The within- and between-laboratories reproducibility and predictive capacity of Amino acid Derivative Reactivity Assay using 4 mM test chemical solution: Results of ring study implemented at five participating laboratories.

Amino acid derivative reactivity assay (ADRA) for skin sensitization was adopted as an alternative method in the 2019 OECD Guideline for the Testing of Chemicals (OECD TG 442C). The molar ratio of the nucleophilic reagent to the test chemicals in the reaction solution was set to 1:50. Imamura et al. reported that changing this molar ratio from 1:50 to 1:200 reduced in false negatives and improved prediction accuracy. Hence, a ring study using ADRA with 4 mM of a test chemical solution (ADRA, 4 mM) was conducted at five different laboratories to verify within- and between-laboratory reproducibilities (WLR and BLR, respectively). In this study, we investigated the WLR and BLR using 14 test chemicals grouped into three classes: (1) eight proficiency substances, (2) four test chemicals that showed false negatives in the ADRA with 1 mM test chemical solution (ADRA, 1 mM), but correctly positive in ADRA (4 mM), and (3) current positive control (phenylacetaldehyde) and a new additional positive control (squaric acid diethyl ester). The results showed 100% reproducibility and 100% accuracy for skin sensitization. Hence, it is clear that the ADRA (4 mM) is an excellent test method in contrast to the currently used ADRA (1 mM). We plan to resubmit the ADRA (4 mM) test method to the OECD Test Guideline Group in the near future so that OECD TG 442C could be revised for the convenience and benefit of many ADRA users.

Internal consistency and compatibility of the 3Rs and 3Vs principles for project evaluation of animal research.

Using animals for research raises ethical concerns that are addressed in project evaluation by weighing expected harm to animals against expected benefit to society. A harm-benefit analysis (HBA) relies on two preconditions: (a) the study protocol is scientifically suitable and (b) the use of (sentient) animals and harm imposed on them are necessary for achieving the study's aims. The 3Rs (Replace, Reduce and Refine) provide a guiding principle for evaluating whether the use of animals, their number and the harm imposed on them are necessary. A similar guiding principle for evaluating whether a study protocol is scientifically suitable has recently been proposed: the 3Vs principle referring to the three main aspects of scientific validity in animal research (construct, internal and external validity). Here, we analyse the internal consistency and compatibility of these two principles, address conflicts within and between the 3Rs and 3Vs principles and discuss their implications for project evaluation. We show that a few conflicts and trade-offs exist, but that these can be resolved either by appropriate study designs or by ethical deliberation in the HBA. In combination, the 3Vs, 3Rs and the HBA thus offer a coherent framework for a logically structured evaluation procedure to decide about the legitimacy of animal research projects.

New European Union statistics on laboratory animal use - what really counts!

Seven years after the last release, the European Commission has again collated and released data on laboratory animal use. The new report is the first to correspond to the requirements of the new Directive 2010/63/EU. Beside minor problems in reporting, the new reporting format is a major step forward, with additional new categories like severity allowing insight into animal use related questions that goes far beyond the previous reports. An in-depth analysis confirms a slight decrease in animal use from 2015 to 2017, but also compared to the 2005, 2008 and 2011 reports, though the new reporting scheme makes this comparison difficult. Notable success is evident for replacing rabbit pyrogen testing but, in general, the implementation of accepted alternative methods lags behind expec-tations. Beside the roughly 10 million animals per year covered in the report, about 8 million animals were identified that fall under the Directive but are not included in this number. Their omission downplays the impact of REACH on animal use. The report, second to none in its detail internationally, represents an important instrument for benchmarking and strategi-cally focusing activities in the 3Rs.

Nonanimal Models for Acute Toxicity Evaluations: Applying Data-Driven Profiling and Read-Across.

