PRELIMINARY IN-VITRO INVESTIGATION INTO THE USE OF ALKALINE ELUTION ASSAY FOR THE BIOMONITORING OF HUMANS EXPOSED TO GENOTOXIC AGENTS

1 This in vitro study was undertaken as a preliminary approach before assessing whether the alkaline elution assay can be applied to periphe ral blood lymphocytes (PBL) for the monitoring of humans exposed to ge notoxic agents such as polycyclic aromatic hydrocarbons (PAH). We have compared in vitro, with the aid of the alkaline elution assay, the fo rmation and the repair of DNA single-strand breaks (ssb) induced by di fferent genotoxic agents [gamma-irradiation, ethyl methanesulfonate (E MS), benzo<a>pyrene diol epoxide (BPDE)] on quiescent and PHA-stimulat ed human lymphocytes and on a fibroblast cell line. 2 Gamma-irradiatio n (4 Gy) induced an equivalent amount of DNA ssb in the three cell typ es. On the other hand, after treatment with EMS (10mM) and BPDE (50 mu M), a higher production of DNA ssb was observed in replicating cells (PHA-stimulated lymphocytes and fibroblasts) when compared with quiesc ent lymphocytes. 3 After gamma-irradiation, all cell types repaired mo re than 65% of ssb within 1 h. After treatment with EMS, we noted a de ficient DNA repair capacity in quiescent lymphocytes in comparison wit h replicating cells. In all cell types treated with BPDE, more breaks were observed after a 2 h repair period than immediately after treatme nt, demonstrating the involvement of a slow repair mechanism after BPD E treatment. 4 Several conclusions can be drawn from this pilot study, (i) when assessing in vitro the induction and the repair of DNA lesio ns induced by chemicals, it seems reasonable to test both non-replicat ing and replicating cells since their response may be different; (ii) in view of the relative persistence of DNA damage induced in vitro by BPDE in resting lymphocytes, chronic exposure to PAH could give rise t o a certain accumulation of DNA damage in coke oven workers lymphocyte s. Further studies will be necessary to determine whether these damage s could be detected by alkaline elution.