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(M/EH033) Comparative toxicity of different herbicides on Bufo arenarum embryos. Pérez-Coll, C.1, Herkovits, J.1, Domínguez, O.1, 1 ABSTRACT- Due to the worldwide declination of the amphibian populations and the increased malformation ratio observed during the last years, there is an important effort to search suspected chemicals which could be eventually related to this phenomenon. Some herbicides such as glyphosate, trifluraline and 2,4-D are intentionally introduced in high quantities into the environment and therefore could achieve high concentrations in sensitive areas such as surface waters where amphibian embryos develop. AMPHITOX tests were conducted employing Bufo arenarum embryos at stage 25 (end of embryonic development) maintaining 10 embryos by triplicate in 10% Holtfreter Solution (HS) with glyphosate (A), trifluraline (B) and 2,4-D (C) in technical grade and formulated form respectively. The concentration ranges were appropriate to obtain the LC50 for acute exposure (48 hours) by means of PROBIT for these chemicals in technical grade and formulate form. The LC50 obtained (in mg/L) were for A: 73,4 and 11,4; B: 2,4 and 7,2; C: 7,9 and 4,6 respectively. The results point out that in the case of glyphosate the formulate product is about 6 times more toxic than the technical grade, for 2,4-D the increase in the toxicity of the formulate is only about 3 times while for trifluraline the formulate product is 2 times less toxic than the technical grade. The results confirm that formulate and technical grade products could exert a significantly different toxicity on no target organisms and provide data for water quality criteria for those substances related to amphibian protection purposes. Key words: AMPHITOX, Herbicides, glyphosate, trifluraline |
