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Exposure factors and exposure assessment for toysJacqueline van Engelen
Christiaan Delmaar
Center for Substances and Integrated
Risk Assessment
Consumer Exposure Assessment
• Model development (ConsExpo)
• Validation experiments
• Exposure factors (factsheets)
• Consumer behaviour (e.g. children)
• Risk assessment
Exposure Assessment for toys
• RIVM Report prepared for DG Enterprise
• Proposal of a risk assessment methodology
• Tiered approach
• Not limited to certain chemicals (but focussed onelements)
Basic Principle:
Starting point:
Exposure of children to substances in toys should not
exceed a certain health-based level (in mg/kg bw/day)
Taking into account background levels and other sources of
exposure
For elements:
The exposure of children to elements in toys may not
exceed X% of the TDI (in mg/kg bw/day)
Responsibility of Industry to assure the safety of products
Only focus on risk assessment, risk management is for the risk managers!
Options for compliance
1) use of migration data
Comparable to EN71-3
2) use of product (toy material) composition data
3) use of a quantitative risk based approach
no
no
Toy (material) can be directly ingested
Chemical can be released by evaporation
Toy (material) can release dust or spray
START
Can contact which body parts
Scenario IIScenario I
Scenario III
Scenario IV
Other body parts
Scenario I: direct ingestionScenario II: mouthing (sucking/licking)Scenario III: inhalation via evaporationScenario IV: inhalation via dust or sprayScenario V: skin contact
Hands
STOP
Scenario V
Scenario V
yes
yes
yes
yes
yes
no
Exposure factors
• Different types of toys, different age groups, different exposure routes
• Different age groups (body weight, skin area) and
different types of time-activity patterns
• Exposure duration
- Depends on child, type of toy, scenario – almost noinformation available (mouthing times)
• Different amounts ingested / mouthed
General information on exposurefactors
Large collection of data
• Scattered
• USA Exposure Factors Handbook
• Expofacts
• HERA projects
• Open Literature
• EISChemRisks Toolbox
• RIVM publications
RIVM publications
• Factsheets for ConsExpo
• Oral exposure of children to chemicals via hand-to-mouth contact
(http://www.rivm.nl/bibliotheek/rapporten/320005004.pdf)
• Non-food products: How to assess children’s exposure? (body weights, skin areas, inhalation rates, crawling, hand to mouth contact)
(http://www.rivm.nl/bibliotheek/rapporten/320005005.pdf)
Exposure factors
• Different routes of exposure
- Oral (mouthing/ ingestion)
- Different types of toys:
- Scrape off
- Liquid
- Powder, dusty
Exposure Scenarios
For elements in toys: oral route
most important
Presently: single value of intake of
8 mg/day
Proposal: default values for oral
contact
* 8 mg/day for material that can
be scaped off (fibers, paint on
pencils)
* 100 mg/day for powder-like
material (chalk)
* 400 mg/day for liquid material
(e.g. fingerpaint)
Example: exposure of children to leadin paint on toys
• toys mouthed
• migration paint into salive
• tolerable weekly intake: 25 ug/kg
• the Netherlands: 2 regulations:
- 0.7 ug bio-available per day per toy
<assuming 8 mg ‘toy intake’ a day> Max release rate: 90 ug/g
- max allowed level 3.5 mg/kg in paint
Case: lead in paint on a top
• lead released from paint: 1970 ug/g in HCl
• lead concentration in paint : 14.8 +/- 0.4 mg/g
Compliance?
