Shirani et al. 2017 — Cd, Pb and tAs in 120 Iranian-, Indian- and Pakistani-origin rice samples on the Mashhad retail market

This Mashhad market-survey paper reports total concentrations of cadmium, lead and arsenic (the latter measured by hydride-generation AAS on the wet-ashed extract, treated here as total arsenic in the absence of any inorganic-species separation step) in 120 packed rice samples collected from local agricultural agencies and retail markets in Mashhad. Samples were split into four producer-origin groups of n=30 each: two domestic Iranian categories (Mazandaran and Gilan provinces — together accounting for >80% of Iranian rice cultivation per the paper) and two imported categories (Pakistani and Indian). Across the full panel the Cd concentrations ranged 0.001-0.156 mg/kg (mean 0.064 ± 0.001 mg/kg), the Pb concentrations ranged 0.108-0.234 mg/kg (mean 0.153 ± 0.001 mg/kg), and the As concentrations ranged 0.039-0.378 mg/kg (mean 0.129 ± 0.017 mg/kg). The paper reports significant differences between Iranian- and imported-origin rice for all three metals but no significant difference between Mazandaran and Gilan or between Pakistani and Indian (one-way ANOVA, Tukey post-test, p<0.05). Estimated daily intakes for the population-weighted “mean rice” via Equation 1 (EF 365 d/y, ED 70 y, FIR 100 g/person/day, WAB 70 kg) were 0.217 µg/kg bw/day for Pb, 0.183 µg/kg bw/day for As, and 0.090 µg/kg bw/day for Cd. Target hazard quotients (THQ = EDI × 7 / PTWI) were below 1 for every metal in every origin group; the hazard index HI summed across the three metals was 0.331 for the population-weighted mean. The paper concludes there is no aggregate health risk from rice-borne Pb, As and Cd at the modelled consumption rate, while noting that 96.66% of the 120 samples exceeded the Iranian national lead ceiling and 58.33% exceeded the Iranian arsenic ceiling (all four origin-group mean Cd concentrations also exceeded the Iranian Cd ceiling). The compliance contrast against FAO/WHO is much milder.

Key numbers

Panel-wide ranges and means (Results §3, p. 251-252; values in mg/kg):

Per-origin mean ± SD concentrations (Results §3, pp. 251-252; values in mg/kg). The Pb and As per-origin means for Gilan and Pakistani groups are reported only via Figures 2 and 3 (bar-chart axis labels, no in-text numeric values); the Mazandaran and Indian values are the in-text published per-origin extremes and are reproduced exactly. The Gilan and Pakistani Pb and As values are read from the bar charts and reported here as approximate (≈) with the per-group SD bars matching the in-text per-origin precision style:

Regulatory ceilings cited by the paper for direct mean-vs-ceiling comparison (Results §3, pp. 251-252; both authorities cited via INSO 2013 and FAO/WHO 2004):

Sample exceedance against the Iranian ceiling (Results §3, pp. 251-252):

• Cd: all four origin-group means (0.052, 0.043, 0.082, 0.081 mg/kg) exceeded the 0.04 mg/kg INSO Cd ceiling.
• Pb: 96.66% of the 120 samples (116 / 120) exceeded the 0.12 mg/kg INSO Pb ceiling, while the panel mean (0.153 mg/kg) was below the 0.20 mg/kg FAO/WHO Pb ceiling.
• tAs: 58.33% of the 120 samples (70 / 120) exceeded the 0.12 mg/kg INSO As ceiling and 15% (18 / 120) exceeded the 0.20 mg/kg FAO/WHO As ceiling.

Estimated daily intake (EDI, µg/kg bw/day) per origin group (Table 1, p. 253; computed with EF 365 d/y, ED 70 y, FIR 100 g/person/day, WAB 70 kg, TA 365 × 70):

Target hazard quotient (THQ, dimensionless; THQ = EDI × 7 / PTWI) per origin group (Table 2, p. 253; PTWIs: Cd 7 µg/kg bw/week, Pb 25 µg/kg bw/week, As 15 µg/kg bw/week per Bilandžić et al. 2011):

Hazard index (HI = ΣTHQ across Pb, Cd, As) for the population-weighted mean rice: 0.331 (Conclusions §4, p. 253). The published HI exceeds the simple arithmetic sum of the Table 2 mean-row THQs (0.060 + 0.091 + 0.084 = 0.235); the discrepancy is unexplained in the paper and is flagged in Verification notes.

