Why 'suitable' in vitro methods, as defined in the final EU REACH legislation, are an inappropriate basis for risk assessment

The final text of the REACH legislation, that has recently been published by the European Parliament, and which will come into force in the middle of 2007, implies that results obtained from so-called 'suitable' in vitro methods could be used for testing. It is also stated that a 'suitable' test is one that has been deemed to be ready to enter a validation study - for example, according to criteria specified by ECVAM. It is argued that, because the wording of the legal text is too vague and imprecise, it is totally unsatisfactory, mainly because it seems to endorse the application of non-validated methods for regulatory risk assessment. While their use might be suitable for providing information for classification in a weight-of-evidence approach, setting safe dose levels should only ever be based on the use of data from a properly validated test method. This concern, and other problems raised by the final legislation, is discussed, and recommendations are made which could avoid the premature use of potentially unsuitable methods for risk assessment, whilst ensuring that potentially suitable tests can be used for this purpose, once they have been formally validated.