ABSTRACT
Perfluorooctanesulfonic acid (PFOS) is a manmade chemical with several industrial applications and also a potential byproduct of many other per- and polyfluorinated substances (PFAS) in the environment. Due to the gathered evidence on its environmental persistence, long-range transport, toxicity, and bioaccumulative and biomagnifying properties, PFOS, its salts and perfluorooctane sulfonyl fluoride (PFOSF), were listed for global restriction under the Stockholm Convention on Persistent Organic Pollutants in 2009. Nevertheless, Brazil has granted an acceptable purpose exemption for using PFOSF to produce sulfluramid (EtFOSA) and to apply it as insecticide to control leaf-cutting ants of the genus Atta and Acromyrmex. Previous studies have pointed out EtFOSA as a precursor of PFOS in the environment, including in soils. Therefore, we aimed to confirm the role of EtFOSA in PFOS formation in soils representing areas where sulfluramid-based ant baits are used. A biodegradation assay was carried out by applying technical EtFOSA in triplicate samples of ultisol (PV) and oxisol (LVd) and measuring the contents of EtFOSA, perfluorooctane sulfonamide acetic acid (FOSAA), perfluorooctane sulfonamide (FOSA), and PFOS at seven moments (0, 3, 7, 15, 30, 60, and 120 days). The monitored byproducts started being noticed on the 15th day. After 120 days, PFOS yields were 30% for both soils, whereas FOSA yields were 46% (PV soil) and 42% (LVd soil) and FOSAA yields were 6% (PV soil) and 3% (LVd soil). It can be expected that FOSAA and FOSA contents will eventually be converted into PFOS in the environment and that the presence of plants could boost PFOS formation. Therefore, the ongoing extensive and intensive use of sulfluramid-based ant baits pose a considerable source of PFOS to the environment.
Subject(s)
Alkanesulfonic Acids , Fluorocarbons , Soil , Brazil , Fluorocarbons/analysis , Alkanesulfonic Acids/metabolismABSTRACT
Phytosanitary control is essential to ensure agricultural productivity and quality. However, approaches based on scheduled use of pesticides, overuse of harmful molecules produce impacts on different types of living organisms. Integrated Pest and Disease Management (IPM-IDM) may significantly reduce the burden of pesticides in the environment. Plant resistance may also be included in the IPM-IDM and even in conventional management due to little requirement of additional knowledge and changes in agricultural practices. Robust environmental assessments using methodology of universal use, life cycle assessment (LCA), may estimate the impacts of specific pesticides that cause major damages, including remarkable category impacts. Therefore the objective of this study was to determine the impacts and (eco)toxicological effects of phytosanitary strategies (IPM-IDM including or not lepidopteran resistant transgenic cultivars) vs. the scheduled approach. Two inventory modeling methods were also applied to gather information on the use and applicability of these methods. Life cycle assessment (LCA) was applied using two inventory modeling methods: 100%Soil and PestLCI (Consensus) using data from Brazilian croplands under tropical conditions, by combining phytosanitary approaches (IPM-IDM, IPM-IDM + transgenic cultivar, conventional, conventional + transgenic cultivar) and modeling methods. Hence, eight soybean production scenarios were established. The IPM-IDM was efficient to reduce the (eco)toxicity impacts of soybean production mainly for freshwater ecotoxicity category. Due to the dynamic character of IPM-IDM approaches, the inclusion of recently introduced strategies (plant resistant and biological control to stink bugs and plant fungal diseases) may diminish even more the principal impacting substances throughout the Brazilian croplands. The PestLCI Consensus method, although its development is yet in progress, to date can be suggested to estimate the agriculture environmental impacts more properly under tropical conditions.
