{ "generated_at": "2026-05-31T14:59:43.721Z", "schema": "data/evidence/schemas/remediation-record.schema.json", "note": "Graded evidence on drivers and interventions that raise/lower heavy-metal contamination in food crops. Evidence only; not HMTc recommendations. Soil concentrations are not food concentrations.", "counts": { "records": 20, "by_tier": { "A": 0, "B": 13, "C": 7 }, "by_type": { "driver": 12, "intervention": 6, "regional_observation": 2 }, "sources": 5 }, "records": [ { "record_id": "cao2023-lead-pakchoi-eps-bacteria#0", "cite_key": "cao2023-lead-pakchoi-eps-bacteria", "source_page": "wiki/sources/cao2023-lead-pakchoi-eps-bacteria.md", "record_type": "intervention", "crop": "leafy-greens", "metal": "Pb", "supply_chain_stage": "soil", "region": "China", "parent_geology": null, "factor": null, "direction": null, "intervention": "Inoculation of Pb-contaminated soil with exopolysaccharide (EPS)-producing bacteria", "intervention_class": "microbial", "effect_direction": "reduces", "effect_magnitude": "14.5–39.2% reduction in pakchoi edible-tissue Pb vs uninoculated controls, depending on strain and soil contamination level", "comparator": "uninoculated controls on the same Pb-contaminated Chinese agricultural soil", "conditions": { "season": null, "water_regime": null, "input": "EPS-producing bacterial inoculants isolated from contaminated soils", "soil_ph": null }, "evidence_tier": "B", "study_design": "pot experiment with field-sourced Pb-contaminated agricultural soil; multiple strains and contamination levels; sequential soil Pb fractionation; ICP-OES/ICP-MS tissue analysis", "confounders": "Pot experiment rather than field trial — rhizosphere dynamics, root architecture, and microbial competition may differ in open fields; effect range spans strains and soil Pb levels, so single-strain field performance is uncertain; control tissue concentrations not fully extracted from abstract; no report of effects under varying soil pH, organic matter, or co-contaminants typical of periurban Chinese soils.", "what_would_confirm": null, "transferability": "Mechanism (EPS adsorption of Pb in the rhizosphere reducing bioavailable fraction) is plausibly transferable to other leafy vegetables grown on Pb-contaminated soils, and potentially to other cationic metals (Cd, Ni) for which EPS binding is known. Field validation across crops, soils, and climates required.", "summary": "EPS-producing bacterial inoculants applied to Pb-contaminated Chinese agricultural soil reduced lead accumulation in edible pakchoi tissue by 14.5–39.2% across strains and contamination levels.", "quote": "EPS-producing bacterial inoculants reduced lead in pakchoi edible tissues by 14.5 to 39.2%, depending on strain and soil contamination level. ... EPS from bacteria adsorbs Pb in the rhizosphere, reducing bioavailable Pb fraction and limiting root uptake.", "extracted_at": "2026-05-31" }, { "record_id": "cao2023-lead-pakchoi-eps-bacteria#1", "cite_key": "cao2023-lead-pakchoi-eps-bacteria", "source_page": "wiki/sources/cao2023-lead-pakchoi-eps-bacteria.md", "record_type": "driver", "crop": "leafy-greens", "metal": "Pb", "supply_chain_stage": "soil", "region": "China", "parent_geology": null, "factor": "Bioavailable (non-residual) soil Pb fraction in the rhizosphere", "direction": "increases", "intervention": null, "intervention_class": null, "effect_direction": null, "effect_magnitude": null, "comparator": null, "conditions": { "season": null, "water_regime": null, "input": null, "soil_ph": null }, "evidence_tier": "C", "study_design": "mechanism inference from sequential soil Pb fractionation alongside tissue Pb response to EPS treatment", "confounders": "Bioavailability inferred from sequential extraction, which is operationally defined and does not directly measure plant-available Pb; reductions in tissue Pb under EPS inoculation could also reflect rhizosphere pH change, root exudate competition, or altered root microbiome composition rather than Pb adsorption alone.", "what_would_confirm": "Paired measurements of CaCl2- or DGT-based bioavailable soil Pb with pakchoi tissue Pb across a gradient