Heavy Metal Analysis of Commercial Rice Grains from Varanasi City of India: Insight into Contamination Level, Daily Intake and Associated Health Risks.

Abstract

Rice (Oryza sativa L.) is a staple food in Many Asian countries and plays a vital role in global food security. Heavy metal contamination of the rice grains is a global concern, yet data on contamination level and associated risks in Northern India remain Limited. Thus, the present study quantified concentrations of Cd, Cr, Pb, As, Ni, Cu, and Zn in 19 rice grain varieties consumed by urban population of India using an Atomic Absorption Spectrophotometer. Hazardous risks of consuming rice grains were assessed through computing estimated daily intake (EDI), target hazard quotient (THQ), and target cancer risk (TCR). Results showed that Pb, As, and Ni levels in rice grains were below the detection thresholds (0.2, 0.2, and 0.04 µg g⁻¹ dw, respectively). However, concentrations of Cd, Cr, Cu and Zn ranged between 0.25-1.3, 0.25-4.1, 1.8-10.5 and 19.5-36.8 µg g⁻¹ dw, respectively. Except Cd, all the heavy metals were below the international and Indian permissible standards. Cd and Cr were detected in six rice varieties only (Jeera 32, Chintu, Cuttack, Silky, Kinki and Gawahi). EDI values via rice consumption were found as Zn > Cu > Cr > Cd for both children and adults. THQ values for Cd, Cr, and Cu exceeds a unit in Sonanchal, Kalanamak, and Moti under high exposure frequency. TCR further revealed that Cd and Cr in rice varieties posed carcinogenic risks to local residents. Ensuring food and public health safety adheres to strict monitoring and regulations of heavy metal contamination in rice grains.