Evaluation of health risks and heavy metals toxicity in agricultural soils in Central Saudi Arabia

Abstract

The present study is among the first to assess the health and environmental risks of heavy metals (HMs) in the soil of palm farms in the Al-Jilah area, west of Riyadh. This was achieved by analyzing HM concentrations in surface soil samples using Inductively Coupled Plasma Mass Spectrometry. The findings revealed that metal concentrations followed a descending order: (µg/g): Fe (14,528) > Mn (163.47) > Sr (156.72) > Zn (30.11) > Cr (28.61) > Ni (20.58) > Cu (11.44) > Co (6.44) > Pb (5.28). The highest concentrations of Cu (42 µg/g), Pb (12 µg/g), and Sr (621 µg/g) were recorded in farm-21, located in the central region of the study area, which is characterized by intensive agricultural activity. Both the geo-accumulation index (Igeo) and the modified contamination degree (mCdeg) indicated no contamination, with Igeo values ranging from -3.00 to -1.86 and mCdeg value of 0.32. These results were further supported by the toxicity risk index, which showed very low toxic risks (0.18–1.38). Health risk assessments, represented by chronic daily intake and hazard index values, were conducted to evaluate potential non-carcinogenic risks. The results indicated that iron had the highest daily intake exposure, particularly in children. However, all HI values remained below 1, confirming health risks from soil exposure. Similarly, the cancer risk and lifetime cancer risk values were below the threshold of concern, indicating that the soil does not pose a carcinogenic threat. These findings suggest that the soil of palm farms in the Al-Jilah area is safe, with no evidence of non-carcinogenic or carcinogenic risks. However, continuous environmental monitoring remains crucial to preserving soil quality, given its significance for food security.