Overview
This study measures toxic and essential element concentrations in 11 traditional Sri Lankan rice varieties from Anuradhapura district using laser ablation ICP-MS (LA-ICP-MS), which provides spatially resolved elemental analysis across the grain cross-section (bran, sub-bran, endosperm). The study is set in the context of CKDu (chronic kidney disease of unknown aetiology) in Sri Lankan agricultural communities, which has been hypothesized to involve cadmium exposure via rice consumption. Multiple traditional rice varieties with different processing states (brown, white) are assessed, including the Suwadel variety known for special cultural significance and elevated Cd accumulation.
Key numbers
- Sample size: 11 rice varieties
- Analytical method: LA-ICP-MS (laser ablation); spatially resolved measurement across grain cross-section
- Cd in Suwadel variety: 113±13 µg/kg (dry weight); notably elevated compared to other varieties tested and approaching the Codex/EU limit of 200 µg/kg for rice
- Pb distribution: predominantly in rice bran layer; markedly reduced in white (polished) rice compared to brown rice; this is consistent with Pb soil uptake concentrating in outer grain layers
- As: detected across varieties; specific values available in source tables; total As reported (iAs speciation not performed with LA-ICP-MS)
- Brown vs. white rice: brown rice retains bran; white (polished) rice has reduced Pb and Cd because these metals concentrate in the bran
- CKDu context: Anuradhapura is a CKDu-endemic region; rice is the staple crop and primary Cd exposure pathway; traditional varieties like Suwadel show higher Cd than modern improved varieties
- Spatial distribution finding: Cd more uniformly distributed across the grain (not bran-concentrated), consistent with Cd being taken up as a mineral nutrient analogue; Pb bran-concentrated, consistent with soil contamination pathway
Methods (brief)
LA-ICP-MS with imaging capability; rice grains embedded in resin and cross-sectioned; ablation performed in lines across the grain section for spatial mapping; ICP-MS quantification against NIST SRM 610 and 612 glass standards; comparison with aqueous-ICP-MS for bulk validation. No speciation for As (total As by LA-ICP-MS). LOD not explicitly stated for all analytes but LA-ICP-MS limits typically 0.1–1 µg/kg for Cd and Pb in grain.
Implications
Certification: This paper provides exact Cd data for a traditional variety (Suwadel, 113 µg/kg) approaching but below the Codex/EU 200 µg/kg limit. The spatial distribution finding (Pb bran-concentrated, Cd more uniform) is directly relevant to the processing effects section of the rice ingredient page, supporting the claim that polishing reduces Pb but not Cd proportionally.
Courses: Excellent case study for the CKDu-cadmium-rice hypothesis; demonstrates LA-ICP-MS spatial imaging as an advanced analytical technique; illustrates the processing effects of polishing on different metals.
App: Rice ingredient profile; Cd in Sri Lankan traditional varieties around 113 µg/kg; Pb reduced by polishing; As total only.
Microbiome: CKDu has been associated with gut dysbiosis; however, the direct microbiome angle is not the focus of this paper.
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Update history
The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.
| Commit | Date | Change | Description |
|---|---|---|---|
| a8052bb | 2026-08-09 | major | 6 sections added; narrative text revised |