1.1 This guide provides recommended guidelines for performing the mammalian in vivo bone marrow micronucleus assay. Under appropriate test conditions, measurement of the frequency of newly formed micronucleated erythrocytes in bone marrow provides a convenient index of chromosomal damage in nucleated erythrocyte precursor cells. The rationale for the occurrence of micronuclei in conjunction with chromosomal damage has been described previously (1). This guide describes conditions under which the frequency of micronucleated erythrocytes in mammalian bone marrow is an appropriate measure of in vivo chromosomal damage, and provides guidelines for the design and technical execution of assays employing this endpoint.

1.2 The following guidelines for mammalian bone marrow erythrocyte micronucleus assays have been published by organizations concerned with the evaluation of genotoxicity test data. These references should be consulted for recommendations on details not covered in depth by this guide and for requirements of specific organizations or government agencies (2-6).

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.