Genotoxicity of Terpenes Present in Wastewater of a Citrus Transformation Factory in Bacterial and Mammalian Cells and Effectiveness of Photocatalytic Degradation

Abstract

The aim of this work was to compare the genotoxic responses of mixtures of terpenes present in wastewaters of a citrus transformation factory with the genotoxicity of the individual compounds. Samplings of wastewater collected before (untreated sample) and past water purification by biological method (treated sample) were analyzed using Solid Phase Micro-extraction (SPME) followed by GC analyses. The chromatograms showed in all effluents the presence of four terpenes: pinene, -pinene, 3-carene, D-limonene. The concentrations of terpenes in the untreated sample were 1–3 orders of magnitude higher than in the treated sample. Genotoxicity was evaluated in the Salmonella reversion assay (Ames test) and in V79 cells by comet assay, by utilizing aqueous solutions the four terpenes at concentrations corresponding at those determined by SPME. In the Ames test, when tested individually, the four terpenes induced no or only a modest increase of genotoxic effects. On the contrary, the mixtures of terpenes present in untreated sample caused an increase highly significant of the revertants in TA100 strain, in presence of metabolic activation, in comparison to the control. The comet assay showed a significant increase in DNA migration in V79 cells after 1 or 6 h treatment with single or mixed terpenes. The possibility to photodegrade terpenes by using polycrystalline TiO2 irradiated with UV light was investigated. Photocatalytic tests carried out on both synthetic and actual aqueous effluents indicated that all terpenes were completely photodegraded, confirming the methodology effectiveness.