Micronucleus and chronic toxicity assays to evaluate surface water genotoxicity in agricultural areas of Buenos Aires

PELUSO, J.; ARONZON C.M; PERÉZ COLL C.S.

Congreso; SETAC Latin America 11th Biennial Meeting "The role of science in environmeantal decision-making"; 2015

Agriculture is the basis ofArgentine economy, and consumes large amounts of pesticides and fertilizers, which finaldestinies are water bodies, establishing a risk for non-target organisms. The objective of the present study was evaluate thewater quality of streams associated to agroecosystems by means of toxicitybioassays in two stages of the earlydevelopment and genotoxicity test (micronucleus (MN) frequency test) usingpremetamorphic tadpoles of native amphibian Rhinella arenarum (Ra). The study area belongs tothe productive nucleus of Buenos Aires where the field crops predominate. Threesampling sites were selected in the districts of Arrecifes (A), Pergamino (P)and Salto (S). In each site, the samples were obtained from surface water. The toxicity bioassayswere performed by exposing groups of 10 embryos or larvae (S.25) of Ra, for triplicate, at differentdilutions of the environmental samples, assessing the lethal toxicity for 504h.In addition, for genotoxicity test,5 premetamorphic tadpoles of Ra (S.28.),for triplicate, were exposed for 96h to non-diluted samples of the sites, a positivecontrol of cyclophosphamide (CF) and a negative control with AMPHITOX Solution(SA) were also conducted to asses MN test on peripheral erythrocytes. Forembryos, the chronic toxicity in increasing order was: (P):NOEC:100%; (S):LOEC:100% y NOEC:75% (A):LC50:45.35%and NOEC<12%. It was observed higher toxicity for the larvae than forembryos.Moreover, in larvae exposure, an inversion in the grade of toxicity ofthe samples was found: (A):LC50:61%; (P):LC50:39% and (S):LC50:28.12%. The MNfrequency of the larvae exposed to the surface water was significantly higherthan negative controls in all the cases: (SA):1,93; (CF):4,84; (S):7,14; (A):8,25; (P):8,6. No significant differences werefound between the three sites; whereas the sites P and A showed a significantlyhigher frequency of micronuclei in comparison with all controls. The presentstudy alerts about the water quality degradation and the genotoxic potential inthe agricultural areas of the province of Buenos Aires, and their impact on thesurvival of the native populations of amphibians.