Integration of epidemiological findings with mechanistic evidence in regulatory pesticide risk assessment: EFSA experiences.

Toxicological risk assessment of plant protection products (PPP) is currently carried out with the principal input from regulatory toxicology studies following OECD test guidelines, with little input from epidemiological data. An EFSA-commissioned systematic review of pesticide epidemiological studies (Ntzani et al. in Literature review on epidemiological studies linking exposure to pesticides and health effects. EFSA supporting publication 2013:EN-497, 2013) revealed statistically significant associations, among others, between pesticide exposures, and Parkinson's disease and childhood leukemia. Thereafter, EFSA launched a project with a mandate for the plant protection products and their residues (PPR) Panel to set the ground for the use of epidemiological data in the risk assessment of pesticides, as requested by Regulation (EC) 1107/2009. The project culminated with the publication of two EFSA's scientific opinions on the potential contribution of experimental investigations and epidemiological studies in PPP risk assessment and with the scientific conference held on 20 November 2017, in Parma, Italy. The application of modern methodologies in exposure assessment, toxicology and epidemiology would improve the pesticide risk assessment process and support a mechanistic shift for the integration of these three disciplines under a novel paradigm in risk assessment. The application of the adverse outcome pathway (AOP) conceptual framework to this approach would contribute to gain insight into the biological plausibility of a hazard identified in epidemiological or experimental studies and would inform an Integrated Approach to Testing and Assessment (IATA) within a regulatory context.

Towards a regulatory use of alternative developmental neurotoxicity testing (DNT).

There is a need for a more effective Developmental Neurotoxicity (DNT) screening which is scientifically driven by the fact that the developing nervous system might be more sensitive to exposures to some hazardous chemical. Additional concern comes from the recent societal concerns that toxic chemicals can contribute to the prevalence of neurodevelopment disabilities. Consequently, hazard identification and actions to reduce exposure to these chemicals is a priority in chemical risk assessment. To reach this goal a cost-efficient testing strategy based on a reliable in-vitro testing battery should be developed. Although this goal is representing a huge challenge in risk assessment, available data and methodologies are supporting the ultimate aim of developing a predictive model able to respond to different regulatory based problem formulations.

Consensus statement on the need for innovation, transition and implementation of developmental neurotoxicity (DNT) testing for regulatory purposes.

This consensus statement voices the agreement of scientific stakeholders from regulatory agencies, academia and industry that a new framework needs adopting for assessment of chemicals with the potential to disrupt brain development. An increased prevalence of neurodevelopmental disorders in children has been observed that cannot solely be explained by genetics and recently pre- and postnatal exposure to environmental chemicals has been suspected as a causal factor. There is only very limited information on neurodevelopmental toxicity, leaving thousands of chemicals, that are present in the environment, with high uncertainty concerning their developmental neurotoxicity (DNT) potential. Closing this data gap with the current test guideline approach is not feasible, because the in vivo bioassays are far too resource-intensive concerning time, money and number of animals. A variety of in vitro methods are now available, that have the potential to close this data gap by permitting mode-of-action-based DNT testing employing human stem cells-derived neuronal/glial models. In vitro DNT data together with in silico approaches will in the future allow development of predictive models for DNT effects. The ultimate application goals of these new approach methods for DNT testing are their usage for different regulatory purposes.

An adverse outcome pathway for parkinsonian motor deficits associated with mitochondrial complex I inhibition.

Epidemiological studies have observed an association between pesticide exposure and the development of Parkinson's disease, but have not established causality. The concept of an adverse outcome pathway (AOP) has been developed as a framework for the organization of available information linking the modulation of a molecular target [molecular initiating event (MIE)], via a sequence of essential biological key events (KEs), with an adverse outcome (AO). Here, we present an AOP covering the toxicological pathways that link the binding of an inhibitor to mitochondrial complex I (i.e., the MIE) with the onset of parkinsonian motor deficits (i.e., the AO). This AOP was developed according to the Organisation for Economic Co-operation and Development guidelines and uploaded to the AOP database. The KEs linking complex I inhibition to parkinsonian motor deficits are mitochondrial dysfunction, impaired proteostasis, neuroinflammation, and the degeneration of dopaminergic neurons of the substantia nigra. These KEs, by convention, were linearly organized. However, there was also evidence of additional feed-forward connections and shortcuts between the KEs, possibly depending on the intensity of the insult and the model system applied. The present AOP demonstrates mechanistic plausibility for epidemiological observations on a relationship between pesticide exposure and an elevated risk for Parkinson's disease development.

