Sharafati Chaleshtori, Rafieian Kopaei & Sharafati Chaleshtori 2016 — Systematic review of Cd, As, Pb, Cr, Co, Ni, and Hg in Iranian rice (2005-2016)

This review article aggregates 28 prior studies (25 full-text plus 3 abstracts) published 2005-2016 on heavy metal contamination of rice (Oryza sativa) cultivated in or imported into Iran, drawn from Iranian and international databases (Magiran, Iran Medex, Irandoc, SID, Google Scholar, Scopus, ISI Web of Knowledge, Cochrane CDSR, PubMed). The authors tabulate province-level means and ranges for cadmium, arsenic, lead, chromium, cobalt, nickel, and mercury reported across the assembled corpus (Table 1) and compute a single Iran-wide estimated weekly intake (EWI) per metal for a 60 kg adult under a 165 g/day average per-capita rice consumption assumption (Table 2). The headline finding: averaged across the assembled corpus, weekly intakes of Cd, As, Pb, Cr, Co, and Ni from rice fall below their respective WHO/FAO provisional tolerable weekly intake ceilings, but the average weekly intake of mercury (9.68 µg/kg body weight per week) exceeds the 4 µg/kg bw/week PTWI by approximately 2.4×. The review also reports that in 14 of 23 Cd-reporting studies and 16 of 22 Pb-reporting studies, province-level mean concentrations exceeded the Iranian national standards (ISIRI 12968: 0.06 µg/g Cd, 0.15 µg/g Pb, 0.15 µg/g As).

Key numbers

Search and inclusion (Figure 1, p. 2):

Iranian national reference standards cited by the review (attributed to ISIRI 12968, 1st ed., 2010):

WHO/FAO provisional tolerable weekly intake (PTWI) reference values used by the review for the risk assessment (µg/kg body weight per week):

Province-level minimum-maximum concentrations across the 28-study corpus (Table 1, p. 3; µg/g on dry-weight basis where reported; “not detected” preserved as published; ranges represent the spread of per-study mean values across the assembled corpus, not within-study variability):

Exceedance counts versus Iranian national standards (review prose, pp. 2-4):

Iran-wide estimated weekly intake (EWI) for a 60 kg adult, computed from per-capita rice consumption (Table 2, p. 4; µg/kg body weight per week; consumption range 158-178 g/day with 165 g/day average per ISIRI 2010):

Hg PTWI exceedance is the review’s headline finding: the Iran-wide average weekly intake of mercury from rice (9.68 µg/kg bw/week) is approximately 2.4× the WHO/FAO total-mercury PTWI of 4 µg/kg bw/week.

Methods (brief)

This is a systematic review of the published literature rather than an original measurement study. The methods section describes only the search-and-inclusion procedure; per-study analytical methodology is reported in each constituent study and not re-described here.

Database search. The authors searched both local Iranian databases (Magiran, Iran Medex, Irandoc, SID) and international databases (Google Scholar, Scopus, ISI Web of Knowledge, Cochrane Database of Systematic Reviews, PubMed). Search terms included “Iran,” “heavy metals,” “pollutant,” “toxic element,” “arsenic,” “cadmium,” “mercury,” “lead,” “cobalt,” “nickel,” “chromium,” and “rice.” The search was limited to manuscripts published between 2005 and 2016.

Inclusion criteria. Manuscripts were selected from the studies aimed to cover the presence and levels of heavy metals in rice, screening on title and/or abstract. Of 342 distinct references identified, 314 were excluded at first screening for (a) inappropriate title/abstract, (b) non-original data, or (c) non-Iran geographic scope. The remaining 28 were retained: 25 sought as full-text and 3 retained as abstracts only.

Aggregated analytical methods (from the constituent studies, as the review describes). The 28 constituent studies collectively used atomic absorption spectrometer, mercury analyzer, and inductively coupled plasma optical emission spectrometer (ICP-OES) instruments for quantitation, with acid digestion for sample preparation. Per-study analytical method, sample preparation, and quality control details are reported in the constituent papers (Table 1 references) and not re-aggregated by the review.

