With the dramatic increase of nano-enabled products entering the market every year, human and environmental exposures are inevitable, which raises concerns in terms of the health and safety of such emerging nanomaterials. Scientific knowledge to assess the exposure to nanomaterials continues to improve. As an example, new exposure tools and models for nanomaterials are being developed. To further promote the development in this area, the OECD compiled an inventory of available models and tools for assessing occupational, consumer and environmental exposure to Nanomaterials. 54 tools and models were initially compiled and following in-depth analyses, 10 occupational, 7 consumer and 6 environmental tools/models were recommended or evaluated as suitable for assessing exposure to nanomaterials. The detailed information on the analyses and evaluations are provided in the reports accessible from the Series on Nanomaterials website (No. 98, 99, 100 and 101). The OECD hosted a webinar on 2 December at 14:00 CET to present the key findings of the reports. Watch the video replay at: https://oe.cd/testing-assessment-webinars

1. Compilation of Available Tools and Models Used for
Assessing Consumer Exposure to Manufactured
Nanomaterials and Evaluation of Their Applicability in
Consumer Exposure Assessments
2 December 2021
Mohammad Zein Aghaji, Yi Zhang, Djordje Vladisavljevic
Health Canada

2. • In 2015, OECD/WPMN/SG8 conducted a survey on Consumer and Environmental
Exposures to Manufactured Nanomaterials
– The survey identified models/tools for consumer and/or environmental exposure to be
of high importance
• In 2017, Canada submitted a proposal to the OECD WPMN to lead a project with
two objectives:
– Compilation of available tools and models for the assessment of environmental and
consumer exposure to manufactured nanomaterials
– Evaluation of their applicability to exposure assessment of manufactured nanomaterials
Background
2 /14

3. • Reviewed international projects and peer-reviewed
publications for tools/models related to consumer
exposure to manufactured nanomaterials
• Compiled an inventory of 23 tools, models and
databases in an Excel file
• Classified the inventory into two categories: nano-
specific and chemical related
• Objective 1 contributors:
– United States (EPA)
– Germany (BfR)
– Netherlands (RIVM)
– Denmark (NRCWE)
Objective 1: Compilation of Models/Tools
3 /14
Literature review & consultation
with SG8 members
Classification
23 Tools/models
8 Chemical
tools/models
15 Nano-specific
tools/models
Category 1 Category 2

4. 4 /14
Screenshot of Inventory

5. • 15 Nano-specific tools/ models subjected
to scope analysis and accessibility and
support examination, focusing only on
the exposure module part:
– Scope analysis examined input
parameters, assumptions, intended
application domain, routes of exposure,
and outputs
– Accessibility and support considered
availability of input parameters and
computational framework of
models/tools
Objective 2: Evaluation of Models/Tools
5 /14
Scope
Analysis
Accessibility
and support
Sensitivity
analysis
Performance testing
 Boxall et al. 2007
 ConsExpo-Nano
 GUIDEnano
 I-NANO tool
 LICARA-nanoScan
 MPPD
 NanoRiskCat
 Nazerenko et al. 2014
 SUNDS
 ANSES CB tool
 NanoSafer
 CB Nanotool
 Precautionary Matrix
 Stoffenmanager Nano
 Engineered Nanoparticle
Airborne Exposure(ENAE) tool
15 Nano specific tools/models

6. Overview of Model Outputs
6 /14

7. Sensitivity Analysis
7 /14
• Investigated variations of model/tool outputs based on input values
• Identified which input parameters have the most influence on model/tool prediction
Input data
Model/tool
prediction
Post analysis
Most sensitive: Least sensitive :
 Amount of product used
 Fraction of nanomaterials in
products
 Emission rate (release rate)
 Inhalation rate
 Origin of nanomaterial/product type
 Activity level
• Collaborated with NRCWE (Denmark), the lead of WPMN SG8 project on compilation of
models for occupational exposure to manufactured nanomaterials