of soils ±EPS inoculation, with bacterial strains heat-killed or EPS-deficient mutants as a negative control to isolate the EPS-binding mechanism.", "transferability": "If confirmed, bioavailable-Pb fraction (rather than total soil Pb) would be the more relevant supply-chain risk metric for leafy-vegetable sourcing on contaminated soils, with implications for Cd and other cationic metals.", "summary": "The bioavailable rhizosphere Pb fraction — not total soil Pb — drives uptake into pakchoi edible tissue, with EPS sequestration lowering that fraction.", "quote": "EPS from bacteria adsorbs Pb in the rhizosphere, reducing bioavailable Pb fraction and limiting root uptake. ... Soil Pb fractionation by sequential extraction.", "extracted_at": "2026-05-31" }, { "record_id": "cao2023-lead-pakchoi-eps-bacteria#2", "cite_key": "cao2023-lead-pakchoi-eps-bacteria", "source_page": "wiki/sources/cao2023-lead-pakchoi-eps-bacteria.md", "record_type": "regional_observation", "crop": "leafy-greens", "metal": "Pb", "supply_chain_stage": "soil", "region": "China (periurban agricultural soils)", "parent_geology": "mining-affected / industrial-source-affected periurban soils", "factor": "Proximity to industrial sources elevating soil Pb", "direction": "increases", "intervention": null, "intervention_class": null, "effect_direction": null, "effect_magnitude": "Soil Pb 7.6–77.27 mg/kg; upper range characterized as moderate-to-heavy agricultural contamination from industrial sources; control pakchoi tissue Pb in higher-contamination treatments exceeded the Chinese MRL of 0.3 mg/kg ww for leafy vegetables.", "comparator": "Typical Chinese background soil Pb (around the lower 7.6 mg/kg end of the observed range)", "conditions": { "season": null, "water_regime": null, "input": null, "soil_ph": null }, "evidence_tier": "C", "study_design": "field-sourced soil characterization used as the experimental substrate; observational characterization of contamination range", "confounders": "Source-page characterization of the upper range as 'consistent with periurban Chinese soils near industrial sources' is contextual rather than directly demonstrated by the study; alternative explanations include legacy leaded-gasoline deposition, Pb-bearing phosphate fertilizers, and irrigation-water inputs; control-treatment tissue Pb values are stated to exceed the MRL but exact concentrations are not extracted from the abstract.", "what_would_confirm": "Paired GPS-located surveys of soil Pb, distance to industrial point sources, and leafy-vegetable tissue Pb across a Chinese periurban catchment, with isotope-source apportionment to attribute Pb origin.", "transferability": "The pattern of moderate-to-heavy Pb contamination in periurban agricultural soils near industrial sources, with leafy-vegetable tissue Pb exceeding regulatory MRLs, is plausibly generalizable to other industrialized regions and to other heavy metals (Cd, Ni) sharing similar emission pathways.", "summary": "Chinese agricultural soils used in this study spanned 7.6–77.27 mg/kg Pb, with the upper end characterized as moderate-to-heavy periurban industrial contamination, and uninoculated control pakchoi at the higher contamination levels carried tissue Pb above the Chinese 0.3 mg/kg leafy-vegetable MRL.", "quote": "The experiment was conducted using Chinese agricultural soil with measured Pb contamination ranging from 7.6 to 77.27 mg/kg. ... The lower range (7.6 mg/kg) is close to typical Chinese background soil values; the upper range (77.27 mg/kg) represents moderate-to-heavy agricultural contamination consistent with periurban Chinese soils near industrial sources. ... Control pakchoi tissue Pb concentrations ... were above Chinese food safety standards (MRL for leafy vegetables: 0.3 mg/kg Pb wet weight) in the higher contamination treatments.", "extracted_at": "2026-05-31" }, { "record_id": "begum2024-rice-fertilization-arsenic#0", "cite_key": "begum2024-rice-fertilization-arsenic", "source_page": "wiki/sources/begum2024-rice-fertilization-arsenic.md", "record_type": "driver", "crop": "rice", "metal": "iAs", "supply_chain_stage": "input-fertilizer", "region": "CN", "parent_geology": null, "factor": "fertilization (mineral fertilizer, wood ash, or pig slurry amendment vs no amendment)", "direction": "increases", "intervention": null, "intervention_class": null, "effect_direction": null, "effect_magnitude": "grain iAs ranged 0.025-0.08 mg/kg across control and fertilized treatments; sum of grain iAs + DMA differed significantly between treatments (P = 0.024)", "comparator": "unamended control", "conditions": { "season": null, "water_regime": "paddy (anaerobic developing over time)", "input": "mineral fertilizer / wood ash / pig slurry / none", "soil_ph": null }, "evidence_tier": "B", "study_design": "controlled growth-chamber experiment with replicated treatments on Chinese paddy soil", "confounders": "Chamber-grown rice on a single Chinese paddy soil; results may not transfer across soil types, climates, or field-scale paddies. Fertilizer source did not materially change speciation concentration per the abstract, so the assimilation-enhancement signal is at the fertilization-vs-no-fertilization contrast rather than between fertilizer types.", "what_would_confirm": null, "transferability": "Likely transferable to other paddy-rice systems where fertilization regime is a sourcing lever; unclear transfer to dryland crops where arsenic mobilization mechanisms differ.", "summary": "Fertilization of paddy rice enhances grain inorganic arsenic assimilation relative to unamended controls in a Chinese paddy soil chamber study.", "quote": "Grain inorganic arsenic varied from 0.025 to 0.08 mg/kg across control and fertilized treatments... The sum of grain inorganic arsenic and DMA differed significantly between treatments (P = 0.024).", "extracted_at": "2026-05-31" }, { "record_id": "begum2024-rice-fertilization-arsenic#1", "cite_key": "begum2024-rice-fertilization-arsenic", "source_page": "wiki/sources/begum2024-rice-fertilization-arsenic.md", "record_type": "driver", "crop": "rice", "metal": "iAs", "supply_chain_stage": "soil", "region": "CN", "parent_geology": null, "factor": "paddy redox / development of anaerobic conditions in porewater", "direction": "modulates", "intervention": null, "intervention_class": null, "effect_direction": null, "effect_magnitude": "porewater inorganic arsenic decreased and methylated arsenic species increased as anaerobic conditions developed; phosphorus and manganese also decreased", "comparator": "earlier-timepoint (more oxic) porewater in the same chamber experiment", "conditions": { "season": null, "water_regime": "flooded paddy progressing to anaerobic", "input": null, "soil_ph": null }, "evidence_tier": "B", "study_design": "controlled growth-chamber experiment with porewater time-series on Chinese paddy soil", "confounders": "Single soil source and chamber conditions; porewater concentrations are not grain concentrations, and the link from porewater speciation shifts to grain speciation is indirect. Co-variation of P, Mn, and arsenic species means individual driver attribution is limited.", "what_would_confirm": null, "transferability": "Redox-driven speciation shifts are well established in paddy systems; likely transferable to paddy rice broadly, less so to non-flooded crops.", "summary": "As paddy soil develops anaerobic conditions, porewater inorganic arsenic decreases while methylated arsenic species rise, indicating redox state is a soil-stage driver of arsenic speciation available to rice.", "quote": "Porewater analysis found inorganic arsenic, phosphorus, and manganese decreased as anaerobic conditions developed, while methylated arsenic species increased over time.", "extracted_at": "2026-05-31" }, { "record_id": "begum2024-rice-fertilization-arsenic#2", "cite_key": "begum2024-rice-fertilization-arsenic", "source_page": "wiki/sources/begum2024-rice-fertilization-arsenic.md", "record_type": "driver", "crop": "rice", "metal": "iAs", "supply_chain_stage": "input-fertilizer", "region": "CN", "parent_geology": null, "factor": "fertilizer source (mineral fertilizer vs wood ash vs pig slurry)", "direction": "modulates", "intervention": null, "intervention_class": null, "effect_direction": "no-effect", "effect_magnitude": "fertilizer