A correlative study of the genetic damage induced by chemical mutagens in bone marrow and spermatogonia of mice. III. 1,3-Bis (2-chloroethyl)-3-nitrosourea (BCNU).

Cytogenetic damage induced by various concentrations of BCNU was evaluated by determining the frequencies of (a) micronuclei in polychromatic erythrocytes of bone marrow, (b) chromatid aberrations in bone marrow, (c) chromatid aberrations in spermatogonia, and (d) reciprocal translocations induced in spermatogonia and scored in spermatocytes. The order of sensitivity for the four parameters tested was: micronuclei greater than chromatid aberrations in bone marrow greater than aberrations in spermatogonia greater than translocations in spermatocytes, a situation similar to that found in an earlier study with CNU-ethanol. When the effect of concentration of the chemical was taken into consideration there was no correlation among the four parameters tested, so that information on induced frequencies of one parameter does not have predictive value for the frequencies of the others. A comparison of the results obtained with the bifunctional BCNU and the mono-functional CNU-ethanol at equal concentrations indicated that BCNU had a similar or a lesser clastogenic effect than did CNU-ethanol. In an experiment in vitro the situation was different in that BCNU was more effective than CNU-ethanol.