Another study shows that glyphosate-based herbicide formulations, such as Roundup, are far more toxic than the isolated "active ingredient" glyphosate

An important study in rats compared the toxicity to the kidneys of the herbicide formulation Roundup with that of its active ingredient glyphosate. The study found that Roundup caused kidney toxicity, whereas glyphosate alone did not.

The study is one of several showing that the complete glyphosate herbicide formulations, which contain additives called adjuvants, are more toxic than glyphosate alone.

The problem is that regulatory approvals of glyphosate-based herbicides are based on long-term toxicity studies that are carried out with the active ingredient glyphosate alone and not with the formulations.

The authors of the study concluded, "The nephrotoxicity [kidney toxicity] observed cannot be due to the active ingredient in the Roundup formulation, as glyphosate alone has virtually no effect on the renal function of the exposed animals. Therefore, the general claim attributing nephrotoxicity of a glyphosate-based herbicide to its active ingredient should be discouraged."

This study shows that regulators are wrong to assess glyphosate alone for long-term toxicity and that the public cannot rely on the regulatory system as it stands to protect their health.
---
Comparative assessment on mechanism underlying renal toxicity of commercial formulation of Roundup herbicide and glyphosate alone in male albino rat
Gabriel A. Dedeke et al.
International Journal of Toxicology
First published June 11, 2018   
https://doi.org/10.1177/1091581818779553

Abstract

There have been major concerns that the nephrotoxicity of commercial formulations of Roundup herbicide is due to the active ingredient glyphosate. We therefore investigated and compared the mechanisms underlining the nephrotoxicity of Roundup herbicide and glyphosate alone in rat. Fifty-six adult male rats randomized into 7 groups of 8 rats per group were exposed to Roundup formulation and glyphosate alone daily by gavage at 3.6, 50.4, and 248.4 mg/kg body weight (bw) of glyphosate concentrations for 12 weeks with distilled water administered to the control group. Kidney biomarker (serum urea and creatinine, plasma cystatin-C, and neutrophil gelatinase-associated lipocalin), oxidative stress indices in the kidney tissue, activities of kidney membrane-bound enzymes (Mg-adenosine triphosphatase [ATPase], Ca-ATPase, Na/K-ATPase, and total ATPase), and histopathological changes in the kidney were monitored. Glyphosate concentration in the kidney was quantified by high-performance liquid chromatography with ultraviolet detection. Significant (P < 0.05) alterations in the levels of the kidney biomarker, oxidative stress markers, and membrane-bound enzymes were observed in the rats exposed to Roundup compared to the rats exposed to glyphosate alone. Rats exposed to Roundup accumulated more glyphosate residue in their kidney tissue. Severe histopathological lesions were only seen in the kidneys of rats exposed to Roundup. The nephrotoxicity observed cannot be due to the active ingredient in the Roundup formulation, as glyphosate alone has virtually no effect on the renal function of the exposed animals. Therefore, the general claim attributing nephrotoxicity of a glyphosate-based herbicide to its active ingredient should be discouraged.