From roadside soil to cow milk: a potentially toxic metal transfer study using Pennisetum glaucum as fodder

This study investigates the occurrence and transfer of potentially toxic metals in roadside and agricultural soils, Pennisetum glaucum fodder, and cow milk across areas with varying traffic density in Kallar Kahar, Pakistan. Samples were digested using a wet acid digestion method and analyzed using Atomic Absorption Spectrometry (AAS) under strict quality control protocols. The analyzed milk samples exhibited a broad range of metal concentrations, with Zn ranging from 1.99 to 3.16 mg/L, Fe from 0.16 to 0.32 mg/L, Mn from 0.02 to 0.28 mg/L, Cu from 0.001 to 0.008 mg/L, Pb from 0.001 to 0.009 mg/L, Cd from 0.0001 to 0.009 mg/L, Co from 0.0002 to 0.008 mg/L, and Mo from 0.001 to 0.004 mg/L. Contamination Factor (CF), Bioconcentration Factor (BCF), Daily Intake of Metal (DIM), and Health Risk Index (HRI) computations suggested that all values are below 1, indicating low levels of contamination and no immediate health risk under the studied conditions. However, values approaching threshold limits (e.g., Cd in milk and Mo in soil) suggest the need for cautious interpretation and long-term monitoring. Comparative analysis with international guidelines confirmed that metal levels in the study area are within safe limits. These findings highlight the suitability of the local environment for fodder production and dairy farming while emphasizing the importance of continuous monitoring to mitigate potential long-term risks.