BACKGROUND: Low-cost, high-throughput in vitro bioassays have potential as alternatives to animal models for toxicity testing. However, incorporating in vitro bioassays into chemical toxicity evaluations such as read-across requires significant data curation and analysis based on knowledge of relevant toxicity mechanisms, lowering the enthusiasm of using the massive amount of unstructured public data. OBJECTIVE: We aimed to develop a computational method to automatically extract useful bioassay data from a public repository (i.e., PubChem) and assess its ability to predict animal toxicity using a novel bioprofile-based read-across approach. METHODS: A training database containing 7,385 compounds with diverse rat acute oral toxicity data was searched against PubChem to establish in vitro bioprofiles. Using a novel subspace clustering algorithm, bioassay groups that may inform on relevant toxicity mechanisms underlying acute oral toxicity were identified. These bioassays groups were used to predict animal acute oral toxicity using read-across through a cross-validation process. Finally, an external test set of over 600 new compounds was used to validate the resulting model predictivity. RESULTS: Several bioassay clusters showed high predictivity for acute oral toxicity (positive prediction rates range from 62-100%) through cross-validation. After incorporating individual clusters into an ensemble model, chemical toxicants in the external test set were evaluated for putative acute toxicity (positive prediction rate equal to 76%). Additionally, chemical fragment -in vitro-in vivo relationships were identified to illustrate new animal toxicity mechanisms. CONCLUSIONS: The in vitro bioassay data-driven profiling strategy developed in this study meets the urgent needs of computational toxicology in the current big data era and can be extended to develop predictive models for other complex toxicity end points. https://doi.org/10.1289/EHP3614.

The Emergence and Early Fate of the Three Rs Concept.

In the 60th year since the publication of The Principles of Humane Experimental Technique by W.M.S. Russell and R.L. Burch, we visited the W.M.S. and Claire Russell Archive at the University of Nottingham to discover, or confirm, answers to certain questions: the origins of the UFAW project which led to its writing; the relationship between Russell and Burch; the project plan; the origin of the Three Rs (Replacement, Reduction, Refinement) concept; the drafting, publication and response to the appearance of the book; and the future careers of its authors. We report on our findings, though many other questions have yet to be answered.

The Overt and Hidden Use of Animal-Derived Products in Alternative Methods for Skin Sensitisation: A Systematic Review.

In vitro methods that can replace animal testing in the identification of skin sensitisers are now a reality. However, as cell culture and related techniques usually rely on animal-derived products, these methods may be failing to address the complete replacement of animals in safety assessment. The objective of this study was to identify the animal-derived products that are used as part of in vitro methods for skin sensitisation testing. Thus, a systematic review of 156 articles featuring 83 different in vitro methods was carried out and, from this review, the use of several animal-derived products from different species was identified, with the use of fetal bovine serum being cited in most of the methods (78%). The use of sera from other animals, monoclonal antibodies and animal proteins were also variously mentioned. While non-animal alternatives are available and methods free of animal-derived products are emerging, most of the current methods reported used at least one animal-derived product, which raises ethical and technical concerns. Therefore, to deliver technically and ethically better in vitro methods for the safety assessment of chemicals, more effort should be made to replace products of animal origin in existing methods and to avoid their use in the development of new method protocols.

An Estimate of the Number of Animals Used for Scientific Purposes Worldwide in 2015.

Few attempts have been made to estimate the global use of animals in experiments, since our own estimated figure of 115.2 million animals for the year 2005. Here, we provide an update for the year 2015. Data from 37 countries that publish national statistics were standardised against the definitions of 'animals' and 'procedures' used in the European Union (EU) Directive 2010/63/EU. We also applied a prediction model, based on publication rates, to estimate animal use in a further 142 countries. This yielded an overall estimate of global animal use in scientific procedures of 79.9 million animals, a 36.9% increase on the equivalent estimated figure for 2005, of 58.3 million animals. We further extrapolated this estimate to obtain a more comprehensive final global figure for the number of animals used for scientific purposes in 2015, of 192.1 million. This figure included animals killed for their tissues, normal and genetically modified (GM) animals without a harmful genetic mutation that are used to maintain GM strains and animals bred for laboratory use but not used. Since the 2005 study, there has been no evident increase in the number of countries publishing data on the numbers of animals used in experiments. Without regular, accurate statistics, the impact of efforts to replace, reduce and refine animal experiments cannot be effectively monitored.

Laboratory animal science course in Switzerland: participants' points of view and implications for organizers.

