1. 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 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/vaporintrusionhttp://iavi.rti.orghttp://epa.gov/oswer/vaporintrusion 1 *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 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’) DCE – Dichloroethylene Source definition can be a challenge - most of this plume found by indoor air

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] Dissolved Contamination LTLT Diffusion Vadose zone Building zone of influence Wind effects Indoor Air Cracks Q soil Air streamlines Convection Top of capillary zone Water Table Stack effects Mixing in indoor air and inhalation Advection Diffusion Phase partitioning C gw to C soil gas Mod. from slide by M. Bolas, Ohio EPA, presented Jan. 2006 Vapor Source Term Contamination Typical Samples: Outdoor Indoor Sub-slab Soil-Gas Groundwater 1 2b 2a 2c 3 4 5 Improving Assess. Methods. 6 Changing Tox., Exposure Durations & Conc. Rn source 3

4. 4 Is Radon* Intrusion Episodic? Same MN home w/ Hourly, 2-, 7-, & 90-day & yearly samples Do these samples support Stopping all Monitoring? * w/ a simpler, more constant & closer source, than most Chemical VI) Would two samples from Winter help?

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

6. Episodic Peaks Drive Exposure – Support SAM*? 25 days (3.5%) present more exposure** than the other 698 days 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 6 Chemical VI (TCE) at ASU’s ‘Sun Devil Manor’ * Stopping All Monitoring (see Schuver AWMA VI 2014) **for Chronic avg. values

7. Some Evidence from ASU’s “Sun Devil Manor” Radon intrudes in Soil Gas ~~ w/ TCE Differences in Baselines; but similar Directions of change 7 https://iavi.rti.org/attachments/WorkshopsAndConferences/02_Holton_Weather-Temporal-Variation-3-22-2012.pdf 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”

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 susceptibility to 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 CVI On-going Screening/Monitoring All existing intensive-(data-rich)-monitoring evidence from both CVI & Radon studies* As well as – Rn, GW-MNA, LTS, Pub-water, NAS evidence-based policies (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.”* 10 *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. 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) – 3 Conotruncal** defects RR = 4.91 (95% CI = 1.58-15.24) * 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 “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.” 3 mos. after TCE in IRIS 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.” Short-Term Risks Some (assoc.) examples*

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] 1)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/LocationIndoor Air (exposure point) % of Exposure Pt. (Bldg.)100% of occupied buildings Parameters/AnalytesSite-specific CVOC-COCs % time covered by samples 100% / Continuous – Duration of samples – Frequency (/intervals between samples) Time to results (for responses)Immediate Real-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 MonitoringAs Long As VI Source Remains CostHigh ($$$$$$$$$) Screening Result Not Exposed Exposed Positive0100% Negative100%0 * (c/st) = for Chronic / Short-Term risks

14. Comparison of Options 1 & 2, & their Downsides CharacteristicIdealDownsides of Ideal ConventionalDownsides Of Conventional Media/LocationIndoor AirBackgroundIndoor AirBackground % Building tested100%Costs & access15%Too few Bldgs. Para./AnalytesSite-COCsAnalysis costSite-COCsAnalysis cost % time sampled100%Not practical1%Missing peaks Sample Duration & Frequency ContinuousNot Practical1 day/3 mos.Unlikely to catch episodic peaks Time b4 resultsReal time (0 d)Not Practical~90 days> Exposure duration Sensitivity*(c/nc)100%/100%Not feasible<40%**/<<40%Too Ineffective ? Specificity*(c/nc)100%/100%Not feasible>95%?/99%High False-Neg. % ? Total Duration of monitoring As Long as Source Remain High Costs1 yearMust predict future & no evidence it can Cost/bldg.$$$$$$$$$Too High/bldg. Not Realistic $$$$$$Moderate cost by adj. # Bldgs. & Freq. *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 Downsides of Options 1 & 2 CharacteristicDownsides of Ideal Downsides of Conventional Objectives for Hybrid Media/LocationBackground ‘No’ Background issues % Bldgs.Costs & accessToo few Bldgs. but still cost & access ~100% possible w/ Lower costs & access? Para./AnalytesAnalysis cost Lower Analysis Cost* % Time sampledNot practicalMissing peaks~100% if feasible/pract. Sample Duration & Frequency Not PracticalMay not catch episodic peaks ~Continuous to catch episodic peaks Time b4 resultsNot Practical> Exposure duration~ Real-time Sensitivity*(c/nc)Not feasibleToo low/IneffectiveHigher e.g., >95% Specificity*(c/nc)Not feasibleHigh False Neg. %Retain High level Total Duration of monitoring High CostsNeeds to predict future – no evidence Make As Long as VI Source Remains possible Cost/bldg.Too High & Not Realistic Moderate by adjusting # Bldgs. & Frequency Lowest over-all *fewer high-certainty (& -cost) CVOCs

16. How can the Hybrid Option meet such Objectives? Make On-Going Screening/Monitoring practical by: – Only screening/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-confident methods for ‘Probable’ CVI *(i.e., more realistic, not trying to go directly from “Potential” to “Certainty”)

17. Hybrid – Step 1 Conclusions Probability for 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 gas is occurring* & – Probably including the VI-COCs in nearby soil gas CVI exposure pathway appears to be ‘probably complete’** Not confirming ‘complete’ or unacceptable 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.) 17

18. Hybrid Option – Step 2 The 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 Less frequently, 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 CharacteristicIdealConventionalHybrid Step 1Hybrid Step 2 Using Radon- SGS Media/LocationIndoor Air Soil Gas nearby Indoor Air % Bldgs.100%15%100% outside100% Para./AnalytesSite-CVOCs Radon (+CVOC) % time sampled100%1%15%100% Sample Duration & Frequency Continuous1 day/3 mos.Qtrly- 14 days per 3 mos. Continuous Time b4 resultsReal time 0 day~90 days~30 days7 days Sensitivity*(c/nc)100%/100%<40%**/<<40% (1% x 3% peaks) >95%?/>95%? Research needed >95%?/>95%? Research needed Specificity*(c/nc)100%/100%>95%?/99%>95%?/>95%? Total Duration of monitoring ALVISR***1 year – typical but adequate? ALVISR*** or until controls ALVISR*** w/ SG controls Cost/building$$$$$$$$$$$$$$$$$$$ (Res.)**** *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 VI Source Remains (ALVISR); ****Incl. typical Res. Mitigation & some CVOCs

20. 20 EPA-ORCR requested slide, by Dr. Hers from EPA VI workshop at AEHS 2014 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) Unlikely true for short-term events Only option providing continuous (short-term) protection is Lowest Cost

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-point monitoring on a frequency: More frequent than shortest period of concern Less frequent chemical monitoring can be appropriate IF : – Soil-gas Intrusion is Prevented – 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 22