dustex:howrelevantisthedustpathwayfor...
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Mar$ne Bakker, Chris$aan Delmaar, Andreas Gerecke, Vilma Šukienė, Natalie von Goetz
CEFIC-‐LRI Workshop 2016, Brussels
DustEx: How relevant is the dust pathway for consumer exposure to SVOCs?
ETH zürich
Partners
Natalie von Goetz Vilma Sukiene Konrad Hungerbühler
Mar$ne Bakker Chris$aan Delmaar
Andreas Gerecke
DustEx Project: Research ques$ons
• Compara$ve importance of dust pathway
• Amount of substance transferred to dust
Conceptual model
5
Research question: compare II to I and III
Exposure pathways: „I“ -‐ via air “II” – via dust „III“ – direct
DUST
indoor air
exposure
product
I II III
6
The structure of the project
Model for SVOC transfer to dust (DustEx model)
Experimental field study
Modeling case studies
Dus
tEx
proj
ect
Generic Substance-‐specific
Decision tree
Comparison of exposure pathways
The DustEx model framework
7
Indoor air (gas
phase)
Product
Dust
Airborne par$cles
Surfaces
ven$la$on
ven$la$on
cleaning
par$$oning
par$$oning
par$$oning
evapora$on
Deposi$on/re-‐suspension
DustEx model [email protected]
The DustEx model framework
8
Indoor air (gas
phase)
Product
Dust
Airborne par$cles
Surfaces
ven$la$on
ven$la$on
cleaning
par$$oning
par$$oning
par$$oning
evapora$on
Deposi$on/re-‐suspension
exposure
inges$on
direct product contact
inhala$on
dermal absorp$on
inhala$on
DustEx model Source-‐to-‐dose exposure modelling [email protected]
Field study: Model substances
9
low K
oa
high K
oa
more vola$le
less vola$
le
deuterium labelled substances
Adipates
2H4-‐DBA
2H4-‐DiBA
2H4-‐DEHA
2H4-‐DOA
Pyrethroid
Tetramethrin
Phthalates
2H4-‐DBP
2H4-‐DiBP
2H4-‐DEHP
2H4-‐DOP
Plas$cizers Insec$cide
log Koa
8
vapor pressure
12
SVOCs
9
11
Small-‐scale field study under controlled condi$ons
10 hkpwww.pixeljoint.compixelart28191.htm
2H4-‐DOP 2H4-‐DBP
Tetramethrin
2H4-‐DEHP 2H4-‐DBA
2H4-‐DEHA 2H4-‐DiBA
2H4-‐DOA 2H4-‐DiBP
3 plasHc produ
cts
carpet
spray
x 3-‐5 8-‐12 weeks
Ar$ficial products SVOCs
Weeks
Dust
samples
Passive air
Floor dust
Ac$ve air
Dust on the product
Type
of sam
ple
2 3 4 5 6 7 8 9 10 1 11 13 14 15 16 12
Liled dust in the room
Air
samples
11
Field study: Sampling scheme
Field study: Consistency between apartments
12 log Koa
1
10
100
1000
10000
ConcentraHon in apartment 1 liPed dust (µg/g dust/ g substance)
4 weeks
8 weeks
12 weeks
PT-‐plas$c (thermal exp.) PV-‐plas$c ver$cal PH-‐plas$c horizontal C-‐carpet S-‐spray
1
10
100
1000
10000
PT-‐low PV-‐low PH-‐low C-‐low PT-‐high PH-‐high PV-‐high S-‐high C-‐high
ConcentraHon in apartment 3 liPed dust
Field study: Comparison AIR and DUST
à Dust is relevant for substances with log Koa > 10 13
PT-‐plas$c (thermal exp.) PV-‐plas$c ver$cal PH-‐plas$c horizontal C-‐carpet S-‐spray
0.01
0.1
1
10
100
1000
ConcentraHon in apartment 3 AIR (ng/m3/g substance)
4 weeks
8 weeks
12 weeks
16 weeks
log Koa
1
10
100
1000
10000
PT-‐low PV-‐low PH-‐low C-‐low PT-‐high PH-‐high PV-‐high S-‐high C-‐high
ConcentraHon in apartment 3 DUST (µg/ g dust / g substance)
Field study: Substance on dust on horizontal product (PH)
Apartment
Apartment 1 2 3 4 5
PV-‐high
1 2 3 4 5
PH-‐high
4 weeks
8 weeks
12 weeks 1
100
10000
1000000
1 2 3 4 5 Concen
traH
on, µ
g/g
dust/g su
bstance
PT-‐high
1 2 3 4 5
PH-‐low
4 weeks
8 weeks
12 weeks 1
100
10000
1000000
1 2 3 4 5 Concen
traH
on, µ
g/g
dust/g su
bstance
PV-‐low
1 2 3 4 5
PT-‐low
Field study: Results Summary
15
air
direct transfer PRODUCT
3. Transfer processes from product to dust: Via air and by direct transfer
2. Dust is more relevant for substances with log Koa > 10
1. Consistent distribu$on between apartments
DustEx model: Valida$on with field study
16
DiBA (more vola$le)
DOP (less vola$le)
Air Dust Product
Concen
tra$
on, g/m
3
0
Concen
tra$
on, g/m
3
0
200
400
600
800
0
500
1000
1500
2000
0
5
10
15
20
0
100
200
300
Time, days 0 20 40 60 80 0 20 40 60 80 0 20 40 60 80
Time, days Time, days
1 x 10-‐5
5 x 10-‐6
1.5 x 10-‐5
4 x 10-‐10
2 x 10-‐10
0
0
exposure contribution per path
log Koa
6 7 8 9 10 11 12 13
0.0
0.2
0.4
0.6
0.8
1.0
dustairdermalairborne particles oral migration
Frac$o
n of th
e expo
sure
log Koa
Example contour plot with fixed parameters: migra$on rate 0.001 µg/cm2/min, weight frac$on 1%
Exposure pathway comparison
17
Scenario: Evapora$on + mouthing
Case stud
y BP
A in a to
y
10% contribu$on
Important elements of the decision tree
19
Product • only assessed if product is not a spray
Scenario • exposure due to mouthing? • direct contact with skin?
Exposure parameters
log Koa Log Koa
Kp_g Exposure via air
Exposure via dust
Conclusions on relevance of dust pathway
Decision tree Inges$on of dust << Tier 1 direct exposure pathway
BUT: in comparison to higher Tier direct exposure,
dust inges$on may be important à calculate with DustEx model
20
air
direct transfer PRODUCT
Field study For large horizontal surfaces direct transfer is relevant
21
Thank you
Sukiene V et al. Environ. Sci. Technol. 2016, 50 (8), 4296–4303. Sukiene V et al., in prepara.on Delmaar C et al., in prepara.on