8. Performance Testing
8 /14
• Assessed the predictive capability of the models/tools by comparing the outputs with
measurement data collected from literature
– In-house exposure release database was established
• Case studies were selected for model performance testing, key considerations include:
– The data availability for input and output of model
– Domain applicability of models
• The selected studies on consumer exposure to nano-contained spray and powder
products.
• Parameterization of model inputs was conducted, to unify the heterogeneous input
data

9. 9 /14
Performance Testing:
Criteria to Assess the Model/Tool Prediction
• The performance testing was conducted for consumer exposure scenarios
only, based on personal or stationary exposure measurement data and the
following criteria agreed in OECD/WPMN/SG8
• The Spearman correlation coefficient between model/tool estimates and measured
exposure values is at least 0.6
• The model/tool estimates a reasonable worst case, which represents the upper bound of
exposure estimates
• Real measurements do not exceed the model/tool estimates for more than 50% of the
total comparisons made in the performance testing of the model/tool
• Separate evaluation for solids, liquids and/or gases/fumes whenever possible

10. 10 /14
Summary of Performance Testing Results
Model/Tool Tester
Number of
comparisons
Spearman
correlation
Trend over total comparison
(overestimation/underestimation)
ENAE v1.0 HC 13 0.75 overestimation
GUIDEnano v.30 HC 7 0.70 overestimation
Boxall et al. 2007 HC 13 0.72 overestimation
Stoffenmanager Nano v1.0 HC 16 0.79 N/A*
ConsExpo nano v3.0^ RIVM 7 N/A overestimation
Swiss Precautionary Matrix v3.1 HC 9 N/A N/A
NanoSafer v1.1 NRCWE and
HC 4 0.63 overestimation
* Not applicable
^ Performed in EU H2020 caLIBRAte project

11. 11 /14
Summary of Models/Tools Evaluated
Overall Summary of Model/Tool Evaluation
• Due to overlap between consumer and occupational projects, a joint report has been published for inventory of models/tools,
scope analysis, accessibility/support examination, sensitivity analysis, but separate reports have been published for performance
testing
• The documents reviewed by WPMN member countries: United States (EPA), Germany (BfR), Netherlands (RIVM, TNO)

12. 12 /14
Conclusion and Consideration
• An inventory of the tools/models was developed, including critical information on each identified
model/tool, such as characteristics, range of applicability, extent of validation, etc.
• The sensitivity analysis identified the most and least sensitive parameters. Increasing accuracy of those
sensitive input parameters will reduce uncertainty of model estimates.
• The performance testing showed that most models/tools tend to overestimate exposure and the
computed Spearman correlation coefficients were above 0.6. Boxall et al. 2007, the ENAE tool,
GUIDEnano, NanoSafer, ConsExpo nano, and Stoffenmanager Nano are considered to be suitable for
predicting the consumer exposure to manufactured nanomaterials.
• Tools/models compiled in this project do not account for agglomeration and aggregation of nanomaterials,
which could influence the performance of the models/tools. New tools/models incorporating these
properties are recommended to be implemented.
• The current performance testing is limited to a few case studies due to availability of measurement data.
More measurement studies on consumer exposure to manufactured nanomaterials are recommended to
be conducted.

13. 13 /14
Published Documents
The report consists of 3 parts:
 Part 1: Joint report on consumer and occupational
exposure models/tools, including scope analysis,
accessibility and support, sensitivity analysis (by
Canada/Denmark) - No. 346
 Part 2: Performance testing on occupational
exposure models/tools (by Denmark) – No. 347
 Part 3: Performance testing on consumer exposure
models/tools (by Canada) – No. 348
https://www.oecd.org/chemicalsafety/testing/series-
testing-assessment-publications-number.htm

14. 14 /14
Thank you!
• OECD delegations, WPMN member countries and organizations that contributed to
projects, reviewed the documents and submitted comments
• Special thanks to the NRCWE team in Denmark for collaborating and creating
documents with us