Rice finding 1634
Source evidence and comparison details for the Rice profile.
Rice grain (form not stated; national standard 'rice' category, sampled as sold, edible portion crushed) · Total mercury (tHg) · 290 rice samples (295 Pb, 296 Cd, 290 As, 290 Hg).
Selected finding and reference
290 rice samples (295 Pb, 296 Cd, 290 As, 290 Hg). Basis: unspecified (as sold; samples cleaned of debris and crushed, no drying step stated).
lower bound: results <LOD set to zero; detection rate 20%. LOD values not reported.
HMI baseline position
Limited data · HMI uncooked-grain tHg reference · 4 sampling families. Mean as reported: 1.8 µg/kg. HMI median 2–2.67 (bounded); Q1 1.21–2 (bounded); Q3 1060–1080 (bounded) µg/kg. 4 families. Reporting bounds prevent a rating.
Reporting bounds or insufficient reference spread prevent a stable Low / Moderate / High classification.
This is an external comparison; the finding does not set the reference.
Sensitivity to weighting
Equal subgroup weight within each family: Limited data. The position remains unresolved under this alternative. This check does not address all sampling, rounding or analytical uncertainty.
Sensitivity to source selection
- Without WHO GEMS/Food: Low.
- Without Ibrahim et al. 2024: Limited data.
- Without James et al. 2020: Limited data.
- Without Yan et al. (2025): Limited data.
These checks show dependence on each sampling family; they are not confidence intervals.
Collection period
2017–2021
No year-by-year sample register is reconstructed from this summary.
Geographic scope
1a. Rice (LB)
All samples in the study.
Sampling, analysis and reporting limits
Microwave HNO3 digestion per GB 5009.11/12/15/17/123/268; AAS, AFS or ICP-MS at regional CDC laboratories.
lower bound: results <LOD set to zero; detection rate 20%. LOD values not reported.
Shared samples and study overlap
Subgroup rows, statistics of the same subgroup and the study total share samples; they are not independent results.
Each table row describes a food/analyte result. Repeated rows do not add independent samples or datasets. No cross-study trend is calculated in this comparison mode.
Reported values, conversion and source locator
| Source statistic | Original result | Displayed unit conversion |
|---|---|---|
| mean | 1a. Rice | Hg Number of samples 290 | >LOD (%) 20 | LB 0.0018 | mg/kg x 1000 |
Table 2 (lower, median and upper bound of mean concentrations), row '1a. Rice', p.8.
No moisture, cooking-yield or species conversion is applied to the original finding above. Any basis conversion used for its HMI comparison is stated separately with the numerical target.
Open the primary publication · HMI source record
Reference and scope
HMI uncooked-grain tHg reference · 4 sampling families. Uncooked grain as analysed (native or unstated moisture), µg/kg. Distribution of subgroup median concentration values.
| Reference (µg/kg) | Q1 | Median | Q3 |
|---|---|---|---|
| Primary HMI reference | 1.21–2 (bounded) | 2–2.67 (bounded) | 1060–1080 (bounded) |
| Alternative weighting | 1.21–2 (bounded) | 2–2.67 (bounded) | 1060–1080 (bounded) |
36 reference units; 4 sampling families. Counts describe evidence units, not independent studies or certainty.
| Contributing family | Reference units | Weight |
|---|---|---|
| WHO GEMS/Food | 22 | 25% |
| Ibrahim et al. 2024 | 1 | 25% |
| James et al. 2020 | 6 | 25% |
| Yan et al. (2025) | 7 | 25% |
Methods
HMI pools subgroup medians from every compatible rice sampling family in the evidence ledger for this analyte, material and basis: published subgroup medians, medians HMI calculates from printed per-sample values and WHO GEMS/Food region-by-year medians (random sampling only). Each family has equal total weight; subgroups have equal weight within a family. Non-detects stay as zero-to-limit intervals, so quartiles carry lower and upper bounds. Means, ranges and maxima never enter as observations. Dry-weight, native-moisture and cooked results are kept in separate references; no moisture conversion is assumed.
Inverse weighted empirical CDF; midpoint at exact cumulative-weight boundaries. At least four reference units and a definitely positive Q1–Q3 spread are required. This is a display eligibility rule, not statistical validation.
Limitations
An evidence-library reference, not a probability sample of the world rice market. Sampling families differ in frame (retail, farm, contaminated sites, monitoring) and period; GEMS/Food regions are reporting regions, not growing origins. Many submissions are non-detects with differing limits, which widens the bounds. A position is descriptive concentration, not a safety or compliance judgment.
Admitted source families
Reference version and interpretation
Frozen evidence selection: 2026-10-22. Method: hmi-pooled-reference-v2.
hmi-pooled-reference-v2:rice-native-tHg:2ef21fc64a06
The reference is computed by HMI from admitted evidence, not copied from a study baseline. It describes the evidence currently in this scope; it is not a worldwide or current-lot benchmark. Source, year and region filters do not change it. Different HMI scopes are not one common ranking.