Chemical exposure and infant leukaemia: development of an adverse outcome pathway (AOP) for aetiology and risk assessment research.

Infant leukaemia (<1 year old) is a rare disease of an in utero origin at an early phase of foetal development. Rearrangements of the mixed-lineage leukaemia (MLL) gene producing abnormal fusion proteins are the most frequent genetic/molecular findings in infant B cell-acute lymphoblastic leukaemia. In small epidemiological studies, mother/foetus exposures to some chemicals including pesticides have been associated with infant leukaemia; however, the strength of evidence and power of these studies are weak at best. Experimental in vitro or in vivo models do not sufficiently recapitulate the human disease and regulatory toxicology studies are unlikely to capture this kind of hazard. Here, we develop an adverse outcome pathway (AOP) based substantially on an analogous disease-secondary acute leukaemia caused by the topoisomerase II (topo II) poison etoposide-and on cellular and animal models. The hallmark of the AOP is the formation of MLL gene rearrangements via topo II poisoning, leading to fusion genes and ultimately acute leukaemia by global (epi)genetic dysregulation. The AOP condenses molecular, pathological, regulatory and clinical knowledge in a pragmatic, transparent and weight of evidence-based framework. This facilitates the interpretation and integration of epidemiological studies in the process of risk assessment by defining the biologically plausible causative mechanism(s). The AOP identified important gaps in the knowledge relevant to aetiology and risk assessment, including the specific embryonic target cell during the short and spatially restricted period of susceptibility, and the role of (epi)genetic features modifying the initiation and progression of the disease. Furthermore, the suggested AOP informs on a potential Integrated Approach to Testing and Assessment to address the risk caused by environmental chemicals in the future.

Adverse outcome pathways: opportunities, limitations and open questions.

Adverse outcome pathways (AOPs) are a recent toxicological construct that connects, in a formalized, transparent and quality-controlled way, mechanistic information to apical endpoints for regulatory purposes. AOP links a molecular initiating event (MIE) to the adverse outcome (AO) via key events (KE), in a way specified by key event relationships (KER). Although this approach to formalize mechanistic toxicological information only started in 2010, over 200 AOPs have already been established. At this stage, new requirements arise, such as the need for harmonization and re-assessment, for continuous updating, as well as for alerting about pitfalls, misuses and limits of applicability. In this review, the history of the AOP concept and its most prominent strengths are discussed, including the advantages of a formalized approach, the systematic collection of weight of evidence, the linkage of mechanisms to apical end points, the examination of the plausibility of epidemiological data, the identification of critical knowledge gaps and the design of mechanistic test methods. To prepare the ground for a broadened and appropriate use of AOPs, some widespread misconceptions are explained. Moreover, potential weaknesses and shortcomings of the current AOP rule set are addressed (1) to facilitate the discussion on its further evolution and (2) to better define appropriate vs. less suitable application areas. Exemplary toxicological studies are presented to discuss the linearity assumptions of AOP, the management of event modifiers and compensatory mechanisms, and whether a separation of toxicodynamics from toxicokinetics including metabolism is possible in the framework of pathway plasticity. Suggestions on how to compromise between different needs of AOP stakeholders have been added. A clear definition of open questions and limitations is provided to encourage further progress in the field.

Targeting the annexin 1-formyl peptide receptor 2/ALX pathway affords protection against bacterial LPS-induced pathologic changes in the murine adrenal cortex.

Hypothalamo-pituitary-adrenocortical dysfunction contributes to morbidity and mortality in a high proportion of patients with sepsis. Here, we provide new insights into the underlying adrenal pathology. Using a murine model of endotoxemia (LPS injection), we demonstrate that adrenal insufficiency is triggered early in the disease. LPS induced a local inflammatory response in the adrenal gland within 4 hours of administration, coupled with increased expression of mRNAs for annexin A1 (AnxA1) and the formyl peptide receptors [(Fprs) 1, 2, and 3], a loss of lipid droplets in cortical cells (index of availability of cholesterol, the substrate for steroidogenesis), and a failure to mount a steroidogenic response to ACTH. Deletion of AnxA1 or Fpr2/3 in mice prevented lipid droplet loss, but not leukocyte infiltration. LPS increased adrenal myeloid differentiation primary response gene 88 and TLR2 mRNA expression, but not lymphocyte antigen 96 or TLR4. By contrast, neutrophil depletion prevented leukocyte infiltration and increased AnxA1, Fpr1, and Fpr3 mRNAs but had no impact on lipid droplet loss. Our novel data demonstrate that AnxA1 and Fpr2 have a critical role in the manifestation of adrenal insufficiency in this model, through regulation of cholesterol ester storage, suggesting that pharmacologic interventions targeting the AnxA1/FPR/ALX pathway may provide a new approach for the maintenance of adrenal steroidogenesis in sepsis.