Estimated weekly intake (EWI) calculation. The review applies a single EWI formula across the corpus:

EWI = C × FIR_w / BW

where C is heavy metal concentration in rice (µg/g), FIR_w is the average weekly intake rate of rice (g/person/week), and BW is the average body weight (set to 60 kg for an Iranian adult). The FIR_w value is derived from per-capita daily rice consumption in Iran ranging 158-178 g/person/day with an average of 165 g/person/day, per ISIRI 2010 — yielding FIR_w ≈ 1,155 g/person/week at the average. The review compares the computed EWI values against the WHO/FAO PTWI references.

Implications

This source is a systematic literature review that aggregates province-level Iranian rice contamination data from 28 prior studies spanning 2005-2016. It does not contribute original measurements to the wiki evidence pool; it contributes a meta-level characterisation of the Iranian rice contamination corpus and a single Iran-wide EWI estimate per metal. Principal contributions:

• Mercury PTWI exceedance signal. The review’s central numerical finding is that the Iran-wide average weekly intake of mercury from rice (9.68 µg/kg bw/week, computed from an average rice Hg content of 0.503 µg/g across the corpus and 165 g/day per-capita rice consumption) exceeds the WHO/FAO total-mercury PTWI of 4 µg/kg bw/week by approximately 2.4×. This is the only PTWI exceedance reported in the aggregated EWI table; all other metals’ average-rice-content-based EWI values fall below their respective PTWI ceilings. The Hg signal is driven by high-mercury rice samples from northern Iranian provinces (Gillan, Mazandaran/Feridonkenar) per Farsani et al. 2014 and Rezaitabar et al. 2015 (review references).
• Pb headroom-only-on-average signal. Iran-wide average rice Pb content (1.158 µg/g) yields an EWI of 22.9 µg/kg bw/week, just under the 25 µg/kg bw/week PTWI ceiling. The per-study maximum rice Pb content reported in the corpus (11.5 µg/g, Zahedan, Mobaraki & Safarzai 2013 per review reference; with one citation of 35 µg/g in Mazandaran per Farsani et al. 2014) yields an upper-bound EWI of 238.81 µg/kg bw/week — nearly 10× the PTWI. The mean is below PTWI; the tail substantially exceeds it.
• Cd corpus-wide exceedance of Iranian standard. 14 of 23 Cd-reporting studies in the corpus reported province-level mean concentrations above the Iranian standard of 0.06 µg/g, though the Iran-wide average-rice-content EWI (3.311 µg/kg bw/week) remained below the WHO/FAO Cd PTWI of 7 µg/kg bw/week.
• As corpus-wide pattern. The Iran-wide average-rice-content EWI (2.91 µg/kg bw/week) sits well below the WHO/FAO As PTWI of 15 µg/kg bw/week, but specific provincial samples (Gillan 3 µg/g, Khuzestan 1.97 µg/g, Feridonkenar 0.545 µg/g per the review prose) exceeded the Iranian 0.15 µg/g standard substantially. The review does not separate inorganic from organic arsenic; treatment of As in the constituent studies is generally total As by AAS or ICP-OES.
• Trace metals (Cr, Co, Ni) below references. Iran-wide average-rice-content EWI values for Cr (10.59 µg/kg bw/week, vs PTWI 23.30), Co (4.75 µg/kg bw/week, vs MTDI 700 µg/kg bw/week), and Ni (15.96 µg/kg bw/week, vs PTWI 35) all fell below their respective WHO/FAO reference ceilings. These metals are present in Iranian rice but the per-capita consumption-based dietary burden does not exceed established intake ceilings on average.
• Geographic pattern across Iranian provinces. Table 1 reports per-province per-study values from at least 17 Iranian sampling locations (Kashan, Tehran, Shiraz, West Azarbaijan, Khuzestan, Ghaemshahr/Mazandaran, Tabriz, Gillan, Kermanshah, Khuzestan province, Golestan, East Azarbaijan, Shahrekord, Yazd, South Caspian, Isfahan/Brojerd, Zahedan, Babol, Lorestan, Mobarakeh, Ghaemshahr-Mazandaran). The northern Caspian-region provinces (Gillan, Mazandaran, Feridonkenar, Golestan) and central agricultural regions (Khuzestan, Ghaemshahr) carry the highest per-study mean values across multiple metals.
• Review-level limitations for downstream pooling. The review aggregates per-study means without re-pooling raw measurements or estimating between-study heterogeneity, and assumes a single 60 kg / 165 g-per-day per-capita scenario for the EWI calculation. The “average rice content” figures in Table 2 are simple summaries across the heterogeneous corpus rather than weighted pooled means. Downstream wiki synthesis should treat this paper as a corpus pointer (it identifies the 28 constituent studies) rather than as an authoritative single-source quantitative estimate; per-study values pulled from Table 1 should be cross-checked against the constituent paper when ingested.

