Acute Toxicity and Sublethal Effects Caused by a Commercial Herbicide Formulated with 2,4-D on Physalaemus albonotatus Tadpoles

CURI, L. M.; PELTZER, P. M.; SANDOVAL, M. T.; LAJMANOVICH, R. C.

WATER AIR AND SOIL POLLUTION

SPRINGER

Año: 2019 vol. 230 p. 1 - 22

0049-6979

The aim of this study was to evaluate the acuteand chronic effects caused by exposure to the 2,4dichlorophenoxyacetic acid (2,4-D)-based commercialherbicide Amina Zamba® on Physalaemus albonotatustadpoles from Gosner stage 25. The lethal concentration(LC50) was determined after exposure to different concentrationsof Amina Zamba® (350 to 2400 mg/L) at96 h. Sublethal effects were evaluated after chronic exposureto four fractions of the LC5096h obtained (12.5,25, 50, and 75% of LC5096h) and a control. The biologicalresponses analyzed included survival, growth anddevelopment, morphological abnormalities, and histologicalchanges in the liver. The LC50 values of AminaZamba® at 48, 72, and 96 h were 1040.2, 754.2, and350 mg/L, respectively. The chronic exposure to theherbicide altered the survival of exposed tadpoles andcaused several morphological abnormalities and liverhistological alterations, mainly at the highest concentrationstested. Oral disc malformations and intestinal abnormalitieswere the most frequent abnormalities in alltreated tadpoles. Histological alterations observed in theliver structure included hepatocyte vacuolization, enlargementof sinusoids, dilation of blood vessels, and as i g n i f i c a n t i n c r e a s e i n t h e number o fmelanomacrophages in tadpoles exposed to 25, 50, and75% LC5096hwith respect to control (P < 0.05). Furthermore,the treated tadpoles showed an accelerated developmentrate, reaching Gosner stages 38 and 42 beforecontrols. These results demonstrate that the chronic exposureto this commercial formulation affects the survival,accelerates metamorphosis, and induces morphologicalabnormalities and liver damage in P. albonotatustadpoles.