Risk Assessment of Potentially Toxic Metals and Metalloids in Soil, Water and Plant Continuum of Fragrant Rice

Abstract

Globally, the demand for food is increasing day by day due to the rapid increase in the human population. Elevated levels of metals and metalloids in soils are biomagnified over time in crops cultivated in metal-contaminated soils, hence posing a risk of food chain contamination. The present investigation aimed to assess metal and metalloid concentrations in soil, water, and rice kernels which are widely cultivated in four districts of Punjab, Pakistan, and to determine the risk to human health. The results revealed that, of five rice varieties, super basmati was the most preferred by farmers due to its yield potential and consumer acceptance due to its taste and to its long kernel. A detailed analysis of metal and metalloid accumulation revealed that their mean concentration fluctuated in the soil, water, and rice samples in the study area. The decreasing trends of heavy metals and metalloids were observed to be Pb > Cu > As > Cr > Cd > Hg > Al in soil samples, Pb > Cr > Cu > Al > As > Hg > Cd in water samples, and Cu > Cr = Pb > Cd = Al > Hg > As in rice kernels. The bioconcentration factor for Cr was the highest in the Faisalabad area among all sampled sites. The pollution load index of As, Cd, and Hg registered the highest values, that were above the recommended safety threshold levels described by World Health Organization. The human health risk index was determined to be low at all sites except for As and Hg. These results point to potential health risks caused by the consumption of fragrant rice by humans. Regular monitoring is recommended to manage and control elevated concentrations and related health hazards as a result of the use of rice contaminated by the accumulation of metals and metalloids.