source did not materially change arsenic speciation concentration in grain (per abstract)", "comparator": "across the three fertilizer treatments", "conditions": { "season": null, "water_regime": "paddy", "input": "mineral fertilizer / wood ash / pig slurry", "soil_ph": null }, "evidence_tier": "B", "study_design": "controlled growth-chamber experiment with replicated fertilizer treatments", "confounders": "Single soil source and chamber setting; null finding between fertilizer types does not exclude effects under different soils, application rates, or field conditions. Statistical power for a null claim is limited.", "what_would_confirm": null, "transferability": "If robust, implies that fertilizer-type swaps within paddy rice are unlikely to be a meaningful reformulation lever for grain arsenic — relevant for sourcing decisions.", "summary": "Choice of fertilizer source (mineral, wood ash, pig slurry) did not materially shift rice-grain arsenic speciation in this chamber study, even though fertilization vs no fertilization did.", "quote": "The abstract states that fertilizer source did not materially change arsenic speciation concentration in grain.", "extracted_at": "2026-05-31" }, { "record_id": "hossain2024-rice-cadmium-soil-ph#0", "cite_key": "hossain2024-rice-cadmium-soil-ph", "source_page": "wiki/sources/hossain2024-rice-cadmium-soil-ph.md", "record_type": "driver", "crop": "rice", "metal": "Cd", "supply_chain_stage": "soil", "region": "Bangladesh", "parent_geology": null, "factor": "soil pH", "direction": "modulates", "intervention": null, "intervention_class": null, "effect_direction": null, "effect_magnitude": null, "comparator": "pH 4 vs pH 7 vs pH 9 in Cd-stressed soil", "conditions": { "season": null, "water_regime": null, "input": null, "soil_ph": "4, 7, 9" }, "evidence_tier": "B", "study_design": "controlled pot experiment", "confounders": "Pot experiment in Cd-spiked soil at 5 mg/kg; effects may not translate to field soils at ambient Cd. Soil pH was crossed with organic matter and genotype, so pH effect is observed within these specific treatments.", "what_would_confirm": null, "transferability": "Soil pH as a Cd-uptake driver is well established across cereals and leafy crops; the directional finding likely transfers to other rice-growing regions and to other Cd-accumulating crops.", "summary": "Lower soil pH increased Cd uptake into rice grain across four genotypes in a Bangladesh pot experiment.", "quote": "The authors state that low-pH soil increased Cd uptake and that increasing pH and organic matter decreased grain Cd concentration.", "extracted_at": "2026-05-31" }, { "record_id": "hossain2024-rice-cadmium-soil-ph#1", "cite_key": "hossain2024-rice-cadmium-soil-ph", "source_page": "wiki/sources/hossain2024-rice-cadmium-soil-ph.md", "record_type": "driver", "crop": "rice", "metal": "Cd", "supply_chain_stage": "soil", "region": "Bangladesh", "parent_geology": null, "factor": "soil organic matter content", "direction": "decreases", "intervention": null, "intervention_class": null, "effect_direction": null, "effect_magnitude": "BRRI 28 grain Cd fell from 1.00 mg/kg at 1% OM to 0.61 mg/kg at 2% OM to 0.10 mg/kg at 3% OM; soil-bioavailable Cd fell from 0.44 to 0.32 to 0.18 mg/kg over the same gradient", "comparator": "1% vs 2% vs 3% organic matter in Cd-stressed soil", "conditions": { "season": null, "water_regime": null, "input": null, "soil_ph": null }, "evidence_tier": "B", "study_design": "controlled pot experiment", "confounders": "Pot experiment in Cd-spiked soil at 5 mg/kg, not ambient field Cd. Organic-matter source and quality not characterized in extracted text; results may depend on OM type. Crossed with pH and genotype treatments.", "what_would_confirm": null, "transferability": "Organic matter binding Cd and reducing bioavailability is a general soil-chemistry mechanism; the directional finding plausibly transfers to other Cd-accumulating crops and other rice regions, though magnitudes will vary by OM type.", "summary": "Increasing soil organic matter from 1% to 3% reduced rice grain Cd by