4. Further considerations for meeting the standard information requirements
Animal testing under UK REACH: application of the 3Rs
As explained previously, testing on vertebrates for the purposes of UK REACH shall be undertaken only as a last resort.
Where registrants have gone through the steps outlined in the process to gather information for REACH registration but conclude that new tests on vertebrates are needed, UK REACH stipulates that they shall be carried out in compliance with the provisions of the Animals (Scientific Procedures) Act 1986 (legislation.gov.uk).
Therefore, the principles of the 3Rs (reduction, refinement or replacement of animals in testing) must be followed. Where there is a choice of tests for a particular end-point, the test of least severity should be used; some examples are given in Table 1 below.
Guidelines for new approach methodologies (NAMs) and other alternative methods
The OECD, in conjunction with member countries and other organisations, develops guidelines for alternative test methods and approaches. Test guidelines and guidelines on defined approaches are covered by the mutual acceptance of data (MAD), which means that tests conducted in accordance with such guidelines and the principles of Good Laboratory Practice (GLP) must be accepted by other OECD countries and full adherents to MAD for assessment purposes.
New approach methodologies (NAMs) include in chemico, in vitro and in silico (computational) approaches, amongst others. In some cases, they can be used as stand-alone replacements for animal tests. They can be incorporated into IATAs and defined approaches and can inform on key events within AOPs or otherwise provide mechanistic information. Where a stand-alone method or internationally-accepted guideline doesn’t yet exist, NAMs might still be used within a weight-of-evidence approach in accordance with Annex 11 or to provide additional support to another adaptation. An example could be the submission of omics data to support a read-across justification.
The validation status of alternative tests and approaches is subject to regular change, and those commissioning tests should take account of this by checking their current status. The most up-to-date guidelines(oecd.org) should be used and their applicability domains taken into account.
Table 1 gives examples of the implementation of OECD IATAs, defined approaches and 3Rs considerations in meeting the UK REACH standard information requirements.
Considerations for meeting the UK REACH standard information requirements
This table contains some considerations for meeting the UK REACH standard information requirements. Please refer to the relevant annexes for full details of column 2 adaptations.
| Endpoint | Considerations |
|---|---|
| Acute toxicity | The Fixed Dose Procedure (OECD TG 420) and Fixed Concentration Procedure (OECD TG 433) offer some animal welfare advantages over the other available test methods for oral and inhalation acute toxicity, supporting the principle of the Animals (Scientific Procedures) Act 1986 that the test of least severity be used. QSAR approaches for the prediction of acute oral toxicity (nih.gov) lethal dose 50 (LD50) values are advancing and could be used in accordance with Annex 11 if the criteria stated therein are met, or in a weight-of-evidence approach. |
| Skin irritation | In vitro approaches with OECD-adopted test guidelines now form the basis of the standard information requirement at Annex 7. For many chemicals, these methods can be used individually or in combination as full replacements for animal tests. The OECD IATA for the assessment of skin corrosion and irritation provides guidance on test strategies and how to integrate information for decision making. |
| Eye irritation | Non-animal approaches with OECD-adopted test guidelines now form the basis of the standard information requirement at Annex 7. For many chemicals, these methods can be used individually or in combination as full replacements for animal tests. The method described by OECD TG 492B provides a full replacement for the Draize acute eye irritation test in animals for the classification of chemicals; it can identify chemicals not requiring classification, those that should be classified for eye irritation (CLP Category 2) and those that should be classified for serious eye damage (CLP category 1). The OECD IATA for the assessment of serious eye damage and eye irritation provides guidance on test strategies and the integration of information for decision making. A guideline on Defined Approaches for Serious Eye Damage and Eye Irritation (OECD.org) provides fixed data interpretation procedures to integrate information from in vitro methods, physicochemical properties, in silico and read-across predictions to conclude on this endpoint. |
| Skin sensitisation | OECD Guideline 497 on Defined Approaches for Skin Sensitisation (DASS) (oecd.org) provides fixed data interpretation procedures to conclude on the skin sensitisation hazard of many substances, and potentially their potency (sub-categorisation as Skin Sens 1A or 1B), from a combination of non-animal approaches (in chemico, in vitro and in silico (computational) methods). |
| Mutagenicity | Where a positive result is obtained in one of the in vitro mutagenicity tests required in Annexes 7 and 8, these annexes state that ‘further mutagenicity studies shall be considered.’ Before proceeding to investigate one type of genetic damage in animals, it is recommended to conduct in vitro tests that investigate both gene mutation (in mammalian cells if a test in bacteria was negative) and chromosome damage (in vitro mammalian chromosomal aberration test or an in vitro mammalian micronucleus test). A single animal study can then address the gene mutation concern, the chromosome damage concern, or both, as appropriate. For example, if the in vitro tests raise a concern for both gene mutation and chromosome damage, a study that combines an in vivo comet assay (OECD TG 489) and an in vivo micronucleus test (OECD TG 474) could be performed, thus reducing the overall number of animals used. |
| Short-term repeated-dose (28-day) toxicity and reproductive toxicity | If both repeated-dose toxicity and reproductive toxicity studies need to be conducted: (a) For substances up to 100 tonnes/annum: conduct a combined study (OECD TG 422) to reduce the number of animals used. (b) For substances at 100 tonnes/annum or more: propose standard reproductive and developmental toxicity studies and long-term repeated-dose toxicity studies, and do not conduct any shorter-term studies for these end-points. However, the CSR should indicate the interim risk-management measures downstream users should take before the findings from the proposed studies are included. |
| Reproductive toxicity – sexual function and fertility | The requirement for an extended one-generation reproductive toxicity study (EOGRTS; OECD TG 443) at Annex 9 depends on information available on the registered substance, for example from the repeated-dose toxicity studies. The standard information requirement in Annex 10 is limited to the basic design of the EOGRTS (i.e., F1 generation only). The additional cohorts for developmental neurotoxicity and developmental immunotoxicity testing and production of F2 pups are triggered if the conditions of column 2 of Annex 10 Section 8.7.3 are met. |
| Reproductive toxicity – developmental toxicity | A decision on the need to perform a pre-natal developmental toxicity study on a second species should be based on the outcome of the first test and all other relevant available data. |
| Short-term toxicity to fish | The threshold approach for acute fish toxicity should be used where possible, if a test is needed. It should also be considered whether a fish embryo toxicity test (OECD TG 236) or fish cell line assay (OECD TG 249) can fulfil the information requirement. |
| Long-term fish toxicity | Need not be proposed unless required to clarify risks. |
| Bioaccumulation in fish | The aquatic exposure test (OECD TG 305) permits modifications that can reduce the use of animals in some circumstances (a minimised design, or a test with a single concentration). It should also be considered whether invertebrate bioaccumulation information or in vitro intrinsic clearance data (OECD TG 319A/B) can fulfil the information requirement. |
| Long-term reproductive toxicity to birds | Need not be proposed if risks to predatory birds can be assessed using mammalian toxicity data. Any need for testing should be carefully considered, taking into account the large mammalian dataset that is usually available at this tonnage level. |