Analysis of residues from dithiocarbamate fungicides in vegetables produced in the region of Vargem Bonita, Federal District

ABSTRACT Dithiocarbamates are the most used fungicide and one of the most detected in food in Brazil. This study aims to analyze the levels of dithiocarbamate residues in vegetables produced in the region of Vargem Bonita, Federal District, and to compare the levels found with the maximum residue limits (MRLs) established by the Brazilian legislation. Eighty-four vegetable samples were obtained directly from 23 Vargem Bonita producers from June to November 2018. The analyzes were carried out using a spectrophotometric method, which determines the level of CS2 produced by degrading the dithiocarbamate present in the sample. In total, 21 samples (25%) contained dithiocarbamate residues above the method’s limit of quantification (LOQ, 0.05 mg/kg CS2). Five of the 27 lettuce samples analyzed (18.5%) contained dithiocarbamates, at levels ranging from 0.06 to 0.50 mg/kg CS2, below the MRL for this crop. Residues were also found in parsley, coriander and chicory samples (0.09 or 0.10 mg/kg CS2), cultures for which there is no registered the use of dithiocarbamate in Brazil. Samples of arugula, chive, leek, and watercress, which also do not have registered use, tested positive; however, these crops are known to provide false positive results for CS2, and the illegality of the residues cannot be confirmed. This study shows proper dithiocarbamate use in vegetables by Vargem Bonita farmers, except for parsley, coriander, and chicory, crops with a limited number of registered pesticides, which was probably the reason for the illegal dithiocarbamate use.

摘要：二硫代氨基甲酸酯类（dithiocarbamates）是巴西应用最广泛的杀菌剂，同时也是该国食品中检出率最高的污染物之一。本研究旨在分析巴西联邦特区瓦尔任博尼塔（Vargem Bonita）产区蔬菜中二硫代氨基甲酸酯类残留水平，并将检测结果与巴西法规规定的最大残留限量（maximum residue limits, MRLs）进行比对。2018年6月至11月，研究人员从23位瓦尔任博尼塔的种植户处直接采集了84份蔬菜样本；本研究采用分光光度法开展检测，该方法通过降解样本中的二硫代氨基甲酸酯类物质，测定其生成的二硫化碳（CS2）含量。总计21份样本（占比25%）的二硫代氨基甲酸酯类残留水平超出该方法的定量限（limit of quantification, LOQ，0.05 mg/kg CS2）。在27份生菜样本中，有5份（占比18.5%）检出二硫代氨基甲酸酯类残留，含量区间为0.06~0.50 mg/kg CS2，且该水平低于该作物对应的最大残留限量。研究还在欧芹、芫荽及菊苣样本中检出残留（含量为0.09或0.10 mg/kg CS2），而巴西尚未登记允许在这些作物上使用二硫代氨基甲酸酯类药剂；芝麻菜、细香葱、韭葱及豆瓣菜样本同样呈阳性反应，但这类作物已被证实会对二硫化碳检测产生假阳性结果，因此无法确认此类残留属于违规使用。本研究表明，瓦尔任博尼塔的种植户在多数蔬菜种植中合理使用了二硫代氨基甲酸酯类杀菌剂，仅欧芹、芫荽及菊苣例外——这类作物可登记使用的农药种类有限，这或许是违规使用二硫代氨基甲酸酯类药剂的原因所在。