Exposure-assessment parameters used in EDI / THQ / HI computation (paper §2.4, pp. 250-251):

Method validation parameters (paper §2.3, p. 250):

Calibration linearity (paper §2.3, p. 250): Cd R² = 0.998 (standards 5, 10, 15, 20 mg/kg); Pb R² = 0.995 (standards 5, 10, 15, 20 mg/kg); As R² = 0.998 (standards 1, 5, 15, 20 mg/kg). The paper does not publish recovery percentages, certified-reference-material results, or measurement-uncertainty values; a “standard plant sample” and reagent blanks are mentioned as quality-assurance controls but their results are not tabulated.

Methods (brief)

Sample collection. 120 packed rice samples were collected from local agricultural agencies and retail markets in Mashhad, the second-most-populous city of Iran. Samples were grouped by producer origin into four categories of n=30: Mazandaran-province domestic rice, Gilan-province domestic rice, Pakistani-origin imported rice, and Indian-origin imported rice. Manufacturer identities were coded and analytical work was conducted by an examiner blind to the producers.

Sample preparation. Dry-ashing for Cd and Pb: 5 g of each sample dried at 80 °C for 2 h, then 105 °C for 6 h; preliminary burning on a hotplate; ashing in oven at 550 °C for 10 h with an initial 200 °C ramp at 50 °C/h. Ash moisturised with distilled water, evaporated to dryness over a water bath, residue dissolved in 10 mL HNO₃ and made up to 100 mL with deionised water (per Morekian et al. 2013 protocol). Wet-ashing for As: 30 mL concentrated HNO₃ added, kept at room temperature for 24 h, heated on hotplate to boiling and simmered to a transparent 3 mL extract, filtered through Whatman filter paper and brought to 100 mL with deionised water (per Morekian et al. 2013 protocol).

Instrumentation. Atomic absorption spectrophotometry on a Varian model AA-1275 (Varian Medical Systems, Inc., Palo Alto, CA, USA). Pb and Cd determined by graphite-furnace AAS with auto-sampler at furnace temperatures of 1,800 °C (Pb) and 2,100 °C (Cd). As determined by hydride-generation AAS on the wet-ashed extracts using the same Varian AA-1275 platform fitted with a hydride generation system. Three replicates per sample. Reagent blanks and a “standard plant sample” run alongside; recovery and CRM values not published.

Speciation. Total As (hydride-generation AAS measures the total arsenic that can be reduced to AsH₃ under the digestion-and-hydride-formation conditions used; no As-species separation step is described). The wiki page accordingly uses tAs rather than iAs per CLAUDE.md Part 14. No Hg panel, no Cr or Cr-VI panel, no Ni panel.

Statistical analysis. SPSS v13.0 (SPSS Inc., Chicago, IL, USA). Mean ± SD by descriptive statistics. One-way ANOVA with Tukey post-test for per-province comparisons. Significance threshold p < 0.05.

Risk assessment. EDI (µg/kg bw/day) per Equation 1: EDI = (EF × ED × FIR × C) / (WAB × TA), with EF 365 d/y, ED 70 y, FIR 100 g/person/day, C = metal concentration in rice (µg/g, equivalent to mg/kg), WAB 70 kg, TA = 365 × ED days. THQ (dimensionless) per Equation 2: THQ = EDI × 7 / PTWI, with the JECFA PTWIs cited via Bilandžić et al. 2011 (Cd 7, Pb 25, As 15 µg/kg bw/week). HI per Equation 3: HI = ΣTHQ across the three metals. Per Lemly 1996, HI ≤ 1.0 indicates no significant health hazard; 1.1-10 moderate hazard; >10 high hazard.

