Unmasking the Secret Ingredients in Pesticides
The unseen chemicals in plant protection products are finally stepping into the spotlight.
When a farmer opens a container of pesticide, they're applying a complex chemical cocktail designed to protect crops. For decades, the spotlight has been almost exclusively on the active ingredient—the component tasked with killing fungi, weeds, or insects. But what about the other substances in the mixture? Scientists are now turning to advanced detective techniques to uncover the complete composition of these products, revealing a hidden world of so-called "inactive" ingredients that may be anything but. This journey into the unknown is revolutionizing our understanding of what we spray on our crops.
At its core, a Plant Protection Product (PPP) is much more than a single pesticide. According to European regulations, it consists of an approved active substance and a variety of other substances, including safeners, synergists, or co-formulants 1 .
Think of it like a pharmaceutical drug: the active substance is the medicine itself, while the co-formulants are the components that make up the pill, helping it dissolve at the right time or be absorbed by the body effectively.
To keep the mixture liquid
To help spread evenly on leaves
To extend shelf life
To protect from cold temperatures
How do you find something when you're not entirely sure what you're looking for? This is the challenge scientists face with co-formulants, which are often not listed on product labels. The solution lies in powerful analytical techniques known as non-targeted analysis.
Here, researchers have a "most-wanted" list of potential co-formulants. They use high-tech instruments to see if any of these suspects are present in the sample 1 7 .
Compile database of potential co-formulants
Screen samples against the suspect list
Confirm presence of identified compounds
This is a true fishing expedition. Scientists analyze the sample without any preconceived list, using the instrument's ability to detect a wide range of chemicals and then working to identify whatever pops up 1 7 .
Detect all possible compounds in sample
Use algorithms to identify unknown compounds
Determine chemical structure of unknowns
Six products with different formulation types
UHPLC-Q-Orbitrap-MS for precise molecular data
Suspect and unknown screening strategies
Matching with pure analytical standards
| Co-formulant | Primary Function | Concentration Range (g L⁻¹) |
|---|---|---|
| Glyceryl Monostearate | Emulsifier, surfactant | Up to 19.00 |
| 1-Monopalmitin | Emulsifier | Up to 0.87 |
| Dimethyl Sulfoxide (DMSO) | Solvent | As low as 0.04 |
| N,N-Dimethyldecanamide | Solvent | Up to 3.46 |
| Hexaethylene Glycol | Surfactant component | Up to 0.65 |
| 1,2-Benzisothiazol-3(2H)-one | Preservative, biocide | Up to 0.21 |
The data revealed that the type of formulation greatly influenced the number of co-formulants found. The study showed that EC and EW formulations contained the largest number of the detected co-formulants (four out of six), while other types like SC and WG contained fewer 1 .
The ability to fully characterize PPPs has profound implications. For regulators, it provides the data needed to make more informed decisions. The European Commission has already begun listing co-formulants that are not accepted for inclusion in PPPs, and this research arms regulators with the tools to enforce such rules 1 .
While the focus has been on active pesticide residues, some studies suggest that co-formulants can have longer half-lives on treated crops than previously assumed, potentially posing an underestimated health risk 4 .
Some co-formulants, like certain volatile benzene derivatives, have been found in nearly all PPPs tested in other studies, sometimes at high concentrations 7 . Knowing the full chemical profile is essential for understanding overall impact.
The use of suspect screening and unknown analysis is a paradigm shift in agricultural chemistry. It moves us from a narrow view focused solely on active ingredients to a holistic understanding of the entire product. As these techniques become more widespread and accessible, we can expect:
Manufacturers can be guided towards using less harmful co-formulants.
Policymakers will have scientific evidence to close regulatory gaps.
Everyone in the food chain will have a clearer picture of what is used.
This scientific journey, peering into the chemical shadows of pesticide formulations, is more than an academic exercise. It is a critical step towards ensuring that the products used to protect our crops do not come at an unintended cost to our health and the environment.