Chlorpyrifos Residues in Citrus Fruits A Statistical Approach to Derive Processing Factors from Routine Analyses Juan Ramirez Cassinello, Peter Krause, Udo Lampe, Francisco Ferrer, Sebastian Bihl Analytica Alimentaria GmbH, Fahrenheitstr. 5, D- 14532 Kleinmachnow, Germany info@analyticaalimentaria.de www.analyticaalimentaria.de Analytica Alimentaria is a leading provider of independent food safety services in the fields of pesticide residue and routine microbiological analysis – especially for fruits, vegetables and grains. Speed and reliability are key for our customers when it comes to the analysis of time-sensitive commodities. In the case of citrus fruits, laboratories have to perform two analyses – on the entire fruit and on the edible part of the fruit. This is both time consuming and costly. The question is whether it is possible to refrain from the second analysis or to only perform it in cases with specific risks – without putting food safety at risk? We have an answer. Introduction Materials and Methods Citrus fruits, e.g. lemons, mandarines and oranges, partly owe their popularity to the high levels of vitamin C. Processing factors (PF) are an indicator for changes of residue concentrations during processing. For peeled citrus fruits the EFSA recommends a PF of 0.03.1 The substantial data found in literature, clearly shows that there is a trend, but not yet enough samples to achieve statistical reliability (statistical reliability is given for 90-110 samples).2 The "Joint Meeting on Pesticide Residues“ (JMPR) states that PF are frequently derived from an insufficient number of measurements (< 50 samples) and that the measuring conditions are not fully reported.3 In conventional agriculture, the application of plant protection agents (one of the most frequently used is chlorpyrifos) is required to ensure agricultural yield and fruit quality. This in turn leads to residues from postharvest protectants and pesticides being found in detectable concentrations, mainly on the skin of the citrus fruits. An analysis of the entire fruit has to performed, in order to check the compliance with MRL’s. A second analysis of the edible part, follows to calculate the ARfD. How reliable are the PF’s? The aim of this study was to calculate and evaluate PF’s of chlorpyrifos for citrus fruits with regard to currently available data, from routine sampling and analyses carried out by Analytica Alimentaria. Citrus fruits (table 1) were processed and analyzed (multi-residue method) to determine pesticide residues. The entire fruits were cut into quarters and homogenized in the presence of dry ice. After a solvent extraction (QUEchERs), pesticides were determined by GC-MS/MS. The pure pulp was treated in the same manner. PF’s were calculated according to the JMPR method, taking into consideration that residues in the processed commodity are undetectable or exhibit less than the limit of quantification (LOQ). The processing factor is calculated using the LOQ and should be described using a “less than” (<) symbol. If several samples have concentrations smaller than the LOQ, the lowest PF-value should be taken, instead of the mean value. Table 1 Overview of samples and current MRL Commodity Number of Samples MRL mg/kg Oranges 483 0.3 Mandarines 133 2.0 Clementines 147 Lemons 71 0.2 Pomelos 39 Satsumas 38 Results and Discussion Only samples containing chlorpyrifos were chosen for this study. In those cases where the chlorpyrifos concentration was smaller than the current MRL, chlorpyrifos was in fact only sometimes found within the fruit pulp of the mandarines (7.4%) and lemons (10.4%). When the MRL was exceeded, chlorpyrifos was also found in the pulp of the oranges. Figures 1 - 4 summarize the cumulative concentration of chlorpyrifos across the total sample population. The chlorpyrifos concentration was found to be smaller or equal to the LOQ for most samples. According to the JMPR method, the PF values were taken from the smallest value calculated for each matrix. Figure 1 Total amount of samples with concentration of chlorpyrifos > LOQ (blue: entire fruit; red: fruit pulp, LOQ = 0.01 mg/kg) Conclusions The PF’s listed in table 2 can be used to calculate the chlorpyrifos concentration in the fruit pulp and thus the ARfD. For pomelo and satsuma the sample population is however still too small. In those cases the PF should only be used for orientation purposes. On the basis of this study, we recommend the use of PF’s in order to reduce costs, save time and still maintain a high level of food safety. For fruits with no available PF’s, repetitive analyses of the edible part should nonetheless be carried out. Table 2 Processing factors (PF) of chlorpyrifos for calculating the MRL and ARfD of the fruit pulp during pesticide residue analysis Commodity PF < Oranges 0.01 Mandarines 0.02 Clementines 0.03 Lemons Pomelos Satsumas rEFERENCES 1) EFSA Journal 10 (2012) 2510 2) Hamilton D, Ambrus A, et al. Pesticide residues in food – acute dietary exposure, Pest. Manag. Sci. 60 (2004) 311.