About 70,000 tonnes of potentially harmful pesticides infiltrate aquifers annually, posing a threat to ecosystems and freshwater resources. A recent global study published in Nature sheds light on the issue.
Every year, the world utilizes approximately three million tonnes of agricultural pesticides, yet little is known about the fate of these chemicals after their initial application.
The study highlights the far-reaching dispersion of pesticides, which often end up downstream, sometimes reaching the ocean in smaller quantities but with significant environmental consequences.
PESTICIDE DEGRADATION AND ENVIRONMENTAL PERSISTENCE
The study indicates that around 80 percent of applied pesticides break down into daughter molecules or by-products within the surrounding soil. However, this degradation process often occurs as a cascade, resulting in molecules that can persist in the environment for extended periods and exhibit toxicity comparable to the parent pesticide. For instance, glyphosate, a widely used pesticide, degrades into a molecule called AMPA, which proves highly persistent and toxic.
IMPACT ON WATER SYSTEMS AND MARINE LIFE
While only a fraction of pesticides enter river systems directly after field application, once they reach the water, most of the active ingredients eventually find their way into the ocean, potentially endangering marine wildlife and coral reefs. This poses a significant risk to the foundations of both marine and freshwater food chains. Although the percentage of pesticides leaching into freshwater might appear small (0.1 percent), even minute quantities can exert detrimental effects on the environment.
RIVERS AND ECOSYSTEM CONSEQUENCES
The study reveals that 730 tonnes of pesticides enter rivers annually, with approximately 13,000 kilometres of river systems experiencing chemical concentrations surpassing safety limits for numerous aquatic plants and invertebrates. The consequences for river ecosystems remain inadequately understood, emphasizing the need for further research.
UNDETECTED RESIDUES AND URGENT ACTION
Dr. Fiona Tang, a co-author of the study, underscores that the absence of visible pesticide residues in soil and water does not imply their absence or lack of impact on critical terrestrial, aquatic, and marine systems. The study’s authors stress the urgency of adopting sustainable management strategies to minimize harmful pesticide applications and implementing robust monitoring systems, aligning with the objectives outlined in the 2030 Sustainable Development Agenda.
SCOPE AND FUTURE MEASURES
The research team based their study on publicly accessible geospatial data, although they acknowledge that their estimates are conservative, as certain types of pesticides were not included in the analysis. The authors did not examine legacy pesticides or those used in aquaculture, private dwellings, and public spaces, indicating that the risks posed to ecosystems and individuals by these chemicals might be higher than estimated.
CALLS FOR ACTION AND REDUCED RISK
Associate Professor Federico Maggi, the lead author of the study, co-authored another paper outlining recommendations to reduce pesticide use and improve monitoring. The paper emphasizes the need for lowering pesticide pollution by targeting reductions in quantity and toxicity, considering that even low quantities of highly toxic pesticides can pose a high risk to certain organisms. Transparency from national authorities regarding the use of agricultural inputs, including fertilizers and pesticides, is seen as vital due to their significant environmental impact and ecosystem services.
BALANCING FOOD SECURITY AND PESTICIDE REDUCTION
Associate Professor Maggi suggests that global pesticide reduction, coupled with food security, is achievable through the implementation of initiatives designed in collaboration with food producers. Advancements in technology and modern crop management practices offer opportunities to increase efficiency and yields while maintaining an abundant food supply.
The global study on agricultural pesticides highlights the concerning affect of these chemicals on freshwater resources, ecosystems, and marine life. The findings underscore the urgent need for sustainable management strategies, reduced pesticide applications, and improved monitoring systems. By focusing on risk reduction, transparency, and collaborative efforts, it is possible to mitigate the environmental risks posed by pesticides while ensuring global food security.
