TP2 Metals in the Environment: Regulatory and Risk Concerns
Tuesday, 15 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall
(HER-1126-557889) Low Level Exposure Of Amphiban Ebryos To Aluminium: Tissue Redidue And Resistence To Challenge Conditions.
Perez-Coll, C1, 2, Servant, R3, Castañaga, L1, Herkovits, J1, 1 Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina2 Escuela de Ciencia y Tecnología, Universidad Nacional de San Martín3 Comisión Nacional de Energía Atómica
ABSTRACT- Low-level exposures to physico-chemical agents are common environmental scenarios. The main purpose of this study was to evaluate the possibility to establish links between tissue residue values in free living vertebrate embryos treated with a wide range of low Al concentrations and their response in case of challenge to lethal concentrations of this metal. Bufo arenarum embryos were treated during 14 days with Al in 3 low but gradually increasing Al concentrations. The final Al concentrations were: 2,6 (A), 26 (B), 256 (C) 
g Al3+/L (in natural fresh water bodies, dissolved Al in the circumneutral pH was found in a range from 1 to 50 g/L). At 48 and 240 hr post treatment the Al uptake was determined with an atomic absorption spectrophotometer resulting in A: 13 and 14.25; B: 13.45 and 12.5; C: 13.5 and 30 g/mg embryo (ww) respectively. Batches of treated embryos plus their controls were challenged with 3.4, 3.7 and 4 mg Al3+/L. The results reported as lethality up till 7 days post challenge point out a significant beneficial effect (higher survival) in the embryos acclimated with a range of concentrations similar to those found in unpolluted fresh water. The results allow concluding that: i) the Al uptake for exposure scenarios bellow and up to values found in unpolluted freshwater achieves its maximal value within the initial 48 hr of exposure and seems not to be related to the Al concentration in the media (the Bioconcentration Factors range from around 80,000 to 800 depending on treatment); however higher exposure to Al resulted in a significant increase in the Al uptake in the embryo, and, ii) the acclimation to Al resulted in an increased resistance to this metal but only in case of treatments with concentrations around the values found in natural fresh water. Thus, Bufo arenarum embryos seems to be very well adapted to Al as found in unpolluted fresh water bodies while their tissue residue values reflect the Al in the media only for concentrations higher than those found in unpolluted freshwater.
Key words: arenarum embryos