## 4 Discussion
### Effect of Immobilizing Agents on Estimated Daily Intake (EDI) and Health Risk Index (HRI)  
Studies related to the accumulation of heavy metals in plants and their further impact on the human diet are mainly focused on vegetables and fruit, so it is difficult to compare the results of this study with those presented in the literature. Nevertheless, the cited literature data constitute grounds for discussion, especially because the presented values of EDI or HRI, regardless of plants, are similar in some cases. [PERSON] et al. [40] analyzed various vegetables and fruit and recorded EDI values for Cu amounting from 5 to 40 \(\mathrm{\SIUnitSymbolMicro kg^{-1}}\) and for Zn from 20 to 110 \(\mathrm{\SIUnitSymbolMicro kg^{-1}}\). In turn, [PERSON] et al. [41] for various fruits obtained very high EDI for Cu ranging from 95 to 990 \(\mathrm{\SIUnitSymbolMicro kg^{-1}}\). Remarkably lower values for EDI (Cu from 0.05 to 0.15 \(\mathrm{\SIUnitSymbolMicro kg^{-1}}\) and Zn from 0.2 to 0.5 \(\mathrm{\SIUnitSymbolMicro kg^{-1}}\)) were found by [PERSON] and [PERSON] [37] for vegetables. [PERSON] et al. [20] also tested vegetables and obtained higher EDI values for Cu (1.66 \(\mathrm{\SIUnitSymbolMicro kg^{-1}}\)) and Zn (13.9 \(\mathrm{\SIUnitSymbolMicro kg^{-1}}\)). Vegetables analysed by [PERSON] et al. [36] showed greater amounts of Cu and Zn, which was expressed in EDI values of 4.48 and 23.7 \(\mathrm{\SIUnitSymbolMicro kg^{-1}}\), respectively. In this study, the estimated daily intake for amelina and oat was calculated separately for adult men and women and, regardless of the metal, the mean values which were obtained were higher for women (Cu: 5.3 to 8.5 \(\mathrm{\SIUnitSymbolMicro kg^{-1}}\) for amelina and 0.4 \(\mathrm{\SIUnitSymbolMicro kg^{-1}}\) for oat; Zn: 9.0 to 12.1 \(\mathrm{\SIUnitSymbolMicro kg^{-1}}\) for amelina and 1.2 to 1.8 \(\mathrm{\SIUnitSymbolMicro kg^{-1}}\) for oat) because of their lower body weight. Regardless of the observed differences between men and women for the EDI values, the effect of applied compost and fly ash was the same and led to a decrease in these amounts by 18 to 34% in comparison to the data found for the control. In order to realistically assess the obtained EDI\({}_{\mathrm{W}}\) and EDI\({}_{\mathrm{M}}\) values for Cu and Zn calculated for amelina and oat, they should be referred to the provisional tolerable daily intake (PTDI) values. It needs to be underlined here that EDI provides information concerning the daily intake of heavy metals (here Cu and Zn) with food products. On the other hand, tolerable daily intake refers to the daily amount of heavy metals in food that can be tolerated by humans over a long period with no adverse health effects. According to [PERSON] et al. [20], PTDI amounts to 60 mg and 3 mg per day for Zn and Cu, respectively. Taking into account the above information and confronting it with the EDI\({}_{\mathrm{W}}\) and EDI\({}_{\mathrm{M}}\) values obtained in this study for both metals, it can be stated that they were considerably lower than those given for PTDI. Therefore, it may be stated that the amounts of Cu and Zn that could be theoretically consumed by adults with oat or amelina products do not pose any health risk. Similarly, although they are weaker, effects may be observed in the case of HRI values, which were significantly higher for the control samples. Regardless of gender, the HRI values were comparable and for Cu amounted on average to 0.008-0.01 for oat and 0.11-0.21 for amelina. On the other hand, for Zn the average HRI values ranged from 0.003 to 0.006 for oat and from 0.002 to 0.004 for amelina. The values shown above are significantly lower than those reported in the literature [20], where HRI for Zn and Cu reached 0.46 and 0.041, respectively. In light of the HRI threshold given by [PERSON] et al.