Implications

This source contributes Iranian retail-market occurrence data for Cd, Pb and total As in 120 packed rice samples (30 each of Mazandaran-domestic, Gilan-domestic, Pakistani-imported, Indian-imported) on the Mashhad market in the mid-2010s, plus a deterministic THQ / HI risk assessment under a generic 70 kg / 100 g/day Iranian-population assumption. Principal contributions to the wiki evidence pool:

• A four-origin contrast within a single Iranian retail city: Mazandaran-domestic rice carries the lowest mean concentrations for Cd (0.052 mg/kg), Pb (0.134 mg/kg) and tAs (0.093 mg/kg); Indian-imported rice carries the highest mean concentrations for Pb (0.171 mg/kg) and tAs (0.188 mg/kg); Pakistani-imported rice carries the highest mean concentration for Cd (0.082 mg/kg) by a narrow margin over Indian (0.081 mg/kg). The Iranian-vs-imported contrast is statistically significant for all three metals (one-way ANOVA p<0.05); the within-country contrasts (Mazandaran vs Gilan, Pakistani vs Indian) are not significant.
• A 100%-origin-mean-exceedance signal for Cd against the Iranian ceiling: all four origin-group means (0.043-0.082 mg/kg) exceed the INSO 0.04 mg/kg Cd cereal ceiling, although none exceed the FAO/WHO 0.10 mg/kg Cd ceiling. This pattern (per-origin mean Cd above the Iranian standard but below the FAO/WHO standard) is consistent with the broader pattern in Iranian-market rice work (cf. sharafi2019-iran-tehran-rice-brands-metals on the Tehran market 2018, roya2016-iran-torbat-heidarieh-rice-metals on the Torbat-Heidarieh market 2015, pirsaheb2015-iran-kermanshah-cereals-metals on the Kermanshah market 2014).
• A 96.66% sample-level Pb-exceedance signal against the Iranian ceiling: 116 of 120 samples exceeded the 0.12 mg/kg INSO Pb cereal ceiling, while the panel mean Pb concentration (0.153 mg/kg) was below the 0.20 mg/kg FAO/WHO ceiling. This is the same divergence pattern between the tighter Iranian ceiling and the looser FAO/WHO ceiling that the abovementioned Iranian-market rice papers report.
• A 58.33% sample-level As-exceedance against the Iranian ceiling and a 15% sample-level As-exceedance against the FAO/WHO ceiling: 70 of 120 samples exceeded the 0.12 mg/kg INSO As cereal ceiling, and 18 of 120 exceeded the 0.20 mg/kg FAO/WHO As ceiling. Indian-imported rice (mean 0.188 ± 0.032 mg/kg) carried the highest As contamination among the four origin groups.
• A deterministic HI / THQ risk-assessment outcome of “no aggregate non-carcinogenic risk” (population-weighted-mean HI 0.331, all individual-origin THQs below 1.0 for every metal), under the paper’s chosen 100 g/day rice ingestion rate, 70 kg adult body weight, and JECFA PTWIs (Cd 7, Pb 25, As 15 µg/kg bw/week). Notable assumption: the 100 g/day FIR is materially lower than the 165 g/day FIR used by sharafi2019-iran-tehran-rice-brands-metals for the Tehran population from ISIRI 12968; the present paper’s HI would scale roughly linearly with FIR and would push toward 0.5 under the Sharafi-style 165 g/day assumption.
• A paper-internal HI-vs-sum-of-THQs anomaly (published HI 0.331; sum of mean-row THQs in Table 2 is 0.235). The wiki Key numbers section reports both values and flags the discrepancy in Verification notes; it does not propagate the published HI as authoritative when the underlying per-metal THQ sum is auditable. No carcinogenic-risk (ILCR) computation is published; the paper restricts its risk framing to non-carcinogenic HI / THQ.
• A small-to-medium-panel (n = 30 samples per origin group, n = 120 total, triplicate measurements per sample), single-city, single-time-period (sampling year not stated; bounded to roughly 2014-2015 by the December-2015 receipt date), single-cohort (generic 70 kg adult / 100 g/day) sampling footprint with no As-species separation, no Hg panel, no Cr or Cr-VI panel, no Ni panel, no recovery / CRM / measurement-uncertainty validation data published, and the per-origin Pb and As values for the Gilan and Pakistani groups available only via Figures 2 and 3 (numeric values not given in the prose). The B-tier classification reflects these limitations; the source should pool with other Iranian-market rice work for occurrence-distribution purposes.

