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. 
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 global variation in inorganic arsenic and dimethylarsinic acid (DMA) concentrations in polished (white) rice, focusing on their implications for dietary exposure and regulatory compliance. The study systematically analyzed 1,180 rice samples collected from 29 major rice-producing regions spanning six continents. The researchers aimed to identify regions that produce rice with low inorganic arsenic content, as inorganic arsenic is a recognized carcinogen and a primary concern for food safety standards, particularly in products intended for infants and young children. The analysis included arsenic speciation (distinguishing inorganic arsenic from DMA), and compared the findings to existing maximum levels (MLs) set by the World Health Organization (WHO) and the European Union (EU). The study also sought to clarify geographical patterns and to determine whether environmental, agronomic, or geological factors correlated with arsenic content in rice grain.
Who was studied?
The study encompassed rice grains rather than human or animal subjects. Specifically, it focused on 1,180 samples of polished, locally produced, market rice purchased from retailers and supermarkets across 29 geographically distinct rice-growing regions. The regions represented included areas in South America, Africa (East and West), the Mediterranean, Asia (including China, Indonesia, Sri Lanka, Vietnam, and others), North America, and Australasia. Sampling density varied by region, and the rice was sourced as close to typical consumer products as possible, reflecting actual dietary exposure. The rice samples were chosen to represent the diversity of global rice production environments, including differences in latitude, climate, cultivation methods, and potential environmental exposures.
Most important findings
| Critical Points | Details |
|---|---|
| Only southern hemisphere, eastern hemisphere regions (East Africa, Southern Indonesian islands) had low-grain inorganic arsenic | East African rice (Malawi, Tanzania) had median inorganic arsenic concentrations of 5 and 9 µg/kg, respectively. Southern Indonesian islands such as Bali and Java also showed low concentrations (median 13 and 35 µg/kg). These levels are far below the global median and regulatory thresholds. |
| South American rice is universally high in inorganic arsenic | All surveyed regions in South America exhibited high inorganic arsenic in rice, with little geographical variation. This trend contrasts starkly with patterns observed in Africa and Asia, and the underlying cause warrants further investigation. |
| Inorganic arsenic dominated at low total arsenic; DMA dominated at higher totals | When the sum of inorganic arsenic and DMA in rice was low, inorganic arsenic was the dominant form. At higher total arsenic levels, DMA became the prevailing species, particularly in temperate and some Mediterranean regions. |
| DMA concentrations highly variable by region | DMA median was 21 µg/kg globally, but ranged from <2 to 690 µg kg. temperate regions tended have higher dma, while tropical southern hemisphere (east africa, indonesia) had very low dma. sri lankan rice was an exception, exhibiting dma but moderate inorganic arsenic.< td> |
| Regulatory compliance: very few samples exceeded adult ML, many exceeded infant ML | Only 0.4% of samples exceeded the 200 µg/kg ML for inorganic arsenic (EU/WHO adult standard), but 17.6% exceeded the stricter 100 µg/kg standard for infant food, indicating a significant proportion of global rice supply is unsuitable for infant products under EU regulations. |
| Environmental and agronomic factors implicated in arsenic variation | East African rice is likely low in arsenic due to a combination of natural geology, rain-fed low-input cultivation, and limited irrigation with contaminated water. Conversely, American paddy systems and management practices may contribute to higher arsenic and DMA levels. |
Key implications
The findings highlight the critical importance of geographical sourcing for heavy metal certification programs, as only specific regions such as East Africa and Southern Indonesia consistently produce rice with low inorganic arsenic, suitable for sensitive groups like infants. Certification schemes should prioritize traceability and enforce stricter controls, especially when sourcing rice for vulnerable populations.
Citation
Carey M, Meharg C, Williams P, Marwa E, Jiujin X, Gomes Farias J, De Silva PMCS, Signes-Pastor A, Lu Y, Nicoloso FT, Savage L, Campbell K, Elliott C, Adomako E, Green AJ, Moreno-Jiménez E, Carbonell-Barrachina AA, Triwardhani EA, Pandiangan FI, Haris PI, Lawgali YF, Sommella A, Pigna M, Brabet C, Montet D, Njira K, Watts MJ, Meharg AA. Global Sourcing of Low-Inorganic Arsenic Rice Grain. Exposure and Health. 2020;12:711–719. doi:10.1007/s12403-019-00330-y
