A study on the seasonal transfer of two metals from pasture to animals: health risk assessment

Accretion of heavy metals in forage is a potential risk to grazing animals due to their uptake by plants and its entrance into the food chain. This study aimed to examine the Mn and Cd concentration from different samples. Sampling was done twice after the interval of 6 months during 2018; five different sites from Chakwal (Pidh, Tobar, Ratoccha, Kalar Kahar Road, Choa Saiden Shah and Chakwal Road, Choa Saiden Shah) were selected. Thirty samples of soil, forage (Acacia nilotica, Ziziphus nummularia, and Acacia modesta), and blood were collected. Forage and soil samples were dried, ground very fine, digested by wet digestion method, and analyzed by atomic absorption spectrophotometer. Samples collected from site I and site II had a very high concentration of heavy metals because these sites were very close to the coal mines and receive higher contamination. Manganese concentration in the soil fluctuated from 5.46 to 1.20, in the forage 6.84 to 1.00, and in the blood 5.21 to 1.03 mg/l, and cadmium concentration in the soil fluctuate from 1.85 to 0.03, in the forage 0.57 to 0.16, and in the blood 1.67 to 0.25 mg/l. Manganese concentration was higher as compared to the Cd. Higher concentration of Mn shows that this metal is due to human activities. Pollution load index value of Cd was higher than 1 in some samples, and the value fluctuates from 0.01 to 1.24 mg/kg. The values of a bioconcentration factor for Mn were greater than 1. Daily intake of metal value fluctuates from 0.01 to 1.03 mg/kg. Health risk index value ranges from 0.03 to 1.09 mg/kg. Health risk index of metals showed the risk which is due to the intake of contaminated fodder. From the soil, the metals can enter forage and bioaccumulate in the food chain. The health risk index was highest for Cd. The result obtained from the present research work indicated that there is a biomagnification of both metals in the food chain due to mining activities.