Acute and subchronic toxicity of arsenite and zinc to tadpoles of Rhinella arenarum both alone and in combination.
The current study evaluated acute and subchronic toxicity of arsenite (As(3+)) and zinc (Zn(2+)) to stage 25 tadpoles of Rhinella arenarum in both single and joint laboratory exposures. LC50 values obtained for As(3+) were elevated and remained within the range of 46 to 50 mg/L of As(3+) between 4 and 17 d of exposure. Growth of tadpoles was completely inhibited with 30 mg/L of As(3+), demonstrating the presence of ecologically relevant sublethal effects at concentrations lower than those resulting in lethality. With respect to Zn(2+), a 96-h LC50 value of 2.49 mg/L was calculated in soft water. Contrary to results obtained for As(3+), LC50 values of Zn(2+) gradually decreased with increasing exposure duration, from 2.49 mg/L at 96 h to 1.30 mg/L after 21 d. In joint exposures to both metals, the type of interaction observed between As(3+) and Zn(2+) was concentration dependent. Lethal effects of As(3+) were mitigated, unaffected, or potentiated by 0.01, 0.1, and 1-2 mg/L of Zn(2+), respectively. However, although 0.01 mg/L of Zn(2+) significantly reduced lethality of As(3+)-exposed tadpoles, the same concentration of Zn(2+) did not help to reverse the stunt growth of these animals. Further studies need to examine which are the lowest concentrations As(3+) required to reduce growth and whether Zn(2+) serves to antagonize growth effects in this range of concentrations.
Brodeur
Julie Céline
JC
Instituto de Ciencias Ambientales y Salud (ICAS), Fundación PROSAMA, Buenos Aires, Argentina. julbrodeur@ hotmail.com
Asorey
Cynthia Melina
CM
Sztrum
Abelardo
A
Herkovits
Jorge
J
D000818:Animals; D018053:Arsenites / Q000008:administration & dosage* / Q000633:toxicity*; D002025:Bufonidae; D004334:Drug Administration Schedule; D004785:Environmental Pollutants / Q000008:administration & dosage / Q000633:toxicity; D007814:Larva / Q000187:drug effects; D008136:Longevity; D015032:Zinc / Q000008:administration & dosage* / Q000633:toxicity*
D018053:Arsenites; D004785:Environmental Pollutants; D015032:Zinc; C015001:arsenite