## 3 Results and Discussion
### Pesticide Residues in Apples and Citrus Fruits--Comparison
#### 3.1.1 Apples
The American Environmental Protection Agency placed restrictions on the use of this substance in the USA [65]. The Forest Stewardship Council put a ban on the use of this substance in forests and plantations certificated by that organisation, and classified disulfoton as \"extremely hazardous\" (class IA according to the World Health Organisation). In the apples analysed in 2020, no cases of exceeded MRL were noted among the detected pesticide residues. It should be emphasised that the samples of apples from 2020 analysed in the experiment did not contain any pesticides that are not approved for use in European Union. The reduction in the diversity of the detected pesticides in 2020 compared to 2012 results from the observed trends of limitation in the use of pesticides and promotion of sustainable development. The available publications of studies on the content of pesticides in food report infrequent instances of exceeded MRL of those agents in apples. Monitoring of pesticide residues in food conducted in Poland in the years 2004-2007 by the State Sanitary Inspection revealed exceeded MRL in 2.3% of analysed samples of apples [66]. In a study conducted by [PERSON] et al. [67] in the years 2008-2011, the presence of pesticides was noted in 11.9% (from 1.7% to 19%) of samples of apples from the regions of north-eastern Poland; pesticide levels exceeding the MRL were observed in the range from 0% to 4.4% of the analysed samples of apples. Nonrecommended substances were identified in 0.5% of analysed samples of apples (among fungicides--boscalid, among insecticides--dimetheoate) [67]. The cited study demonstrated that 32.4% of fruit samples and 67.6% of samples of vegetables were free of residues of plant protection agents [67]. [PERSON] et al. (2010) identified, in apples from the 2009 harvest, the following pesticides: acetaminophen (6.6%), bifenthrin (1.7%), boscalid (0.8%%), captan (22.3%), carbendazim (5.8%), chlororyrifos (3,3%), cypermethrin (1.7%), cyprodinil (3.3%), difenoconazole (0.8%), dimethe (0.8%), and dithiocarbamates (11.6%), but none of them were at levels exceeding the MRL value. Another study on agricultural produce from the area of south-eastern Poland, conducted in 2011 by [PERSON] et al. (2008) [68], demonstrated that 46% of analysed samples of apples contained residues of plant protection agents such as: boscalid (20%), chlororyrifos (8%), cypermethrin (6%), cyprodinil (8%), diazinon (2%), difenoconazole (1%), dithiocarbamates (2%), fenazquin (4%), fenitrothon (2%), flusilazole (1%), iprodione (1%), captan (46%), kresoxim-methyl (2%), pirimethanil (8%), pirimicarb (7%), and trifoxystrobin (8%). In the case of diazinon (0.02 mg/kg, MRL 0.01 mg/kg) and fenitrothon (0.01-0.03 mg/kg, MRL 0.01 mg/kg), the observed levels exceeded the MRL, and in addition, the use of those two pesticides was prohibited [68]. A 9-year experiment on apples produced in Poland (2009-2013), conducted by [PERSON] [69], revealed that in 66.5% of analysed samples, 34 pesticides were identified, among which the MRL was exceeded in 3% of the analysed samples. Furthermore, 35% of the samples contained from two to six pesticides, and one sample contained seven identified compounds. Among the 34 identified pesticides, the most frequently detected were fungi cides. Samples with pesticide levels exceeding the highest permissible concentrations were more often identified in the group of insecticides. According to the Ministry of Health Report [70], in Poland in 2017, in all 85 analysed samples of apples, the presence of a total of 29 pesticides residues were identified (out of 280 pesticides included in the analyses). In four samples, five instances of exceeded MRL values were noted. In 29% of the analysed samples no presence of pesticide residues was found [70]. In 71% of the samples residues of at least one pesticide was detected. In 39% of the sample, residues of at least two pesticides were noted. None of the analysed samples contained residues of more than six pesticides.