Peer Review of Validation Studies: An Assessment of the Role of the OECD by Reference to the Validation of the Uterotrophic Assay for Endocrine Disruptors

The involvement of the OECD in managing the validation of the rat uterotrophic assay for endocrine disruptors, and in organising the peer review of the results of this study, has been assessed and compared with the many conclusions and recommendations in several published reports of international workshops on validation, and information in guidance documents, produced by the European Centre for the Validation of Alternative Methods (ECVAM), the US Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) and the OECD itself. It is concluded that the OECD has not followed the recommendations for full transparency and independence of the peer-review process. This is based on the fact that it has published a draft guidance document that differs from the report of a recent OECD workshop on validation, in such a way as to give the OECD the flexibility to fully control the peer-review process and, in so doing, to avoid full transparency. Comparison of the timing of the organisation of workshops by the OECD and the progression of the validation study, together with the fact that a draft test guideline for the assay was written before completion of the peer review, suggest that the OECD has given a higher priority to the expedition of the validation and regulatory acceptance of the uterotrophic assay than it has to good scientific and logistical practice. This severely undermines its credibility in the validation process, so, in order for the OECD to be rightly perceived as an honest broker, it is recommended that the OECD should play no role in the validation of new or revised tests, until after they have been successfully validated, peer reviewed, and endorsed by the appropriate authorities, and are ready for test guideline development. With regard to the on-going OECD validation studies of other in vivo assays for endocrine disruptors, the OECD should take immediate steps to ensure full independence and transparency of their peer review.

A Critical Assessment of the OECD Collaborative Study to Validate the Uterotrophic Assay for the Detection of Oestrogenic and Anti-oestrogenic Chemicals

The design and execution of a recently completed validation study on the rat uterotrophic assay for detecting oestrogens and anti-oestrogens, managed by the OECD, are critically assessed with respect to internationally agreed criteria for the validation of new in vitro and in vivo toxicity test methods. It is concluded that, while the design of the study did not take account of several important criteria for validation, the uterotrophic assay appears to reliably detect the strong and weak oestrogenic substances used in the study, which act via binding to the oestrogen receptor in vivo. However, the reliability of the assay has not been substantiated for detecting anti-oestrogens that act as antagonists, due to the involvement of an insufficient number of experiments and test chemicals. Moreover, the data do not permit an assessment of the accuracy of the prediction of oestrogenicity, and the protocols have not been sufficiently optimised with regard to controlling variables. This problem has been exacerbated by a wish to introduce as much flexibility as possible into the protocols during the formal validation phase of the study, rather than during a separate prevalidation stage. In addition, the choice between surgically treated and/or immature animals, and details of housing and husbandry conditions that are necessary for increasing the sensitivity and efficiency of the assay, need to be clarified. The assay also lacks a well-defined prediction model by which the overall relevance of the data to toxicity, and especially to human hazard, can be assessed, and no performance criteria have been established. The results of this analysis of the study indicate that it would be premature to produce an OECD test guideline for the uterotrophic assay at this time, before some of the above issues have been satisfactorily resolved.

The Mouse Bioassay for Diarrhetic Shellfish Poisoning: A Gross Misuse of Laboratory Animals and of Scientific Methodology

The UK shellfish industry has recently been affected by the statutory closure of several cockle beds, following the detection of samples causing rapid and severe reactions in the regulatory approved test for diarrhetic shellfish poisoning (DSP) toxins, the mouse bioassay (MBA). It is contended that these so-called atypical results are due to procedural artefacts of the MBA; so far, several studies have failed to identify their cause. This paper critically assesses the development, regulatory use and methodological deficiencies of the MBA. It also discusses how testing for DSP toxins could and should have been improved and made more humane by applying the Three Rs concept of Reduction, Refinement and Replacement, and by the proper validation of the test method used. It is concluded that the MBA should not have been developed for the routine screening of shellfish samples, as it has a substantially severe endpoint and is not used as part of a tiered-testing strategy with non-animal methods. Moreover, during the UK monitoring programme for DSP toxins, the assay has been used without an optimised and universal protocol, and apparently without due regard to the principles of basic scientific methodology. In view of this, the atypical results obtained for cockle samples cannot be relied on as evidence of a human health hazard. It is recommended that the use of the MBA should be discontinued as soon as possible, in favour of other methods, especially those involving non-animal techniques. In the short-term, these methods should be based on analytical chemical detection systems and the essential availability of the relevant pure toxin standards. The lack of any known toxins in samples should be taken as evidence of lack of contamination. The suitability of the existing non-animal methods needs to be assessed as a matter of urgency. It is crucial that all new methods should be properly validated, and that their acceptability for their stated purposes should be endorsed by recognised criteria and validation centres, before being recommended to, or required by, regulatory agencies. In this way, the possibility that scientifically unsuitable methods will once again be used for monitoring for the contamination of shellfish with toxins can be avoided. This gross misuse of laboratory animals and ill-judged application of science should never be allowed to occur again.

FRAME and the Royal Commission on Environmental Pollution: Common Recommendations for Assessing Risks Posed by Chemicals under the EU REACH System

This document discusses recommendations made by FRAME and the Royal Commission on Environmental Pollution (RCEP) with regard to the current European Commission proposals on the Registration, Evaluation and Authorisation of Chemicals (REACH) system for assessing the risks of chemicals to humans, wildlife and the environment. Of several common aims and recommendations, the two most important are: a) the greater use of non-animal testing methods, especially computational prediction methods (for example, [quantitative] structure–activity relationships, expert systems and biokinetic modelling) for prioritising chemicals for hazard assessment; and b) the greater use of intelligent exposure-based targeted risk assessment, with less emphasis being placed on tonnage-triggers. FRAME has produced a decision-tree testing scheme to illustrate the way in which these approaches could be used, together with in vitro test methods. This scheme has been slightly modified to take account of proposals subsequently made by the RCEP. In addition, FRAME points out that new and improved computational methods are needed through more coordinated research, and that these and existing methods need to be validated. The similarities between the independent publications of FRAME and the RCEP add weight to the recommendations that each have made concerning the implementation of the REACH system.

