Impacts of (Nano)formulations on the Fate of an Insecticide in Soil and Consequences for Environmental Exposure Assessment

Abstract

The development of nanopesticides has recently received an increased level of attention. However, there are very few data about the environmental fate of these new products, and it is not known whether nanoformulations can be evaluated within the current pesticide regulatory framework. Sorption and degradation parameters of the insecticide bifenthrin were measured in two soils for (i) the pure active ingredient, (ii) three nanoformulations, and (iii) a commercially available formulation. In most cases, fate parameters derived for the nanopesticides were significantly different from those derived for the pure active ingredient (factors of up to 10 for sorption and 1.8 for degradation), but discrepancies were not easy to relate to the characteristics of the nanocarriers. In some cases, differences were also observed between the commercial formulation and the pure active ingredient (factors of up to 1.4 for sorption and 1.7 for degradation). In the regulatory context, the common assumption that formulations do not influence the environmental fate of pesticide active ingredients after application seems therefore not always adequate. In the absence of direct measurement, an inverse modeling approach was successfully applied to evaluate the durability of the formulations in soil (release half-life ranged between 11 and 74 days). Predicted groundwater concentrations very much depended on the modeling approach adopted but overall suggest that the nanoformulations studied could reduce losses to groundwater.

Fate, uptake, and distribution of nanoencapsulated pesticides in soil–earthworm systems and implications for environmental risk assessment

“…Sorption coefficients are lower than previously reported for the a.i., which range from 882 to 6000 mL g −1 in different soil types (Pesticide Properties Database ). Sorption coefficients are also lower than those observed by Kah et al () for bifenthrin a.i. and bifenthrin in traditional and nanoencapsulated formulations.…”

“…The observed dissipation half-life for the analytical-grade bifenthrin is at the lower end of the values reported in the field for bifenthrin and lower than that reported in laboratory studies (Pesticide Properties Database 2017). Half-lives are also lower than those obtained by Kah et al (2016) in similar investigations into the differences in persistence of analytical-grade bifenthrin and the a.i. in Capture LFR and nanoencapsulated treatments, although the order of half-lives is the same.…”

“…in Capture LFR and nanoencapsulated treatments, although the order of half-lives is the same. Release rates and associated release half-times for the nano-formulations (Table 1) are lower than those found by Kah et al (2016). Overall, these results indicate that even traditional formulations can affect the persistence of an a.i., but this impact is more enhanced in the nanoencapsulated treatments, possibly attributable to the nanocapsules "shielding" the unreleased a.i.…”

Recent developments in nanotechnology transforming the agricultural sector: a transition replete with opportunities

“…The existing antifungal drugs are well known for their fate, toxicity and environmental pollution, thus new formulations need to be discovered and industrialised to sustain the plant protection practices . Aguilar‐Méndez and colleagues showed that silver nanoparticles significantly delayed the growth of Colletotrichum gloesporioides , which causes anthracnose in a wide range of fruits in a dose‐dependent manner .…”

“…Engineered nanoparticles also have significant advantage in improving crop protection and pesticide residual detection , . However, nanoagrochemicals established for agricultural use are expensive in comparison to conventional agrochemicals . Furthermore, comprehensive investigations are required to ensure the ease of use of the nanoproduct to fulfill the safety parameters and have the ability to provide improved alternatives to the traditional formulations …”