Silva et al. 2023 — Inorganic arsenic (and mycotoxins) in 36 Portuguese rice samples
Silva et al. measured inorganic arsenic (iAs) — reported in the paper as InAs — along with mycotoxins (AFB1, OTA, ZEN) in 36 rice samples produced and commercialized in Portugal. iAs was measured by ICP-MS with LOD 3.3 µg/kg. All 36 samples had iAs above the LOD; none exceeded the EU MPL of 200 µg/kg (at the time of the study, citing EU Reg. 2015/1006 amending 1881/2006). No correlation was found between mycotoxin and iAs contamination. This paper is classified here as a food concentration source for the iAs-in-rice data.
The analytical method is reported as “ICP-MS” with a LOD of 3.3 µg/kg. The authors refer to their target analyte throughout as “inorganic arsenic” (InAs/iAs). However, without HPLC coupling, standard ICP-MS typically measures total arsenic. The abstract and text consistently use “inorganic arsenic” for the target analyte and describe the EU MPL (200 µg/kg) as an iAs limit. The LOD of 3.3 µg/kg is plausible for an ICP-MS-based speciation method. Given the authors’ explicit framing of their results as iAs, the values are recorded as iAs per the source’s own reporting, with the caveat that the speciation methodology is not fully described (no HPLC column or chromatographic conditions stated), and independent confirmation of the iAs/tAs split is not available from this paper.
Key numbers
All concentrations in µg/kg (dry weight implied; not explicitly stated in abstract). From Table 2 of the source.
| Subgroup | n | Frequency | Min | Max | Mean ± SD |
|---|---|---|---|---|---|
| Total | 36 | 100% | >LOD | 100.0 | 35.3 ± 28.2 |
| Supermarket | 14 | 100% | >LOD | 90.0 | 25.9 ± 26.9 |
| Producers (direct) | 22 | 100% | >LOD | 100.0 | 41.2 ± 28.0 |
| White label | 6 | 100% | >LOD | 23.0 | 10.5 ± 7.1 |
| Private brand | 8 | 100% | >LOD | 90.0 | 37.5 ± 30.9 |
| Long grain | 16 | 100% | >LOD | 90.0 | 26.9 ± 26.1 |
| Short grain | 20 | 100% | >LOD | 100.0 | 41.9 ± 28.6 |
| Brown rice | 14 | 100% | 23.0 | 100.0 | 55.1 ± 27.7 |
| White rice | 22 | 100% | >LOD | 80.0 | 22.6 ± 20.5 |
| Portugal origin | 27 | 100% | >LOD | 100.0 | 38.3 ± 26.1 |
| Abroad origin | 9 | 100% | >LOD | 90.0 | 26.1 ± 33.9 |
LOD: 3.3 µg/kg. EU MPL for iAs in non-parboiled milled rice: 200 µg/kg (EU Reg. 2015/1006). All 36 samples compliant. Brown rice mean (55.1 µg/kg) significantly higher than white rice (22.6 µg/kg), p < 0.0001.
Methods (brief)
ICP-MS; LOD 3.3 µg/kg. Analytical details (instrument model, extraction conditions, speciation column) not fully reported in the available text. Authors consistently describe the analyte as inorganic arsenic (InAs) throughout. The EU MPL they reference (200 µg/kg) is the iAs limit for non-parboiled rice; the authors’ framing is internally consistent with iAs measurement but speciation methodology details are not fully disclosed in the abstract or introduction sections available.
Implications
Certification: Portuguese market rice shows iAs (per authors’ reporting) up to 100 µg/kg, mean 35.3 µg/kg across 36 samples; none exceeded the EU MPL of 200 µg/kg. Brown rice had substantially higher values (mean 55.1 µg/kg) than white rice (mean 22.6 µg/kg).
Courses: Illustrates brown vs white rice iAs differential in a European market; rice from direct producers tended to be more contaminated than supermarket samples, possibly reflecting less post-harvest processing/blending.
App: Portuguese rice (n=36): iAs max 100 µg/kg; mean 35.3 µg/kg (all types); brown rice mean 55.1 µg/kg; white rice mean 22.6 µg/kg. All below EU MPL 200 µg/kg.