Vera Ritz

Scientific principles for the identification of endocrine-disrupting chemicals: a consensus statement

Endocrine disruption is a specific form of toxicity, where natural and/or anthropogenic chemicals, known as “endocrine disruptors” (EDs), trigger adverse health effects by disrupting the endogenous hormone system. There is need to harmonize guidance on the regulation of EDs, but this has been hampered by what appeared as a lack of consensus among scientists. This publication provides summary information about a consensus reached by a group of world-leading scientists that can serve as the basis for the development of ED criteria in relevant EU legislation. Twenty-three international scientists from different disciplines discussed principles and open questions on ED identification as outlined in a draft consensus paper at an expert meeting hosted by the German Federal Institute for Risk Assessment (BfR) in Berlin, Germany on 11–12 April 2016. Participants reached a consensus regarding scientific principles for the identification of EDs. The paper discusses the consensus reached on background, definition of an ED and related concepts, sources of uncertainty, scientific principles important for ED identification, and research needs. It highlights the difficulty in retrospectively reconstructing ED exposure, insufficient range of validated test systems for EDs, and some issues impacting on the evaluation of the risk from EDs, such as non-monotonic dose–response and thresholds, modes of action, and exposure assessment. This report provides the consensus statement on EDs agreed among all participating scientists. The meeting facilitated a productive debate and reduced a number of differences in views. It is expected that the consensus reached will serve as an important basis for the development of regulatory ED criteria.

Regulatory toxicology in the twenty-first century: challenges, perspectives and possible solutions

Abstract The advent of new testing systems and “omics”-technologies has left regulatory toxicology facing one of the biggest challenges for decades. That is the question whether and how these methods can be used for regulatory purposes. The new methods undoubtedly enable regulators to address important open questions of toxicology such as species-specific toxicity, mixture toxicity, low-dose effects, endocrine effects or nanotoxicology, while promising faster and more efficient toxicity testing with the use of less animals. Consequently, the respective assays, methods and testing strategies are subject of several research programs worldwide. On the other hand, the practical application of such tests for regulatory purposes is a matter of ongoing debate. This document summarizes key aspects of this debate in the light of the European “regulatory status quo”, while elucidating new perspectives for regulatory toxicity testing.

Assessment strategies and decision criteria for pesticides with endocrine disrupting properties relevant to humans

There is growing concern that environmental substances with a potential to modulate the hormonal system may have harmful effects on human health. Consequently, a new EU regulation names endocrine disrupting properties as one of the cut-off criteria for the approval of plant protection products, although it currently fails to provide specific science-based measures for the assessment of substances with such properties. Since specific measures are to be presented by the European Commission in 2013 the development of assessment and decision criteria is a key challenge concerning the implementation of this new EU regulation. Proposals of such decision criteria for substances with potential endocrine disrupting properties in human health risk assessment were developed by the German Federal Institute for Risk Assessment (BfR) and discussed at an expert workshop in November 2009. Under consideration of the requirements laid down within the new plant protection product legislation and the scientific discussions during the workshop, a conceptual framework on evaluation of substances for endocrine disrupting properties in a regulatory context is presented in this paper. Central aspects of the framework include assessment of adversity of effects, establishment of a mode/mechanism of action in animals, considerations concerning the relevance of effects to humans and two options for a regulatory decision.

Human health risk assessment from combined exposure in the framework of plant protection products and biocidal products

Cumulative risk assessment (CRA) is of major importance and one of the biggest challenges for the future as a legal requirement within the EU for active substances used in plant protection products (PPP) and biocidal products (BP). Therefore, it is important to develop a methodology to take into account cumulative and synergistic effects for both active substances and substances of concern (SoC). The implementation of cumulative aspects in regulatory decisions is highly demanded and promoted by EU parliament, EU commission, European Food Safety Authority (EFSA), European Chemicals Agency (ECHA) and national authorities. Based on EFSA’s and ECHA’s work on CRA, the Federal Institute for Risk Assessment (BfR) drafted a concept on how to take cumulative aspects into account in the regulatory context in risk assessments for operators, consumers and other uninvolved third parties. Application of this concept as part of the routine risk assessment for PPP and BP is envisaged as soon as suitable experience has been gained in a testing phase. The BfR draft concept uses dose-addition of individual active substances and SoC as the toxicological standard concept for CRA and proposes a tiered approach. It recommends to start with calculation of a hazard index (HI) for all relevant substances contained in the PPP or BP under consideration. Proceeding to higher tiers is currently foreseen if the HI is larger than 1, i.e., an unacceptable risk cannot be excluded. In higher tiers, the HI should be calculated with respect to common targets and might consider effect-specific NOAEL’s (No Observed Adverse Effect Level) or relative potency factors, if available. Refinements should consider both the toxicity and the exposure part of the CRA and will depend on availability of relevant data. BfR acknowledges the complexity of the refinement work in mixture risk assessment to be done. The exposure assessment for operators, bystanders/residents and workers as well as the acute exposure assessment for consumers rely mainly on the active substances in a PPP or BP under consideration or on combinations of products for which simultaneous use is notified. Chronic consumer exposure assessment needs to take into account all relevant substances contained in the PPP or BP under consideration, but also the residue background of other pesticides in food, which have to be derived from representative food monitoring programmes. A representative food monitoring database is currently being developed. The assessment requires the application of complex probabilistic methods. It is planned that BfR will review the chronic CRA for each active substance and each CAG regularly as soon as all essential monitoring data are available. It is planned to carry out case studies on the impact on regulatory decisions. The paper is intended to promote further discussions of risk assessors, risk managers as well as stakeholders in this area on the applicability of CRA in routine authorisation procedures for PPP and BP and to encourage the flexible use of strategies in CRA.

