For global pesticide technical material equivalence assessment, impurity risk assessment, and new pesticide development, REACH24H provides QSAR prediction, toxicological data assessment, Read-Across, Weight of Evidence (WoE), and further toxicological assessment services.
Based on the regulatory requirements of the target market, chemical structure, impurity profile, and available data, our experts develop fit-for-purpose prediction models and assessment strategies to support pesticide registration, technical justification, and R&D decision-making.
When Is Pesticide QSAR Prediction Needed?
QSAR prediction can support multiple stages of pesticide registration and development, particularly where technical equivalence, impurity safety, or early-stage screening requires additional non-testing evidence.
Technical Material Equivalence
When a new source of technical material contains new impurities or increased levels of existing impurities compared with the reference source, QSAR prediction and expert review can support Tier II toxicological and ecotoxicological equivalence assessment.
Impurity Toxicological Assessment
QSAR can be used to assess the health toxicity or ecotoxicity of new or increased impurities and to help fill critical data gaps for regulatory assessment.
New Pesticide Development
QSAR modeling and virtual screening can also support pesticide R&D, including lead discovery and early evaluation of candidate compounds.
What Is QSAR in Pesticide Regulatory Submissions?
Quantitative Structure–Activity Relationship (QSAR) models use mathematical, statistical, or expert rule-based approaches to predict physicochemical, biological, toxicological, or environmental properties from molecular structure. In regulatory and technical documents, SAR and QSAR are often collectively referred to as (Q)SAR.
Generally, the development of a (Q)SAR model consists of the following five steps:
(Q)SAR approaches are usually applied to assess health toxicity or ecotoxicity of new/increased levels of impurities present in a new source of technical materials (TC/TK). The predicted toxicities, especially for genotoxicity, obtained by using (Q)SAR are important data for assessing whether the new source of technical material is toxicologically equivalent to the reference source, and the data are required by an increasing number of countries, regions or organizations including the EU, Australia, Brazil, Mexico, Russia, Argentina, etc.
Under international pesticide equivalence frameworks (such as EU SANCO/10597/2003 Rev. 10.1), when a generic technical material fails Tier I (Chemical Equivalence) due to newly introduced or elevated impurities, a Tier II (Toxicological & Ecotoxicological Equivalence) assessment is triggered. In silico (Q)SAR prediction combined with toxicological Expert Review serves as an internationally recognized, non-testing pathway to evaluate impurity hazard profiles, fill critical data gaps, and support the waiver of unnecessary in vivo animal testing.
Global Regulatory Requirements for Pesticide QSAR and Technical Equivalence
Regulatory expectations can vary by jurisdiction, submission purpose, and case-specific conditions. The following summarizes key requirements and assessment practices addressed in the current technical framework.
European Union (EU): Tier II equivalence assessments under GD SANCO/10597/2003 Rev. 10.1 may use scientifically justified (Q)SAR analysis to assess the toxicological relevance of new or increased impurities, supported by expert interpretation and other available evidence.
Brazil (ANVISA/MAPA): Technical equivalence submissions require three specialist expert systems (e.g., Derek Nexus, OECD QSAR Toolbox, VEGA HUB). A tiered assessment strategy applies based on impurity content: 0.1%–<0.3% (mutagenicity, carcinogenicity, sensitization), 0.3%–<1.0% (+ reproductive toxicity), and 1.0%–<10% (+ target organ toxicity, irritation, acute oral toxicity).
Australia (APVMA): For Health 6 applications, APVMA guidance lists in silico genotoxicity analysis including both a rules-based and a statistically based method as part of the data that may be submitted, together with other evidence or scientific justification as applicable.
Mexico (COFEPRIS): Equivalence assessments primarily focus on acute oral toxicity (rat LD50) using recognized databases or (Q)SAR tools (e.g., T.E.S.T.). Five-batch impurity data are integrated with active ingredient toxicity to calculate worst-case contribution via the dose-additivity model; other endpoints are addressed if specifically requested.
FAO/WHO Specifications: Impurity evaluations for chemical pesticides recommend at least two independent (Q)SAR models (rule-based and statistical-based) to maximize prediction sensitivity and specificity, combined with dose-additivity modeling (LD50, ADI, BMD) to determine worst-case-possible toxicological contribution.
The US, Canada, Argentina & Other Markets: Customized in silico predictions and weight-of-evidence (WoE) dossiers to support registrations under EPA, PMRA, SENASA, and other regional authorities, tailored to specific chemical profiles and regulatory objectives.
Pesticide QSAR & Toxicological Assessment Services
Global (Q)SAR Prediction & Reporting Services for Agrochemicals(EU, Brazil, Argentina, Australia, Mexico, Russia, Canada, FAO/WHO, etc.)
