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COMPARATIVE TOXICITY OF DIURON ON SURVIVAL AND GROWTH OF PACIFIC TREEFROG, BULLFROG, RED-LEGGED FROG, AND AFRICAN CLAWED FROG EMBRYOS AND TADPOLES
Schuytema, G. AND A. Nebeker. COMPARATIVE TOXICITY OF DIURON ON SURVIVAL AND GROWTH OF PACIFIC TREEFROG, BULLFROG, RED-LEGGED FROG, AND AFRICAN CLAWED FROG EMBRYOS AND TADPOLES. Archives of Environmental Contamination and Toxicology 34(4):370-376, (1998).
The effects of the herbicide diuron on survival and growth of Pacific treefrog (Pseudacris regilla),bullfrog(Rana catesbeiana), red-legged frog(Rana aurora),and African clawed frog(Xenopus laevis)embryos and tadpoles were determined in static-renewal tests. P.regilla and X.laevis embroys had reduced growth and developed increased deformities in diuron concentrations over 20 mg/L. Hindlimb bud and forelimb development were retared in R.aurora following 14 days exposure to diuron concentrations of >7.6 mg/L. Mean 14-day LC50s for P.regilla and X.laevis tadpoles were 15.2 and 11.3 mg/L diuron, respectively. The 21-day LC50 for R.catesbeiana tadpoles was 12.7 mg/L diuron. The 14-day LC50 for R. aurora tadpoles was 22.2 mg/L. The lowest NOAELs calculated in embryo tests were 14.5 mg/L for P.regilla (10 days) and 7.6 mg/L diuron for X. laevis(4 days). The lowest NOAELs calculated in tadpole tests were:P.regilla, 14.5 mg/L (14 days);R.catesbeiana, 7.6 mg/L (21 days);R.aurora,7.6 mg/L(14 days);and X.laevis,>29.1 mg/L (14 days). Diuron concentrations having an effect on survival, growth, and malformation in the laboratory were much higher than those found in normal field spray situations; field studies would be needed to determine the hazard to amphibians in areas of localized pooling of recently applied herbicide in the environment.