Wiki pages this source may touch

• cadmium
• arsenic-total
• lead
• mercury-total
• chromium
• cobalt
• nickel
• rice
• rice-bulk-grain

Verification notes

• Source type and evidence tier. This is a peer-reviewed review article in Toxin Reviews (Taylor & Francis), aggregating 28 prior peer-reviewed and grey-literature studies. Graded B-tier: peer-reviewed methodology with explicit search and inclusion procedure, but conveys secondary (review-summarised) values rather than original measurement data. Per-study figures pulled from Table 1 should be verified against the constituent papers when those papers are ingested individually.
• Identity checks (all three clean). DOI 10.1080/15569543.2016.1252932 grep against wiki/sources/ returned no hits. raw_handle: MFK_sharafatichaleshtori2016 grep returned no hits. ls wiki/sources/ | grep sharafati returned no hits. No collision with existing pages.
• Frontmatter discipline. All metal, ingredient, product, matrix, and jurisdiction slugs verified against the 2026-05-18 taxonomy snapshot. Metals use the Part 14 abbreviation vocabulary (Cd, tAs, Pb, Cr, Co, Ni, tHg). Jurisdiction is IR (Iran) only — the review’s geographic scope is Iranian rice production and import; no other-country jurisdictions are in scope.
• Speciation discipline (Part 14). The constituent studies aggregated by this review used atomic absorption spectrometry, mercury analyzer, and ICP-OES instruments — none of which provide intrinsic species separation. Where individual studies measured total elemental concentrations, the review reports those as published. The wiki page accordingly uses tAs (total arsenic) and tHg (total mercury), not iAs or MeHg. Cr is reported as total Cr (no Cr-VI separation in the constituent studies). The review’s Hg PTWI comparison is against the total-mercury PTWI of 4 µg/kg bw/week, which is the JECFA reference for inorganic and total Hg; for methylmercury specifically, the JECFA PTWI is 1.6 µg/kg bw/week (not used by this review).
• Brand firewall (Part 12). The review aggregates province-level and study-level mean concentrations. No brand names, no per-brand attribution, no commercial-cultivar identifiers are carried in the review’s tables or prose. The page accordingly contains no brand-name redactions because no brand names were present to redact. Scientific-method vendor identifiers (mercury analyzer, ICP-OES) appear in the methods description per Part 12 Exception 2.
• Wiki/HMTc firewall (Part 2). The review reports what 28 constituent studies found; it does not propose HMT&C thresholds, does not advocate for regulatory action, and does not target consumer-audience messaging. The wiki page mirrors this register: it reports the review’s numerical findings (corpus ranges, EWI calculations, PTWI comparisons) without synthesising across other wiki pages or proposing certification levers. The cross-paper synthesis work that this review’s data should feed into (e.g., updating the rice contamination_profile block with Iran-specific occurrence data) is the Part 9 synthesis workflow’s job and is not done in this ingest pass.
• Reference-value attribution. Iranian standards are attributed by the review to ISIRI 12968, 1st ed., 2010 (Cd 0.06 µg/g, As 0.15 µg/g, Pb 0.15 µg/g for rice; water-only standards for Ni 0.02 mg/L and Hg 0.001 mg/L). PTWI values are attributed to WHO/FAO (Cd 7, As 15, Pb 25, Hg 4 µg/kg bw/week total Hg). Per-capita rice consumption (158-178 g/day with 165 g/day average) is attributed to ISIRI 2010. These attributions are reported as the review publishes them.
• Paper-internal data anomalies catalogued (none rise to stop-condition severity).
  1. Pb prose vs Table 2 EWI digit. The review’s Pb section (p. 4) states the Iran-wide weekly Pb intake is “22.9 µg/kg body weight/week.” Table 2 publishes the corresponding value as “22.29.” The Key numbers table reports both as published. The 0.61 µg/kg bw/week discrepancy is small and almost certainly a rounding or transcription artefact.
