– Roundup and glyphosate toxicity underestimated – study (GM Watch, July 3, 2013):
NOTE: Below is yet another study throwing into question the reliability of regulatory classifications of glyphosate and Roundup.
The levels of Roundup and glyphosate found in this study to be toxic to Daphnia magna, the water flea, are minuscule and are well within levels expected to be found in the environment.
But glyphosate is classed by regulators as “practically nontoxic” to aquatic invertebrates.
Daphnia magna is a widely accepted model for environmental toxicity.
This study follows an earlier study by some of the same authors which showed that Bt maize fed to daphnia magna reduced their fitness:
Clone- and age-dependent toxicity of a glyphosate commercial formulation and its active ingredient in Daphnia magna
Marek Cuhra, Terje Traavik, and Thomas Bøhn
Ecotoxicology. 2013 March; 22(2): 251–262
Low levels of glyphosate based herbicide induced significant negative effects on the aquatic invertebrate Daphnia magna. Glyphosate herbicides such as brands of Roundup, are known to be toxic to daphnids. However, published findings on acute toxicity show significant discrepancies and variation across several orders of magnitude. To test the acute effects of both glyphosate and a commercial formulation of Roundup (hereafter Roundup), we conducted a series of exposure experiments with different clones and age-classes of D. magna. The results demonstrated EC50 (48) values in the low ppm-range for Roundup as well as for the active ingredient (a.i.) isopropylamine salt of glyphosate (glyphosate IPA) alone. Roundup showed slightly lower acute toxicity than glyphosate IPA alone, i.e. EC50 values of 3.7–10.6 mg a.i./l, as compared to 1.4–7.2 mg a.i./l for glyphosate IPA. However, in chronic toxicity tests spanning the whole life-cycle, Roundup was more toxic. D. magna was exposed to sublethal nominal concentrations of 0.05, 0.15, 0.45, 1.35 and 4.05 mg a.i./l for 55 days. Significant reduction of juvenile size was observed even in the lowest test concentrations of 0.05 mg a.i./l, for both glyphosate and Roundup. At 0.45 mg a.i./l, growth, fecundity and abortion rate 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 tested parameters, including mortality. D. magna was adversely affected by a near 100% abortion rate of eggs and embryonic stages at 1.35 mg a.i./l of Roundup. The results indicate that aquatic invertebrate ecology can be adversely affected by relevant ambient concentrations of this major herbicide. We conclude that glyphosate and Roundup toxicity to aquatic invertebrates have been underestimated and that current European Commission and US EPA toxicity classification of these chemicals need to be revised.