The Use of Human Cells in Biomedical Research and Testing

The ability to use human cells in biomedical research and testing has the obvious advantage over the use of laboratory animals that the need for species extrapolation is obviated, due to the presence of more-relevant morphological, physiological and biochemical properties, including receptors. Moreover, human cells exhibit the same advantages as animal cells in culture in that different cell types can be used, from different tissues, with a wide range of techniques, to investigate a wide variety of biological phenomena in tissue culture. Human cells can also be grown as organotypic cultures to facilitate the extrapolation from cells to whole organisms. Human cell lines have been available for many years on an ad hoc basis from individual researchers, and also from recognised sources, such as the European Collection of Animal Cell Cultures (ECACC) and, in the USA, the Human Cell Culture Centre (HCCC). Such cells have usually been derived from tumours and this has restricted the variety of types of cells available. This problem has been addressed by using primary human cells that can be obtained from a variety of sources, such as cadavers, diseased tissue, skin strips, peripheral blood, buccal cavity smears, hair follicles and surgical waste from biopsy material that is unsuitable for transplantation purposes. However, primary human cells need to be obtained, processed, distributed and handled in a safe and ethical manner. They also have to be made available at the correct time to researchers very shortly after they become available. It is only comparatively recently that the safe and controlled acquisition of surgical waste and non-transplantable human tissues has become feasible with the establishment of several human tissue banks. Recently, the formation of a UK and European centralised network for human tissue supply has been initiated. The problems of short longevity and loss of specialisation in culture are being approached by: a) cell immortalisation to generate a cell type possessing the properties of both primary cells and cell lines; b) the inhibition of intracellular activities resulting in oxidative stress; and c) the use of stem cells, both of embryonic and adult origin.

Endocrine Disruptors: A Critical Review of In Vitro and In Vivo Testing Strategies for Assessing Their Toxic Hazard to Humans

Currently, there is much concern that a wide range of both synthetic and naturally occurring environmental chemicals can act as endocrine disruptors (EDs), and can adversely affect humans and wildlife. Many in vivo and in vitro tests have been proposed for screening EDs, and several regulatory agencies, including the US Environmental Protection Agency (EPA), have recommended tier-testing schemes. Unfortunately, most of the proposed toxicity tests have substantial problems, including non-specificity and lack of reproducibility. There is also uncertainty concerning their relevance for generating useful hazard data for risk assessment purposes, in view of the diversity of the possible ED mechanisms of action (for example, receptor binding, steroidogenesis and modulation of the homeostatic processes which regulate endogenous responses to hormones). Moreover, most of the suggested test methods have yet to be validated according to internationally accepted criteria, although the OECD and the US EPA have defined tests for validation, and an interlaboratory “prevalidation” exercise has been initiated by the OECD. All this is compounded by the lack of information regarding human exposure levels to EDs, and a lack of direct evidence for a causal link between exposure and the development of adverse human health effects. In addition, the regulatory testing of EDs has important negative implications for animal welfare, as some of the proposed in vivo tests require large group sizes of animals and stressful procedures. From a detailed analysis of the available published literature, it is concluded that it is impossible to assess the relative values of currently available in vitro and in vivo toxicity tests for EDs, or to recommend any test or test battery. Any plans for the widespread testing of EDs are therefore premature and might be unnecessary, at least for detecting possible human effects. Several recommendations are made for rectifying this unsatisfactory situation, including the postponement of screening programmes pending: a) more information on human exposure; b) further details of the mechanisms of action of EDs; and c) the development of improved tests, followed by their proper scientific validation.

The Use of Non-Human Primates in Biological and Medical Research: Evidence Submitted by FRAME to the Academy of Medical Sciences/Medical Research Council/Royal Society/Wellcome Trust Working Group

The Academy of Medical Sciences, the Medical Research Council, the Royal Society and the Wellcome Trust are undertaking a study into the use of non-human primates in biological and medical research. An independent working group of scientific experts, led by Sir David Weatherall, aims to produce a report summarising the findings of this study, early in 2006. The trends in primate research, and the nature and effects of recent and proposed changes in the global use of non-human primates in research, will be investigated. The associated ethical, welfare and regulatory issues, and the role and impact of the Three Rs principles of refinement, reduction and replacement will also be reviewed. As part of this study, a call for evidence was made. The evidence submitted by FRAME emphasised that the use of non-human primates for fundamental research or for regulatory testing still fails to take into account the fact that, although non-human primates are anatomically and physiologically similar to humans, they are not necessarily relevant models for studies on human disease or human physiology. FRAME continues to believe that we have a duty to ensure that these animals are not used without overwhelming evidence that they are the only suitable and relevant models for use in work of undeniable significance.

A Survey of Stakeholder Organisations on the Proposed New European Chemicals Policy

In February 2001, the European Commission published a White Paper proposing that a single new system of chemical regulation should be applied throughout the Member States of the European Union. The proposed Registration, Evaluation and Authorisation of Chemicals (REACH) system was to include both new and existing chemicals, with the aim of ensuring that sufficient pertinent data were made available to enable human health and the environment to be protected. The policy was founded on the principle of sustainable industrial development, and ambitiously attempted to incorporate the needs and views of key stakeholder organisations, such as industry, trade associations, consumer groups, environmentalists, animal welfarists and Member State governments. During the period between the publication of the White Paper and the on-line publication of consultation documents, as part of a public consultation exercise, in May 2003, many of these key stakeholder organisations produced material in support of or critical of the White Paper, either in part or as a whole. In this paper, we have attempted to review this extensive material and to present it in the context of the current chemical regulatory system that the REACH system will replace. Emphasis is placed on the impact of the new policy on the number of animals used in the testing regimes within the REACH system and the inclusion of alternative methods into the legislation. Although supportive of the overriding aims of the new policy, FRAME believes that the fundamental concept of a risk-free environment is flawed, and that the new REACH system will involve the unjustifiable use of millions of laboratory animals. The new policy does include alternative methods, particularly for baseset substances. Nevertheless, alternative testing methods that are already available have been excluded and replaced with outdated in vivo versions. There is also insufficient detail with regard to the further development and validation of alternative methods, particularly for substances of high concern, such as endocrine disrupters or reproductive toxins, for which no alternative testing methods currently exist.

