The 19th FRAME Annual Lecture, November 2022: Safer Chemicals and Sustainable Innovation Will Be Achieved by Regulatory Use of Modern Safety Science, Not by More Animal Testing.

The decisions we make on chemical safety, for consumers, workers and the environment, must be based on the best scientific data and knowledge available. Rapid advances in biology, in cell-based technologies and assays, and in analytical and computational approaches, have led to new types of highly relevant scientific data being generated. Such data enable us to improve the safety decisions we make, whilst also enabling us to avoid animal testing. Stimulated by the UK and EU bans on animal testing for cosmetics, Next Generation Risk Assessment (NGRA) approaches, which integrate various types of non-animal scientific data, have been established for assessing the safety of chemical ingredients used in cosmetics and other consumer products. In stark contrast, the chemicals regulations in Europe and other parts of the world have not kept pace with modern safety science and regulators are now mandating even more animal testing. Urgently closing this science-regulation gap is essential to upholding the EU's legislative requirement that any animal testing is a last resort. The ongoing revisions of UK and EU chemicals strategy and regulations provide an opportunity to fundamentally change the design and assessment paradigm needed to underpin safe and more sustainable innovation, through applying the best science and tools available rather than continuing to be anchored in animal tests dating back many decades. A range of initiatives have recently been launched in response to this urgent need, in the UK as well as in the EU.

The ECVAM international validation study on in vitro tests for acute skin irritation: report on the validity of the EPISKIN and EpiDerm assays and on the Skin Integrity Function Test.

ECVAM sponsored a formal validation study on three in vitro tests for skin irritation, of which two employ reconstituted human epidermis models (EPISKIN, EpiDerm), and one, the skin integrity function test (SIFT), employs ex vivo mouse skin. The goal of the study was to assess whether the in vitro tests would correctly predict in vivo classifications according to the EU classification scheme, "R38" and "no label" (i.e. non-irritant). 58 chemicals (25 irritants and 33 non-irritants) were tested, having been selected to give broad coverage of physico-chemical properties, and an adequate distribution of irritancy scores derived from in vivo rabbit skin irritation tests. In Phase 1, 20 of these chemicals (9 irritants and 11 non-irritants) were tested with coded identities by a single lead laboratory for each of the methods, to confirm the suitability of the protocol improvements introduced after a prevalidation phase. When cell viability (evaluated by the MTT reduction test) was used as the endpoint, the predictive ability of both EpiDerm and EPISKIN was considered sufficient to justify their progression to Phase 2, while the predictive ability of the SIFT was judged to be inadequate. Since both the reconstituted skin models provided false predictions around the in vivo classification border (a rabbit Draize test score of 2), the release of a cytokine, interleukin-1alpha (IL-1alpha), was also determined. In Phase 2, each human skin model was tested in three laboratories, with 58 chemicals. The main endpoint measured for both EpiDerm and EPISKIN was cell viability. In samples from chemicals which gave MTT assay results above the threshold of 50% viability, IL-1alpha release was also measured, to determine whether the additional endpoint would improve the predictive ability of the tests. For EPISKIN, the sensitivity was 75% and the specificity was 81% (MTT assay only); with the combination of the MTT and IL-1alpha assays, the sensitivity increased to 91%, with a specificity of 79%. For EpiDerm, the sensitivity was 57% and the specificity was 85% (MTT assay only), while the predictive capacity of EpiDerm was not improved by the measurement of IL-1alpha release. Following independent peer review, in April 2007 the ECVAM Scientific Advisory Committee endorsed the scientific validity of the EPISKIN test as a replacement for the rabbit skin irritation method, and of the EpiDerm method for identifying skin irritants as part of a tiered testing strategy. This new alternative approach will probably be the first use of in vitro toxicity testing to replace the Draize rabbit skin irritation test in Europe and internationally, since, in the very near future, new EU and OECD Test Guidelines will be proposed for regulatory acceptance.

Working together to respond to the challenges of EU policy to replace animal testing.

This paper presents a personal perspective on efforts during the past 15 years to replace animal testing for assessing the safety of chemicals and products. It is based on an invited lecture--the FRAME Annual Lecture--given in October 2005, with the theme of "making progress by working together" (government-industry-academia-NGOs). Where we have achieved some successes, these have clearly been due to effective cooperation and collaboration between the relevant stakeholders. In recent times, there has not been this same level of active commitment and coordination. This needs to change, since, if we are to make good progress in the years to come in responding to the new challenges of the EU policy to replace animal testing, this will undoubtedly require us to work together, hopefully facilitated by effective leadership and coordination from the EU policy-makers themselves.