Statement on the toxicological properties and maximum residue levels of acetamiprid and its metabolites.

Acetamiprid is a pesticide active substance with insecticidal action whose approval was renewed by Commission Implementing Regulation (EU) 2018/113. In January 2022, the EFSA PPR Panel published a statement following a request from the European Commission to advise on human health or the environment based on new scientific evidence presented by France during the decision-making phase. In July 2022, by means of a further mandate received from the European Commission, EFSA was requested to provide advice if new information and any other scientific evidence that has become available since the assessment conducted for the renewal in 2018 warrant re-evaluation of (i) toxicological parameters used for the risk assessment of acetamiprid during the renewal process, including toxicological endpoints; (ii) the residue definition for acetamiprid in products of plant origin; and (iii) the safety of existing maximum residue levels (MRLs). Meanwhile, the applicant of acetamiprid in the EU submitted new toxicology studies regarding the toxicological profile of the metabolite IM-2-1. Furthermore, the European Commission was made aware that several recent publications in scientific literature were made available after the literature searches conducted by EFSA. As the new data could affect the advice that EFSA was expected to deliver through the 2022 mandate, EFSA was further requested to consider this information by means of a revised mandate received in September 2023. As regards re-evaluation of point (i) in this statement, this was addressed by an EFSA Working Group integrating all the available evidence. The results of the weight of evidence indicated that there are major uncertainties in the body of evidence for the developmental neurotoxicity (DNT) properties of acetamiprid and further data are therefore needed to come to a more robust mechanistic understanding to enable appropriate hazard and risk assessment. In view of these uncertainties, the EFSA WG proposed to lower the acceptable daily intake (ADI) and acute reference dose (ARfD) from 0.025 to 0.005 mg/kg body weight (per day). A revised residue definition for risk assessment was proposed for leafy and fruit crops as sum of acetamiprid and N-desmethyl-acetamiprid (IM-2-1), expressed as acetamiprid. Regarding pulses/oilseeds, root crops and cereals, the new data received did not indicate a need to modify the existing residue definition for risk assessment, which therefore remains as parent acetamiprid. Regarding the residue definition for enforcement, the available data did not indicate a need to modify the existing definition because acetamiprid is still a sufficient marker of the residues in all crop groups. Considering the new health-based guidance values derived in the present statement, a risk for consumer has been identified for 38 MRLs currently in place in the EU Regulation. Consequently, EFSA recommended to lower the existing MRLs for 38 commodities based on the assessment of fall-back Good Agricultural Practices received within an ad hoc data call. Some fall-back MRLs proposals require further risk management considerations.

Updated reasoned opinion on the toxicological properties and maximum residue levels (MRLs) for the benzimidazole substances carbendazim and thiophanate-methyl.

In compliance with Article 43 of Regulation (EC) No 396/2005, EFSA received from the European Commission in 2020 a mandate to provide its reasoned opinion on the toxicological properties and maximum residue levels (MRLs) for the benzimidazole substances carbendazim and thiophanate-methyl. Specifically, EFSA was asked to assess whether thiophanate-methyl or carbendazim has clastogenic potential and, in case clastogenic potential can be excluded, to derive toxicological reference values necessary for consumer risk assessment and assessment of maximum residue levels (MRLs). Although these active substances are no longer authorised within the European Union, MRLs were established by the Codex Alimentarius Commission (codex maximum residue limits; CXLs), and import tolerances are in place. Based on the assessment of the available data, toxicological reference values and MRL proposals were derived and a consumer risk assessment was carried out. Some information required by the regulatory framework was found to be missing and a possible acute risk to consumers was identified. Hence, the consumer risk assessment was considered indicative only and all MRL proposals derived by EFSA still require further consideration by risk managers. In October 2022, to ensure that MRLs derived by EFSA in its assessment of 2021 are safe for consumers also in view of endocrine-disrupting properties, EFSA was requested to carry out a follow-up assessment taking into account the scientific criteria for identifying endocrine disruptors (ED). Based on the outcome of the assessment, the experts agreed that the reference values are also covering the concern related to the identified hazards indicative of endocrine disruption for thiophanate-methyl. No further considerations on the impact of the ED assessment on the current reference values were needed for carbendazim since the ED criteria are not met for this substance. Therefore, the risk assessment and the MRL recommendations derived in 2021 are confirmed.

Peer review of the pesticide risk assessment of the active substance lenacil.