Questionable Progress in the Application of the Three Rs to Improve Science, Human Well-being and Animal Welfare

While the standard of animal experimentation in the UK is generally very high, the aim of the Home Office appears to be to maintain the status quo, rather than to achieve significant Replacement and Reduction, and ensure Refinement

The Replacement of Animal Tests

Progress toward the acceptance and application of validated alternative test methods as replacements for animal tests, is being frustrated by the unsatisfactory procedures involved in approving new test guidelines and deleting existing ones

The use of in vivo, ex vivo, in vitro, computational models and volunteer studies in vision research and therapy, and their contribution to the Three Rs

Much is known about mammalian vision, and considerable progress has been achieved in treating many vision disorders, especially those due to changes in the eye, by using various therapeutic methods, including stem cell and gene therapy. While cells and tissues from the main parts of the eye and the visual cortex (VC) can be maintained in culture, and many computer models exist, the current non-animal approaches are severely limiting in the study of visual perception and retinotopic imaging. Some of the early studies with cats and non-human primates (NHPs) are controversial for animal welfare reasons and are of questionable clinical relevance, particularly with respect to the treatment of amblyopia. More recently, the UK Home Office records have shown that attention is now more focused on rodents, especially the mouse. This is likely to be due to the perceived need for genetically-altered animals, rather than to knowledge of the similarities and differences of vision in cats, NHPs and rodents, and the fact that the same techniques can be used for all of the species. We discuss the advantages and limitations of animal and non-animal methods for vision research, and assess their relative contributions to basic knowledge and clinical practice, as well as outlining the opportunities they offer for implementing the principles of the Three Rs (Replacement, Reduction and Refinement).

On the safety of e-cigarettes: "I can resist anything except temptation"

Strategic policy decisions are being made about e-cigarettes, based on the plausibility of their greater safety, rather than on essential scientific evidence which would permit a proper risk assessment. If e-cigarettes are really ‘safer’, then their use should be recommended, but only after an intelligent analysis of their risk to human health, based on integrated in silico, in vitro and clinical studies for both scientific and logistical reasons

A critical assessment of the scientific basis, and implementation, of regulations for the safety assessment and marketing of innovative tobacco-related products

Our scientific, logistical, ethical and animal welfare-related concerns about the latest US Food and Drug Administration (FDA) regulations for existing and so-called 'new' tobacco products, aimed at reducing harmful exposures, are explained. Such claims for sales in the USA now have to be based on a wide range of information, a key part of which will increasingly be data on safety and risk. One of the pathways to achieve marketing authorisation is to demonstrate substantial equivalence (SE) with benchmark products, called predicates. However, the regulations are insufficiently transparent with regard to: a) a rationale for the cut-off date for 'old' and 'new' products, and for exempting the former from regulation; b) the scientific validity and operation of SE; c) options for product labelling to circumvent SE; d) the experimental data required to support, and criteria to judge, a claim; and e) a strategy for risk assessment/management. Scientific problems related to the traditional animal methods used in respiratory disease and inhalation toxicology, and the use of quantitative comparators of toxicity, such as the No Observed Adverse Effect Level, are discussed. We review the advantages of relevant in vitro, mechanism-based, target tissue-oriented technologies, which an advisory report of the Institute of Medicine of the US National Academy of Sciences largely overlooked. These benefits include: a) the availability, for every major site in the respiratory tract, of organotypic human cell-based tissue culture systems, many of which are already being used by the industry; b) the accurate determination of concentrations of test materials received by target cells; c) methods for exposure to particulate and vapour phases of smoke, separately or combined; d) the ability to study tissue-specific biotransformation; and e) the use of modern, human-focused methodologies, unaffected by species differences. How data extrapolation, for risk assessment, from tissue culture to the whole animal, could be addressed, is also discussed. A cost (to animal welfare)-benefit (to society, including industry and consumers) analysis was conducted, taking into account the above information; the potential for animal suffering; the extensive data already available; the existence of other, less hazardous forms of nicotine delivery; the fact that much data will be generated solely for benchmarking; and that many smokers (especially nicotine-dependents) ignore health warnings. It is concluded that, in common with policies of several tobacco companies and countries, the use of laboratory animals for tobacco testing is very difficult, if not impossible, to justify. Instead, we propose and argue for an integrated testing scheme, starting with extensive chemical analysis of the ingredients and by-products associated with the use of tobacco products and their toxicity, followed by use of in vitro systems and early clinical studies (involving specific biomarkers) with weight-of-evidence assessments at each stage. Appropriate adjustment factors could be developed to enable concentration-response data obtained in vitro, with the other information generated by the strategy, to enable the FDA to meet its objectives. It is hoped that our intentionally provocative ideas will stimulate further debate on this contentious area of regulatory testing and public safety.

