Abstract
Vine leaves are consumed in many countries but little attention is paid to the residues left on them after the application of pesticides that help prevent pests and protect the grapes, the economically important target. Therefore, it is of outmost importance to study the dissipation of the pesticides applied to this crop to protect the consumers that also eat vine leaves. Dissipation kinetics of chlorpyrifos, chlorpyrifos-methyl, diazinon and dimethoate residues were studied in vine leaves grown under sunny conditions in Syria, using an ethyl acetate based sample preparation followed by GC-MS/MS determination. The dissipation rate for all doses applied followed first-order kinetics, with half-lives in grape leaves in the range of 2.9 – 3.9 days. At the recommended application dose, a withholding period of 8.9-37.1 days before consumption should be applied to meet current MRLs and minimise risks to consumers. The effectiveness in the reduction of pesticide loads in vine leaves through washing with either cold or hot water was dependant on the physicochemical properties of the studied pesticides. Hot water washing was very effective for dimethoate, a polar and water-soluble pesticide, with an effective reduction of 92% of the residue level; but no significant effect was observed for chlorpyrifos, the most apolar compound in this study.
Highlights
Grape (Vitis vinifera) was estimated by Food and Agriculture Organisation of the United Nations to be the most widely cultivated fruit crop in the world [1]
Dissipation rates are usually expressed as the pesticide half-life; the half-life being the time required for the pesticide residue level to fall to half of the initial concentration directly after application
Paramasivam et al [40] used Equation 5 to calculate the pre-harvest interval (PHI) defined as the maximum time required for the residues to fall below the Maximum Residues Limits (MRLs)
Summary
Grape (Vitis vinifera) was estimated by Food and Agriculture Organisation of the United Nations to be the most widely cultivated fruit crop in the world [1]. In assessing the impact of dietary exposure to pesticides, a number of parameters have to be taken into account and carefully evaluated, including MRLs, withholding times and dissipation rates and post-harvest management, amongst others These parameters are obtained either experimentally or through modelling and they vary according to the pesticide, the type of crop and the prevailing environmental conditions. The dissipation rate for pesticides applied on a specific crop depends on several factors: the chemical formulation and application method, climatic conditions - especially rainfall and temperature, vapour pressure of the pesticides, and the potential for photodegradation and other chemical degradation [14] This means that dissipation curves are very specific to local conditions in each growing area [15,16,17,18,19,20], and generation of precise knowledge of pesticide degradation kinetics is very important to produce reliable data for international bodies, such as Codex Alimentarius Commission, that set MRLs [21]. After sampling, vine leaves were analysed unwashed, washed with cold water, and washed with boiling tap water to assess whether domestic washing can offer a practical method for decreasing the intake of pesticides for consumers
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
