Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. What was studied?
This original research article investigated the concentrations of both toxic and essential elements in rice and other commonly consumed grains sourced from the United States and other countries, specifically Italy, India, and Thailand. The focus was on key toxic metals—arsenic (As), lead (Pb), and cadmium (Cd)—as well as essential nutrients including magnesium (Mg), calcium (Ca), potassium (K), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn). Using Inductively Coupled Plasma Mass Spectrometry (ICP-MS), the researchers analyzed white and brown rice (including varieties from different US states), along with grains such as lentils, barleys, beans, oats, wheat, and peas. The study also assessed the effect of washing rice on the removal of toxic elements and the potential concurrent loss of essential nutrients. These findings are crucial for heavy metal certification programs because they highlight regional and varietal differences in toxic metal accumulation, compliance with international standards, and the impact of common food preparation practices on both contaminant exposure and nutritional value.
Who was studied?
The samples studied were not human subjects but rather food products—specifically, 28 white and 11 brown rice samples collected from retail stores in Louisiana, US, with white rice originating from US states (California, Texas, Louisiana), and imports from Thailand, India, and Italy. Brown rice samples were exclusively from US states (Louisiana, Arkansas, Texas). Additional grain samples—lentils, barleys, beans, oats, wheat, and peas—were obtained from local stores and sourced from various US states and Canada. In the washing experiment, nine randomly selected white rice samples were rinsed-washed to mimic typical household preparation. The study’s analytic focus on these diverse sources and types of grains allows for a broad comparison of toxic and essential element profiles relevant to consumers and regulators in different regions.
Most important findings
| Critical Points | Details |
|---|---|
| Toxic metal concentrations in rice vs. other grains | Both white and brown rice, regardless of origin, had higher median concentrations of arsenic, lead, and cadmium compared to other grains. Brown rice from the US showed especially high levels (As: 217 µg/kg, Pb: 4.5 µg/kg, Cd: 17.4 µg/kg), while other grains had much lower values (As: 5.4 µg/kg, Pb: 4.6 µg/kg, Cd: 6.7 µg/kg). |
| Geographic differences in toxic metal accumulation | White rice from Thailand, India, and Italy had higher median toxic metal concentrations (As: 155 µg/kg, Pb: 3.6 µg/kg, Cd: 8.4 µg/kg) than US white rice (As: 131 µg/kg, Pb: 2.8 µg/kg, Cd: 6.5 µg/kg). Within the US, Louisiana rice often had the highest levels. |
| Compliance with Codex standards | All samples were below Codex standards for Pb (200 µg/kg) and Cd (100 µg/kg for cereals/pulses, 400 µg/kg for polished rice). However, six brown rice samples and one long-grain white rice sample from the US exceeded the Codex limit for As (200 µg/kg). |
| Essential elements distribution | Other grains (lentils, beans, oats, etc.) had higher concentrations of essential elements (Ca, K, Fe, Cu, Zn) than both white and brown rice, except brown rice, which was richer in Mg and Mn. |
| Effect of washing on element concentrations | Washing white rice significantly reduced toxic elements (Pb by 57%, Cd by 46%), but also led to substantial losses of essential nutrients (Ca by 51%, Mg by 74%, K by 43%, Fe by 74%, Zn by 8%). |
Key implications
For heavy metal certification, these results show that rice, especially brown rice, poses a higher risk of arsenic exposure compared to other grains. Monitoring and enforcing Codex standards is essential, and washing rice can reduce, but not reliably eliminate, toxic metal content while also reducing essential nutrients. Certification programs should consider both origin and processing methods when setting guidelines.
Citation
TatahMentan M, Nyachoti S, Scott L, Phan N, Okwori FO, Felemban N, Godebo TR. Toxic and Essential Elements in Rice and Other Grains from the United States and Other Countries. Int J Environ Res Public Health. 2020;17(21):8128. doi:10.3390/ijerph17218128
Arsenic is a naturally occurring metalloid that ranks first on the ATSDR toxic substances list. Inorganic arsenic contaminates water, rice and consumer products, and exposure is linked to cardiovascular disease, cognitive deficits, low birth weight and cancer. HMTC’s stringent certification applies ALARA principles to protect vulnerable populations.
Lead is a neurotoxic heavy metal with no safe exposure level. It contaminates food, consumer goods and drinking water, causing cognitive deficits, birth defects and cardiovascular disease. HMTC’s rigorous lead testing applies ALARA principles to protect infants and consumers and to prepare brands for tightening regulations.
Cadmium is a persistent heavy metal that accumulates in kidneys and bones. Dietary sources include cereals, cocoa, shellfish and vegetables, while smokers and industrial workers receive higher exposures. Studies link cadmium to kidney dysfunction, bone fractures and cancer.
