Dietary exposure to toxic trace elements through cooked rice in high rice consuming populations: A comprehensive risk assessment in Sri Lanka

Abstract

Toxic Trace Element (TTE) exposure is an increasing public health concern, and rice, Sri Lanka’s primary staple, requires ongoing monitoring. This study analysed Cd, As, Pb, and Cr in 25 rice grain composites (from 54 samples) across most commonly consumed varieties in Sri Lanka, assessing differences by pericarp colour, parboiling status, and variety types. Median (IQR) concentrations of TTEs in raw rice were; Cd: 0.032 (0.062 – 0.008), As: 0.049 (0.063 – 0.035), Pb: 0.095 (0.170 – 0.047), and Cr: 0.376 (0.532 – 0.166) mg kg⁻¹ . While no samples exceeded JECFA limits for Cd or As, one exceeded the Pb limit, and 20% surpassed the stricter 0.1 mg kg−1 Cd; a rigorous threshold specific to several rice consuming countries. Cooking significantly reduced TTE availability (p < 0.001). Estimated daily intakes (EDIs) for a typical Sri Lankan adult upon average cooked rice consumption were; Cd: 0.271 ± 0.279 µg kg−1 bw−1, As: 0.297 ± 0.126 µg kg−1 bw−1, Pb: 0.643 ± 0.500 µg kg−1 bw−1 and Cr: 0.379 ± 0.333 µg kg−1 bw−1 respectively, with the JECFA-PTMI for Cd exceeded by 8.3% and the EFSA-TDI by 25% of samples. Non-carcinogenic risk was evident only for Pb, while Cd and As indicated potential carcinogenic risks. Findings highlight the need to establish maximum country-specific threshold/cut-off values for continuous surveillance of TTE contamination in Sri Lankan rice to safeguard consumers with higher rice consumption habits.