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 !