Nanos and agriculture

Nanos and agriculture

By AVICENN Team – Last Added June 2022

The "promises" of nanos in agriculture

Many promises surround nanomaterials in phytosanitary products. Schematically, we can distinguish several types of benefits sought for fertilizers and pesticides :

• limit the amount of active ingredient used, thanks to an active ingredient whose effectiveness is increased by a higher surface-to-volume ratio at the nanoscale
• trigger self-defense mechanisms of certain plants against diseases (“elicitor” products)
• promote the bioavailability of the active ingredient :
  • thanks to its nanometric size, the active ingredient is more easily absorbed by plants
  • or through a nanoencapsulation which allows a slower and more spread out release of the active ingredient over time (“delay effect”)
• avoid washing off by rain or degradation by light, thanks to the'encapsulation active ingredient

Another aspect of nanotechnology applications concerns so-called “precision” agriculture., thanks to nanosensors to optimize growing conditions¹A French team is working on these subjects: agrotic. In the USA, an experiment involving the implantation of nanosensors inside a plant itself to detect water stress early is reported in 2018. To deepen the question of the digitalization of agriculture, see in particular: The ongoing digitalization of agriculture:
identifying key research areas, Science for Environment Policy, 581, June 2022.

Finally, nanotechnologies could help in the design of more efficient sensors making it possible to detect pathogens more easily²See for example An overview on the nanotechnological expansion, toxicity assessment and remediating approaches in Agriculture and Food industry, Muthukrishnan L, Environmental Technology & Innovation, 25, February 2022 or traces of phytosanitary in crop products³See for example:
- Nano-sensor detects pesticides on fruit in minutes, Karolinska Institutet, June 2022
- Nanoparticles Make Pesticide Detection Super Sensitive, Asian Scientist Magazine, March 5, 2018.

What nano applications are already on the market?

In the agricultural sector as in all the others, we are really left in the dark when it comes to identifying the nano-additive products already on the market : phytosanitary products are not subject to any obligation tolabeling [nano]⁴Le biocides regulation, which makes [nano] labeling mandatory, does not apply to phytosanitary products, and safety sheets almost never mention the presence of nanomaterials in the products.

What the statements about R-nano tell us

Thanks to the mandatory declaration instituted by France since 2013, we know, however, that some of the 500 tons of nano substances declared each year in the R-Nano register is used in agriculture, without further indication of the exact volume or the properties of these nanomaterials actually used in the agricultural sector.

Since 2014, theagriculture certainly tops the declared sectors of use, but this “first place” does not necessarily reflect a high tonnage – it is perhaps simply the manifestation of the good transmission of information within the agricultural sector and the higher number, in this sector, of intermediaries between manufacturers and professional users (in this case, the farmers)⁵Distributors in the agricultural sector are well versed in the transmission of information, in particular with the management of pollution fees, via the national database on sales PhytoData..

In the 2016 balance sheet, about forty substances in the nanoparticle state are listed : alumina, silica, calcium, sulphur, titanium dioxide, copper, pigments and various clays (kaolin, attapulgite, Fuller's earth, etc.). Rather than active substances, these would essentially be bulking agents / co-formulants. Since 2017, ANSES has been carrying out checks on this point.

Two main families of nanopesticides

While it is difficult to accurately estimate the extent of nano applications in phytosanitary products, the analysis of patents and scientific literature makes it possible to measure the large number of products that are or will probably be marketed. In a article published in Nature Nanotechnology⁶Wang, D., Saleh, NB, Byro, A. et al. Nano-enabled pesticides for sustainable agriculture and global food security. Nat. Nanotechnology.17, 347–360 (2022). https://doi.org/10.1038/s41565-022-01082-8 , researchers analyze 1163 patents and 500 scientific articles and identify two main families of nanopesticides: 

• Nanomaterials used as active principle and mainly metallic, the most widely applied being the nano-silver (such as nanobactericides, nanofungicides and nanoinsecticides) and nanoparticles of titanium dioxide (as nanobactericides and nanofungicides)⁷Two products already marketed in the United States are mentioned: Nu-Clo silvercide (EPA registration number 7124-101, approved in 2007) and DuPont Kocide 3000 (EPA registration number 352-662, approved in 2007).
• Nanomaterials which are used for the nano-encapsulation of the active ingredient, the most common being polymers such as chitosan, cellulose and polyethylene existing as nanocapsules, nanospheres, nano(hydro)gels and nanomicelles, clay nanoparticles (e.g. silica, montmorillonite and kaolinite ), nanocomposites or even carbon nanotubes⁸See Figure 1 of the article quoted above .

Lack of transparency from manufacturers

Few distributors were aware of the presence of these nanomaterials in phytosanitary products before 2013: it was only with the introduction of compulsory declaration that they gradually discovered their existence. If manufacturers were more transparent, things would be less complicated. But they don't want to communicate and refuse even respond to requests for information on their nanomaterials made by the European Chemicals Agency (ECHA).

In 2014, AVICENN was nevertheless able to identify around forty products sold in agriculture that had been declared to the R-nano register by half a dozen companies, without us being able to obtain more information:Companies do not provide any information on the nanomaterials they use, nor in safety sheets of the products concerned (sheets which were however updated after the implementation of R-nano), neither on their sites nor on the site of the Union of plant protection industries (UIPP): info-pesticides.org.

The delay effect (sought after in the field) is thus also very noticeable… in information! The Union of Chemical Industries (UIC become France Chemistry) and the Medef, supported by the Agricultural Trade Federation (FNA), Co-op of France andUIPP Since 2015, they have even been asking to exempt distributors from completing the mandatory declaration, which would only increase the information deficit, which is already too great today.

Transparency, the basis of the necessary vigilance in the face of risks

Conversely, AVICENN made proposals that would help strengthen collective vigilance efforts⁹For example, asking manufacturers to update the registry e-phy (catalogue of fertilizers and pesticides authorized in agriculture available online), specifying with the marketing authorization number (AMM) when the product contains nanomaterials and is therefore concerned by the R-nano declaration; when distributors would then populate the national sales database Phytodata with the postal codes of the end-buyer farmers, the information on uses would be more complete than in the R-nano register, without additional registration. (Postal codes are admittedly relatively imprecise for geolocating uses, but sufficient to prioritize and, if necessary, lighten surveillance where there is no issue or increase it by targeting "at-risk" practices on territories or population groups to prevent). More broadly, see our suggestions for improvements to the R-nano device.. Indeed, the risks associated with nanos in agriculture are not to be taken lightly, both from the point of view of the environment and the health of farmers and local residents. Transparency is therefore essential in order to be able to exercise the required due diligence.

What about the risks?

As summarized by Indian researchers in a review of the scientific literature published in 2022, “Nanotechnology often involves the use of metal or metal oxide nanoparticles, which can enter the human body and accumulate there through biomagnification. Although their effects on human health are not known, nanoparticles can reach toxic concentrations in soil and flow into rivers and other water bodies, with their disposal becoming a huge economic burden."¹⁰See A comprehensive overview of nanotechnology in sustainable agriculture, Arora S et al., Journal of Biotechnology, 355: 21-41, Aug 2022.