Threshold of Toxicological Concern

Threshold of Toxicological Concern

Expanding the use of a science-based tool for toxicological health risk assessment objectives

Task Force Information

Objectives and list of Task Force members

Contact Information

Contact details in case you have specific questions

Activity Overview

Overview of ongoing and
upcoming activities

Expert Groups

Objectives, output and list of experts involved in each activity

Publications

List of publications of this
Task Force

Multimedia

Links to Task Force related documents, recordings and much more...

Completed Expert Groups

Details including experts involved of
each activity

Task Force Information

Objectives

The Task Force aims to strengthen the scientific fundamentals for TTC and to expand its applicability as a risk assessment tool for substances to which humans are exposed at low levels.

Task Force Members

Contact Information

For more detailed information, please contact Geraldine Borja at gborja@ilsieurope.be

Activity Overview

Ongoing

- Uncertainty in Hazard Assessment: a Comparison of TTC versus Chemical-Specific Approaches

The review will aid to develop knowledge and understanding of different stakeholders about the sources of uncertainty and allow a conclusion if and if so, how much additional uncertainty may be associated with the application of the TTC approach as compared to substance-specific risk assessment. Such understanding will enable appropriate communication of uncertainty, and would also allow to design future activities to minimize potential additional uncertainties.

Start date: Jan 2017 | End date: Mar 2024

- Combined toxicity screening assessment using TTC thresholds

There is a growing need for screening and prioritisation risk assessment on combinations of compounds in regulatory contexts of poorly characterised compounds at low exposure levels. These might be metabolites/impurities of pesticides, chemicals, or biocides, food contact material migrants, packaging materials, or processrelated contaminants.
Start date: Jul 2021 | End date: Dec 2024

In the pipeline

- Genotoxicity alert problem
- Mapping different regulatory approaches
- Less than lifetime exposure

Expert Groups

Uncertainty in Hazard Assessment: a Comparison of TTC versus Chemical-Specific Approaches

Background and Objectives

The probabilistic approach using the genotoxicity and non-cancer (Cramer class) Thresholds of Toxicological Concern (TTC) is often perceived as accepting a higher risk than traditional risk assessments.
However, robust scientific activities to describe the sources of uncertainty within the TTC approach have not yet been conducted or published.

Output
The Expert Group examines how much uncertainty may be associated with the application of the TTC approach, compared to a substance-specific risk assessment. The group expects to produce two reviews: an initial focus on qualitative description and ranking of the identified sources of uncertainty. A subsequent quantitative assessment of the remaining quantifiable uncertainties.

Expert Group Members

 

Building cumulative assessment groups for combined exposure risk assessment based on TTC thresholds or read-across

Background and Objectives

Develop scientific approaches for refinement of TTC-based co-exposure risk assessments, using real-world case examples and focus on data-poor substances and poorly characterized compounds at low exposure levels (metabolites/impurities of pesticides, chemicals, or biocides, food contact material migrants, packaging materials, or process-related contaminants). Solidify the scientific basis for combined toxicity screening assessment using TTC threshold values
Output

Provide guidance on methods to predict specific toxicity or general toxicological similarity to enable grouping into cumulative assessment groups. Develop a workflow relevant for different regulations for coexposure risk assessment based on TTC thresholds, possibly combined with specific read-across groups. Evaluate if and in which cases it might be sufficient to compare the TTC thresholds to individual coexposure component levels and in which cases all or some coexposure components should be added.

Expert Group Members

 

Publications

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Multimedia

Introductory video

One-Pager

Completed Expert Groups

Overview of completed activities

 

- Is the 0.15 µG/Day Tier of the Threshold of Toxicological Concern (TTC) still Appropriate?