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2014 International Radon Symposium (AARST ) Charleston, SC – Sept. 30

Developing-Draft … Still Learning from Rn, & now we’d like to use it Indoor Radon as an Option for On-going Screening/Monitoring of Short-Term Risks from Episodic C hemical V apor I ntrusion*. 2014 International Radon Symposium (AARST ) Charleston, SC – Sept. 30

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2014 International Radon Symposium (AARST ) Charleston, SC – Sept. 30

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  1. Developing-Draft … Still Learning from Rn, & now we’d like to use itIndoor Radon as an Option for On-going Screening/Monitoring of Short-Term Risks from Episodic Chemical Vapor Intrusion* 2014 International Radon Symposium (AARST) Charleston, SC – Sept. 30 Presented by Henry Schuver, DrPH(Epi), MS (Geology) USEPA – Office of Resource Conservation & Recovery (ORCR) Wash. DC Personal perspective by (does not represent Agency policy) 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); &AWMA VI 2014 – What is the Evidence for Stopping All Monitoring – of the VI pathway? - [for Recalcitrant vapors]

  2. Chemical Vapor Intrusion‘Potential’Defined by Source Area Source definition can be a challenge - most of this plume found by indoor air DCE – Dichloroethylene Growing Awareness of Subsurface Vapor Sources - Especially in Non Drinking Water Aquifers If you look for low enough concentrations (DCE is ‘unique tracer’ of Groundwater) Proximity to a source appears to ‘determine’ its presence in indoor air (‘completeness’)

  3. Indoor Radon is the ‘simplest’ part of this Conceptual Site Model of Soil-Gas Intrusion[as an Outline of categories of variables 1-6] 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.

  4. 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?

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

  6. 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’ * Stopping All Monitoring (see Schuver AWMA VI 2014) **for Chronic avg. values 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

  7. Some Evidence from ASU’s “Sun Devil Manor” Radon intrudes in Soil Gas ~~ w/ TCEDifferences in Baselines; but similar Directions of change ASU’s Cautious Conclusions While “not … a strong indicator of when VI is occurring at this site ” “With a lot of data, radon may tell us that VI can occur at this site” https://iavi.rti.org/attachments/WorkshopsAndConferences/02_Holton_Weather-Temporal-Variation-3-22-2012.pdf

  8. Spoiler Alert! – Preview Can we use Radon as a tracer/surrogate/indicator? • … of soil gas migration and more specifically: • Indoor-radon levels (relative to outdoor) as a tracer/surrogate/indicator of building-specific susceptibilityto the intrusion of nearby soil-gas • Not just the absolute Magnitude-# of Rn conc. • as predictor of the magnitude of CVOC conc. in indoor air • Too many additional CVOC variables (e.g., Schuver & Mosely 2009) • Yes - Magnitude of Indoor Rn - relative to outdoor • Yes - Direction of change – Increasing Rn & CVOCs • “strong statistical relationship … statistically significant at the 1% level and … predict 40 to 60% of the variability … indoor air VOC”* *Internal EPA-ORD draft report text based on Indy house (Schumacher et al., 2014)

  9. Summary of the Need for CVIOn-goingScreening/Monitoring • All existing intensive-(data-rich)-monitoring evidence from both CVI & Radon studies* • As well as • Rn, GW-MNA, LTS, Pub-water, NAS evidence-basedpolicies(Schuver, Battelle 2014) • Most/all Rn & CVOC VI appears to be episodic (Re: ‘stds’) • Most CVI cases with source conc. w/n 100x of screening levels • Small % of sites w/ more obvious (high- or low-baselines) • On-going(across time) & Source-wide (all bldgs.) monitoring (LTS) is as, or more, appropriate • Than for any other (chemical) pathway for exposure • Traditionally primarily-considering Chronic Exposure durations *see (Schuver AWMA VI 2014)

  10. TCE toxicity in IRIS Sept. 2011*Changing Tox. help SAM? “Based on a weight-of-evidence evaluation … • Including • Human epidemiologic studies, [primarily occupational] • Animal dosing studies, and • Experimental mechanistic studies • The assessment concluded that TCE poses … • Non-cancer toxicity [can be sub-chronic] 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 Listed last & perhaps w/ least evidence, but notable

  11. Short-Term RisksSome (assoc.) examples* “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) • 248 effects ~ ~ 1/4 • 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 Week 3: 15-21 days from fertilization - “Primitive heart tube is forming” Week 4: 22-28 days from fertilization - “The heart bulges, further develops, and begins to beat in a regular rhythm.”

  12. Some [CVI] Options are Needed(and some Lessons from Radon would help) • Current-Conventional CVI assessments take limited, but typically extended* amounts of time • Seeking permanent ‘walk-away’ decisions • Based on ‘high-certainty’ samples for Predictions [for all future cond.] • Leaving Un-Monitored Natural Attenuation as the only protection for all future conditions [not ok for GW] • Predictions are incompatible objective for the Radon (simpler) pathway (Schuver, Battelle 2014) 2) For short-term** effects extended study can be “a public health issue” [ORCR-Immediate-Office comment] • Is it “Only a matter of time” … ? • i.e., Plausibly assoc. short-term health effects in home(s) under study for ‘potential’ VI • Plausible scenario since most time (under study) is un-sampled? *Relative to the (short-term) exposure periods of concern **For example some effects (e.g., TCE in IRIS) plausibly assoc. with exposures as short as 1 to 21 days.

