Insight into the confusion over surfactant co-formulants in glyphosate-based herbicides

Area of Science:

• Environmental Science
• Toxicology
• Chemical Safety

Background:

• Glyphosate is the primary active ingredient in glyphosate-based herbicides (GBHs).
• Co-formulants, particularly surfactants, in GBHs are often presumed inert and overlooked in safety assessments.
• Previous research indicates that some surfactants in GBHs possess significant toxicity.

Purpose of the Study:

• To identify surfactants in various GBH formulations.
• To compare the acute toxic effects of these surfactants.
• To evaluate the evolving toxicity of surfactants used in GBHs over time.

Main Methods:

• Analysis of surfactants in a selection of GBH formulations.
• Comparative assessment of the acute toxic effects of identified surfactants.
• Review of historical changes in GBH surfactant composition.

Main Results:

• The first generation of polyethoxylated amine (POEA) surfactants (POE-tallowamine) in Roundup were found to be more toxic than glyphosate itself.
• Subsequent generations of POEA surfactants, such as ethoxylated etheramines, demonstrated reduced non-target toxicity.
• Newer propoxylated quaternary ammonium surfactants, used in the EU, are approximately 100 times less toxic to aquatic ecosystems and human cells compared to earlier GBH-POEA surfactants.
• Confusion exists regarding GBH co-formulant identity and concentration due to confidential commercial information laws.

Conclusions:

• Surfactants in GBHs contribute significantly to their overall toxicity, with varying levels of risk associated with different chemical classes.
• Evolution in surfactant technology has led to less toxic alternatives, but concerns remain.
• Full disclosure of GBH chemical composition is essential for accurate risk assessment and regulatory oversight.
• Further research into the health implications of ingesting GBH co-formulants is warranted.