The ABCG2 efflux transporter from rabbit placenta: Cloning and functional characterization

In human placenta, the ATP-binding cassette efflux transporter ABCG2 is highly expressed in syncytiotrophoblast cells and mediates cellular excretion of various drugs and toxins. Hence, physiological ABCG2 activity substantially contributes to the fetoprotective placenta barrier function during gestation. Developmental toxicity studies are often performed in rabbit. However, despite its toxicological relevance, there is no data so far on functional ABCG2 expression in this species. Therefore, we cloned ABCG2 from placenta tissues of chinchilla rabbit. Sequencing showed 84-86% amino acid sequence identity to the orthologues from man, rat and mouse. We transduced the rabbit ABCG2 clone (rbABCG2) in MDCKII cells and stable rbABCG2 gene and protein expression was shown by RT-PCR and Western blot analysis. The rbABCG2 efflux activity was demonstrated with the Hoechst H33342 assay using the specific ABCG2 inhibitor Ko143. We further tested the effect of established human ABCG2 (hABCG2) drug substrates including the antibiotic danofloxacin or the histamine H2-receptor antagonist cimetidine on H33342 accumulation in MDCKII-rbABCG2 or -hABCG2 cells. Human therapeutic plasma concentrations of all tested drugs caused a comparable competitive inhibition of H33342 excretion in both ABCG2 clones. Altogether, we first showed functional expression of the ABCG2 efflux transporter in rabbit placenta. Moreover, our data suggest a similar drug substrate spectrum of the rabbit and the human ABCG2 efflux transporter.

CHAPTER 9:Legal Background and Procedures on Pesticides

This chapter, Legal Background and Procedures on Pesticides, provides an overview of the main topics and legal procedures for the regulatory toxicology of pesticides in the European Union. Legal requirements and procedural steps for approval of active substances, as well as the authorisation of plant protection products and biocidal products, are described, particularly those relevant to regulatory toxicology and human health risk assessment. Furthermore, an overview is given of the procedure of setting of maximum residue levels for plant protection products as a prerequisite for the authorisation of plant production products and the stipulation of import tolerances. Based on the different regulations, comprehensive information is given on the data requirements, evaluation, risk assessment and decision making regarding human health assessment. Further information is provided on the mutual recognition of products and simplified authorisation procedures for special product types.

CHAPTER 8:Regulatory Toxicology of Pesticides: Concepts

In this chapter, Regulatory Toxicology of Pesticides: Concepts, the main topics summarised are the key processes of human health risk assessment of pesticidal active substances as well as plant protection products and biocidal products. Based on submission of various toxicity studies from the applicants and also consideration of the peer-reviewed literature, the hazards are identified, dose–response relationships are characterised and toxicological threshold values are derived. This is followed in the authorisation procedure by comparison of toxicological thresholds with the exposure data in the risk assessment. Future trends and new methodologies in regulatory toxicology will improve the risk assessment, including the consideration of metabolites, the development of test guidelines as well as cumulative risk assessment. Microorganisms used as pesticides also have to be given attention.

Science-based decision matrix for the identification of endocrine disruptors for regulatory purposes

Recent EU legislation for chemical substances requires a particular assessment of endocrine disrupting properties that may cause adverse effects in humans. Especially for pesticidal active substances, measures concerning specific scientific criteria for the determination of endocrine disrupting properties should have been presented by the European Commission until December 2013. But presently, no specific science-based approach for the assessment of these substances has been agreed upon. This paper is discussing common scientific principles for the evaluation and grouping of substances with endocrine disrupting properties that may cause adverse effects in humans. A matrix-based approach is proposed to be applied in various fields of scientific evaluation of chemical substances, which is based on a scientific evaluation of all available data that may contribute to ensure a high level of protection of human health. This evaluation is expected to be proportionate, consistent and predictable to support administrative decisions in regulatory toxicology. However, a scientifically based categorisation in a decision matrix as a backbone for specific and legally binding rules should be performed according to the relevant EU regulations for the aforementioned groups of substances. Considering the complexity of the matter, it appears appropriate to base possible categorisation on considerations in a decision matrix, which take into account severity, reversibility, potency and consistency of an adverse effect. Based on this decision matrix it should be possible to allocate substances falling under the WHO/IPCS definition to categorise as endocrine disruptors (EDs) or even dispense such substances from categorisation.

Report of the Workshop on Harmonized Classification and Labelling (CLH) of Active Substances in Plant Protection Products Held in Berlin on 12 and 13 April 2011

The Federal Institute for Risk Assessment (BfR) hosted a workshop, co‐organized by the European Commission, the European Food Safety Authority (EFSA) and the European Chemicals Agency (ECHA), on active substances in plant protection products (PPPs) on 12 and 13 April 2011 in Berlin. The workshop dealt with cooperation at European level in the assessment of human health hazards of active substances in PPPs under Regulation (EC) No 1107/2009 on the placing of plant protection products on the market and the harmonized classification and labelling of active substances under Regulation (EC) No 1272/2008.