Weight-of-Evidence (WoE)-Based Toxicological Data Retrieval and Assessment
Rule-based and Statistical-based QSAR models
Application of Threshold of Toxicological Concern (TTC)
Derivation of Health-Based Exposure Limits (HBELs): PDE/ADE, AI, TTC
Read-Across and chemical similarity searching
Defined Approaches on skin sensitization (OECD TG 497)
Endocrine Disruptor (ED) Assessment
Molecular Docking Simulations for Endocrine Targets
Computational Toxicology for Novel Agrochemical Discovery & Development
QSAR Prediction Report Format (QPRF)
QSAR Model Report Format (QMRF)
Custom (Q)SAR Modeling & Profiling
QSAR Prediction Systems and Tools
REACH24H combines a broad range of in silico tools with scientific expertise to support the assessment of (eco)toxicity, environmental fate, and physicochemical properties of impurities or target compounds.
Publicly available tools: OECD QSAR Toolbox, Toxtree, T.E.S.T, VEGA hub, OPERA, ECOSAR, EPI Suite™, etc.
Commercial tools: Derek Nexus™, Sarah Nexus™, Case Ultra, etc.
Cheminformatic tools: ChemDraw, RDkit, ChemMine, AMBIT, CPDB/LCDB, etc.
QSAR Prediction Endpoints
Physico-chemical properties: Log Kow, pKa, BCF, etc.
Mammalian toxicology: genotoxicity/mutagenicity, carcinogenicity, developmental/reproductive toxicity, acute oral toxicity (rat LD50), endocrine disruption, skin sensitization, etc.
Ecotoxicology: aquatic toxicity, toxic to honeybees, etc.
Environmental behavior: persistence, hydrolysis rate, Koc, etc.
Metabolites and degradation or metabolic pathways of molecules
Genotoxicity and Endocrine Disruption Assessment
Genotoxic impurity assessment approaches informed by established frameworks such as ICH M7, where relevant
in silico evaluation of clastogenicity
Molecular docking
Postulate MoA(s) based on adverse outcome pathway (AOP) framework
Weight of Evidence (WoE)
QSAR Model Building
Data cleaning
Molecular descriptors
Model selection: linear models & machine learning
Validation
Application domain
Release
Selected Project Examples
The following anonymized examples illustrate how REACH24H applies QSAR, Weight of Evidence, computational toxicology, and expert review to address complex pesticide regulatory challenges.
Addressing Mutagenicity Concerns for a New Impurity Without Additional In Vivo Testing
For a new impurity raising genotoxicity concerns during a Tier II equivalence assessment in the EU, REACH24H combined recognized in silico prediction systems with a multi-source Weight of Evidence (WoE) assessment and expert toxicological review.
The resulting technical justification addressed the regulatory concern and supported acceptance of the assessment without additional in vivo testing, helping the client avoid significant testing costs and potential submission delays.
Navigating Brazil’s Tiered Impurity Assessment for a Complex Impurity Profile
For a technical material with a complex impurity profile, REACH24H developed a tiered assessment strategy aligned with current Brazilian review requirements.
Multiple expert systems and toxicological evidence were integrated to address the relevant endpoints and provide a clear regulatory justification. The technical package was accepted without additional technical information requests, helping the project avoid delays associated with dossier rework and resubmission.
Establishing a Scientifically Justified Limit for a Trace Impurity That Could Not Be Isolated
A trace impurity in a technical material could not be isolated in sufficient quantity for conventional toxicological testing.
REACH24H applied non-testing toxicological approaches together with quantitative exposure assessment to characterize the potential risk and establish a scientifically justified impurity limit.
The assessment supported the regulatory justification of the impurity at the proposed level, helping avoid disproportionate testing and unnecessary manufacturing-process changes.
Responding to a Critical Regulatory Impurity Concern Under a Tight Deadline
Following submission, a regulatory authority raised a significant toxicological concern regarding an impurity and requested additional technical justification within a limited response period.
REACH24H rapidly supplemented the dossier with targeted computational toxicology evidence, expert interpretation, and an integrated Weight of Evidence assessment.
The response successfully addressed the authority’s concern and allowed the review to proceed without the originally anticipated additional testing requirement.
Why Choose REACH24H for Pesticide QSAR?
Experienced Multidisciplinary Team: Multidisciplinary team of toxicologists, in silico computational chemists, and regulatory specialists.
Rigorous Internal Quality Review: Rigorous internal peer review to support scientifically robust and submission-ready reporting.
Global Expert and GLP Laboratory Network: Long-standing collaboration with research institutes, subject-matter experts, and established GLP testing facilities.
Regulatory Communication Experience: Experience supporting communication with regulatory agencies in the EU, Latin America, Asia-Pacific, and international bodies.
Responsive Project Delivery and Cost Control: Quick turnaround to help pesticide applicants meet submission timelines while optimizing testing budgets.
Confidentiality and Data Protection: Strong commitment to data security, confidentiality, and protection of client intellectual property.
End-to-End Project Management: End-to-end milestone tracking and tailored support across multiple jurisdictions.
Pesticide QSAR Frequently Asked Questions
Not sure which QSAR or toxicological assessment approach applies to your project?
REACH24H can review your target market, technical material or impurity profile, and available data to identify potential data gaps and define an appropriate assessment pathway.
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