Lack of information hinders regulation of ‘green’ nanopesticides
Scientists warn that terms such as “sustainable” must be used correctly and that the natural components of these products do not eliminate environmental concerns.
Fundação de Amparo à Pesquisa do Estado de São Paulo
image:
Evolution of weed control 7 days after application of green nanoherbicide, compared to control without application
view moreCredit: Vanessa Takeshita
New formulations of nanopesticides with natural ingredients have appeared in specialized literature using terms such as “green pesticide,” “ecological,” “based on natural elements,” and “with natural nanoparticles,” among others. However, there is no consensus on what truly constitutes a green pesticide, and these terms are used even when the active ingredients are synthetic or conventional and only encapsulated in formulations based on natural polymers.
“Commercial formulations of pesticides used in the field consist of active ingredients and so-called co-formulants, such as surfactants, dispersing agents, and emulsifiers. They represent between 50% and 90% of the total composition of commercial products, but are often vaguely labeled as ‘inert compounds’ and poorly documented, although they can sometimes be more toxic to the environment than the active ingredient itself,” warns Vanessa Takeshita, lead author of a review on the subject published in Sustainable Materials and Technologies by the Environmental Nanotechnology Group at the Institute of Science and Technology of São Paulo State University (ICT-UNESP), Sorocaba campus, Brazil.
According to her, over the last 20 years of developing nanoformulations for agriculture, the academic community has changed its strategy and approach. Initially, the focus was on reducing the amount of the formulation deposited in the environment. “The focus was on gaining efficiency for dose reduction,” she recalls, emphasizing that nanotechnology was a fundamental tool for that purpose. She adds that the products of this first generation of nanoformulations are already better for the environment than the traditional formulations used in agriculture for decades, but they still need to reach the market.
As the work progressed, however, the team led by Leonardo Fernandes Fraceto, currently innovation coordinator at the Center for Research on Biodiversity Dynamics and Climate Change (CBioClima), a FAPESP Research, Innovation, and Dissemination Center (RIDC), and coordinator of INCT NanoAgro, found that formulations with natural characteristics capable of promoting biorecognition by the plant tended to be more efficient. “When natural molecules or natural compounds are used, the plant identifies them as known compounds. We realized that it was easier and less environmentally hazardous to be efficient using non-synthetic ingredients. So, we moved forward in developing increasingly sustainable formulations.”
According to Takeshita, this “green shift” has been an international trend in research on the subject. However, she says the search for green nanoformulations has become a means of achieving publication and scientific dissemination. “If it has ‘green’ in the name, it gets media coverage, is published, and is successful. But is it really green? To answer this question, we began scrutinizing the published work. Sometimes the polymers and active ingredients are natural, but synthetic surfactants are used in the composition for stability, or only the polymer is natural. Therefore, these terms should be used sparingly to define this new generation of pesticides.”
According to her, a product must have an active ingredient and polymer of natural origin, as well as a clean production chain, to be considered “green.” Additionally, even if a product is classified as environmentally friendly, it is essential to assess its toxicity, as biodegradability does not exempt products from associated environmental impacts.
The article traces the history of green nanopesticide research and suggests a flowchart to help decision-makers classify formulations. Based on this information, they can then move forward with registering these new, efficient, environmentally safe molecules.
“We believe that the registration process for proven green molecules should be facilitated. As long as it can be shown, throughout the various stages, that the product is more efficient, has low or no toxicity, that the formulation without the active ingredient is also non-toxic, and that the result is as good as that of a conventional formulation, or one that isn’t entirely green, the registration process could be accelerated. That’s what we’re proposing at the end of the study. We want green molecules to reach the market and producers more quickly,” the researcher argues.
Tracking and registration
Brazil still lacks specific standards for regulating nanoformulations. Everything is analyzed and reviewed on a case-by-case basis. Three institutions are involved in registering these new and conventional formulations: the Ministry of Agriculture and Livestock (MAPA), the Brazilian Health Regulatory Agency (ANVISA), and the Brazilian Institute of the Environment and Renewable Natural Resources (IBAMA). Europe is slightly ahead; the Organization for Economic Cooperation and Development (OECD) is developing guidelines to help regulate these products. Brazilian institutions require these guidelines for registering similar products, including tests of molecule mobility in the environment and toxicity levels.
“We need to show MAPA that the formulation works at least as well as those already on the market; prove to ANVISA that the molecule has low toxicity, through a series of studies; and IBAMA will also request information on toxicity to non-target organisms, whether the molecule has the potential to reach groundwater, whether it’s mobile in the soil, whether it’s degradable in the environment, among other questions,” Takeshita explains. According to her, the process is usually lengthy, and even a conventional molecule can take more than ten years to be approved.
The ideal regulatory mechanism for the agronomist would be a kind of bonus system: the greener the molecule, the faster the registration process. “But that doesn’t exempt companies from submitting all the necessary dossiers. Most likely, for nanoformulations, it’ll be necessary to submit all the studies that are already submitted for conventional pesticides, plus some additional information. The detailed characterization of this nanoparticle, for example, according to established and recognized criteria, will likely be an important step, since, as mentioned, it interacts differently with the environment.”
Nano vs. conventional
Vanessa Takeshita explains that conventional formulations are mixtures of ingredients, such as the surfactant, active ingredient, and emulsifier, that are blended together. “The molecules are loose in a mixture. This helps the active ingredient reach the plant, adhere to the surface, and remain present in the plant’s environment. A nanoformulation, on the other hand, is a structure that can be assembled in various formats, such as small squares made of layers of clay, capsules, or hydrogels. For pesticides, the capsule format [<1000 nm] is most interesting. In this case, the active ingredient is inside the capsule, which protects and carries it into the plant.”
There are many advantages. For example, the plant can be “tricked” by the capsule. The scientists call this mechanism a Trojan horse. “The plant recognizes the capsule as a compound that’s good for it, but it’s inside that the active ingredient is found. In the case of herbicides, which we need to apply to weeds in large quantities, we can apply a smaller dose because it’s possible to deliver more product directly into the plant, which is more efficient.”
The researcher reiterates that progress has been made and that it is possible to have sustainable products that benefit agriculture. However, she acknowledges that there are bottlenecks. “It’s possible to have truly green formulations that can reach national and international markets and be used on a large scale, even for first-generation nanopesticides, i.e., those that combine synthetic or synthetic and natural compounds. The active ingredients can come from plants, microorganisms, or the substances they produce, but we know that there’s still a large gap in identifying these molecules, determining which compounds work, and extracting the active ingredients.”
Nanostructures, on the other hand, can be made with bioproducts such as zein, a protein extracted from corn; lignin, a biopolymer that supports plants; and cellulose, among others. “However, in addition to all the regulatory issues, the industry must be willing to adapt its industrial plants or develop these greener molecules for the market. A study has shown that producers are willing to pay 22% to 40% more for nanoformulations that are more efficient and less dangerous than conventional products. In other words, producers are willing to accept technology that helps them,” Takeshita summarizes.
FAPESP also supported the work through a Regular Research Grant; four postdoctoral fellowships (24/07260-2, 23/16519-7, 23/00335-4, and 23/07905-0); a research internship abroad; a doctoral scholarship; and a scholarship for Retention of Young Doctors in Brazil.
About São Paulo Research Foundation (FAPESP)
The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.
Journal
Sustainable Materials and Technologies
Article Title
The green horizon of agricultural nanotechnology: A pathway for truly sustainable pesticide formulations