•lead released from paint: 1970 ug/g in
HCl
•lead concentration in paint : 14.8 +/- 0.4
mg/g
Migration data:
90 ug/g
Toy composition
data: 3.5 mg/kg
Exposure scenario
• mouthing/chewing : pieces of paint migrate into
saliva/gastro-intestinal tract
• population : children of 1.5 years
• time scale: week average exposure
• background levels are not considered (but may be
relevant)
Use of a quantitative approach
1. deterministic evaluation using worst case values
2. refine assessment using more ‘realistic’ data and
experiments
3. include quantitative evaluation of uncertainty and
variability in probabilistic assessment
1rst step: deterministic evaluation
• exposure evaluation for hypothetical ‘worst case’
exposed child, representing entire population
• conservative assumptions exposure factors/parameters
• single values
• estimation of maximum exposure, no information on
uncertainty/variability (distribution of exposure in
population)
Exposure model & deterministic evaluation
E = (frequency x migrated amount of paint x uptake fraction) / body weight
ConsExpo defaults:
- body weight : 10 kg
- uptake fraction : 100%
- exposure frequency: 3x a week
- amount paint migrated into saliva: 0.1 g
Exposure:
1) E = 0.45 mg/kg/week = 450 ug/kg per week, based on concentration
2) E = 0.06 mg/kg/week = 60 ug/kg per week, based on HCl leaching
test
Tolerable weekly intake
25 ug/kg
Refining the deterministic assessment
• Experimental determination
- bioaccessible fraction
• Variability
- body weight
• uncertainties
- frequency
- migration fraction paint (dependent on mouthing time)
- fraction of lead in paint (experimental error)
Bioaccessibility and bioavailability
External
exposure
small intestine
portal vein
liver
mouth
oesophagus,
stomach,
small intestine
systemic
circulation
Internal exposure
Exposure to contaminant in a matrix
Ingestion of matrix + contaminant
FB = Fraction released from matrix = bioaccessible fraction
FA= Fraction of FB absorbed by small intestine
FH = Fraction of FA passing liver without being metabolised
F = Fraction reaching systemic circulation = bioavailable fraction
F = FB x FA x FH
In vitro digestion models
• Principle
- Various compartments of the human gastrointestinal tract are simulated
- Digestive juices are prepared artificially
- Matrix (toy, consumer product) is introduced in mouth compartment, mixed according to physiological transit
times, and transferred to next compartment
- Bioaccessibility: amount of compound released from matrix
• Mouth: simulating sucking on matrices
• Intestine: simulating ingestion of matrices
In vitro digestion model RIVM
rotate 5-30
min at 37 °C
+ 6 ml saliva + 12 ml gastric
juice
+ 12 ml duodenal juice
+ 6 ml bile
pH ± 6.5
+ matrix
empty test
tube
rotate 2 h
at 37 °C
rotate 2 h
at 37 °C
centrifuge,
separate chyme
and pellet
chyme
pH ± 6.5
+
pellet
mouth stomach intestine
pH ± 2-3
Probabilistic assessment: distributions
• distributions for exposure parameters
- frequency : log normal : mean 3 - s.d. 1 (times/week)
- paint migration fraction: uniform: 0.001- 0.1 g
- bio-accessibility: uniform 2-10 %
- body weight log normal: mean 11.1 – s.d. 1.1 kg
- lead fraction paint log normal: mean 14.8 – sd 0.4 mg/g
Probabilistic assessment: distributionsX-Delimiters Series 1
11.10025 0
9.322505 0 1 0.053669
12.90251 0 2 0.174424
3 0.322014
4 0.362266
5 0.241511
6 0.120755
7 0.053669
8 0.013417
Distribution for Wbody (kg)
Mean = 11.10025
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
8 9 10 11 12 13 14 15
Distribution for Fbioavailable
Mean = 0.059969
0
2
4
6
8
10
12
14
16
0.02 0.04 0.06 0.08 0.10
Distribution for frequency (1/week)
Mean = 3.000224
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
1 3 5 7
Distribution for Wf mg/g
Mean = 14.79897
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
13.5 14.125 14.75 15.375 16
Amount leached (mg)
Mean = 50.50094
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0.016
0.018
0.02
0 25 50 75 100
Probabilistic assessment: results
Distribution for E (ug/kg/week)
Mean = 12.34
X <=25
88%
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 14 28 42 56 70
Conclusions
• Screening assessment gives insight in order of magnitude
• More refined methods (like in vitro digestion method) give
more realistic values
• Probabilistic assessment takes uncertainty (and variability) into account and provides insight in (sub)-population exposure
Thank you for your attention !
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