  13. Option 1 .‘Ideal’ . • Media/Location Indoor Air (exposure point) • % of Exposure Pt. (Bldg.) 100% of occupied buildings • Parameters/Analytes Site-specificCVOC-COCs • % time covered by samples 100% / Continuous • Duration of samples • Frequency (/intervals between samples) • Time to results (for responses) ImmediateReal-time • Confidence Positive Screen-In (c/st)*100% / 100% • Didn’t miss any problems & no errors (0 False-Positives) • Confidence Negative Screen-Out*100% / 100% • Didn’t miss any non-exposed & no errors (0 False-Negatives) • Overall duration of Monitoring As Long As VI Source Remains • Cost High ($$$$$$$$$) * (c/st) = for Chronic / Short-Term risks

  14. Comparison of Options 1 & 2, & their Downsides *Sensitivity (TP/(TP+FN)) & Specificity (TN/(TN+FP)) per bldg. for Chronic / Short-Term risks **Interpretation from Holton et al., 2013 for chronic risk (for long-term avg. exposures)

  15. Objectives for Hybrid – Decreasing the Downsidesof Options 1 & 2 *fewer high-certainty (& -cost) CVOCs

  16. How can the Hybrid Option meet such Objectives? • MakeOn-Going Screening/Monitoring practical by: • Onlyscreening/monitoring for now (current conditions) • Not intended for screening-out forever (all future cond.) • Approach the Ideal option while still being practical by: • Breaking into Two (‘rapid’ & practical/sustainable) Steps: 1) Priority-Screening based on Probability of CVI • Not Certainty* 2) More-confidentmethods for ‘Probable’CVI • *(i.e., more realistic, not trying to go directly from “Potential” to “Certainty”)

  17. Hybrid – Step 1 ConclusionsProbabilityfor a ‘complete’ VI Pathway? • Finding Buildings (with all three conditions): • 1) Overlie VI source, & [VI Potential] • 2) VI-COCs detected in near-foundation soil gas; [VI Possible] • 3) Indoor Radon conc. >3-5x outdoor [VI Susceptible] • Intrusion of near-building soil gasis occurring* & • Probably including the VI-COCs in nearby soil gas • CVI exposure pathway appears to be ‘probablycomplete’** • Not confirming ‘complete’ orunacceptable exposures • But Informative (evidence-based) priority-screening *Note, indoor Rn is a ‘one-way’ indicator of SG/VI - Low indoor Rn is not as meaningful **At some conc. level (not necessarily at unacceptable conc.)

  18. Hybrid Option – Step 2The Decision • Finding Probable(‘low’/episodic) CVI conditions; • Further on-going-screening/monitoring could involve: • High-quality/confidence indoor air samples analyzed for CVI-chemicals* and collected: • At an on-going-frequency appropriate for the shortest exposure period of concern, [e.g., possibly 1/every day] • ~ ~Conventional assessment methods, amplified [both +/-] • or • Lessfrequently, when combined with intrusion-reducing Controls (of ~1/100x reduction factor)** & with ‘continuous’ Indoor-Radon (verification) monitoring = A radon-monitored ‘Soil Gas Safe’ Option * Including addressing ‘Background’ concerns **Controls also allows further stress-testing of CVI source term, for confident ‘exit’ strategy

  19. Comparison of Options 1, 2 & 3 *Sensitivity& Specificity per building for Chronic and Non-Chronic risks (c/nc) **Interpretation from Holton et al., 2013 for chronic risk (long-term avg. exposures) ONLY ***As Long as VISource Remains (ALVISR); ****Incl. typical Res. Mitigation & some CVOCs

  20. Qualifications for this use: -Not incl. Step1 soil-gas -Not incl. Less Freq. IA CVOC samples w/ mitigation; - Assumes same Freq. of non-Mitigation samples over long periods; Decreases likely appropriate (as per CSM) EPA-ORCR requested slide, by Dr. Hers from EPA VI workshop at AEHS 2014 Only option providing continuous (short-term) protection is Lowest Cost Unlikely true for short-term events

  21. In Closing:Evidence Indicates: • Long-Term/On-going Monitoring/management • of ‘Low/episodic’ Chemical Vapor Intrusion • Is Appropriate/Needed (ALVISR)* • Short-term exposure risk scenarios suggest: • Exposure-pointmonitoring on a frequency: • More frequent than shortest period of concern • Less frequentchemical monitoring can be appropriate IF: • Soil-gasIntrusion isPrevented – Significantly-Reduced • w/ ‘continuous’ validation of effectiveness (e.g., Rn tracer) • Cost/Benefit Ratio << % by being ‘Soil Gas Safe’

  22. Acknowledgements • To those who have designed &/or collected some of the most important (&highest-quality) evidence for assessing/managing VI risks: • D. Steck • P. Johnson • B. Schumacher • C. Lutes • C. Holton • T. McAlary, H. Dawson, W. Wertz

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