Rittirong and Saenboonruang 2018 - Metals in cooked rice and cooking utensils
Rittirong and Saenboonruang quantified aluminium and seven heavy metals in Thai cooked-rice samples prepared with different cooking utensils and water chemistries. The study found high Al and Zn relative to the other measured elements, but no strong indication that the tested utensils substantially increased metal concentrations compared with raw rice. The health-risk calculations identified Pb, As, Al, and Cd as the dominant contributors.
Key numbers
| Finding | Source-reported value |
|---|---|
| Metals | Al, Cr, Fe, Cu, Zn, As, Cd, Pb |
| Raw rice Al | 76.50 mg/kg |
| Cooked rice Al | 76.83 mg/kg |
| Raw rice Zn | 22.86 mg/kg |
| Cooked rice Zn | 22.43 mg/kg |
| Relative order | Al > Zn > Fe > Pb approximately Cu > Cr > As approximately Cd |
| Utensil conditions | New Al cooker, used Al cooker, Teflon-coated Al cooker, stainless steel cooker, glass beaker |
| Water conditions | Tap water, de-ionized water, acidic water, basic water |
| Weekly intake from 0.3 kg rice/day | Al 181.07 mg/kg-week; Pb 4.85 mg/kg-week as reported by authors |
| Source PTWI comparators for 60 kg person | Al 120 mg/kg-week; Pb 1.5 mg/kg-week |
| Hazard index | 9.18, with Pb 3.19, As 2.67, and Al 1.51 as largest contributors |
| Total cancer risk | 2.45 x 10^-2, with Pb 1.0 x 10^-2 and Cd 1.2 x 10^-2 as largest contributors |
Methods (brief)
The authors purchased three brands of white rice from a local grocery store in Thailand. Rice was cooked with five utensil types and four water conditions, dried, ground, digested with nitric acid, and analyzed by ICP-MS. The study used t-tests at p < 0.05 to compare cooked and raw rice conditions and calculated non-carcinogenic and carcinogenic risk metrics.
Arsenic is reported as total/unspecified arsenic. The basis is dried cooked-rice material after preparation, not wet ready-to-eat rice.
Implications
For rice pages, this is direct Thailand-market occurrence evidence for cooked rice. For cookware pages, the study suggests tested utensil conditions did not substantially change metal concentrations in rice relative to raw grain under the tested design.
For standards work, cooked-rice values must be kept on the study’s dried cooked-rice basis unless a later contribution log converts to as-consumed wet rice.
Wiki pages this source may touch
- rice
- rice-bulk-grain
- utensils-metal
- cookware-metal-alloy
- cookware-nonstick-coated
- aluminum
- lead
- cadmium
- arsenic-total
- chromium
Verification notes
The abstract provides the headline concentrations and risk metrics. The source does not support an inorganic arsenic claim.
Page history
The five most recent substantive edits to this page. 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 | Description |
|---|---|---|
| c1aef38 | 2026-06-02 | audit-queue: hamid2021-bacterial-plant-biostimulants-review → audited-promote |