## 3 Results and Discussion
### Probabilistic Assessment: Conventional Versus Organic  
As already mentioned in the Material and methods section, a probabilistic model approach was developed to estimate the intake level of trace elements, which were derived from the consumption of 15-20 g (around 150-200 g of fresh matter) of these _Brassicas_. It should be pointed out that in developing the model, only the concentrations of trace elements for the _Brassica rapa_ species (turnip greens and turnip top) were considered as they are the one most consumed. Dietary reference intakes (DRI) for the Spanish population were considered [12]. There is not DRI for Co; however, this element represents approximately a 4.3% of vitamin B12. Considering a DRI for vitamin B12 between 2-2.4 \(\mathrm{\SIUnitSymbolMicro g}\), this corresponds to around 0.10 \(\mathrm{\SIUnitSymbolMicro g}\)/day [27]. In the case of Ni [14] and Cd [13], considering that they are heavy metals,the tolerable intake (TI) of 2.8 ug/kg body weight-day and 2.5 ug/kg body weight-week (0.36 ug/kg body weight-day) was used. For Pb a benchmark dose (BMDL\({}_{01}\)) for cardiovascular effects (1.50 ug/kg body weight-day) was considered [15]. It should also be noted that the present statistical tool was completed using the variability of inorganic elements present in plants as well as the variability of the _Brassica_ vegetable ingested. Both aspects determine the total intake of the inorganic elements. Thus, the results obtained from the simulation of the probabilistic model with conventional _Brassica_, indicated values for Co, Cr, Cu, Fe, Mn and Zn of 2.58 ug, 17.41 ug, 0.14 mg, 1.74 mg, 0.55 mg and 0.56 mg, respectively, for 50 th percentile (Figure 2). This shows that the intake of trace elements of at least half of the population consuming these conventional _Brassica_ will not be lower than these values. That intake fulfills Co DRI and complies with the following percentages of DRI for studied elements: Cr 69.6%, Cu 12.7%, Fe: 9.7%, Mn 30.6% and Zn 8.0%. When the same simulation of the probabilistic model is developed with concentrations belonging to organic _Brassica_, the values obtained for 50 th percentile were 3.61 ug, 9.60 ug, 0.12 mg, 1.20 mg, 0.65 mg and 0.49 mg for Co, Cr, Cu, Fe, Mn and Zn, respectively (Figure 3), which satisfy similarly to the conventional _Brassica_ the DRI percentages for these trace elements. Regarding heavy metals, we have considered intakes for 95 th percentile as being the most unfavorable situation. Thus, Ni, Pb and Cd intakes for 95 th percentile with conventional _Brassica_ were 39.00, 47.34 and 6.82 ug, respectively (Figure 4), whereas intakes with organic _Brassica_ were 25.70, 15.55 and 4.56 ug for Ni, Pb and Cd, respectively (Figure 5). According to these values, organic _Brassica_ led to a decrease in the intake of these three elements metals. However, when these results were expressed as percentages of TI for these elements, we only found slight differences (mainly in the case of Pb) between both agriculture systems. The TI percentages for a mean body weight of 70 kg per person were 19.9, 45.1 and 27.1% for Ni, Pb and Cd, respectively, with conventional _Brassica_, and 13.1, 14.8 and 18.1 % for organic _Brassica_. These results indicate that Cd, Ni and Pb contents in vegetable _Brassica rapa_ harvested under both conventional and organic farming conditions are below the accepted safety limits and do not represent any toxicologic risk. Figure 2: Simulated data and fitted probabilistic distribution for Co, Cr, Cu, Fe, Mn and Zn in conventional _Brassicas_. Figure 3: Simulated data and fitted probabilistic distribution for Co, Cr, Cu, Fe, Mn and Zn in organic _Brassicas_. Figure 4: Simulated data and fitted probabilistic distribution for Cd, Ni and Pb in conventional Brassicas. Figure 5: Simulated data and fitted probabilistic distribution for Cd, Ni and Pb in organic Brassicas.