Direct analysis of the clastogenic effect of formaldehyde in unstimulated human lymphocytes by means of the premature chromosome condensation technique.

The cytogenetic effect of formaldehyde (FA) on unstimulated human lymphocytes was studied by means of conventional chromosome analysis and the premature chromosome condensation (PCC) technique. In first post-treatment metaphases no significantly increased yields of chromosomal changes could be observed. The analysis of PCCs, however, showed high yields of chromosome fragments. Bleomycin (BLM) used as positive control was also highly clastogenic in PCCs and resulted in significantly increased yields of chromosome-type aberrations. As recently argued, a premitotic selection against heavily damaged cells could be an explanation for the discrepancy between the chromosome findings in metaphase and PCC analysis after FA treatment. In addition, a differential effectiveness may exist in unstimulated lymphocytes to convert multiple fragmentation into chromatid- or chromosome-type aberrations through S-phase-dependent or S-phase-independent mechanisms.