The conclusions of the European Food Safety Authority (EFSA) following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Belgium, and co-rapporteur Member State, Austria, for the pesticide active substance lenacil are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012, as amended by Commission Implementing Regulation (EU) No 2018/1659. The conclusions were reached on the basis of the evaluation of the representative uses of lenacil as a herbicide on sugar and fodder beet (field use). The reliable end points, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are reported where identified.

Peer review of the pesticide risk assessment of the active substance clove oil.

The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State, Malta, for the pesticide active substance clove oil are reported. The context of the peer review was that required by Regulation (EC) No 1107/2009 of the European Parliament and of the Council. The conclusions for the amendment of approval were reached on the basis of the evaluation of the representative use of clove oil as a preharvest nematicide on tomatoes and cucumbers (permanent greenhouse use). The representative use evaluated for the renewal of approval of clove oil was as post-harvest fungicide and bactericide on apples, pears and peaches (indoor uses). The reliable endpoints appropriate for use in regulatory risk assessment are presented. Endpoints not relevant to the scope of the proposed amendment of approval conditions will be addressed in the context of the renewal of approval procedure of clove oil running in parallel (AIR IV, EFSA Q-2016-00809). Missing information identified as being required by the regulatory framework is listed. Concerns are reported where identified.

Updated peer review of the pesticide risk assessment of the active substance dichlorprop-P and variant dichlorprop-P-2-ethylhexyl.

The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Ireland, and co-rapporteur Member State, Poland, for the pesticide active substance dichlorprop-P and the variant dichlorprop-P-2-ethylhexyl and the assessment of applications for maximum residue levels (MRLs) are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative uses of dichlorprop-P as a herbicide on cereals, grassland and grass seed crops and of the variant dichlorprop-P-2-ethylhexyl as a plant growth regulator on citrus. MRLs were assessed in mandarin and lemon. The conclusions from 2018 were updated in 2024 following the request from the European Commission with regard to the endocrine-disrupting properties. The reliable end points, appropriate for use in regulatory risk assessment and the proposed MRLs, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are reported where identified.

Peer review of the pesticide risk assessment of the active substance quinolin-8-ol.

The conclusions of the European Food Safety Authority (EFSA) following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Spain, and co-rapporteur Member State, the Netherlands, for the pesticide active substance quinolin-8-ol are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative use of quinolin-8-ol as a fungicide and bactericide against soil-borne pathogens in tomato cultivation in permanent greenhouses applied by drip irrigation. The reliable end points, appropriate for use in regulatory risk assessment are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are reported where identified.

Updated peer review of the pesticide risk assessment of the active substance pydiflumetofen.

The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State, France, and co-rapporteur Member State, Austria, for the pesticide active substance pydiflumetofen and the assessment of applications for maximum residue levels (MRLs) are reported. The context of the peer review was that required by Regulation (EC) No 1107/2009 of the European Parliament and of the Council. The conclusions were reached on the basis of the evaluation of the representative uses of pydiflumetofen as a fungicide field application on pome fruits, grapes, potato, fruiting vegetables, cucurbits and Brassica vegetables and updated following the request from Commission to consider additional information submitted and review the risk assessment. The reliable endpoints, appropriate for use in regulatory risk assessment and the proposed MRLs, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are reported where identified.

Functions of nitric oxide-mediated post-translational modifications under abiotic stress.

Environmental conditions greatly impact plant growth and development. In the current context of both global climate change and land degradation, abiotic stresses usually lead to growth restriction limiting crop production. Plants have evolved to sense and respond to maximize adaptation and survival; therefore, understanding the mechanisms involved in the different converging signaling networks becomes critical for improving plant tolerance. In the last few years, several studies have shown the plant responses against drought and salinity, high and low temperatures, mechanical wounding, heavy metals, hypoxia, UV radiation, or ozone stresses. These threats lead the plant to coordinate a crosstalk among different pathways, highlighting the role of phytohormones and reactive oxygen and nitrogen species (RONS). In particular, plants sense these reactive species through post-translational modification (PTM) of macromolecules such as nucleic acids, proteins, and fatty acids, hence triggering antioxidant responses with molecular implications in the plant welfare. Here, this review compiles the state of the art about how plant systems sense and transduce this crosstalk through PTMs of biological molecules, highlighting the S-nitrosylation of protein targets. These molecular mechanisms finally impact at a physiological level facing the abiotic stressful traits that could lead to establishing molecular patterns underlying stress responses and adaptation strategies.

Establishment of a human cell-based in vitro battery to assess developmental neurotoxicity hazard of chemicals.

