## 3 Results and Discussion
### Pesticide Residues in Apples and Citrus Fruits--Comparison
#### 3.1.2 Citrus Fruits  
Figures 4 and 5 present the content of identified pesticides in edible parts of citrus fruits (flesh), in samples from 2012 and 2020, respectively. Figure 3: Frequency of occurrence of pesticides in the analysed samples of whole apples in 2012 and 2020, expressed as percentage share. In 2012, the presence of four pesticides were found in the flesh of citrus fruits--chlorpyrifos (insecticide), imazalil (fungicide), prochloraz (fungicide) and pyrimethanil (fungicide). In 2020, in the flesh of the analysed samples of citrus fruits the following pesticides were identified: imazalil, pyrimethanil and compounds from the spirotetramat group (insecticides), such as spirotetramat-enol and spirotetramat-enol-glucoside. In the years of the analyses, no instances of exceeded MRL values were noted for the identified pesticide residues. Figure 4: Content of pesticides from the edible parts of citrus fruits from the harvest of 2012. Figure 5: Content of pesticides from the edible parts of citrus fruits from the harvest of 2020. [PERSON] et al. [66] conducted a study in the years 2004-2007 analysing the residues of pesticides in samples of fruits, including, among others, oranges, mandarins and nectarines. Exceeded values of MRL were observed by the authors only in the case of nectarines, and the pesticide with excessive concentration was chlorpyrifos. [PERSON] et al. [75] identified prochlorotaz and imazalil, and their primary products of degradation, in extracts of citrus fruits. [PERSON] et al. [76] assayed pesticide residues in oranges and tangerines from Valencia (Spain). Among 116 samples analysed by the authors, 52 contained residues of plant protection agents. The most frequently detected pesticides were the following: carbendazim, hexythiazox, metydation, imidalcoprid and metiokarb, and in addition, in some samples they also identified piriproksyfen, thiabendazole, trichlorofon and imazalil. In 22 instances, the cited authors detected hexythiazox at concentrations in the range of 0.02-0.05 mg/kg, and in eight samples they assayed imazalil at levels from 0.02 to 1.2 mg/kg. However, they did not observe any nonconformance with MRL in force in the territory of the EU. In a majority of cases, the samples contained residues of individual pesticides. Infrequently, two or three pesticides were identified in a sample, and in only one sample, residues of four pesticides were identified at the same time--carbendazim, hexythiazox, imazalil and metydation. In a study on apples and lemons, [PERSON] et al. [77] demonstrated that 18.3% of analysed samples were contaminated with pesticides. The most frequently identified compound was izmalil, detected in 18 analysed samples (range of 0.02-4.10 mg/kg), followed by chlorpyrifos, identified in 8 samples, at concentrations from 0.03 mg/kg to 0.27 mg/kg. Imazalil constituted the highest percentage (66.6%) of pesticides identified in the analysed fruits. In eight samples of the fruits, pesticide residues were higher than the MRL and were identified as hazardous for human consumption. A study by [PERSON] et al. [78] focused on pesticide contamination of citrus fruits (oranges, lemons and mandarins) cultivated in Italy, and demonstrated that 60% of the analysed samples of fruits contained residues of one pesticide, while in two samples (4%) the presence of two pesticides was noted. Samples of oranges contained the highest average levels of pesticides (2491 \(\pm\) 1024 ug/kg), with the maximum level (4468 ug/kg) being that of imazalil, which was the most frequently identified pesticide in orange samples (83%). This confirms the extensive use of this compound in the protection of citrus fruits. The presence of imazalil was noted also in samples of mandarins, with an average level of 3841.25 \(\pm\) 2145 ug/kg and a maximum of 4456 ug/kg. A study on pesticide residues in citrus fruits (peeled grapefruit, lemon, orange and mandarin) grown in the Jordan Valley [79] revealed the presence of chlorothalonil and daminozide in the majority of the analysed samples.