  2. Mazandaran Pb maximum: 11.5 vs 35. Table 1 publishes the Zahedan (Mobaraki & Safarzai 2013) Pb value as 11.5 ± 6.4 µg/g. The review prose (p. 4) states “the maximum Pb concentration was for Mazandaran cultivated rice samples (35 µg/g)” citing Farsani et al. 2014. Table 1’s Mazandaran row in fact shows no single-figure Pb value of 35 µg/g — the closest table entry is the 0.032-0.358 µg/g range for Mazandaran. The 35 µg/g figure is plausibly from a Farsani et al. 2014 per-sample maximum or from a separate Mazandaran-region study not directly tabulated. The wiki page reports both figures (11.5 in Table 1, 35 in prose) as published and notes the inconsistency; the per-study constituent paper (Farsani et al. 2014) would need to be ingested individually to resolve which is the correct upper-bound figure.
  3. Cd minimum-maximum framing. The review prose (p. 2) states “the minimum and maximum amounts of Cd were 0.008 and 0.3802 µg/g in rice samples of Kermanshah and Gillan, respectively.” Table 1 reports values higher than 0.3802 in some rows (Mazandaran province 0.40 ± 0.16, Mobaraki 0.178 ± 0.048 — the latter under the 0.3802 threshold, but the Mazandaran 0.40 exceeds it). The prose minimum-maximum framing appears to refer to cultivated-domestic-rice studies specifically (excluding imported-rice studies and including a subset of provinces); the Table 1 cells include a wider range of study types. The wiki page reports both as published.
  4. Hg framing. The review’s headline Hg EWI of 9.68 µg/kg bw/week is computed using an “average rice content” of 0.503 µg/g, which is itself the simple mean of only two cited Hg studies (Farsani et al. 2014 mean 0.963 µg/g; Rezaitabar et al. 2015 mean 0.044 µg/g). The 9.68 figure is therefore based on a corpus of only two studies for the Hg-content denominator, not on the broader 28-study corpus that the review otherwise summarises. The PTWI-exceedance conclusion accordingly rests on a thin Hg-evidence base within the review itself. The wiki page reports the figure as the review computes it and flags this attribution caveat.
• Basis. Concentration values in the review’s Table 1 are reported in µg/g (mg/kg) on a dry-weight basis as the constituent studies publish them; the review does not re-state the wet-vs-dry basis explicitly but the constituent papers cited (e.g., Naseri et al. 2015, Rahman et al. 2009) report dry weight. EWI calculations apply these dry-weight per-rice concentrations against the 165 g/day per-capita rice consumption, which is on an as-purchased basis; the review does not adjust for the dry-vs-cooked rice mass conversion.
• Data integrity. All values in the Key numbers section transcribed from Table 1 (province-level concentrations, p. 3), Table 2 (EWI summary, p. 4), and the prose on pp. 2-5 (Iranian standards, PTWI references, exceedance counts, search-and-inclusion summary). The four anomaly catalogue entries above are the only paper-internal inconsistencies observed; none requires the source to be quarantined or held back from ingest. Constituent-study figures should be cross-verified against the original papers if those papers are independently ingested.
• Downstream pooling caveat. Because this is a review aggregating prior values rather than a primary measurement source, the Part 9 synthesis workflow should treat per-study values surfaced by Table 1 as pointers to the constituent paper (the cited study should be ingested individually for authoritative per-study figures), not as independent quantitative observations. The review’s value to the wiki is as (a) a corpus pointer for Iranian rice heavy-metals literature 2005-2016, (b) an Iran-wide PTWI-exceedance flag for Hg from rice, and (c) a consolidated Iranian-standard reference table for rice.

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.