Nanos and agriculture

Nanos and agriculture

By the AVICENN team – Last added June 2022

The “promise” of nanotechnology in agriculture

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

• limit the quantity of active material used, thanks to an active material whose effectiveness is increased by a higher surface/volume ratio at the nanometric scale
• triggering self-defence 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 the plants
  • or thanks to a nano-encapsulation which allows a slower release of the active ingredient and more spread out in time (“delay effect”)
• avoid leaching by rain or degradation by light, thanks to theencapsulation of the active ingredient

Another application of nanotechnologies concerns “precision” agriculture, using nanosensors to optimize growing conditions¹A French team is working on these topics: Agrotic. In the US, experimentation with implanting nanosensors inside a plant itself to detect water stress early is reported in 2018. For more information on the digitization of agriculture, see: The ongoing digitization of agriculture:
identifying key research areas, Science for Environment Policy, 581, June 2022.

Finally, nanotechnology could help in the design of more efficient sensors that can more easily detect pathogenic elementsSee²for example An overview on the nanotechnological expansion, toxicity assessment and remediating approaches in Agriculture and Food industry, Muthukrishnan L, Environmental Technology & Innovation, 25, February 2022or traces of plant protection agents in crop productsSee³for example:
–⁴Nano-sensor detects pesticides on fruit in minutes, Karolinska Institutet, June 2022
–⁵Nanoparticles Make Pesticide Detection Super Sensitive, Asian Scientist Magazine, 5 March 2018.

What nano applications are already on the market?

In the agricultural sector as in all others, we are still in the dark when it comes to identifying nano-additivated products already on the market Plant protection products are not subject to any obligation tolabeling [nano]⁶The Biocides Regulation, which makes labelling mandatory [nano], does not apply to plant protection products, and safety data sheets almost never mention the presence of nanomaterials in products.

What the statements on R-nano tell us

Thanks to the mandatory reporting instituted by France since 2013, it is nevertheless known that a part of the 500 000 tons of nano substances declared each year in the R-Nano register is used in agriculture, with no further indication of the exact volume or properties of these nanomaterials actually used in the agricultural sector.

Since 2014, theagriculture is certainly the most important sector of use reported by thebut this “first place” does not necessarily reflect a high tonnage – it may simply be the manifestation of the good transmission of information within the agricultural sector and the a higher number of intermediaries in this sector between manufacturers and professional users (in this case, farmers)⁷The distributors of the agricultural sector are well versed in the transmission of information, in particular with the management of pollution charges, via the national database on sales PhytoData..

In the 2016 report, about forty substances in the nanoparticulate state are listed: alumina, silica, calcium, sulfur, titanium dioxide, copper, pigments and various clays (kaolin, attapulgite, Fuller’s earth,…). Rather than active substances, they are essentially fillers/coformulants. ANSES has been conducting audits on this issue since 2017.

Two main families of nanopesticides

While it is difficult to estimate the precise scope of nanos applications in crop protection, analysis of patents and scientific literature allows us to measure the significant number of products that are or will probably be commercialized. In a paper published in Nature Nanotechnology⁸Wang, D., Saleh, N.B., Byro, A. et al. Nano-enabled pesticides for sustainable agriculture and global food security. Nat. Nanotechnol.17, 347-360 (2022). https://doi.org/10.1038/s41565-022-01082-8 researchers analyzed 1163 patents and 500 scientific articles and identified two main families of nanopesticides:

• Nanomaterials used as active ingredient and mainly metallicthe most widely applied being the nanosilver (as nanobactericides, nanofungicides and nanoinsecticides) and nanoparticles of titanium dioxide (as nanobactericides and nanofungicides)⁹Two 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 ingredientThe most common are polymers such as chitosan, cellulose and polyethylene in the form of nanocapsules, nanospheres, nano(hydro)gels and nanomicelles, clay nanoparticles (e.g. silica, montmorillonite and kaolinite), nanocomposites or carbon nanotubes¹⁰Cf Figure 1 of the article quoted above .

Lack of transparency from manufacturers

Few distributors were aware of the presence of these nanomaterials in plant protection products before 2013: it is only with the introduction of mandatory reporting that they gradually discovered their existence. If manufacturers were more transparent, things would be less complicated. But they do not want to communicate and even refuse to respond to requests for information on their nanomaterials made by the European Chemicals Agency (ECHA).

In 2014, AVICENN was nevertheless able to identify about forty products sold in agriculture that had been declared to the R-nano register by half a dozen companies, without more information being available: theCompanies do not provide any information on the nanomaterials they usenor in the safety data sheets of the products concerned (although they were updated after the implementation of R-nano), nor on their sites nor on the site of the Union des industries de la protection des plantes (UIPP) : info-pesticides.org.

The delay effect (sought in the field) is thus also very sensitive… in the information! The Union of Chemical Industries(UIC , now France Chimie) and Medef, supported by the Federation of Agricultural Trade(FNA), Coop de France andUIPP have even been asking since 2015 to exempt distributors from filling out the mandatory declaration, which would only increase the information deficit that is already too great today.

Transparency, the basis for vigilance in the face of risk

Conversely, AVICENN has made proposals that would help strengthen collective vigilance efforts¹¹For example, requiring manufacturers to update the registry e-phy (catalog of fertilizers and pesticides authorized in agriculture available online), specifying with the marketing authorization number (MA) when the product contains nanomaterials and is therefore concerned by the R-nano declaration; when then the distributors would inform the national database on sales Phytodata with the postal codes of the end-buyer farmers, the information on uses would be more complete than in the R-nano register and without additional registration. (The postal codes are certainly relatively imprecise for geolocating uses, but they are sufficient to prioritize and, if necessary, reduce surveillance where there is no issue or increase it by targeting “risky” practices on territories or population groups to be prevented). 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 exercise the required vigilance.

What about the risks?

As summarized by Indian researchers in a review of the scientific literature published in 2022, “nanotechnologies often involve 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 leach into rivers and other water bodies, making their disposal a huge economic burden.”¹²Cf. A comprehensive overview of nanotechnology in sustainable agricultureArora S et al, Journal of Biotechnology, 355: 21-41, August 2022.