Switzerland has implemented a mandatory training in laboratory animal science since 1999; however a comprehensive assessment of its effects has never been undertaken so far. The results from the analysis of participants in the Swiss Federation of European Laboratory Animal Science Associations (FELASA) Category B compulsory courses in laboratory animal science run in 2010, 2012, 2014 and 2016 showed that the participants fully appreciated all elements of the course. The use of live animals during the course was supported and explained by six arguments characterized with cognitive, emotional and forward-looking factors. A large majority considered that the 3R (replacement, reduction and refinement) principles were adequately applied during the course. Responses to an open question offered some ideas for improvements. This overall positive picture, however, revealed divergent answers from different subpopulations in our sample (for example, scientists with more hindsight, scientists trained in biology, or participants from Asian countries).

Animal welfare officers in Australian higher education: 3R application, work contexts, and risk perception.

Acceptance of the concept of replacement, refinement, and reduction (the 3Rs) and the need for their implementation is widespread in the research community, and is also backed by local governance requirements in many key jurisdictions. Yet concerns about underutilization of these concepts and practices remain. From a survey of animal welfare officers (AWOs) in Australia, the attitudes to, and the adoption of, 3Rs in Australian public universities is explored. The survey finds that Australian AWOs have considerable concerns about 3R uptake, with 44% agreeing that '3R possibilities often remain unused'. At the same time, these officers see access to relevant information, and the implementation of the 3Rs, as comparatively easy. Thus, a problem of under-implementation appears to exist. A number of explanations for this are put forward. AWOs are comparatively junior professional staff in the Australian university system, constrained from going beyond basic regulative functions and to the training and promotion of the 3Rs. When compared with their international counterparts, Australian AWOs spend less time providing information and advice on the 3Rs to researchers working in their institutions. Significantly, while AWOs tend to see themselves as being well supported institutionally, they have comparatively poor relationships with active researchers who are using animal models. The implications of this are examined, with recommendations for research institutions, as well as for further research.

The cost of standing strong for replacement.

The testimonies of these individuals largely speak for themselves. The responses point to the importance of specific institutions or research groups that focus on the development and use of alternatives, and these should, of course, be better supported. Those who find themselves outside such institutions or teams, are more likely to feel stranded and isolated. Then again, Liz did have the support of a research group dedicated to replacement, but she has still had a significant struggle to find funding. The interviews with some of these particular young researchers indeed pointed toward a tangible 'cost' in terms of having to steer their career on the often difficult path toward the use of non-animal based methods.

Bayesian integrated testing strategy to assess skin sensitization potency: from theory to practice.

Frameworks to predict in vivo effects by integration of in vitro, in silico and in chemico information using mechanistic insight are needed to meet the challenges of 21(st) century toxicology. Expert-based approaches that qualitatively integrate multifaceted data are practiced under the term 'weight of evidence', whereas quantitative approaches remain rare. To address this gap we previously developed a methodology to design an Integrated Testing Strategy (ITS) in the form of a Bayesian Network (BN). This study follows up on our proof of concept work and presents an updated ITS to assess skin sensitization potency expressed as local lymph node assay (LLNA) potency classes. Modifications to the ITS structure were introduced to include better mechanistic information. The parameters of the updated ITS were calculated from an extended data set of 124 chemicals. A detailed validation analysis and a case study were carried out to demonstrate the utility of the ITS for practical application. The improved BN ITS predicted correctly 95% and 86% of chemicals in a test set (n = 21) for hazard and LLNA potency classes, respectively. The practical value of using the BN ITS is far more than a prediction framework when all data are available. The BN ITS can develop a hypothesis using subsets of data as small as one data point and can be queried on the value of adding additional tests before testing is commenced. The ITS represents key steps of the skin sensitization process and a mechanistically interpretable testing strategy can be developed. These features are illustrated in the manuscript via practical examples.

Statistics of Scientific Procedures on Living Animals 2011: another increase in experimentation, but is there a shift in emphasis?

The 2011 Statistics of Scientific Procedures on Living Animals reveal that the level of animal experimentation in Great Britain continues to rise, with almost 3.8 million procedures being conducted. Unlike those in previous years, this increase is not exclusively due to the breeding and utilisation of genetically altered animals, although they are still involved in the greatest proportion of procedures. That a shift toward fundamental research may have become the primary cause of increases in animal experiments is discussed. The general trends in the species used, and the numbers and types of procedures, are reviewed. In addition, some areas of concern and optimism are outlined.

Acute oral toxicity: variability, reliability, relevance and interspecies comparison of rodent LD50 data from literature surveyed for the ACuteTox project.

