CHronic exposure scenarios driving enviRONmental rIsks of Chemicals

Project Information

CHRONIC

Grant agreement ID: 956009

DOI

10.3030/956009

Project closed

EC signature date 19 August 2020

Start date 1 March 2021

End date 31 August 2025

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 3 627 872,64

EU contribution

€ 3 627 872,64

Coordinated by

ROSKILDE UNIVERSITET
Denmark

Periodic Reporting for period 2 - CHRONIC (CHronic exposure scenarios driving enviRONmental rIsks of Chemicals)

Reporting period: 2023-03-01 to 2025-08-31

Summary of the context and overall objectives of the project

CHronic exposure scenarios driving enviRONmental rIsks of Chemicals (CHRONIC)

Environmental Risk Assessment (ERA) of chemicals has traditionally focused on short-term effects in a few species, often overlooking long-term, low-dose exposures. However, such chronic exposures—especially when combined with other stressors—can lead to population declines and ecosystem disruptions. These effects are often mediated through non-standard endpoints such as behaviour, immune modulation, and genotoxicity, which are not captured by conventional ERA methods.

CHRONIC addressed this gap by training 13 Early Stage Researchers (ESRs) and developing tools to integrate chronic exposure and non-standard endpoints into ERA. The project aimed to:
• Train ESRs in interdisciplinary, cross-sectoral ERA approaches.
• Develop mechanistic understanding of chronic toxicity.
• Establish experimental tools and Adverse Outcome Pathways (AOPs).
• Assess implications for regulatory frameworks.

CHRONIC successfully delivered on its objectives by:
• Equipping ESRs with scientific and transferable skills.
• Advancing ERA methodologies with non-standard endpoints and multi-stressor scenarios.
• Producing 12 peer-reviewed publications, including joint manuscripts.
• Organizing a stakeholder workshop with SETAC.
• Contributing to policy development through outreach and proposed updates to OECD guidelines.

CHRONIC laid the foundation for a paradigm shift in ERA, emphasizing ecological relevance and long-term impact.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

CHRONIC developed mechanistic understanding of chronic chemical exposure across biological levels and taxa. Each ESR implemented a PhD project addressing low-dose exposure in macrophytes, invertebrates, and vertebrates, across freshwater, sediment, and soil systems. Projects focused on behaviour, immune modulation, and epigenetic change, structured around AOPs linking molecular events to ecological effects.

Experimental systems assessed:
• Behavioural changes and population/community dynamics.
• Interactions between chemical and environmental stressors.
• Biomarker links to ecological endpoints.

All ESRs developed and refined AOPs. Several conducted multigenerational studies, revealing species-specific sensitivities. Novel assays and modelling tools (e.g. TKTD, DEB) were applied to extrapolate findings to population-level outcomes.
Training included six joint events and a final SETAC workshop. ESRs earned 21 ECTS credits through CHRONIC modules and followed personalized development plans.
All ESRs completed at least one secondment, most completed two or three across academic, industrial, NGO, and governmental sectors.

Dissemination included:
• Project website, logo, newsletters, and SharePoint.
• LinkedIn group and WhatsApp community.
• Over 90 dissemination activities, including SETAC Europe presentations.
• 12 peer-reviewed publications and a joint outreach article for SETAC Globe.
• Development of assay compendia, innovation logs, and stakeholder matrices.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

CHRONIC advanced ERA by integrating mechanistic understanding, non-conventional endpoints, and multi-stressor scenarios. It moved beyond traditional short-term toxicity testing by applying AOPs to link molecular changes to ecological effects. Experimental systems enabled assessment of behavioural, immunological, and epigenetic endpoints under chronic exposure to metals, pesticides, pharmaceuticals, and radionuclides.
CHRONIC officially ended on August 31, 2025, having delivered all planned outputs. However, several ESRs are still completing their PhDs due to delayed starts, part-time employment, or 4-year programmes.

As of October 2025:
• 2 ESRs have defended, 1 has submitted, 8 will submit by March 2026, and 2 by October 2026.

Expected results include:
• Completion of all 13 PhD theses.
• Additional publications and outreach materials.
• Continued dissemination of tools and stakeholder outputs.
• Policy-relevant contributions to OECD guidelines and ERA frameworks.
• Ongoing engagement via SETAC and open-access platforms.

CHRONIC trained interdisciplinary ERA professionals ready to work across sectors. Its findings support safer chemical use, biodiversity protection, and public trust. Stakeholder engagement included:
• Final workshop with 37 participants.
• Outreach article for SETAC Globe.
• Engagement with EFSA, ECHA, NGOs, and industry.

Policy contributions include:
• Proposed updates to OECD guidelines.
• Support for behavioural and genetic markers in ERA.
• Recommendations for multi-stressor and multigenerational testing.

In summary, CHRONIC has laid the foundation for a more inclusive, mechanistic, and ecologically relevant ERA framework. Its legacy includes methodological advances, policy contributions, and a cohort of skilled researchers ready to shape the future of chemical risk assessment in Europe and beyond.

Group photo of happy CHRONIC'ers during a training event

An aquatic community collected from an experimental ditch

An emergence trap for mayflies, damselflies and chironomids

CHRONIC'ers, mainly ESRs, in a meeting

Experimental exposure system with the worm Lumbriculus variegatus

Lumbriculus variegatus is an organism often used for sediment tests