The Three Rs — Opportunities for Improving Animal Welfare and the Quality of Scientific Research

In 2013, an undercover investigation by the BUAV raised serious concerns about the use, treatment and care of laboratory animals involved in regulated procedures at Imperial College, London. This led to an inquiry, set up by the college, which found deficiencies in the local ethical review process and a general lack of focus on the implementation of the Three Rs ( Replacement, Refinement and Reduction). The Three Rs concept is the foundation of UK and EU legislation, but surveys of the published literature show that lack of its adoption is widespread. In spite of numerous guidelines, publications and publicity material extolling the benefits of the Three Rs to both animals and science, as well as substantial advances in the development, validation, and deployment of mechanistically-based non-animal methods, many scientists prefer to use traditional animal-based approaches. In addition, such scientists tend to pay less attention than they should to strategic planning, experimental design and the choice of appropriate statistical procedures. They are often unaware of the existence of replacement test methods to address all or some of their objectives, and are reluctant to develop and use new replacement methods. We explore some possible reasons for these shortcomings. We summarise the welfare and scientific effects of each of the Three Rs, and argue that: a) there is an urgent need for evidence to be made readily accessible to prospective licensees, which directly demonstrates the beneficial effects on animal welfare of the implementation of the Three Rs, separately and in combination, and the direct link this has with the quality of the scientific data obtained; b) a detailed systematic review of this evidence should be undertaken to augment the inadequate content of the prescribed Module 5 licensee training offered currently in the UK; c) such training (including that suggested in new EU-wide proposals) should be much more comprehensive, with stronger emphasis on the Three Rs, all parts of the syllabus should be fully examined, and there should be no exemptions from Module 5 training; and d) as the responsible Government department in the UK, the Home Office should take measures to tighten up its guidance for local ethical review, and its system of inspection of designated establishments, to obviate the justification for future undercover investigations.

Every silver lining has a cloud: the scientific and animal welfare issues surrounding a new approach to the production of transgenic animals

The scientific basis and advantages of using recently developed CRISPR/Cas-9 technology for transgenesis have been assessed with respect to other production methods, laboratory animal welfare, and the scientific relevance of transgenic models of human diseases in general. As the new technology is straightforward, causes targeted DNA double strand breaks and can result in homozygous changes in a single step, it is more accurate and more efficient than other production methods and speeds up transgenesis. CRISPR/Cas-9 also obviates the use of embryonic stem cells, and is being used to generate transgenic non-human primates (NHPs). While the use of this method reduces the level of animal wastage resulting from the production of each new strain, any long-term contribution to reduction will be offset by the overall increase in the numbers of transgenic animals likely to result from its widespread usage. Likewise, the contribution to refinement of using a more-precise technique, thereby minimising the occurrence of unwanted genetic effects, will be countered by a probable substantial increase in the production of transgenic strains of increasingly sentient species. For ethical and welfare reasons, we believe that the generation of transgenic NHPs should be allowed only in extremely exceptional circumstances. In addition, we present information, which, on both welfare and scientific grounds, leads us to question the current policy of generating ever-more new transgenic models in light of the general failure of many of them, after over two decades of ubiquitous use, to result in significant advances in the understanding and treatment of many key human diseases. Because this unsatisfactory situation is likely to be due to inherent, as well as possibly avoidable, limitations in the transgenic approach to studying disease, which are briefly reviewed, it is concluded that a thorough reappraisal of the rationale for using genetically-altered animals in fundamental research and by the pharmaceutical industry, and for its support by funding bodies, should be undertaken. In the meantime, the use of CRISPR/Cas-9 to generate new transgenic cells in culture is to be guardedly encouraged.

A critical review of anaesthetised animal models and alternatives for military research, testing and training, with a focus on blast damage, haemorrhage and resuscitation

Military research, testing, and surgical and resuscitation training, are aimed at mitigating the consequences of warfare and terrorism to armed forces and civilians. Traumatisation and tissue damage due to explosions, and acute loss of blood due to haemorrhage, remain crucial, potentially preventable, causes of battlefield casualties and mortalities. There is also the additional threat from inhalation of chemical and aerosolised biological weapons. The use of anaesthetised animal models, and their respective replacement alternatives, for military purposes -- particularly for blast injury, haemorrhaging and resuscitation training -- is critically reviewed. Scientific problems with the animal models include the use of crude, uncontrolled and non-standardised methods for traumatisation, an inability to model all key trauma mechanisms, and complex modulating effects of general anaesthesia on target organ physiology. Such effects depend on the anaesthetic and influence the cardiovascular system, respiration, breathing, cerebral haemodynamics, neuroprotection, and the integrity of the blood-brain barrier. Some anaesthetics also bind to the NMDA brain receptor with possible differential consequences in control and anaesthetised animals. There is also some evidence for gender-specific effects. Despite the fact that these issues are widely known, there is little published information on their potential, at best, to complicate data interpretation and, at worst, to invalidate animal models. There is also a paucity of detail on the anaesthesiology used in studies, and this can hinder correct data evaluation. Welfare issues relate mainly to the possibility of acute pain as a side-effect of traumatisation in recovered animals. Moreover, there is the increased potential for animals to suffer when anaesthesia is temporary, and the procedures invasive. These dilemmas can be addressed, however, as a diverse range of replacement approaches exist, including computer and mathematical dynamic modelling of the human body, cadavers, interactive human patient simulators for training, in vitro techniques involving organotypic cultures of target organs, and epidemiological and clinical studies. While the first four of these have long proven useful for developing protective measures and predicting the consequences of trauma, and although many phenomena and their sequelae arising from different forms of trauma in vivo can be induced and reproduced in vitro, non-animal approaches require further development, and their validation and use need to be coordinated and harmonised. Recommendations to these ends are proposed, and the scientific and welfare problems associated with animal models are addressed, with the future focus being on the use of batteries of complementary replacement methods deployed in integrated strategies, and on greater transparency and scientific cooperation.

