Glyphosate vs Glyphosate Bioactive

Glyphosate is one of the most widely used herbicides for weed control. Setting aside the political noise, it remains one of the most efficient, flexible, economical and accessible herbicides available. Its original formulations were optimised for broadacre agriculture, its largest market, but these formulations were not suitable for use near waterways due to their aquatic toxicity.

What is in glyphosate that makes it toxic to waterways?

• Glyphosate products (Roundup Advance®, Zero®, No Grow® and many others) contain two key components:
  Glyphosate (usually as an isopropylamine or potassium salt), which disrupts a plant metabolic pathway
• Surfactants, which help the herbicide spread across and penetrate plant leaves (breaks the surface tension in water droplets)

Glyphosate itself has low toxicity to mammals (Van Bruggen et al. 2018). However, the surfactants used in many agricultural formulations, most likely polyethoxylated tallow amines (POEA), are far more toxic to aquatic organisms than glyphosate. Surfactants reduce surface tension of water and can disrupt cell membranes in aquatic species. They can damage gills, affect eyesight, and reduce dissolved oxygen in water (Arora et al. 2022).

The majority of aquatic toxicity in glyphosate formulations is caused by the surfactants. This finding is echoed in multiple scientific reviews (Mesnage et al. 2019; Qiang et al. 2024). Because of this, the manufacturer label of glyphosate explicitly states its products must not be applied near water or where it will contaminate dams, rivers or streams. Complicating matters further, most Australian glyphosate SDSs do not disclose the specific surfactants used, citing commercial confidentiality. Mesnage et al. (2019) identified at least eight different surfactant groups used globally, and the same product name may contain different surfactants in different countries.

To reduce aquatic toxicity and expand glyphosate’s safe use near water, manufacturers developed “bioactive” or “aquatic approved” formulations. These products replace POEA surfactants with alternatives that are significantly less toxic to aquatic organisms. Several such products are available in Australia, but most still do not disclose their surfactant chemistry:
For example:

Roundup Biactive® is one of the few that identifies its surfactants. One is a non ionic plant derived surfactant, and the other is an ethoxylated etheramine.

For context:
•    Non bioactive formulations commonly use POEA, which is up to 100 times more toxic to aquatic organisms than the ethoxylated etheramines used in bioactive products.  To explain this in another way, in a pond with 1000 fish, the bioactive formulation might kill 10 fish, whereas the non-bioactive formulation will kill 1000 fish.

•    Bioactive formulations therefore represent a major reduction in aquatic hazard, but not a complete removal of risk.

•    Pulse Penetrant (a polyether modified polysiloxane) is a common adjuvant often added to herbicides including glyphosate to improve penetrability of the herbicide.  Pulse Penetrant is also toxic in waterways and should not be added to bioactive formulations applied near water.  

Bioactive glyphosate formulations are substantially less toxic to aquatic organisms compared with older POEA based products. However, they are not entirely non toxic. All surfactants have some level of aquatic impact, and even “safer” alternatives can still affect gill function, membrane integrity and oxygen exchange in sensitive species.
For this reason, the same caution should still apply when using bioactive glyphosate near waterways:

• avoid direct application to water
• prevent spray drift
• follow all label restrictions
• treat bioactive products as “reduced risk”, not “risk free”
• Do not add penetrants or adjuvants unless the label says its safe for waterways.

Bioactive formulations expand the situations where glyphosate can be used safely, but responsible application remains essential to protect aquatic ecosystems.

1. Arora, J., Ranjan, A., Chauhan, A., Biswas, R., Rajput, V.D. & Sushkova, S. et al. (2022) Surfactant pollution, an emerging threat to ecosystem: Approaches for effective bacterial degradation. Journal of Applied Microbiology, 133, 1229–1244. https://doi.org/10.1111/jam.15631 
2. Shuping Qiang, Fahim Mohamed, Jacques Raubenheimer, Nicholas A. Buckley, Michael S. Roberts & Lorraine Mackenzie (2024) Clinical toxicology of acute glyphosate self-poisoning: impact of plasma concentrations of glyphosate, its metabolite ndpolyethoxylated tallow amine surfactants on the toxicity, Clinical Toxicology, 62:8, 483-496, https://DOI.org/10.1080/15563650.2024.2375584
3. Van Bruggen AH, He MM, Shin K, Mai V, Jeong KC, Finckh MR, Morris JG (March 2018). "Environmental and health effects of the herbicide glyphosate". The Science of the Total Environment. 616–617: 255–268