Wiki pages this source may touch

• arsenic-total
• cadmium
• lead
• rice
• rice-bulk-grain

Verification notes

• Identity checks (three-way) clean. DOI grep (10.3920/QAS2015.0667) returned no existing wiki/sources page; raw-handle grep (MFK_shirani2017) returned no existing page; cite-key glob (shirani*) returned no existing page. The page is a fresh NEW-path ingest.
• Frontmatter discipline. All ingredient, product, metal, matrix, and jurisdiction slugs verified against the 2026-05-18 taxonomy snapshot (docs/gpt-collaboration/taxonomy-snapshot.md). Metals use the Part 14 abbreviation vocabulary (tAs, Cd, Pb). Jurisdictions: IR is the sampling-and-consumption jurisdiction; IN (India) and PK (Pakistan) are the origin countries of two of the four sample categories. The matrix slug rice-grain matches the precedent set by sharafi2019-iran-tehran-rice-brands-metals and roya2016-iran-torbat-heidarieh-rice-metals.
• Speciation discipline (Part 14, locked). Hydride-generation AAS following wet-ashing with HNO₃ measures the total arsenic that can be reduced to AsH₃ under the digestion-and-hydride conditions used; the paper describes no As-species separation step (no iAs / DMA / MMA distinction). The metals: field uses tAs (total arsenic), not iAs. The paper does not compute carcinogenic risk (no ILCR / CSF-application step), so the iAs-vs-tAs distinction does not propagate into a misapplication of the inorganic-arsenic CSF in this paper (contrast with sharafi2019-iran-tehran-rice-brands-metals where it does). No mercury panel, no Cr or Cr-VI panel, no Ni panel.
• Brand firewall (Part 12). The paper explicitly codes manufacturer identities and conducts the analysis blind to producer (Methods §2.1, p. 250: “manufacturers were defined with code and the research was done by an examiner blind to the producers”). No brand names appear in the source text and none appear on this wiki page. Scientific-method vendor identifiers retained per Part 12 Exception 2 (Varian model AA-1275 instrument, Varian Medical Systems Palo Alto location, Whatman filter paper, SPSS v13.0 software).
• Wiki/HMTc firewall (Part 2). No threshold proposals, no consumer-audience advisories. Cross-paper comparisons in the Implications section are limited to descriptive band-placement against three other Iranian-market rice papers (sharafi2019-iran-tehran-rice-brands-metals, roya2016-iran-torbat-heidarieh-rice-metals, pirsaheb2015-iran-kermanshah-cereals-metals) and a methodological FIR-assumption contrast. Full cross-paper synthesis (e.g., updating the rice contamination_profile block) is the Part 9 workflow’s job and is not done in this ingest pass.
• HI-vs-sum-of-THQs internal inconsistency. The paper reports HI = 0.331 in the Conclusions (p. 253) and Abstract (p. 249) but Table 2 (p. 253) publishes per-origin and mean-row THQ values that sum to 0.235 across the three metals on the mean row (0.060 Pb + 0.091 Cd + 0.084 As). The per-origin sums are: Mazandaran 0.186, Gilan 0.182, Pakistani 0.304, Indian 0.269; the highest per-origin sum (Pakistani 0.304) is close to but does not match the published HI of 0.331. The paper does not explain the discrepancy. Two plausible reconciliations: (i) HI is a weighted mean across origins using per-country consumption-share weights that the paper does not publish for Mashhad specifically; (ii) HI was computed at an earlier draft using slightly different EDI values or a different FIR. The wiki Key numbers section reports the Table 2 row values verbatim and the published HI separately, with this caveat.
• Per-origin Pb and As means for Gilan and Pakistani groups. The Results §3 prose publishes only the Mazandaran (lowest-Pb 0.134 ± 0.008) and Indian (highest-Pb 0.171 ± 0.009) Pb means, and the Mazandaran (lowest-As 0.093 ± 0.009) and Indian (highest-As 0.188 ± 0.032) As means. The Gilan and Pakistani Pb and As values are available only via the bar-chart labels in Figures 2 and 3 (concentration in mg/kg on the y-axis, no numeric data label on each bar in the published figures). The wiki Key numbers per-origin table reports the in-text Mazandaran and Indian values exactly, and reports the Gilan and Pakistani values approximately as read from the figures (Gilan Pb ≈0.142, Pakistani Pb ≈0.165, Gilan As ≈0.102, Pakistani As ≈0.137) with an explicit ≈ prefix and a “Fig. 2” / “Fig. 3” citation in the cell. The per-origin Cd means are all four published in-text (Mazandaran 0.052 ± 0.009, Gilan 0.043 ± 0.006, Pakistani 0.082 ± 0.006, Indian 0.081 ± 0.009) and are reproduced exactly.
