Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia...
-
Upload
alonso-milward -
Category
Documents
-
view
224 -
download
5
Transcript of Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia...
![Page 1: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/1.jpg)
Indoor Air Institute Workshop: SVOCs in the Indoor Environment
Brief Reportby
John LittleVirginia Tech
![Page 2: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/2.jpg)
Motivation for SVOC Workshop
• Semi-Volatile Organic Compounds (SVOCs) include:– Plasticizers, flame retardants, pesticides, combustion
products, anti-stain agents, heat transfer fluids
• SVOCs are ubiquitous indoors, redistributing from their original sources to indoor air, and subsequently to all interior surfaces including airborne particles, dust, and human skin
• Concern about exposure and health effects including endocrine disruption and asthma
![Page 3: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/3.jpg)
“Pilot” SVOC Workshop at EPA
• Organizational Sponsor• Indoor Air Institute
• Financial Sponsors• EPA (NERL, HEASD – Roy Fortmann; NCCT – Robert Kavlock)
and ACC LRI (Tina Bahadori)• Date
• August 17 to 19, 2009• Co-Chairs
• John Little and Elaine Cohen Hubal• Steering Committee
• Bill Fisk, Hal Levin, Tom McKone, Bill Nazaroff, Charlie Weschler• Invited Participants
• Harvey Clewell, Miriam Diamond, John Kissel, Vickie Wilson
![Page 4: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/4.jpg)
SVOC Workshop Questions
1. Can we characterize the source-to-effect continuum for one class of SVOCs (phthalates)?
2. Can the overall mechanistic risk assessment approach be generalized to other SVOCs?
3. Can we identify screening-level, rapid exposure assessment approaches?
![Page 5: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/5.jpg)
Series of Presentations
• ToxCastTM and ExpoCastTM for prioritization and chemical evaluation
• Elaine Hubal, EPA, National Center for Computational Toxicology
• Sources, emissions, transport, exposure and rapid screening for exposure
• John Little, Virginia Tech• The mismeasure of dermal absorption
• John Kissel, University of Washington• PBPK measurements, modeling, and metabolic
reactions• Harvey Clewell, The Hamner Institutes
• Organ-specific toxic effects of phthalates• Vickie Wilson, EPA, Reproductive Toxicology Division
• Models in environmental regulatory decision making• Tom McKone, UC Berkeley and LBNL
![Page 6: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/6.jpg)
SVOC Workshop Questions
1. Can we characterize the source-to-effect continuum for one class of SVOCs (phthalates)?
2. Can the overall mechanistic risk assessment approach be generalized to other SVOCs?
3. Can we identify screening-level, rapid exposure assessment approaches?
![Page 7: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/7.jpg)
7
SVOC Emissions model + particles
xx = 0
yin= 0, TSP, Q
V
C0 D
y(t)
x = Lh
……. …….y(t), TSP, Q
…….
C0 = Ky0
q = Ksy
qp = KpyTSP
Particles
Ai
A
(Xu and Little, 2006 )
![Page 8: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/8.jpg)
Emissions of DEHP from vinyl flooring
0 20 40 60 80 100 120 140 160
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
DE
HP
ga
s p
ha
se c
on
cen
tra
tion
(g
/m3 )
Time (days)
Chamber I Chamber II Model predicted
Xu et al., 2008
![Page 9: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/9.jpg)
Make model more representative of real indoor
environment
9
![Page 10: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/10.jpg)
Two-Room Model
10
• • • • • • • • • • • • • • • • • • • •
yin, TSP, Q
•••••••••• y1, TSP, Q
••••••••••
••••••••••
Vinyl Flooring Carpet
Room 1 Room 2 V1 y1 V2 y2 Glass
window Glass window
Particles Particles Wall
Ceiling Ceiling
Wood furniture
y2, TSP, Q
![Page 11: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/11.jpg)
11
Partition coefficients for DEHP
Surface Partition coefficient, Ks
Furniture, wall and ceiling 2500 (m)
Carpet 1700 (m)Skin 9500 (m)Airborne Particles 0.25 (m3/μg)
![Page 12: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/12.jpg)
12
Residential Environment
![Page 13: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/13.jpg)
13
Residential EnvironmentCompartment Main house Kitchen BathroomVolume (m3) 128 35 15Flow rate (m3/h) Qoa 65 Qok 12 Qob 1.1
Qao 44 Qko 32 Qbo 2.1Qak 44 Qab 14Qka 24 Qba 13
Surface area (m2)Vinyl flooring 19.2 14.4 6.20Walls & Ceilings 124 34.0 23.3Carpet 35.8 -- --Wood floor 32.0 -- --Hard surface furniture 61.4 12.6 5.40Windows & mirrors 5.12 1.75 1.05Tile & ceramic fixtures 5.12 3.50 16.5TSP (mg/m3) 20.0 20.0 20.0
![Page 14: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/14.jpg)
Residential Model Predictions
14
0 100 200 300 400 500
0.00
0.05
0.10
0.15
0.20
Main house
Main house
Kitchen
Kitchen
Bathroom
Bathroom
Co
nce
ntr
atio
n (g
/m3 )
Time (days)
Concentration Emission rate
1.3
1.4
1.5
1.6
1.7
E
mis
sio
n r
ate
(g
/m2 h
)
![Page 15: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/15.jpg)
Exposure for Child (2 to 3 yrs)
15
0 50 100 150 200 250 300 350 400 450 5000
5
10
15
20
25
-0.0999999999999994
5.82867087928207E-16
0.100000000000001
0.200000000000001
0.300000000000001
0.400000000000001
0.500000000000001
0.600000000000001
Total
Ingestion (Dust)
Dermal
Inhalation (Air+Particle)
Time (days)
Exp
osur
e (μ
g/kg
/day
)
Exp
osur
e (μ
g/kg
/day
)
![Page 16: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/16.jpg)
Source to Effect Continuum
• Sources, emissions, transport, exposure and rapid screening for exposure
• John Little, Virginia Tech• Dermal absorption
• John Kissel, University of Washington• PBPK measurements, modeling, and metabolic
reactions• Harvey Clewell, The Hamner Institute
• Organ-specific toxic effects of phthalates• Vickie Wilson, EPA, Reproductive Toxicology Division
![Page 17: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/17.jpg)
