radon*Intrusion Episodic?Same MN home w/Hourly, 2-, 7-, & 90-day (& yearly) samples * w/ a simpler, more constant & closer source, than most Chemical VI) Do these samples support Stopping all Monitoring? Would two samples from Winter help?

  24. Does this evidence supportStopping All Monitoring?With 2-, 30-, & 90-day samples? Consistent w/ ORD’s to-be-discussed? rate-of-change concept?

  25. Do these 1-yr samples supportStopping all Monitoring, after _ yrs? >4x variation in 17 years Fig. from Steck in draft Lessons from Radon Studies …

  26. Does the Evidence for the Validity of (short-term) Assessment/Screening for ‘Simpler-’Rn support SAM? • Given the high level of temporal variability … • In a High radon region ~analogous to CVI study areas • High prevalence of intrusion near the ‘std’ FP TP FN TN Appears - Grab sample from log-normal dist. is biased to underestimate long-term risks

  27. Do evidence-based (simpler-) Radon policiessupport SAM? … NO • USEPA (NAS-based) policy (1993)* recommends: • Sample every home** (across space) • Re-sample every2 years1 (across time) • Sample for a minimum of2 diurnal cycles • 48-hours*** • & chem-VI appears to be more complex than Rn for at least 6 reasons(Schuver & Mosley, 2009) 1 USEPA Radon – Consumer’s Guide http://www.epa.gov/radon/pubs/consguid.html *Long-researched & long-standing, & reaffirmed world-wide by the WHO (2009) **Under closed house conditions (not typical (or documented) for chemical VI studies) ***And preferably long-term (>90 days) & >1 yr. for human studies (w/o misclassification)

  28. Does the NAS panel/report on closing out sitessupportStopping all Monitoring? • Panel reported increasing use of controls for closing out many/most ‘complex’ sites and • that would ‘of course’ include continued monitoring to be sure there would be no inappropriate exposures • And when asked if that meant on-going monitoringfor VIthey … agreed it would* NO • *2014 Battelle Chlorinated Remediation Conf.

  29. To Summarize: IsStopping All Monitoring (SAM)supportedby: • Any • of CVI or Rn evidence (presented here)? • Majority • of CVI &Rn evidence (anywhere out-there)? • If “no” the era of Presumption-based Triage-Screening (w/ the objective of SAM) is … over? & • Era of evidence-based management begun?* • *Only 21 years after Radon (1993)

  30. Acknowledgements • To those who have designed &/or collected some of the highest-quality & important VI evidence: • D. Steck • P. Johnson • B. Schumacher • C. Lutes • C. Holton • H. Dawson

More Related