Update on the validation and regulatory acceptance of alternative tests for skin corrosion and irritation.

The European Centre for the Validation of Alternative Methods (ECVAM) has supported validation studies on in vitro tests for skin corrosion, resulting in the validities of four alternative tests being endorsed. The US Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) has also evaluated the validity of these alternative methods for skin corrosion testing. In the European Union, a new Test Method on Skin Corrosion (B.40), incorporating the rat skin transcutaneous electrical resistance and human skin model assays, was included in Annex V of Directive 67/548/EEC in mid-2000. At an international level, two OECD Test Guidelines (430 and 431) on these alternative methods have been approved as of May 2002. To date, there are no validated in vitro tests for predicting the dermal irritancy of chemicals. ECVAM supported prevalidation studies on five in vitro tests for acute skin irritation during 1999-2001. These tests were based on human, pig and mouse skin. However, none of them met the criteria set for inclusion in a large-scale formal validation study. Following additional work on the test protocols and/or prediction models, it appears that several modified tests could now be ready for validation in 2003.

Follow-up to the ECVAM prevalidation study on in vitro tests for acute skin irritation. The European Centre for the Validation of Alternative Methods Skin Irritation Task Force report 2.

The European Centre for the Validation of Alternative Methods (ECVAM) Skin Irritation Task Force was established in 1996, to review the status of the development and validation of alternative tests for skin irritation and corrosion, and to identify appropriate non-animal tests for predicting human skin irritation that were sufficiently well-developed to be prevalidated and validated by ECVAM. The EpiDerm method, based on a reconstituted human skin model, was proposed as being sufficiently well advanced to enter a prevalidation (PV) study. Based on a review of test protocols, prediction models (PMs), and data submitted by test developers on ten specified chemicals, with 20% sodium lauryl sulphate as a reference standard, the task force recommended the inclusion of four other tests: EPISKIN and PREDISKIN, based on reconstituted human epidermis or on human skin; the non-perfused pig-ear test, based on pig skin; and the skin integrity function test (SIFT), with ex vivo mouse skin. The prevalidation study on these methods was funded by ECVAM, and took place during 1999-2000. The outcome of the PV study was that none of the methods was ready to enter a formal validation study, and that the protocols and PMs of the methods had to be improved in order to increase their predictive abilities. Improved protocols and PMs for the EpiDerm and EPISKIN methods, the pig ear test, and the SIFT were presented at an extended Task Force meeting held in May 2001. It was agreed that, in the short term, the performance of the revised and harmonised EpiDerm and EPISKIN methods, as well as the modified SIFT, should be evaluated in a further study with a new set of 20 test chemicals. In addition, it was decided that the SIFT and the pig ear test would be compared to see if common endpoints (transepidermal water loss, methyl green-pyronine stain) could be identified.

ECVAM's activities in validating alternative tests for skin corrosion and irritation.

ECVAM has funded and managed validation studies on in vitro tests for skin corrosion, resulting in the validities of four in vitro tests being endorsed by the ECVAM Scientific Advisory Committee: the rat skin transcutaneous electrical resistance (TER) assay, two tests based on the use of commercial reconstituted human skin equivalents, EPISKIN and EpiDerm, and another commercially-produced test, CORROSITEX. In the European Union (EU), a new test method on skin corrosion (B.40), incorporating the rat skin TER and human skin model assays, was included in Annex V of Directive 67/548/EEC in mid-2000, thereby making the use of in vitro alternatives for skin corrosion testing of chemicals mandatory in the EU. At the recommendation of its Skin Irritation Task Force, ECVAM has funded prevalidation studies on five in vitro tests for acute skin irritation: EpiDerm, EPISKIN, PREDISKIN, the pig-ear test, and the mouse-skin integrity function test (SIFT). However, none of the tests met the criteria (set by the Management Team for the studies) for inclusion in a large-scale formal validation study. Thus, to date, there are no validated in vitro tests for predicting the dermal irritancy of chemicals. Following further work on the EPISKIN, EpiDerm and SIFT test protocols and/or prediction models after the completion of the prevalidation studies, it appears that the modified tests could meet the performance criteria defined for progression to a validation study. This will now be assessed independently by the ECVAM Skin Irritation Task Force, with the objective of taking a decision before the end of 2002 on whether to conduct a formal validation study.