TOXIC ELEMENTAL COMPOSITION OF RICE AND LENTILS CONSUMED IN THE UNITED STATES

Cereals such as rice and lentils accumulate toxic metals including arsenic (As), cadmium (Cd) and lead (Pb), which could lead to adverse health effects depending on the amount and duration of exposure. Chemical analysis is continually needed to determine the concentrations of these toxic metals in cereals produced globally. We purchased a total of 63 rice and 18 lentils samples from retail stores and determined elemental composition using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Our results showed mean concentrations (in µg/kg) of 177±79, 21±24, and 23.7±42 for As, Cd, and Pb respectively in brown rice. Wild rice had mean concentrations (in µg/kg) of 150±73, 28±26, and 7.8±9.6 for similar elements, respectively. Mean concentrations (in µg/kg) of 137±59, 16±18, and 22±42 for As, Cd, and Pb were measured in white rice, respectively. Lentils had mean concentrations of 8.49±4.5, 2.8±3.4, and 24.4±40 for As, Cd, and Pb respectively. Arsenic was significantly higher in cereals produced in southern states of the US (p = 0.015) and Europe (p=0.019). Cadmium and Pb concentrations were below the codex standard set for these elements in rice and other grains; however, two brown rice samples had values exceeding the similar standard of As (300 µg/kg). All white rice samples from Europe exceeded the European Food Safety Authority (EFSA) standards of 200 µg/kg. Principal component analysis (PCA) shows that PC1, PC2 and PC3 explain 62% of the data variation. Concentrations of Cd and As were major contributors of PC1 while Pb was the major contributor of PC2. A strong correlation between As and Cd suggests higher soil-plant transfer and accumulation rates especially in rice. We provide additional data on accumulation of heavy metals in cereals purchased in the USA that would inform the public about the potential of dietary exposure and minimize associated health risks.