Clone- and age-dependent toxicity of a glyphosate commercial formulation and its active ingredient in Daphnia magna.

摘要

Low levels of glyphosate based herbicideinduced significant negative effects on the aquatic invertebrateDaphnia magna. Glyphosate herbicides such as brandsof Roundup, are known to be toxic to daphnids. However,published findings on acute toxicity show significant discrepanciesand variation across several orders of magnitude.To test the acute effects of both glyphosate and a commercialformulation of Roundup (hereafter Roundup), we conducteda series of exposure experiments with different clones andage-classes of D. magna. The results demonstrated EC50 (48)values in the low ppm-range for Roundup as well as for theactive ingredient (a.i.) isopropylamine salt of glyphosate(glyphosate IPA) alone. Roundup showed slightly loweracute toxicity than glyphosate IPA alone, i.e. EC50 values of3.7–10.6 mg a.i./l, as compared to 1.4–7.2 mg a.i./l forglyphosate IPA. However, in chronic toxicity tests spanningthe whole life-cycle, Roundup was more toxic. D. magnawas exposed to sublethal nominal concentrations of 0.05,0.15, 0.45, 1.35 and 4.05 mg a.i./l for 55 days. Significantreduction of juvenile size was observed even in the lowesttest concentrations of 0.05 mg a.i./l, for both glyphosate andRoundup. At 0.45 mg a.i./l, growth, fecundity and abortionrate was affected, but only in animals exposed to Roundup.At 1.35 and 4.05 mg a.i./l of both glyphosate and Roundup,significant negative effects were seen on most testedparameters, including mortality. D. magna was adverselyaffected by a near 100 % abortion rate of eggs andembryonic stages at 1.35 mg a.i./l of Roundup. The resultsindicate that aquatic invertebrate ecology can be adverselyaffected by relevant ambient concentrations of this majorherbicide. We conclude that glyphosate and Roundup toxicityto aquatic invertebrates have been underestimated andthat current European Commission and US EPA toxicityclassification of these chemicals need to be revised.