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A More Efficient and Effective Testing and Assessment Paradigm for Chemical Risk Management. Edward O denkirchen , Ph.D. Office of Pesticide Programs US Environmental Protection Agency. Business Case: Pesticide Risk Management. Mission Statement –

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A more efficient and effective testing and assessment paradigm for chemical risk management

A More Efficient and Effective Testing and Assessment Paradigm for Chemical Risk Management

Edward Odenkirchen, Ph.D.

Office of Pesticide Programs

US Environmental Protection Agency

Business case pesticide risk management
Business Case: Pesticide Risk Management Paradigm for Chemical Risk Management

Mission Statement –

  • Best possible regulatory decisions to protect public health and environment.

  • Rely on all best available scientific information.

  • External Peer-Review; Public Participation.

    Goal – Timely & targeted credible information to inform decisions.

Time & Cost


  • Benefits:

  • Resource Savings

  • Efficiency

  • Increase Reliability

  • Public Trust

Challenges for risk assessment
Challenges for Risk Assessment Paradigm for Chemical Risk Management

Risk Management Tools

Risk Assessment Capability & Capacity

Scientific & Technological Advancement

Common risk management needs
Common Risk Management Needs Paradigm for Chemical Risk Management

Ecological & Human Health Risk Assessment

  • Transparency & trust in decision-making.

  • Resource demands: Effectiveness and efficiency.

  • Spatial, temporal & biological decision scales.

  • Integration of multiple stressors: Chemical and Non-Chemical.

2009 nrc science decisions
2009 NRC Science & Decisions Paradigm for Chemical Risk Management

The committee encourages EPA to focus greater attention on design in the formative stages of risk assessment, specifically on planning and scoping and problem formulation, as articulated in EPA guidance for ecologic and cumulative risk assessment (EPA 1998, 2003).

Characterization of Paradigm for Chemical Risk ManagementExposure

Characterization of Ecological Effects

Communicating Results to the Risk Manager

Risk Management

Ecological Risk Assessment

Planning (Risk Assessor/ Risk Manager Dialogue)











PROBLEM FORMULATION Paradigm for Chemical Risk Management




Integrate Available Information

Source and Exposure Characteristics

Ecosystem Potentially at Risk

Ecological Effects

Planning (Risk Assessor/ Risk Manager Dialogue)

As Necessary: Acquire Data, Iterate Process, Monitor Results

Assessment Endpoints

Conceptual Model

Analysis Plan


Nrc 2007 toxicity testing in the 21st century a vision strategy
NRC 2007 “Toxicity Testing in the 21st Century: A Vision & Strategy”


Foster transformative paradigm shift based largely on increased use of in vitro andin silicosystems that will:

Broaden coverage of chemicals, endpoints, life stages.

Reduce cost and time of testing, increase efficiency and flexibility.

Use fewer animals.

Provide more robust data using mode of action and dosimetry information.

Enhanced integrated approaches to testing and assessment
Enhanced Integrated Approaches to Testing and Assessment & Strategy”

Combine existing exposure and toxicity data including information from new technologies (in silico, in vitro and –omics) to:

  • Formulate hypotheses about the toxicity potential of a chemical or a chemical category.

  • Target further data needs specific to a chemical or members of a chemical category for a given exposure.

Progressive, Tiered-Evaluation Approach: “Integrate, Formulate, Target”

Adverse Outcome Pathways – definition and example & Strategy”

Paradigm Shift in Toxicology: Pathway-based assessment to predict adversity.


Uptake-Delivery to Target Tissues







Cell injury, Inability to regulate



(e.g., Mortality,




Chemical Extrapolation

Cellular response pathway

Early cellular




Species Extrapolation

Adverse outcome

relevant to

risk assessment


initiating event

Perturbed cellular

response pathway

Chemical & Non- Chemical Stressors

Modified From NRC 2007

Spatial temporal and biological scales
Spatial, Temporal and Biological Scales & Strategy”

Integration of Scales:

Source to Outcome

Adverse outcome pathway

In vivo studies & Strategy”

Structure Activity Relationships

In vitro studies

Communities within landscapes

Molecular Target

Cellular Response


Pharmaco- kinetics

Tissue Organ




Adverse Outcome Pathway

Toxicity Pathways


initiating event

Key events or predictive

relationships spanning

levels of biological


Adverse outcome

relevant to

risk assessment

Greater Toxicological Understanding

Greater Risk Relevance

NAS Review of Ecological Risk Assessments Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Endangered Species Act (ESA)

Examining scientific and technical issues related to methods and assumptions used by EPA, FWS, and NOAA to carry out joint responsibilities under the ESA and FIFRA.

Nas review of ecological risk assessments under fifra and esa
NAS Review of Ecological Risk Assessments Under FIFRA and ESA

Charge Questions - Topic Areas:

  • Best Available Scientific Data & Information

  • Geospatial Information and Datasets

  • Mixtures

  • Sub-lethal, Indirect, and Cumulative Effects

  • Models

  • Interpretation of Uncertainty

Habitat-Species Response ESA

Habitat/Biota Distribution Data Layers

Demographic Data

Life History


Spatial Models

Population Models

Chemical Data Layers

Species Physiology Data

Chemical, Species Dose-Response Data & Models

Building Capacity for Explicit Risk Assessments


Efficient-effective site-specific risk assessment

Moving forward back to the future
Moving Forward – “Back to the Future” ESA

  • The technology may be “new”, but the logic for advancing the science to change risk assessment and risk management is not.

OECD Principles for QSAR Validation:Transparency & Utility for a Specified Application

  • Predicted endpoint is defined.

  • Mechanistic interpretation associated with predictions, if possible.

  • Defined chemical domain of applicability for the model.

  • Appropriate measures of goodness of fit, robustness, ability to predict.

  • An unambiguous algorithm.

Challenges to accelerate risk assessment in the 21st century
Challenges to Accelerate Risk Assessment in the 21st Century

Overall objectives are monumental.

  • Incremental steps; identify opportunities for success; focus on tangible applications (categories, read across, priority setting).

    Building libraries of information will take time.

  • Effective use of information technology can help accelerate AOP discovery, development, and evaluation.

    Establishing linkages depicted in AOPs.

  • Support transition from qualitative to quantitative uses; species and chemical extrapolations.

    Establishing linkages across toxicology (human health and ecology).

  • Multi-talented individuals and teams.

    Continuum of learning and refining.