Rice finding 1704
Source evidence and comparison details for the Rice profile.
Rice grain unspecified (market rice, crushed to powder before digestion) · Total mercury (tHg) · 2720 rice samples.
Selected finding and reference
2720 rice samples. Basis: unspecified (no drying or moisture correction stated).
Source substitutes LOD/2 for results below LOD (section 2.4); LOD values are not reported. Statistics include those substituted values; minima (and medians/percentiles where the detection rate is below 50%) equal the substitution value, not a measurement.
HMI baseline position
Moderate · HMI uncooked-grain tHg reference · 4 sampling families. Median as reported: 2 µg/kg. HMI median 2–2.67 (bounded); Q1 1.21–2 (bounded); Q3 1060–1080 (bounded) µg/kg. 4 families. Not a safety grade.
Low is below Q1; Moderate includes Q1 through Q3; High is above Q3. Reporting bounds must give the same category throughout.
This finding’s sampling family contributes to the fixed reference.
Sensitivity to weighting
Equal subgroup weight within each family: Moderate. The position is unchanged under this alternative. This check does not address all sampling, rounding or analytical uncertainty.
Sensitivity to source selection
- Without WHO GEMS/Food: Moderate.
- Without Ibrahim et al. 2024: Moderate.
- Without James et al. 2020: Moderate.
- Without Yan et al. (2025): Moderate.
These checks show dependence on each sampling family; they are not confidence intervals.
Collection period
2020–2022
No year-by-year sample register is reconstructed from this summary.
Geographic scope
Rural
Sampling site within one study.
Sampling, analysis and reporting limits
ICP-MS after microwave digestion of 0.3 g powder in 7 mL HNO3 (section 2.2); no arsenic speciation step described.
Source substitutes LOD/2 for results below LOD (section 2.4); LOD values are not reported. Statistics include those substituted values; minima (and medians/percentiles where the detection rate is below 50%) equal the substitution value, not a measurement.
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 |
|---|---|---|
| median | Median 0.002 | mg/kg x 1000 |
Table 3 (levels of heavy metals in rice in urban and rural areas of Henan, mg/kg), Rural rows, column Hg; page 5.
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.