roughly 10x in BRRI 28 and reduced soil-bioavailable Cd in parallel.", "quote": "Table 3 reports grain Cd and soil-bioavailable Cd examples under organic-matter treatments: BRRI 28 at 1% OM = 1.00 mg/kg grain Cd, 2% OM = 0.61, 3% OM = 0.10; the authors state that increasing pH and organic matter decreased grain Cd concentration.", "extracted_at": "2026-05-31" }, { "record_id": "hossain2024-rice-cadmium-soil-ph#2", "cite_key": "hossain2024-rice-cadmium-soil-ph", "source_page": "wiki/sources/hossain2024-rice-cadmium-soil-ph.md", "record_type": "driver", "crop": "rice", "metal": "Cd", "supply_chain_stage": "cultivation", "region": "Bangladesh", "parent_geology": null, "factor": "rice cultivar / genotype (BRRI 28, Heera, BRRI 67, BRRI 47; salt-tolerant vs non-salt-tolerant)", "direction": "modulates", "intervention": null, "intervention_class": null, "effect_direction": null, "effect_magnitude": "Grain Cd at 1% OM: BRRI 28 = 1.00 mg/kg, Heera = 1.15 mg/kg (later varieties truncated in extracted table)", "comparator": "Across four genotypes (BRRI 28, Heera, BRRI 67, BRRI 47) under matched soil treatments", "conditions": { "season": null, "water_regime": null, "input": null, "soil_ph": null }, "evidence_tier": "C", "study_design": "controlled pot experiment", "confounders": "Only partial data extracted (salt-tolerant varieties' grain Cd values truncated in source table per verification note); pot-experiment artifacts; small genotype set; the salt-tolerant vs non-salt-tolerant contrast confounds genotype with breeding lineage.", "what_would_confirm": "A replicated multi-site field trial comparing the same four cultivars in Cd-bearing paddy soils at matched pH and OM, with grain Cd as endpoint, would confirm whether genotype effects observed here transfer outside the spiked-pot setting.", "transferability": "Cultivar-selection as a Cd-mitigation lever is established for rice in other systems; the specific BRRI/Heera ranking is region-specific to Bangladeshi cultivar availability.", "summary": "Rice grain Cd differed across four Bangladeshi cultivars under matched Cd-stressed soil conditions, suggesting cultivar selection is a candidate Cd-mitigation lever.", "quote": "It compared non-salt-tolerant rice varieties BRRI 28 and Heera with salt-tolerant BRRI 67 and BRRI 47. Soil pH and organic-matter treatments were varied, and grain Cd and soil-bioavailable Cd were measured.", "extracted_at": "2026-05-31" }, { "record_id": "hossain2024-rice-cadmium-soil-ph#3", "cite_key": "hossain2024-rice-cadmium-soil-ph", "source_page": "wiki/sources/hossain2024-rice-cadmium-soil-ph.md", "record_type": "intervention", "crop": "rice", "metal": "Cd", "supply_chain_stage": "soil", "region": "Bangladesh", "parent_geology": null, "factor": null, "direction": null, "intervention": "raising soil pH (liming-equivalent) toward neutral/alkaline", "intervention_class": "soil-amendment", "effect_direction": "reduces", "effect_magnitude": null, "comparator": "pH 4 (acidic) vs pH 7 and pH 9 in Cd-stressed pot soil", "conditions": { "season": null, "water_regime": null, "input": null, "soil_ph": "raised from 4 to 7-9" }, "evidence_tier": "B", "study_design": "controlled pot experiment", "confounders": "Pot-experiment evidence on Cd-spiked soil, not field; pH was imposed as a treatment, not via a specific liming material, so the operational lever (lime type/rate) is not directly tested. Magnitudes not extracted from the available table.", "what_would_confirm": null, "transferability": "Liming to suppress Cd uptake is an established practice across cereals and leafy crops in Cd-impacted soils; the directional result transfers, but field rates depend on soil buffering capacity.", "summary": "Raising soil pH from acidic toward neutral/alkaline reduced rice grain Cd in Cd-stressed pot soils, supporting liming as a Cd-mitigation lever.", "quote": "The authors state that low-pH soil increased Cd uptake and that increasing pH and organic matter decreased grain Cd