Sequential monitoring of cytogenetic damage in rat lymphocytes following in vivo exposure to aflatoxin B1 and N-nitrosophenacetin

Rats were treated intraperitoneally with different concentrations of aflatoxin B1 (AFB1) or N-nitrosophenacetin (NP). Blood was sequentially drawn by venous puncture at 6, 24, 72, 120 h and 14 days after a single injection of AFB1 or NP. After AFB1 the frequency of SCEs and chromosome aberrations increased progressively and reached a maximum level after 24 h and then decreased with time. By 2 weeks post treatment, the SCE and chromosome aberration values were within the control range. A small but significant SCE induction was observed when rats were treated with NP, but no chromosome breakage was induced even at the highest dose (20 mg/kg). We suggest that the elimination of DNA damage by repair mechanisms and lymphocyte turnover is responsible for the reduction of SCEs and chromosome aberrations with time. This assay seems promising for sequential monitoring of cytogenetic damage in rat lymphocytes following in vivo exposure to genotoxicants.