Genotoxicity of di-butyl-phthalate and di-iso-butyl-phthalate in human lymphocytes and mucosal cells

The genotoxicity of phthalates, widely used plasticizers, has been shown previously for di‐butyl‐phthalate (DBP) and di‐iso‐butyl‐phthalate (DiBP) in human mucosal cells of the upper aerodigestive tract in a previous study using the Comet assay. Furthermore, higher genotoxic sensitivities of patients with squamous cell carcinomas of either the larynx or the oropharynx compared to non‐tumor patients were described. Other authors have demonstrated DNA damage by a different phthalate in human lymphocytes. It was the aim of the present study to determine whether there is a correlation between the genotoxic sensitivities to DBP and its isomer DiBP in either mucosal cells or lymphocytes. The single‐cell microgel electrophoresis assay (Comet assay) was applied to detect DNA strand breaks in human epithelial cells of the upper aerodigestive tract (n=132 specimens). Human mucosa was harvested from the oropharynx in non‐tumor patients and patients with squamous cell carcinomas of the oropharynx. Laryngeal mucosa of patients with laryngeal squamous cell carcinomas was harvested as well. Peripheral lymphocytes (n=49 specimens) were separated from peripheral blood. Xenobiotics investigated were DBP, DiBP, and N′methyl‐N′‐nitro‐N‐nitrosoguanidine (MNNG) as positive control, respectively. For statistical analysis, the SPSS™ correlation analysis according to Pearson and the Wilcoxon test were performed. Genotoxicity was found for DBP and DiBP in epithelial cells and lymphocytes (P