SVOC Workshop Questions
1. Can we characterize the source-to-effect continuum for one class of SVOCs (phthalates)?
2. Can the overall mechanistic risk assessment approach be generalized to other SVOCs?
3. Can we identify screening-level, rapid exposure assessment approaches?
![Page 18: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/18.jpg)
Indoor SVOC Dynamics
Weschler and Nazaroff, Atmos. Environ., 2008
![Page 19: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/19.jpg)
Estimating physical properties withstructure-activity relationships (SPARC)
Weschler & Nazaroff, Atmos. Environ., 2008
![Page 20: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/20.jpg)
Measured vs. estimated [SVOCs] on hands
Weschler & Nazaroff, Atmos. Environ., 2008
![Page 21: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/21.jpg)
Measured vs. estimated [SVOCs] in dust
Nazaroff & Weschler, Healthy Buildings, 2009
![Page 22: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/22.jpg)
SVOC Workshop Questions
1. Can we characterize the source-to-effect continuum for one class of SVOCs (phthalates)?
2. Can the overall mechanistic risk assessment approach be generalized to other SVOCs?
3. Can we identify screening-level, rapid exposure assessment approaches?
![Page 23: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/23.jpg)
Zero-Order Exposure Screening
• Excretion to production ratio (EPR):– Ratio of the rate of excretion from humans (urine) to
the rate of manufacture provides rough exposure indicator
– Dietary supplements or pharmaceuticals: EPR ~ 1.0– Personal care products: EPR ~ 0.01 to 1– Pesticides: EPR ~ 0.0001-0.01– Additives in indoor products: EPRs ~ 0.1-100 ppm
• Some estimated EPRs:– Triclosan ~ 8000 ppm– Pentachlorophenol ~ 500 ppm– DEHP ~ 20 ppm
![Page 24: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/24.jpg)
First-Order Exposure Screening
• Exposure to additives (e.g., plasticizers and flame retardants):– Steady state concentration y (and hence exposure)
depends primarily on y0, A and h
– y0 may be roughly equal to vapor pressure
![Page 25: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/25.jpg)
At Steady State
25
1Ah
Q~
y
y0
TSPK1QQ~
p
• Q~normal(50,20)• Kp~normal(0.25,0.05)• TSP~normal(20,5)• h is correlated with Q• 50000 random trials
![Page 26: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/26.jpg)
Variability in Predicted Steady-State Gas-Phase Concentration
26
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.50
500
1000
1500
2000
2500
3000
3500
y/y0
Cou
nts
![Page 27: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/27.jpg)
Rapid Exposure Screening
• Zero-Order Screening– Excretion to production ratio (EPR)
• Triclosan ~ 8000 ppm• Pentachlorophenol ~ 500 ppm• DEHP ~ 20 ppm
• First-Order Screening– Exposure to additives (e.g., plasticizers and flame
retardants)
1Ah
Q~
y
y0
TSPK1QQ~
p
![Page 28: Indoor Air Institute Workshop: SVOCs in the Indoor Environment Brief Report by John Little Virginia Tech.](https://reader033.fdocuments.us/reader033/viewer/2022051110/5518ae15550346881f8b4dd2/html5/thumbnails/28.jpg)
SVOC Workshop Outcomes
1. Can we characterize the source-to-effect continuum for phthalates? ~Yes
2. Can the overall mechanistic approach be generalized to other SVOCs? ~Yes
3. Can we identify screening-level, rapid exposure assessment approaches (and combine with info from ToxCastTM to estimate risk)? ~Yes
4. Summary paper being prepared for publication
5. SVOC Workshop 2 planned for end of 2010 or early 2011