Toxic effects found at levels that people and animals regularly eat and that are deemed safe by regulators
 

Glyphosate residues in ready-for-market Roundup Ready soybeans had negative effects on Daphnia magna (water flea) in a new life-long feeding study.

These were normal soybeans that people and animals normally eat.

The investigated residue levels were within current permitted residue limits for soybeans in the USA (40 mg/kg) – and were found to be toxic. High levels of glyphosate residues in the soybean feed tested correlated with:
1) higher mortality
2) reduced growth and fertility in some parts of the life-cycle
3) delayed reproduction, and a reduced total number of offspring.

The authors concluded that normally occurring levels of glyphosate can have negative biological effects. They added that “potential health consequences in consumer organisms” (humans and livestock animals) should be further researched.

Daphnia are considered to be a good model for assessing ecological toxicity.

Glyphosate-Residues in Roundup-Ready Soybean Impair Daphnia magna Life-Cycle

Cuhra, M., Traavik, T., Dando, M., Primicerio, R., Holderbaum, D. and Bøhn, T. (2015)
Journal of Agricultural Chemistry and Environment, 4, 24-36. doi: 10.4236/jacen.2015.41003.
http://www.scirp.org/journal/PaperInformation.aspx?paperID=53681#.VNE6G3ZXLtZ (open access)

ABSTRACT
Herbicide tolerant plants such as Roundup-Ready soybean contain residues of glyphosate herbicide. These residues are considered safe and previous animal-feeding-studies have failed to find negative effects related to such chemical residues. The present study tests 8 experimental soy-meal diets as feed in groups (each containing 20 individuals) of test-animals (D. magna). The diets have different levels of glyphosate residues and we show that animal growth, reproductive maturity and number of offspring are correlated with these chemicals. The tested soybeans are from ordinary agriculture in Iowa USA and the residues are below the regulatory limits. Despite this, clear negative effects are seen in life-long feeding. The work enhances the need for including analysis of herbicide residues in future assessment of GMO.