Journal of Toxicology and Environmental Health Sciences Vol. 3(6) pp. 155-163, June 2011 Available online at http://www.academicjournals.org/JTEHS ISSN 2006-9820 ©2011 Academic Journals Full Length Research Paper Micronucleus test in post metamorphic Odontophrynus cordobae and Rhinella arenarum (Amphibia: Anura) for environmental monitoring Beatriz Bosch 1 *, Fernando Mañas 2,3 , Nora Gorla 2,3 and Delia Aiassa 1 1 Departamento de Ciencias Naturales, Facultad de Ciencias Exactas Físico-Químicas y Naturales (FCEFQN), Universidad Nacional de Río Cuarto (UNRC), Argentina. 2 Facultad de Agronomía y Veterinaria (FAV) Universidad Nacional de Río Cuarto (UNRC), Argentina. 3 CONICET, Argentina. Accepted 28 March 2011 The genotoxic effect of cyclophosphamide and glyphosate in a commercial formulation were determined using the micronucleus test in peripheral blood erythrocytes of Odontophrynus cordobae and Rhinella arenarum, amphibians widely distributed in the Province of Córdoba, Argentina. For this, the basal frequency of the micronucleated erythrocytes (MNE) was determined by: 0.40±0.18 MNE/1000 erythrocytes in Odontophrynus cordobae and 0.30±0.09 MNE/1000 erythrocytes in Rhinella arenarum. The frequency of MNE in Odontophrynus cordobae increased after 5 days of exposure to glyphosate (100 mg ai/L) and cyclophosphamide. After 2 and 5 days of exposure to glyphosate (200, 400 and 800 mg ai/L), the MNE frequency in Rhinella arenarum was higher than the basal frequency, as it occurred in the group exposed to cyclophosphamide. Regarding acute toxicity and genotoxicity, the results show that Odontophrynus cordobae is more sensitive to cyclophosphamide and glyphosate exposure than Rhinella arenarum. A correlation was detected between exposure concentration and MNE frequency in Rhinella arenarum. Key words: Genotoxicity, micronucleus test, roundup ® , glyphosate, amphibians. INTRODUCTION Many authors have reported that in the past 30 years there has been a significant decline in amphibian populations in diverse parts of the world (Hayes et al., 2010). Multiple causes have been suggested to explain this decline and among them, environmental pollution due to chemicals is gaining attention. Amphibians, like other organisms inhabiting agroecosystems, are highly exposed to agrochemicals and a correlation has been reported between the use of pesticides and the decline of amphibian populations (Beebee and Griffiths, 2005; *Corresponding author. E-mail: betinabosch@gmail.com. Tel/Fax: 54-358-4676230. Jones et al., 2010). Pesticides, including insecticides and herbicides, are particularly detrimental to amphibians due to its aquatic habitat, sensitive skin and unprotected eggs (Govindarajulu, 2008; Bouhafs et al., 2009). Glyphosate based herbicides are the most widely non- selective, broad-spectrum herbicides used in the world. In Argentina, glyphosate use on its wide variety of commercial formulations has increased dramatically. With the increased use of glyphosate-based herbicides containing the surfactant polyethoxylated tallowamine (POEA) increased concern about the potential impact that the formulations may have on amphibians’ populations. Some studies indicate that the toxic effect of glyphosate herbicides containing surfactants is higher than the active ingredient (ai) per se. Thus, the toxicity of