Comparison of results from XXXX bone marrow chromosome aberration and micronucleus tests.

@entity21045 @entity19 @entity74 @entity18519 @entity2008
Tests for the induction of chromosomal @entity2008 ( @entity2008 ) and micronuclei (MN) in bone marrow cells of @entity19 have been conducted on 65 chemicals. Although these tests were not conducted with the purpose of comparing the outcomes of these two in vivo @entity74 endpoints, the availability of these test results permits such a comparison. Based on studies to date, results from the 2 tests agree for more than 80% of the chemicals; 17 gave positive results in both tests, and 36 gave negative results in both. Seven chemicals were positive only for @entity2008 and 5 were positive only for MN. Three chemicals that were originally concluded to be positive for @entity2008 but not for MN were found to induce MN when the MN protocol was modified to more closely reflect the @entity2008 protocol. Among the 12 chemicals for which there are discrepant results, there are only 2 for which the difference is convincing. One of these, @entity18519 (MN negative, @entity2008 positive) remains an enigma; further studies are being conducted. The second, @entity21045 (MN positive, @entity2008 negative) will be difficult to pursue because the studies reported here were done by inhalation exposure. Based on the outcomes of these comparisons, protocol factors, rather than endpoint specificity, appear to be the major source of discrepant test results. Thus, these results do not support a recommendation that both tests be conducted in a primary testing scheme for @entity74 .
