Glyphosate-based herbicides (such as Roundup^® branded agricultural formulations) have been an important tool for farming. The herbicides act as effective broad spectrum weed killers and enable crops to be grown while using natural resources more efficiently. The glyphosate-based herbicide formulations and components of these formulations undergo extensive safety assessments to ensure that they are safe when used per label instructions. 

The endocrine system produces hormones that help our bodies function properly and regulate growth, development and metabolism. A comprehensive investigation of glyphosate’s potential to interact with the endocrine system demonstrated that glyphosate does not have potential to interact with estrogen, androgen and thyroid pathways, including steroidogenesis.^{1, 2, 3}  This conclusion is supported by the large database of safety studies for glyphosate that inform an assessment of potential endocrine disruption.

A paper published by Walsh et al. stated that a glyphosate-based herbicides were an endocrine disrupter by affecting steroidogenesis1. As an outcome of this study, Monsanto initiated an intensive research effort with one of the leading researchers in the field of the molecular regulation of steroidogenesis at Georgetown University’s Lombardy Medical Center. The new study confirmed that glyphosate and glyphosate-based formulations do not directly impact steroidogenesis. The conclusion of Walsh et al. that glyphosate-based herbicides, such as Roundup^® branded agricultural formulations,  inhibits translation of the Steroidogenic Acute Regulatory (StAR) protein was shown to be an artifact of the way they performed their laboratory experiments. The same type of responses observed with glyphosate were observed when common house-hold surfactants were tested with this assay. In the end, it was clearly shown that the results of Walsh et al. were driven by cytotoxicity occurring at supraphysiological concentrations, not a direct effect on steroidogenesis.

This study provides a cautionary tale to researchers to include a comprehensive assessment of factors that could confound in vitro laboratory assays.  In summary, care should be exercised when interpreting results from in vitro experiments that are conducted at high concentrations of adjuvants and don’t reflect environmentally relevant exposures. The full journal publication can be accessed here: https://bit.ly/2ENeigy