concentration.", "extracted_at": "2026-05-31" }, { "record_id": "hossain2024-rice-cadmium-soil-ph#4", "cite_key": "hossain2024-rice-cadmium-soil-ph", "source_page": "wiki/sources/hossain2024-rice-cadmium-soil-ph.md", "record_type": "intervention", "crop": "rice", "metal": "Cd", "supply_chain_stage": "soil", "region": "Bangladesh", "parent_geology": null, "factor": null, "direction": null, "intervention": "increasing soil organic matter (e.g., via compost/OM amendment) from 1% toward 3%", "intervention_class": "soil-amendment", "effect_direction": "reduces", "effect_magnitude": "BRRI 28 grain Cd fell 1.00 -> 0.61 -> 0.10 mg/kg as OM rose 1% -> 2% -> 3%; ~10x reduction over the gradient", "comparator": "1% vs 2% vs 3% soil organic matter at matched pH and Cd loading", "conditions": { "season": null, "water_regime": null, "input": null, "soil_ph": null }, "evidence_tier": "B", "study_design": "controlled pot experiment", "confounders": "Pot experiment with Cd-spiked soil at 5 mg/kg; OM source/composition not characterized in extracted text; results depend on OM stability and may be transient in field. Crossed with pH and genotype.", "what_would_confirm": null, "transferability": "OM amendment as a Cd-suppression lever generalizes to other Cd-accumulating crops in mineral soils; field magnitudes will be smaller and OM type-dependent.", "summary": "Amending Cd-stressed soil to 3% organic matter reduced rice grain Cd by roughly an order of magnitude vs 1% OM in BRRI 28, supporting OM-based amendments as a Cd-mitigation intervention.", "quote": "BRRI 28 at 1% OM grain Cd 1.00 mg/kg, 2% OM 0.61 mg/kg, 3% OM 0.10 mg/kg; soil bioavailable Cd 0.44, 0.32, 0.18 mg/kg respectively.", "extracted_at": "2026-05-31" }, { "record_id": "hossain2024-rice-cadmium-soil-ph#5", "cite_key": "hossain2024-rice-cadmium-soil-ph", "source_page": "wiki/sources/hossain2024-rice-cadmium-soil-ph.md", "record_type": "intervention", "crop": "rice", "metal": "Cd", "supply_chain_stage": "cultivation", "region": "Bangladesh", "parent_geology": null, "factor": null, "direction": null, "intervention": "cultivar selection among locally available rice varieties (BRRI 28, Heera, BRRI 67, BRRI 47)", "intervention_class": "cultivar-selection", "effect_direction": "reduces", "effect_magnitude": null, "comparator": "Across four genotypes under matched Cd-stressed pot conditions", "conditions": { "season": null, "water_regime": null, "input": null, "soil_ph": null }, "evidence_tier": "C", "study_design": "controlled pot experiment", "confounders": "Per-variety grain Cd values for salt-tolerant cultivars truncated in extracted source text; pot vs field differences; small cultivar set; salt-tolerant trait confounded with cultivar genetics.", "what_would_confirm": "Replicated field trials in Cd-bearing paddies comparing the same cultivars head-to-head, with grain Cd as the endpoint, would confirm whether the observed across-genotype differences are large enough and stable enough to drive sourcing recommendations.", "transferability": "Cultivar-selection for low-Cd rice is established in Japanese and Chinese breeding programs; the specific Bangladeshi cultivar ranking does not transfer outside that seed market, but the lever does.", "summary": "Choosing among the four tested Bangladeshi rice cultivars produced differing grain Cd under matched Cd-stressed soil, supporting cultivar selection as a candidate Cd-mitigation lever.", "quote": "It compared non-salt-tolerant rice varieties BRRI 28 and Heera with salt-tolerant BRRI 67 and BRRI 47 ... grain Cd and soil-bioavailable Cd were measured.", "extracted_at": "2026-05-31" }, { "record_id": "guo2024-cadmium-bioaccessibility-pak-choi#0", "cite_key": "guo2024-cadmium-bioaccessibility-pak-choi", "source_page": "wiki/sources/guo2024-cadmium-bioaccessibility-pak-choi.md", "record_type": "intervention", "crop": "pak-choi", "metal": "Cd", "supply_chain_stage": "soil", "region": "CN", "parent_geology": null, "factor": null, "direction": null, "intervention": "Combined wollastonite + sodium hexametaphosphate (WSHMP) soil amendment", "intervention_class": "soil-amendment", "effect_direction": "reduces", "effect_magnitude": "-66.13% Cd bioaccessibility in gastric PBET phase; gastric bioaccessibility from ~50-70% in control to <30% with