Heavy metals and health risk assessment in vegetables grown in the vicinity of a former non-metallic facility located in Romania

Soil contamination represents a serious and significant issue, especially when it comes to soil used in agricultural practices. This research was carried out in order to investigate the accumulation level of potentially toxic trace elements (Cr, Cd, Cu, Mn, Ni, Pb and Zn) in soil and vegetables (Solanum lycopersicum and Daucus carota). The transfer of the trace elements from soil to vegetables and the potential risk assessment were studied as well. Results indicated relatively high levels of heavy metals. Cd, Cu and Pb exceeded the alert limits established by the Romanian legislation. Zn was high as well. Positive correlations between the Cr, Cu and Pb indicated similar source of pollution, possibly related to the activities occurred in the non-metallic facility, nearby the study area. The heavy metals determined in the Solanum lycopersicum fruits and Daucus carota roots were below the maximum allowable concentrations, according to the WHO/FAO guideline. Slightly higher amounts of Cr and Cu were measured in tomatoes, compared to the carrots. Nevertheless, carrots were richer in Ni and Mn. The applied pollution indices indicated a contamination with heavy metals in 90% of the soil samples, with 9% probability of toxicity, the remaining 10% being classified into the precaution domain category. The plant bioconcentration of heavy metals into the Solanum lycopersicum fruits and Daucus carota roots is characterized using transfer factors. Generally, the results indicate that Daucus carota was the most susceptible to uptake Cu and Mn, while Solanum lycopersicum would rather uptake Cd and Zn. The estimated non-carcinogenic risk, based on the human health risk indices, indicates that the studied vegetables are safe for consumption with no impact on the human health. The results are lower than the critical value. Similarly, the carcinogenic risk indices results showed acceptable risks of cancer developing. It is important to assess and monitor the heavy metals levels in soil and in the vegetables intended to be consumed, in order to prevent contamination and potential negative effects on the environment and implicitly on the human health. The obtained data can be used in remediation techniques, as well as in implementing control measures of heavy metal contamination in soil and vegetables.