Global Sourcing of Low-Inorganic Arsenic Rice Grain

Overview

This study is the largest published global market survey of arsenic speciation in polished (white) rice, analysing 1,180 samples from 29 distinct sampling zones across 6 continents. The global mean inorganic arsenic (iAs) was 66 µg/kg and the global mean dimethylarsinic acid (DMA) was 21 µg/kg. Critically, the paper identifies a pronounced regional structure: southern hemisphere South American rice (Argentina, Bolivia, Chile, Paraguay, Uruguay) was universally high in iAs (medians 60–198 µg/kg), while East African rice (Mali, Ghana region) and southern Indonesian island rice were consistently low (means below 10–20 µg/kg). This geographic pattern has direct implications for supply-chain sourcing strategies aimed at reducing consumer iAs exposure.

Key numbers

Global summary (n = 1,180 polished white rice samples):

• Global mean iAs: 66 µg/kg; global mean DMA: 21 µg/kg
• iAs range across all regions: <2 to 399 µg/kg
• DMA range: <2 to 690 µg/kg

Selected regional iAs medians (Table 1, µg/kg dry weight):

• Argentina: 45; Bolivia: 66; N. Brazil: 18; C. Brazil: 92; S. Brazil: 77
• Chile: 138; Paraguay: 198; Uruguay: 113
• Ghana: 23; Côte d’Ivoire: 13; Mali: 32
• Egypt: 52; France: 68; Italy: 92; C. Spain: 156; S. Spain: 64; Turkey: 82
• Bali: 2; China: 27; Java: 39; Malaysia: 80; S. Korea: 88; Sri Lanka: 36; N. Vietnam: 69; S. Vietnam: 70; Mexico: 91; Australia: 102

75th percentile iAs by region (selected):

• S. Brazil: 112 µg/kg; C. Spain: 211 µg/kg; Paraguay: 207 µg/kg; Chile: 189 µg/kg
• Ghana: 32 µg/kg; Mali: 40 µg/kg; Côte d’Ivoire: 20 µg/kg; Bali: 4 µg/kg

Maximum iAs observed: 399 µg/kg (S. Brazil region)

Methods (brief)

Polished (white) rice purchased from retailers in each region; freeze-dried and milled. Arsenic speciation by ICP-MS with HPLC (ORS-ICP-MS, Agilent 7500c). NIST CRM 1568b rice flour used for QC; CRM recovery 94 ± 5%. LOD for As: equivalent to 0.019 µg/g (19 µg/kg). Sample sizes per region ranged from 6 to 142.

Limitations

Sampling was market-based, not a randomised agricultural survey; geographic density varied by region. The study cannot distinguish varietal from soil/water effects within regions. Atmospheric arsenic deposition modelling (included as a covariate in Table 1) partially explains DMA variation in temperate regions but not the elevated iAs in South America.

Implications

• Certification: Strongly supports origin-based sourcing specifications. South American-origin white rice carries iAs distributions that routinely exceed 100 µg/kg (the EU ML for white rice). East African and Balinese-origin rice provides a low-iAs alternative pool. A supply-chain screening rule based on origin is evidence-based per this study.
• Courses: Key teaching case for the proposition that “rice origin matters more than processing type” for iAs. The contrast between Bali (median iAs 2 µg/kg) and Chile (median 138 µg/kg) in the same grain is striking.
• App: Supports a geographic_breakdown entry on Rice for iAs. Do not update contamination_profile directly; flag for synthesis pass.

Wiki pages updated on ingest

• Arsenic
• Rice

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