Topological structural alerts modulations of mammalian cell mutagenicity for halogenated derivatives

Genotoxicity is a key toxicity endpoint for current regulatory requirements regarding new and existing chemicals. However, genotoxicity testing is time-consuming and costly, and involves the use of laboratory animals. This has motivated the development of computational approaches, designed to predict genotoxicity without the need to conduct laboratory tests. Currently, many existing computational methods, like quantitative structure-activity relationship (QSAR) models, provide limited information about the possible mechanisms involved in mutagenicity or predictions based on structural alerts (SAs) do not take statistical models into account. This paper describes an attempt to address this problem by using the TOPological Substructural MOlecular Design (TOPS-MODE) approach to develop and validate improved QSAR models for predicting the mutagenicity of a range of halogenated derivatives. Our most predictive model has an accuracy of 94.12%, exhibits excellent cross-validation and external set statistics. A reasonable interpretation of the model in term of SAs was achieved by means of bond contributions to activity. The results obtained led to the following conclusions: primary halogenated derivatives are more mutagenic than secondary ones; and substitution of chlorine by bromine increases mutagenicity while polyhalogenation decreases activity. The paper demonstrates the potential of the TOPS-MODE approach in developing QSAR models for identifying structural alerts for mutagenicity, combining high predictivity with relevant mechanistic interpretation.

Is Phenylbutazone a Genotoxic Carcinogen? A Weight-of-Evidence Assessment

Published in silico, in vitro, in vivo laboratory animal and human data, together with information on biotransformation and data from structure-activity analyses with two decision-tree systems (ACToR and Toxtree), have been used in a weight-of-evidence (WoE) assessment to determine whether phenylbutazone (PBZ) is a genotoxic or a non-genotoxic carcinogen. This was undertaken to facilitate the risk assessment of human exposure to this veterinary drug via the consumption of horsemeat from treated animals. Despite problems with data interpretation at all tiers of the database, it was concluded that PBZ behaves like a genotoxic carcinogen with a threshold dose. This conclusion is based mainly on the results of a definitive rodent bioassay, and on the following observations: a) that PBZ has weak in vitro activity only at high concentrations in some genotoxicity assays, accompanied by high levels of cytotoxicity; b) that it (and a major metabolite) is able to cause sister chromatid exchanges in vivo in rodents; and c) that it can induce cytogenetic effects in vivo in humans. It also takes into account the known and predicted activities of the parent drug, some of its metabolites and two structural analogues, and, importantly, several of the drug's other biochemical effects that are unrelated to toxicity. However, this conclusion is not fully supported by all the evidence, and much of the information is based on old papers. Therefore, more studies are required to establish whether the concentration thresholds seen in vitro would translate to dose thresholds for carcinogenicity, such that a safe dose-level could be defined for the purposes of assessing risk. It was disappointing that a WoE approach to evaluating all of the available hazard data, as is increasingly being advocated to improve the hazard identification paradigm, was unable to provide definitive answers in this case, particularly in view of the large numbers of animals that had been used to provide much of the information.

Cell transformation assays: are we barking up the wrong tree?

There has been a current resurgence of interest in the use of cell transformation for predicting carcinogenicity, which is based mainly on rodent carcinogenicity data. In view of this renewed interest, this paper critically reviews the published literature concerning the ability of the available assays to detect IARC Group 1 agents (known human carcinogens) and Group 2A agents (probable human carcinogens). The predictivity of the available assays for human and rodent non-genotoxic carcinogens (NGCs), in comparison with standard and supplementary in vitro and in vivo genotoxicity tests, is also discussed. The principal finding is that a surprising number of human carcinogens have not been tested for cell transformation across the three main assays (SHE, Balb/c 3T3 and C3H10T1/2), confounding comparative assessment of these methods for detecting human carcinogens. This issue is not being addressed in the ongoing validation studies for the first two of these assays, despite the lack of any serious logistical issues associated with the use of most of these chemicals. In addition, there seem to be no plans for using exogenous bio-transformation systems for the metabolic activation of pro-carcinogens, as recommended in an ECVAM workshop held in 1999. To address these important issues, it is strongly recommended that consideration be given to the inclusion of more human carcinogens and an exogenous source of xenobiotic metabolism, such as an S9 fraction, in ongoing and future validation studies. While cell transformation systems detect a high level of NGCs, it is considered premature to rely only on this endpoint for screening for such chemicals, as recently suggested. This is particularly important, in view of the fact that there is still doubt as to the relevance of morphological transformation to tumorigenesis in vivo, and the wide diversity of potential mechanisms by which NGCs are known to act. Recent progress with regard to increasing the objectivity of scoring the transformed phenotype, and prospects for developing human cell-based transformation assays, are reviewed.

The use of integrated and intelligent testing strategies in the prediction of toxic hazard and in risk assessment

There is increasing concern that insurmountable differences between humans and laboratory animals limit the relevance and reliability for hazard identification and risk assessment purposes of animal data produced by traditional toxicity test procedures. A way forward is offered by the emerging new technologies, which can be directly applied to human material or even to human beings themselves. This promises to revolutionise the evaluation of the safety of chemicals and chemical products of various kinds and, in particular, pharmaceuticals. The available and developing technologies are summarised and it is emphasised that they will need to be used selectively, in integrated and intelligent testing strategies, which, in addition to being scientifically sound, must be manageable and affordable. Examples are given of proposed testing strategies for general chemicals, cosmetic ingredients, candidate pharmaceuticals, inhaled substances, nanoparticles and neurotoxicity.