WSHMP", "comparator": "Untreated Cd-contaminated soil control", "conditions": { "season": null, "water_regime": null, "input": "Wollastonite (calcium silicate) + sodium hexametaphosphate", "soil_ph": "Wollastonite raises soil pH" }, "evidence_tier": "B", "study_design": "Greenhouse pot experiment with Cd-spiked soil and in vitro PBET bioaccessibility assay", "confounders": "Greenhouse pot experiment with Cd-spiked (not naturally contaminated) soil may not translate to field conditions; in vitro PBET bioaccessibility is a proxy for human absorption, not a direct measure; effect on total Cd in tissue vs. bioaccessible fraction not fully disentangled in the extracted numbers.", "what_would_confirm": null, "transferability": "Wollastonite (pH raising) and phosphate (Cd-phosphate precipitation) are general Cd-immobilization mechanisms; plausibly transferable to other leafy vegetables and other Cd-accumulating crops grown in acidic or moderately contaminated soils, but field validation across soil types is needed.", "summary": "Combined wollastonite + sodium hexametaphosphate soil amendment reduced Cd bioaccessibility in pak choi by up to 66% in greenhouse pot trials, via pH-driven immobilization and Cd-phosphate precipitation.", "quote": "Combined wollastonite + sodium hexametaphosphate (WSHMP) treatment reduced Cd bioaccessibility in pak choi by up to 66.13% in the gastric phase of the PBET in vitro digestion ... wollastonite raises soil pH, immobilizing Cd; phosphate forms insoluble Cd-phosphate precipitates; combined effect greater than individual treatments.", "extracted_at": "2026-05-31" }, { "record_id": "guo2024-cadmium-bioaccessibility-pak-choi#1", "cite_key": "guo2024-cadmium-bioaccessibility-pak-choi", "source_page": "wiki/sources/guo2024-cadmium-bioaccessibility-pak-choi.md", "record_type": "driver", "crop": "pak-choi", "metal": "Cd", "supply_chain_stage": "soil", "region": "CN", "parent_geology": null, "factor": "Soil pH (raised via wollastonite/calcium silicate)", "direction": "decreases", "intervention": null, "intervention_class": null, "effect_direction": null, "effect_magnitude": null, "comparator": "Lower-pH untreated soil", "conditions": { "season": null, "water_regime": null, "input": "Wollastonite", "soil_ph": "Raised by wollastonite" }, "evidence_tier": "B", "study_design": "Greenhouse pot experiment", "confounders": "Wollastonite delivers both pH change and Ca/Si; the pH effect cannot be isolated from silicate-mediated Cd sequestration in pak choi tissue without a separate pH-only control.", "what_would_confirm": null, "transferability": "Soil pH is a well-established Cd-mobility lever across Cd-accumulating crops (rice, leafy greens, root vegetables); transferability to other leafy greens and acidic-soil systems is high.", "summary": "Raising soil pH via calcium silicate (wollastonite) immobilizes soil Cd and reduces Cd uptake/bioaccessibility in pak choi.", "quote": "wollastonite raises soil pH, immobilizing Cd", "extracted_at": "2026-05-31" }, { "record_id": "guo2024-cadmium-bioaccessibility-pak-choi#2", "cite_key": "guo2024-cadmium-bioaccessibility-pak-choi", "source_page": "wiki/sources/guo2024-cadmium-bioaccessibility-pak-choi.md", "record_type": "driver", "crop": "pak-choi", "metal": "Cd", "supply_chain_stage": "soil", "region": "CN", "parent_geology": null, "factor": "Soil phosphate availability (Cd-phosphate precipitation)", "direction": "decreases", "intervention": null, "intervention_class": null, "effect_direction": null, "effect_magnitude": null, "comparator": "Soils without phosphate amendment", "conditions": { "season": null, "water_regime": null, "input": "Sodium hexametaphosphate and other phosphate forms", "soil_ph": null }, "evidence_tier": "B", "study_design": "Greenhouse pot experiment with multiple phosphate amendment forms", "confounders": "Phosphate amendments can also affect plant P nutrition, root growth, and rhizosphere chemistry; sole-mechanism attribution to Cd-phosphate precipitation requires sequential extraction or speciation data not summarized here.", "what_would_confirm": null, "transferability": "Phosphate-driven Cd