The ACuteTox project has aimed to optimise and prevalidate an in vitro testing strategy for predicting human acute toxicity. Ninety-seven reference substances were selected and an in vivo acute toxicity database was compiled. Comprehensive statistical analyses of the in vivo LD50 data to evaluate variability and reliability, interspecies correlation, predictive capacities with regard to EU and GHS toxicity categories, and deduction of performance criteria for in vitro methods is presented. For the majority of substances variability among rodent data followed a log normal distribution where good reproducibility was found. Rat and mouse interspecies comparison of LD50 studies by ordinary regression showed high correlation, with coefficients of determination, ranging between 0.8 and 0.9. Substance specific differences were only significant for warfarin and cycloheximide. No correlation of compound LD50 range with presumed study quality rank (by assigning Klimisch reliability scores) was found. Modelling based on LD50 variability showed that with at least 90% probability ∼54% of the substances would fall into only one GHS category and ∼44% would fall within two adjacent categories. These results could form the basis for deriving a predictive capacity that should be expected from alternative approaches to the conventional in vivo acute oral toxicity test.

The ReProTect Feasibility Study, a novel comprehensive in vitro approach to detect reproductive toxicants.

ReProTect is a project within the 6th European Framework Program which has developed alternative methods aimed to reduce or replace animal experimentation in the field of reproductive toxicology. In its final year, a ring trial, named the "Feasibility Study", was conducted, in which 10 blinded chemicals with toxicologically well-documented profiles were analyzed by employing a test battery of 14 in vitro assays. EC(50) (half maximal effective concentration) or equivalent endpoints were determined and the test compounds were ranked relative to chemicals previously assayed in the tests of the battery. This comparative analysis together with a weight of evidence approach allowed a robust prediction of adverse effects on fertility and embryonic development of the 10 test chemicals in vivo. In summary, the vast majority of the predictions made based on the in vitro results turned out to be correct when compared to the whole animal data. The procedure used here, a nearest neighbor analysis coupled with a weight of evidence approach, may guide future activities in the field of alternative toxicity testing.

Reflections on improved health status of rodents bred for research: contributions to the reduction and refinement of animal use.

Reductions and refinements in the use of animals have steadily occurred over the last century. The need for improved health status has been a catalyst for much of this effort. This has also driven improvements in the housing and husbandry techniques required to maintain the health status of animals produced or used for biomedical research. This has decreased the number of animals used in biomedical research studies, contributed to refinements in animal care and use, and has resulted in better science as well as better animal welfare.

Mode of action clustering of chemicals and environmental samples on the bases of bacterial stress gene inductions.

Over the years, environment and the human population have seen an increasing exposure to both existing and newly developed chemicals. It is generally accepted that at least some of those are toxic, albeit as pure compound or in combination with others. In response to a growing public awareness and scientific data, the new European chemicals legislation (Registration, Evaluation and Authorization of Chemicals) is under implementation at the moment. As a consequence, during the coming years about 30,000 chemicals have to be assessed on their potential hazard for man and biota. Part of this assessment will be done using existing and new in vitro tests offering insight into the toxicity of chemicals and into their toxicological mode of action. This study presents data on a battery of 14 bacterial reporter gene assay allowing mode of action determination and statistical grouping of chemicals based on their induction profile. Gene induction results are used to group reference chemicals in a statistical cascade employing hierarchical tree and k-means clustering for initial grouping. Both complementary, yet mathematically different, algorithms are consequently confirmed by principal component analysis (PCA). The gene induction profiles of an environmental extract with documented in vivo effects and a chemical with limited toxicological are data available and projected in the PCA vector space. The projection allows correct mode of action grouping and indicates that effect predictions based on the known toxicological effects of the reference compounds can be made.

[Austria: fewer experimental animals used in 2005]. / Oesterreich: Versuchstierzahlen 2005 gesunken.

The number of animals used in experiments in Austria decreased in 2005 by 10%. This overall positive development must be regarded critically, as the number of big mammals, e.g. cows, used for experimental purposes has increased substantially and as a lot of relevant and necessary data, e.g. on the use of transgenic animals, is still not being collected. The information given in the Austrian statistics on animals used for scientific purposes is inadequate and requires revision.