Integrated testing strategies for toxicity employing new and existing technologies

We have developed individual, integrated testing strategies (ITS) for predicting the toxicity of general chemicals, cosmetics, pharmaceuticals, inhaled chemicals, and nanoparticles. These ITS are based on published schemes developed previously for the risk assessment of chemicals to fulfil the requirements of REACH, which have been updated to take account of the latest developments in advanced in chemico modelling and in vitro technologies. In addition, we propose an ITS for neurotoxicity, based on the same principles, for incorporation in the other ITS. The technologies are deployed in a step-wise manner, as a basis for decision-tree approaches, incorporating weight-of-evidence stages. This means that testing can be stopped at the point where a risk assessment and/or classification can be performed, with labelling in accordance with the requirements of the regulatory authority concerned, rather than following a checklist approach to hazard identification. In addition, the strategies are intelligent, in that they are based on the fundamental premise that there is no hazard in the absence of exposure - which is why pharmacokinetic modelling plays a key role in each ITS. The new technologies include the use of complex, three-dimensional human cell tissue culture systems with in vivo-like structural, physiological and biochemical features, as well as dosing conditions. In this way, problems of inter-species extrapolation and in vitro/in vivo extrapolation are minimised. This is reflected in the ITS placing more emphasis on the use of volunteers at the whole organism testing stage, rather than on existing animal testing, which is the current situation.

Challenges for computational structure-activity modelling for predicting chemical toxicity: future improvements?

INTRODUCTION

Structure-activity modelling for predicting toxicology as a discipline is now 50 years old, and great strides have been taken in developing methods for the physicochemical analysis of molecules and their toxicity evaluation, both essential stages in modelling. Computational toxicology also has huge potential for speeding up the screening and prioritisation of chemicals for further testing and for reducing the numbers of expensive and time-consuming conventional tests. Yet, the realisation of this potential has been largely stifled by many problems inherent in developing and validating new structure-activity models of toxicity.

AREAS COVERED

Problems of computational toxicology discussed include i) the use of inappropriate molecular descriptors and tools that are not transparent; ii) the undetected existence of chemicals that cause large changes in toxicity with only small differences in molecular structure (causing 'activity cliffs' in the structure-activity landscape); iii) spurious correlations between structure and activity; iv) lack of quality control of toxicity data; v) difficulties in determining predictivity for novel chemicals; and vi) an over-reliance on complex mathematics and statistics.

EXPERT OPINION

Greater emphasis needs to be placed on i) the selection of training and test sets of chemicals to enable both internal and external validation of models to be undertaken for more accurate assessment of model predictivity and ii) the use of recently developed techniques for characterising structure-activity landscapes.

Quantitative structure-activity relationship modelling of the carcinogenic risk of nitroso compounds using regression analysis and the TOPS-MODE approach

Worldwide, legislative and governmental efforts are focusing on establishing simple screening tools for identifying those chemicals most likely to cause adverse effects without experimentally testing all chemicals of regulatory concern. This is because even the most basic biological testing of compounds of concern, apart from requiring a huge number of test animals, would be neither resource nor time effective. Thus, alternative approaches such as the one proposed here, quantitative structure-activity relationship (QSAR) modelling, are increasingly being used for identifying the potential health hazards and subsequent regulation of new industrial chemicals. This paper follows up on our earlier work that demonstrated the use of the TOPological Substructural MOlecular DEsign (TOPS-MODE) approach to QSAR modelling for predictions of the carcinogenic potency of nitroso compounds. The data set comprises 56 nitroso compounds which have been bio-assayed in female rats and administered by the oral water route. The QSAR model was able to account for about 81% of the variance in the experimental activity and exhibited good cross-validation statistics. A reasonable interpretation of the TOPS-MODE descriptors was achieved by means of bond contributions, which in turn afforded the recognition of structural alerts (SAs) regarding carcinogenicity. A comparison of the SAs obtained from different data sets showed that experimental factors, such as the sex and the oral administration route, exert a major influence on the carcinogenicity of nitroso compounds. The present and previous QSAR models combined together provide a reliable tool for estimating the carcinogenic potency of yet untested nitroso compounds and they should allow the identification of SAs, which can be used as the basis of prediction systems for the rodent carcinogenicity of these compounds.

The FRAME Research Programme under the direction of Dr Richard Clothier

The work of Dr Richard Clothier (Reader in Cellular Toxicology and Director of the FRAME Alternatives Laboratory in the University of Nottingham Medical School) in relation to the FRAME Research Programme, is reviewed. He made a very substantial contribution to FRAME's laboratory research work over the last 20 years, by publishing many research papers, mainly with respect to method development and the application of new replacement toxicity test methods, particularly those involving the use of human cells in tissue culture. In addition, he participated in a number of international validation studies that have facilitated the regulatory acceptance of certain new methods. Lastly, he has been closely involved in the logistical aspects of obtaining and maintaining external research funding for FRAME from industrial sponsors.

Quantitative structure activity relationship for the computational prediction of nitrocompounds carcinogenicity

Several nitrocompounds have been screened for carcinogenicity in rodents, but this is a lengthy and expensive process, taking two years and typically costing 2.5 million dollars, and uses large numbers of animals. There is, therefore, much impetus to develop suitable alternative methods. One possible way of predicting carcinogenicity is to use quantitative structure-activity relationships (QSARs). QSARs have been widely utilized for toxicity testing, thereby contributing to a reduction in the need for experimental animals. This paper describes the results of applying a TOPological substructural molecular design (TOPS-MODE) approach for predicting the rodent carcinogenicity of nitrocompounds. The model described 79.10% of the experimental variance, with a standard deviation of 0.424. The predictive power of the model was validated by leave-one-out validation, with a determination coefficient of 0.666. In addition, this approach enabled the contribution of different fragments to carcinogenic potency to be assessed, thereby making the relationships between structure and carcinogenicity to be transparent. It was found that the carcinogenic activity of the chemicals analysed was increased by the presence of a primary amine group bonded to the aromatic ring, a manner that was proportional to the ring aromaticity. The nitro group bonded to an aromatic carbon atom is a more important determinant of carcinogenicity than the nitro group bonded to an aliphatic carbon. Finally, the TOPS-MODE approach was compared with four other predictive models, but none of these could explain more than 66% of the variance in the carcinogenic potency with the same number of variables.

