The Ministry of University, Research, and Innovation has funded a research project at the University of Almería that certifies that two widely used compounds as biopesticides and present in orange and cinnamon extracts or oils do not persist in the aquatic environment. Their ability to degrade under sunlight makes them ideal allies for a more environmentally friendly agriculture.
The compounds called limonene and trans-cinnamaldehyde are known for their effectiveness as natural pesticides. However, until now, no studies had been conducted to analyze how their degradation occurred, whether their accumulation could pose a problem for the environment, or if new molecules that could be toxic were produced after contact with water. In an article published in the journal ‘Water, Air, & Soil Pollution,’ the team presents the data from the work demonstrating that neither of the two compounds presents risks.
Experts have confirmed that these products do not accumulate in water, due to relatively rapid degradation. Furthermore, they have validated that after decomposition, they do not become additional threats to ecosystems. «These findings reinforce the argument that biopesticides can play a significant role in a more ecological agriculture with less reliance on persistent chemicals,» says researcher Roberto Romero from the University of Almería, co-author of the article.
The study results have confirmed that both compounds have rapid decomposition. While limonene takes between 0.08 and 2.82 days to degrade, trans-cinnamaldehyde takes between 1.58 and 13.14 days. They have also shown that sunlight accelerates the process. Furthermore, they have evidenced the appearance of metabolites in the separation of the molecules, without any modification to the toxicity of these substances.
Safe Biopesticides
Specifically, the researchers wanted to determine if these two natural biopesticides were safe for the aquatic environment. To do this, they prepared water samples with the two compounds, leaving them in two different conditions: exposed to sunlight and in complete darkness. This simulates how degradation occurs in the real environment where the compounds can remain in open or underground waters. After analyzing the degradation time, they used chemical techniques to identify the substances that appeared when the original compounds decomposed.
Specifically, they used gas and liquid chromatography coupled with mass spectrometry (GC-MS and LC-MS) to separate the different compounds present in the sample and to identify them by analyzing their molecular structure through fragmentation. This technique, besides being very sensitive and detecting small amounts, is very precise as it can highlight compounds even with low concentrations.
To determine the toxicity level of the compounds, experts used a software known as ‘Predictive Toxicity Modeling’ (EPA TEST). With it, an estimation is made based on previous data on how the compounds degrade, accumulate, and the possibility of transfer to the food chain.
Experts propose expanding studies with other compounds also used in this type of pesticides and in other environments such as soil or sediments. Additionally, they suggest including the relationship of these substances with other pollutants so that both farmers and regulators promote the use of products that do not pose a long-term threat to biodiversity or human health.
This research, in addition to receiving funding from the Ministry of University through the FEDER Andalucía 2021-2027 program, also has the support of the University of Almería’s Research and Transfer Plan.
