Stage-dependent toxicity of 2,4-dichlorophenoxyacetic on the embryonic development of a South American toad, Rhinella arenarum

ARONZON, CM ; SANDOVAL, MT; HERKOVITS, J; PÉREZ-COLL, CS.

ENVIRONMENTAL TOXICOLOGY

JOHN WILEY & SONS INC

Año: 2010 p. 1 - 7

1520-4081

The acute and short term chronic toxicity of the herbicide 2,4-Dichlorophenoxyacetic acidand a commercial formulation (CF) were evaluated on Rhinella (=Bufo) arenarum embryosat different developmental stages. Adverse effects were analyzed by means of theisotoxicity curves for lethality, malformations, stage-dependent susceptibility andultrastructural features. For all experimental conditions, the CF was more toxic, up to tentimes, than the active ingredient with the open mouth stage (S.21) as the most susceptible tothe herbicide. For continuous treatment conditions, the early embryonic development wasthe most susceptible to 2,4-D, LC50s for 96 and 168h were 9.06 and 7.76 mg L-1respectively. In addition, both the active ingredient and the CF were highly teratogenicresulting in reduced body size, delayed development, microcephaly, agenesis of gills andabnormal cellular proliferation processes as the main adverse effects. The fact thataccording US EPA, 2,4-D in agricultural scenarios may be up to three times higher than theNOEC values for teratogenic effects reported in this study, it might represent a risk foramphibians. This study also points out the relevance to report the susceptibility of embryosat different developmental stages to both the active ingredient and the CF of agrochemicalsin order to protect non-target organisms.