Assessing risk to humans from chemical exposure by using non-animal test data

The use of data from non-animal toxicity methods in risk assessment has mainly been limited to hazard identification and for elucidating mechanisms of toxicity. However, there is a need to extend the use of in vitro tests to hazard characterisation and risk assessment. This might be feasible by: (a) increased use of human cells of different types; (b) better maintenance of differentiated cells in culture for long periods; (c) use of genetically-engineered cells with useful characteristics; (d) development of complex organotypic cell systems; (e) development of co-cultures of different cell types; and (f) development of techniques for long term culturing, repeat dosing and assessment of recovery. Also, it will be necessary to obtain more information on the differences between cells in culture and in situ in tissues, and on the effects of dosing in vitro and in vivo, to develop realistic and meaningful uncertainty factors to allow in vitro information to be used for risk assessment in its own right, and in conjunction with animal data. These issues and a suggested proposal for using in vitro data in risk assessment are discussed.

The case for taking account of metabolism when testing for potential endocrine disruptors in vitro

Legislation in the USA, Europe and Japan will require that chemicals are tested for their ability to disrupt the hormonal systems of mammals. Such chemicals are known as endocrine disruptors (EDs), and will require extensive testing as part of the new European Union Registration, Evaluation and Authorisation of Chemicals (REACH) system for the risk assessment of chemicals. Both in vivo and in vitro tests are proposed for this purpose, and there has been much discussion and action concerning the development and validation of such tests. However, to date, little interest has been shown in incorporating metabolism into in vitro tests for EDs, in sharp contrast to other areas of toxicity testing, such as genotoxicity, and, ironically, such in vitro tests are criticised for not modelling in vivo metabolism. This is despite the existence of much information showing that endogenous and exogenous steroids are extensively metabolised by Phase I and Phase II enzymes both in the liver and in hormonally active tissues. Such metabolism can lead to the activation or detoxification of steroids and EDs. The absence of metabolism from these tests could give rise to false-positive data (due to lack of detoxification) or false-negative data (lack of activation). This paper aims to explain why in vitro assays for EDs should incorporate mammalian metabolising systems. The background to ED testing, the test methods available, and the role of mammalian metabolism in the activation and detoxification of both endogenous and exogenous steroids, are described. The available types of metabolising systems are compared, and the potential problems in incorporating metabolising systems into in vitro tests for EDs, and how these might be overcome, are discussed. It is recommended that there should be: a) an assessment of the intrinsic metabolising capacity of cell systems used in tests for EDs; b) an investigation into the relevance of using the prostaglandin H synthase system for metabolising EDs; and c) a feasibility study into the generation of genetically engineered mammalian cell lines expressing specific metabolising enzymes, which could also be used to detect EDs.

A Scientific and Animal Welfare Assessment of the OECD Health Effects Test Guidelines for the Safety Testing of Chemicals under the European Union REACH System

We have assessed each of the OECD Health Effects Test Guidelines (TGs) that were included in an annex to the Internet consultation issued by the European Commission relating to the Registration, Evaluation and Authorisation of Chemicals (REACH) legislation for the testing of new and existing chemical substances. Each guideline has been analysed with respect to its design and its scientific and animal welfare implications, the extent to which it makes use of modern techniques, and its suitability to be used in the REACH system for the testing of large numbers of chemicals. The scientific basis of the test and its justification are considered, as well as the numbers of animals required, and the potential adverse effects on them. The prospects and possibilities for applying the Three Rs ( reduction, refinement and replacement) to each of the TGs are also discussed. We have proposed an overall testing strategy for how these TGs and other methods could best be deployed for chemicals testing, should it be necessary to fill data gaps. Certain TGs have been omitted from the strategy, when we have considered them to be unnecessary for chemicals testing. A series of recommendations has been made for improving the TGs with regard to both their scientific content and ways in which they could be better designed in relation to optimising the use of the animals concerned, and minimising adverse welfare consequences to them. Our investigations show that there is an urgent need to update the TGs to reflect modern techniques and methods, and to use current approaches for applying refinement strategies to improve the scientific and animal welfare aspects of the procedures used. Improvements can and should be made in all aspects of toxicity testing, from sample preparation, and animal housing, care and feeding, to dose formulation, test material administration, and the histopathological and clinical analysis of tissue samples. Opportunities for streamlining individual assays are very limited, but testing could be made more efficient by: a) only undertaking studies that provide relevant data; b) making greater use of screens and preliminary testing; c) applying some tests simultaneously to the same animals; d) using one sex; and e) eliminating redundant tests. In conclusion, it is clear that, as they stand, the OECD Health Effects TGs are unsuitable for use in the European Union REACH system, for which potentially very large numbers of laboratory animals will be needed for the testing of a very large number of chemicals.

The Third FRAME Toxicity Committee: working toward greater implementation of alternatives in toxicity testing