• Sample-exceedance percentages: derived counts. The paper reports the percentages in Results §3 (96.66% for Pb against INSO; 58.33% for As against INSO; 15% for As against FAO/WHO). The Cd “100% of origin-group means exceed INSO 0.04 mg/kg” statement is a wiki-side reading of the four origin-group means against the INSO ceiling; the paper publishes the comparison qualitatively (“the survey results showed that the mean concentrations of cadmium in Mazandaran (0.052 ± 0.009 mg/kg), Gilan (0.043 ± 0.006 mg/kg), Pakistanis (0.082 ± 0.006 mg/kg) and Indian (0.081 ± 0.009 mg/kg) rice are higher than the maximum allowed set by INSO but under the FAO/WHO”). The Cd individual-sample exceedance percentages against the two ceilings are not published.
• Abstract-vs-text EDI rounding inconsistency. The Abstract (p. 249) states the EDIs for Pb, As and Cd are “0.217, 0.183 and 0.090 µg/kg bw/day, respectively.” Table 1 (p. 253) gives mean-row values of 0.216 (Pb), 0.184 (As) and 0.091 (Cd) µg/kg bw/day. The differences are within rounding (third decimal place) and do not affect the THQ / HI computation. The wiki Key numbers table uses the Table 1 values.
• Sampling-year not stated. The paper does not publish the calendar year of the sample collection; the manuscript receipt date (20 December 2015) bounds the sampling no later than late 2015. The frontmatter sampling_year_range field accordingly says “not stated (manuscript received 20 December 2015 and accepted 9 December 2016, bounding the sampling to roughly 2014-2015).”
• Data-integrity transcription notes. Panel-wide ranges and means transcribed from Results §3 Cd subsection (p. 251), Pb subsection (p. 252), and As subsection (p. 252). Per-origin Cd values transcribed from Results §3 Cd subsection (p. 251). Per-origin Mazandaran-and-Indian Pb and As values transcribed from Results §3 Pb subsection (p. 252) and As subsection (p. 252). Per-origin Gilan and Pakistani Pb and As values read approximately from Figures 2 and 3 (p. 252) — see prior note. EDI values transcribed from Table 1 (p. 253). THQ values transcribed from Table 2 (p. 253). HI value transcribed from Conclusions §4 (p. 253) and matched against the abstract claim of 0.331. Exposure-parameter values transcribed from Methods §2.4 (pp. 250-251). LOD values transcribed from Methods §2.3 (p. 250). Regulatory-ceiling values transcribed from Results §3 (pp. 251-252) and cross-referenced against INSO 2013 and FAO/WHO 2004 citations in the references list (p. 254). No paper-internal contradictions beyond those flagged above were identified.
• Basis. The paper does not state explicitly whether the published concentrations are on a wet-weight or dry-weight basis, but the dry-ashing protocol (samples dried at 80 °C for 2 h then 105 °C for 6 h before ashing) effectively removes the free water and ash-trapped values are referenced back to the original “5 g of each sample” weight. The “5 g of each sample” weighing step is described after the drying step in the Methods §2.2 dry-ashing paragraph, indicating that the 5 g is the dry weight; values are therefore on a dry-weight basis. The wiki Key numbers tables label the values in mg/kg without an explicit dw suffix because the paper itself does not make the basis explicit; downstream pooling work that needs the basis explicit should treat the values as dry-weight per this transcription note. The Iranian and FAO/WHO cereal ceilings cited (0.04-0.20 mg/kg) are not basis-labelled in either standard but are conventionally interpreted on the as-marketed packed-rice basis (low moisture, effectively dry); the discrepancy between the paper’s dry-weight measurements and the ceilings’ as-marketed reference frame is small for polished packed rice and is not flagged by the paper.

Page history

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