Developmental neurotoxicity (DNT) is a major safety concern for all chemicals of the human exposome. However, DNT data from animal studies are available for only a small percentage of manufactured compounds. Test methods with a higher throughput than current regulatory guideline methods, and with improved human relevance are urgently needed. We therefore explored the feasibility of DNT hazard assessment based on new approach methods (NAMs). An in vitro battery (IVB) was assembled from ten individual NAMs that had been developed during the past years to probe effects of chemicals on various fundamental neurodevelopmental processes. All assays used human neural cells at different developmental stages. This allowed us to assess disturbances of: (i) proliferation of neural progenitor cells (NPC); (ii) migration of neural crest cells, radial glia cells, neurons and oligodendrocytes; (iii) differentiation of NPC into neurons and oligodendrocytes; and (iv) neurite outgrowth of peripheral and central neurons. In parallel, cytotoxicity measures were obtained. The feasibility of concentration-dependent screening and of a reliable biostatistical processing of the complex multi-dimensional data was explored with a set of 120 test compounds, containing subsets of pre-defined positive and negative DNT compounds. The battery provided alerts (hit or borderline) for 24 of 28 known toxicants (82% sensitivity), and for none of the 17 negative controls. Based on the results from this screen project, strategies were developed on how IVB data may be used in the context of risk assessment scenarios employing integrated approaches for testing and assessment (IATA).

Acceptance criteria for new approach methods in toxicology and human health-relevant life science research - part I.

Every test procedure, scientific and non-scientific, has inherent uncertainties, even when performed according to a standard operating procedure (SOP). In addition, it is prone to errors, defects, and mistakes introduced by operators, laboratory equipment, or materials used. Adherence to an SOP and comprehensive validation of the test method cannot guarantee that each test run produces data within the acceptable range of variability and with the precision and accuracy determined during the method validation. We illustrate here (part I) why controlling the validity of each test run is an important element of experimental design. The definition and application of acceptance criteria (AC) for the validity of test runs is important for the setup and use of test methods, particularly for the use of new approach methods (NAM) in toxicity testing. AC can be used for decision rules on how to handle data, e.g., to accept the data for further use (AC fulfilled) or to reject the data (AC not fulfilled). The adherence to AC has important requirements and consequences that may seem surprising at first sight: (i) AC depend on a test method's objectives, e.g., on the types/concentrations of chemicals tested, the regulatory context, the desired throughput; (ii) AC are applied and documented at each test run, while validation of a method (including the definition of AC) is only performed once; (iii) if AC are altered, then the set of data produced by a method can change. AC, if missing, are the blind spot of quality assurance: Test results may not be reliable and comparable. The establishment and uses of AC will be further detailed in part II of this series.

TKPlate 1.0: An Open-access platform for toxicokinetic and toxicodynamic modelling of chemicals to implement new approach methodologies in chemical risk assessment.

This publication is linked to the following EFSA Supporting Publications articles: http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2023.EN-8441/full, http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2023.EN-8440/full, http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2023.EN-8437/full.

Development of adverse outcome pathways relevant for the identification of substances having endocrine disruption properties Uterine adenocarcinoma as adverse outcome.

Development of adverse outcome pathways (AOPs) for uterine adenocarcinoma can provide a practical tool to implement the EFSA-ECHA Guidance (2018) for the identification of endocrine disruptors in the context of Regulations (EU) No 528/2012 and (EC) No 1107/2009. AOPs can give indications about the strength of the relationship between an adverse outcome (intended as a human health outcome) and chemicals (pesticides but not only) affecting the pathways. In this scientific opinion, the PPR Panel explored the development of AOPs for uterine adenocarcinoma. An evidence-based approach methodology was applied, and literature reviews were produced using a structured framework assuring transparency, objectivity, and comprehensiveness. Several AOPs were developed; these converged to a common critical node, that is increased estradiol availability in the uterus followed by estrogen receptor activation in the endometrium; therefore, a putative AOP network was considered. An uncertainty analysis and a probabilistic quantification of the weight of evidence have been carried out via expert knowledge elicitation for each set of MIEs/KEs/KERs included in individual AOPs. The collected data on the AOP network were evaluated qualitatively, whereas a quantitative uncertainty analysis for weight of the AOP network certainty has not been performed. Recommendations are provided, including exploring further the uncertainties identified in the AOPs and putative AOP network; further methodological developments for quantifying the certainty of the KERs and of the overall AOPs and AOP network; and investigating of NAMs applications in the context of some of the MIEs/KEs currently part of the putative AOP network developed.