Sulfentrazone and Flumetsulam herbicides caused DNA damage and Instability in Allium cepa test
Abstract
Boral 500® (sulfentrazone as active ingredient) and Scorpion® (flumetsulam as active ingredient) are herbicides widely used in Brazil´s soybean crops. U.S. Environmental Protection Agency classificated them a s non -carcinogenic and no mutagenic, but literature shows that often this classification is misguided. Allium cepa assay was chosen to evaluate these herbicides, once it analyzes the frequency of micronuclei (MN), chromosomal aberrations (CA) and the mitotic index (MI). Four concentrations of each herbicide (50, 75, 100 and 125 %) were tested in triplicate using distilled water (negative control) and methyl methanesulfonate (positive control) as controls. Three experimental repetitions were realized. Boral 500® showed a higher MI in all concentrations, and higher CA and MN in the 75%, 100% and 125% concentration, with no recovery. Scorpion® showed a higher MI, CA and MN in 100% and 125% concentration, with recovery only for MI and CA. Both herbicides showed mutagenic damage and increased proliferative capacity in Allium cepa. So on, these herbicides should be revaluated as mutagenicity and carcinogenicity for responsible agencies.
Keywords
Download Options
Introduction
Environmental contamination by toxic agents become matters of concern to agricultural and / or industrial economic-based countries, (1) once it interacts with soils and groundwater, affecting human populations and other species, with deleterious effects, such as chronical diseases development, like cancer.(2)
The herbicides Boral 500® (sulfentrazone as active ingredient) and Scorpion® (flumetsulam as active ingredient) are widely used in soybean crops. Recently, sulfentrazone and flumetsulam were classified as “evidence of non‐carcinogenicity for humans” and “no mutagenic” by U.S. Environmental Protection Agency (EPA).(3) However, data about mutagenicity of these compounds are not presented in the label products, and there is only one published paper evaluating DNA damage of sulfentrazone(4) that showed controversial results of its classification, but none using Allium cepa test.
Indeed, several herbicides formulations, such as those with butachlor, atrazine and trifuralin as active ingredients, induced clastogenic and aneugenic effects assesed by Allium cepa test.(5-8) It is disturbing once A. cepa test showed good correlation with the results obtained in mammalians test,(9-11) and it were observed that this test could be more sensitive than the Ames test,(12) being effective to evaluate the potential risk to human health and other species.(13-14)
The increased frequencies of MN and CA in this assay are strong evidence of mutagenicity of the substance evaluated.(15-17) The mitotic index (MI) is an indicator of cell proliferation(18) and can be used to evaluate the level of cytotoxicity of a compound.(7) Furthermore, a recovery assay is necessary, once it evaluates the ‘cell cycle delay’, which leads to late cell responses, and even though the cells are no longer subjected to direct toxic exposure, they continue to express genotoxic or mutagenic effects.(19,20)
Thus, considering the lack of data and controversial information about the toxicity and the effects on DNA of Boral 500® and Scorpion®, this study aimed to evaluate the mutagenicity of such herbicides by the A. cepa test.
Conclusion
Allium cepa test showed to be an efficient test to evaluate the mutagenicity of Boral 500® and Scorpion®. Both herbicides showed mutagenic damage and increased proliferative capacity in A. cepa . The use of these herbicides should be revaluated and tests of mutagenicity and carcinogenicity should be made.