What is the Evidence for Stopping All Monitoring?

of the Vapor Intrusion Pathway

A&WMA, Sept. 10-11, 2014Philadelphia, 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

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*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

Does this (simplest) Conceptual Site Model [Outline: of variable categories 1-6] support

Stopping All Monitoring (SAM)?

Dissolved Contamination

LT Diffusion

Vadose zone

Building zone of influence

Wind effects

Indoor Air

CracksQsoil

Air streamlines

Convection

Top of capillary zone

Water Table

Stack effects

Mixing in indoor air and inhalation

Advection

Diffusion

Phase partitioningCgw to Csoil gas

Mod. from slide by M. Bolas, Ohio EPA, presented Jan. 2006

Vapor Source Term

Contamination

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

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Introduction . – Why are we asking about SAM?

• Most VI monitoring is for a:– Presumed one-time, limited-duration ‘Assessment’• i.e., That can be used to Predict the future VI

» Often making it complex, difficult, costly and lengthy, but

• That is always seeking/Goal to: – ‘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 Stopping All* Monitoring (while VI-source remains)?

3*Across all buildings (space) and all time

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

4IA = Indoor Air ALSR = As Long as [VI] Source Remains

Do unavoidable Inhalation Exposure Factors support Stopping 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 equal Exposures 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):» 1 ug/m3 ~ exposures from an MCL of 10 ug/l » 2 ug/m3 ~ exposures from an MCL of 20 ug/l» 10 ug/m3 ~ exposures from an MCL of 100 ug/l » 100 ug/m3 ~ exposures from an MCL of 1,000 ug/l » 1000 ug/m3 ~exposures from an MCL of 10,000 ug/l

MCL = US EPA’s Maximum Contaminant Level for drinking water.

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.”*6

*Aug. 27, 2014; OSRTI Memo: Compilation of Information Relating to Early/Interim Actions at Superfund Sites and the TCE IRIS Assessment

Disease Assoc.* Support SAM? . .

• 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)

– 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

Who thinks EPA’s VI-db (GW) supports Stopping All Monitoring?

8https://iavi.rti.org/attachments/WorkshopsAndConferences/04_For_Web_Dawson2012_AEHSfinal%20v2.pdf

[*Using a few (short-term) Indoor Air samples per building, for up to ~year]

>100,000x variability across both space (24 sites) & time*

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Slide by Dr. Paul Johnson – presented in AEHS March 20, 2012 – blue text added

See – https://iavi.rti.org/attachments/WorkshopsAndConferences

Does variability in SS conc. in both:Space & Time (under ASU house) support SAM?

Note, no SS conc.> 5 ppbv;

(Some State’s SS matrix 5 level = No Further Action)

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Who thinks … >10,000x* Variation in SS-IA Attenuation … supports SAM?

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)

[*Using a few (short-term) Indoor Air samples per building, for up to ~year @ 12 sites]

11* 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

(Lowry Air Force Base, Colo.)

~100x more atten. in building than in subsurface

*

Does this Support SAM ?

3) Do differences & changes in Buildings support Stopping All Monitoring? • Design, incl:

– Ground contact– Heating type, HVAC– Height, elevation, orientation …– Vegetation surrounding?

• Construction• Condition• Occupants/Operation• Natural changes• Man-made changes

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House-to-house (simpler-)Radon conc. distribution in a typical small MN town

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.

Figure from EPA’s draft “Lessons from Radon for Vapor Intrusion Research & Programs” by Dr. Steck

1-yr samples?

Support SAM?Across space

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Occupant-OperationsHourly Rn Variation

0

2

4

6

8

10

12

0 50 100 150 200 250 300 350 400

Rado

n (p

Ci/L

)

Hours

Fig. from Lessons from Radon Studies …

Windows: Closed, Open

Rn testing procedures use Closed-house conditions – How many CVI investigations/datasets do?

Does this Support SAM?

~5x factor

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Do Radon Studies illustrating effects of changes inbuilding-structural factors – Support SAM?

Steck 2007, see: http://www.aarst.org/proceedings/2007/8-SteckYTYRnvariation07.pdf

~ 5x change for both locations~ 1/4x change for Stairwell

Note, the difficulty of estimating changes in heating or air condition or adding porches; and also impacts to VI.

Both man-made + natural changes: Earthquakes, Settling, Drying soils, Burrowing …1-yr samples

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

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Chemical VI(TCE) at ASU’s ‘Sun Devil Manor’

Some data from USEPA-ORD’s VI Research Housewith ~similarly Episodic behavior support SAM?

Slide 7 of 22, audio also available at:https://iavi.rti.org/attachments/WorkshopsAndConferences/06_Truesdale_03-19-13.pdf 17

Heated side of duplex

Do studies of ‘conventional’ Sample vs. True mean*

(at ASU’s house) support SAM?• 32% probability 4-Qtr sample mean <0.3x true

• 60% probability 4-Qtr sample mean within**– Order of magnitude (from 0.3x to 3x) of true mean

• 8% probability 4-Qtr sample mean >3x true

» Some regulators may Note:

– 4x more likely to under-estimate true mean by >3x» 32/8 = 4x

18* 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?

Who thinks ‘conventional’ Screening methods*

(at ASU’s house) support SAM?• With True (actual) mean conc. 5x ‘std’– 6% probability all 4 Qtr 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 4 Qtr 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 4 Qtr sample results <‘std’ (FN)• If ‘normal’ distribution, should be ~0.54 = 6% [not ~40:60]

19*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’

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 not episodic? • 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)

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Is (simpler-)* Radon Intrusion Episodic?Looks to be in this Swedish home w/ unusual 1-day samples

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* 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?

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Is (simpler-)* Radon Intrusion Episodic?Looks to be in this USA-MN home w/ calculated 1-day samples*

0

2

4

6

8

10

12

14

0 30 60 90 120 150 180 210 240 270 300 330 360 390 420 450 480 510 540 570 600 630 660 690 720 750

Rn (p

Ci/L

)

Days since 30 June 2003

Fig. from Steck in draft Lessons from Radon Studies …

Do these daily samples (of Radon*) support SAM?

* w/ a more constant & closer source, than most Chemical VI)

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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?

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Does this evidence support Stopping All Monitoring?With 2-, 30-, & 90-day samples?

Consistent w/ ORD’s to-be-discussed? rate-of-change concept?

Do these 1-yr samples supportStopping all Monitoring, after _ yrs?

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0

1

2

3

4

5

6

7

8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Rado

n (p

Ci/L

)

Year After Construction

Fig. from Steck in draft Lessons from Radon Studies …

>4x variation in 17 years

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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’

TN

FN

FP TP

Appears - Grab sample from log-normal dist. is biased to underestimate long-term risks

Do evidence-based (simpler-) Radon policies support SAM? … NO

• USEPA (NAS-based) policy (1993)* recommends: • Sample every home** (across space)• Re-sample every 2 years1 (across time)• Sample for a minimum of 2 diurnal cycles • 48-hours***

• & chem-VI appears to be more complex than Rn for at least 6 reasons (Schuver & Mosley, 2009)

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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)

Does the NAS panel/report on closing out sites support Stopping 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 monitoring for VI they … agreed it would* NO

28*2014 Battelle Chlorinated Remediation Conf.

To Summarize: Is Stopping All Monitoring (SAM) supported by:

• 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?*

29*Only 21 years after Radon (1993)

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

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