The present investigation was undertaken to study the cytotoxic and genotoxic potential of the essential
oils (palmarosa, citronella, lemongrass and vetiver) and monoterpenoids (citral and geraniol) in human
lymphocytes. Trypan blue dye exclusion and MTT test was used to evaluate cytotoxicity. The genotoxicity
studies were carried out by comet and DNA diffusion assays. Apoptosis was confirmed by Annexin/PI
double staining. In addition, generation of reactive oxygen species was evaluated by DCFH-DA staining
using flow cytometry. The results demonstrated that the four essential oils and citral induced cytotoxicity
and genotoxicity at higher concentrations. The essential oils were found to induce oxidative stress evidenced
by the generation of reactive oxygen species. With the exception of geraniol, induction of apoptosis
was confirmed at higher concentrations of the test substances. Based on the results, the four
essential oils are considered safe for human consumption at low concentrations.