In vitro Assessment of cytotoxic, genotoxic and carcinogenic effects of trifluralin

Trifluralin is a widely used pre-emergence herbicide belonging to the dinitroaniline group. Environmental Protection Agency has classified trifluralin as a Group C, possible human carcinogen without establishing a reference concentration. Trifluralin can be considered as one of major occupational hazard causing herbicide. Existing reports characterize trifluralin as a highly acute toxic substance but there are not enough descriptions of its chronic toxicity and cytotoxic effect. Studies mainly related to its genotoxic, mutagenic and carcinogenic potential are mostly inconclusive or even contradictory. Hence the present study was carried out to assess the In vitro cytotoxic, genotoxic and carcinogenic effects of trifluralin.Cytotoxicity was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, microscopic examination of cells, mouse lymphoma assay and morphological studies using acridine orange ethidium bromide. Genotoxicity was assessed using mammalian chromosome aberration assay while carcinogenicity was assessed by standard cell transformation assay. The results of the present study revealed trifluralin to be cytotoxic with a mean inhibitory concentration 50 (IC₅₀) value of 65.05±9.00 μg/mL. Cytotoxicity was also evident by vacuolization and reduction in relative survival in a dose dependent manner. Morphologic studies using acridine orange ethidium bromide revealed that trifluralin treatment at various concentrations induced necrosis as observed by orange staining of the cells. In the present study, trifluralin did not produce any chromosomal structural abnormality in the cultured mammalian cell used under the test conditions. However the present study revealed the transformation of fibroblast cells into spindle shaped cells with random orientation at the focus edge indicating the carcinogenic effect of trifluralin. Thus it can be concluded that trifluralin is an herbicide that can cause cytotoxic and carcinogenic effects but no genotoxicity.