FRAME (the Fund for the Replacement of Animals in Medical Experiments; http://www. frame.org.uk) is a scientific charity, which has, for over 30 years, been advocating and conducting its own research on the application of the Three Rs (reduction, refinement and replacement) to animal experimentation. FRAME develops and validates scientifically based replacement alternative methods to facilitate their acceptance by scientists and regulators. As part of these activities, FRAME established a FRAME Toxicity Committee in 1979, and a report of its work was published in 1982, and discussed in the proceedings of a subsequent meeting, published in 1983. A Second Toxicity Committee formed in 1988, reported its work in 1990, which was discussed in the proceedings of a subsequent conference, published in 1991. The work of these committees was extremely successful and influential in laying the foundation for later activities in alternatives research. A Third FRAME Toxicity Committee was formed in 1999, since much progress had been achieved in the previous decade, especially with regard to the successful validation of several non-animal replacement methods and the start of their regulatory acceptance. Moreover, some new test methods are on the point of being validated, and many new techniques and discoveries are impacting on toxicity testing. Also, interest in reduction and refinement in toxicology has increased. However, there is considerable scope and need for the further implementation of the Three Rs in toxicity testing, especially due to recent plans for the large-scale testing of high-production volume, hormonally-active and existing chemicals, and the increasing use of transgenic animal models. The new committee comprises 18 experts from industry, academia, animal welfare, legislative and regulatory bodies, with one observer from the UK Government Home Office. The main objective is to review progress made in the application of the Three Rs in the development and safety evaluation of medicines, biologicals, cosmetics, agrochemicals and other products, as well as industrial chemicals, and to make recommendations as a basis for further sensible progress according to sound scientific and ethical criteria. The main committee is to be augmented by several working parties that will focus on specific scientific issues: 1) targeted risk assessment versus hazard identification; 2) data sharing; 3) endocrine disruption; and 4) carcinogenicity testing. The Committee is also to publish a status report on the current situation regarding alternatives in toxicity testing, based on the recommendations of the Second Toxicity Committee, and will organise a conference to discuss its overall conclusions and recommendations.

Early microdose drug studies in human volunteers can minimise animal testing: Proceedings of a workshop organised by Volunteers in Research and Testing

Testing the safety and efficacy of a successful human medicine involves many laboratory animals, which can sometimes be subjected to considerable suffering and distress. Also, it is necessary to extrapolate from the test species to humans. UK and European legislation requires that Replacement, Reduction and Refinement of animal procedures (the Three Rs) are implemented wherever possible. Over the last decade, there has been substantial progress with applying in vitro and in silico methods to both drug efficacy and safety testing. This paper is a report of the discussions and recommendations arising from a workshop on the role that might be played by human volunteer studies in the very early stages of drug development. The workshop was organised in November, 2001 by Volunteers in Research and Testing, a group of individuals in the UK which launched an initiative in 1994 to identify where and how human volunteers can participate safely in biomedical studies to replace laboratory animals. It was considered that conducting pre-Phase I very low dose human studies (sub-toxic and below the dose threshold for measurable pharmacological or clinical activity) could enable drug candidates to be assessed earlier for in vivo human pharmacokinetics and metabolism. Moreover, accelerator mass spectrometry (AMS), nuclear magnetic resonance (NMR) spectroscopy and positron emission tomography (PET) are potentially useful spectrometric and imaging methods that can be used in conjunction with such human studies. Some, limited animal tests would still be required before pre-Phase I microdose studies, to take account of the potential risk posed by completely novel chemicals. The workshop recommended that very early volunteer studies using microdoses should be introduced into the drug development process in a way that does not compromise volunteer safety or the scientific quality of the resulting safety data. This should improve the selection of drug candidates and also reduce the likelihood of later candidate failure, by providing in vivo human ADME data, especially for pharmacokinetics and metabolism, at an earlier stage in drug development than is currently the case.

The ECVAM workshops: a critical assessment of their impact on the development, validation and acceptance of alternative methods

ECVAM initiated its workshop programme in 1994, to enable it to become well informed about the state of the art of non-animal test development and validation, and about the possible incorporation of alternatives into regulatory requirements for safety testing. Fifty-one such workshops have been held on specific topics, up to 2002. In these workshops, the current status of in vitro tests and their potential uses were reviewed and recommendations were made as to the best ways forward to progress and enhance the utilisation of in vitro methods. Reports for 46 of these workshops have been published in ATLA. Most of the workshops focused on in vitro replacement methods, although an increasing number have dealt with reduction and refinement. The recommendations in the ECVAM workshops have been progressed further by: a) the formation of ECVAM task forces; b) the organisation of further workshops; c) the activities of scientific committees; d) the provision of earmarked research funding; and e) the conduct of validation studies. Examples of each of these activities are discussed. Some individual workshops are covered in more detail and several recommendations that have so far not been acted on are also considered. The workshops and their reports have had a substantial effect on the development and implementation of alternative methods, and have been a major factor in contributing to the success of the first nine years of ECVAM's existence. It is strongly recommended that ECVAM continues to organise workshops and to publish their findings, and several suggestions are made for topics of future workshops.

Comments on the report of the House of Lords Select Committee on Animals in Scientific Procedures

This commentary comprises our responses to each of the seven conclusions and twenty-four recommendations made in the report of the House of Lords Select Committee on Animals in Scientific Procedures, published in July 2002.

The implications of microarray technology for animal use in scientific research

Microarray technology has the potential to affect the number of laboratory animals used, the severity of animal experiments, and the development of non-animal alternatives in several areas scientific research. Microarrays can contain hundreds or thousands of microscopic spots of DNA, immobilised on a solid support, and their use enables global patterns of gene expression to be determined in a single experiment. This technology is being used to improve our understanding of the operation of biological systems during health and disease, and their responses to chemical insults. Although it is impossible to predict with certainty any future trends regarding animal use, microarray technology might not initially reduce animal use, as is often claimed to be the case. The accelerated pace of research as a result of the use of microarrays could increase overall animal use in basic and applied biological research, by increasing the numbers of interesting genes identified for further analysis, and the number of potential targets for drug development. Each new lead will require further evaluation i n studies that could involve animals. In toxicity testing, microarray studies could lead to increases in animal studies, if further confirmatory and other studies are performed. However, before such technology can be used more extensively, several technical problems need to be overcome, and the relevance of the data to biological processes needs to be assessed. Were microarray technology to be used in the manner envisaged by its protagonists, there need to be efforts to increase the likelihood that its application will create new opportunities for reducing, refining and replacing animal use. This comment is a critical assessment of the possible implications of the application of microarray technology on animal experimentation in various research areas, and makes some recommendations for maximising the application of the Three Rs.