immobilization is a general mechanism applicable to other leafy and root vegetables grown in Cd-contaminated soils, subject to local soil P status and risk of P runoff.", "summary": "Phosphate amendments form insoluble Cd-phosphate precipitates in soil, lowering Cd availability to pak choi.", "quote": "phosphate forms insoluble Cd-phosphate precipitates", "extracted_at": "2026-05-31" }, { "record_id": "guo2024-cadmium-bioaccessibility-pak-choi#3", "cite_key": "guo2024-cadmium-bioaccessibility-pak-choi", "source_page": "wiki/sources/guo2024-cadmium-bioaccessibility-pak-choi.md", "record_type": "regional_observation", "crop": "pak-choi", "metal": "Cd", "supply_chain_stage": "soil", "region": "CN", "parent_geology": null, "factor": "Cd-contaminated agricultural soils (Chinese paddy/vegetable soils) drive elevated Cd in pak choi sufficient to push child THQ above 1", "direction": "increases", "intervention": null, "intervention_class": null, "effect_direction": null, "effect_magnitude": "Target hazard quotient (THQ) >1 for children in untreated contaminated-soil control; WSHMP treatment reduced THQ <1 for adults and children", "comparator": "WSHMP-amended soil scenario", "conditions": { "season": null, "water_regime": null, "input": null, "soil_ph": null }, "evidence_tier": "C", "study_design": "Health risk assessment (THQ) built on greenhouse pot Cd concentrations and Chinese national vegetable consumption / body-weight data", "confounders": "THQ was calculated from greenhouse pot Cd concentrations using Cd-spiked soil rather than measured field pak choi from actual production regions; THQ is sensitive to assumed consumption rates and body weights; bioaccessibility-adjusted vs total Cd choice changes the result.", "what_would_confirm": "Survey of total Cd in market pak choi sampled across known Cd-contaminated Chinese agricultural regions, paired with regional consumption data, to confirm child THQ exceedance under realistic exposure.", "transferability": "The pattern — child THQ exceedance driven by Cd-accumulating leafy greens grown on contaminated soils — is plausibly relevant to other high-Cd vegetable-producing regions globally (e.g., parts of South and East Asia with legacy mining/industrial Cd burdens).", "summary": "In Cd-contaminated Chinese agricultural soils, pak choi accumulates enough Cd to drive child non-carcinogenic risk (THQ) above 1, with soil amendments (WSHMP) bringing THQ back below 1.", "quote": "THQ exceeded 1 for children in untreated soil control condition, indicating non-carcinogenic risk; WSHMP treatment reduced THQ to below 1 for adults and children.", "extracted_at": "2026-05-31" }, { "record_id": "blommaert2022-cd-cacao-translocation#0", "cite_key": "blommaert2022-cd-cacao-translocation", "source_page": "wiki/sources/blommaert2022-cd-cacao-translocation.md", "record_type": "driver", "crop": "cocoa", "metal": "Cd", "supply_chain_stage": "soil", "region": "BE", "parent_geology": null, "factor": "soil Cd concentration (bioconcentration into nib)", "direction": "increases", "intervention": null, "intervention_class": null, "effect_direction": null, "effect_magnitude": "nib Cd = 10–28× topsoil Cd", "comparator": "topsoil Cd concentration in the same pot", "conditions": { "season": null, "water_regime": null, "input": "Cd-spiked soil at environmentally relevant and elevated concentrations", "soil_ph": null }, "evidence_tier": "B", "study_design": "greenhouse pot experiment with isotope fractionation, XAS, and LA-ICP-MS", "confounders": "Single greenhouse pot experiment in Belgium with spiked soil; bioconcentration factor in field-grown cacao across diverse tropical soils, climates, and cultivars may differ; small plant set; ratio varied by plant and treatment.", "what_would_confirm": null, "transferability": "Bioconcentration framing transfers to other Cd-accumulating tree crops (e.g., cassava, leafy greens) and supports origin-screening logic for any crop with strong soil-to-edible-tissue transfer.", "summary": "Cd concentrations in cacao nibs were 10–28× higher than in the topsoil, demonstrating strong soil-to-bean bioconcentration in Theobroma cacao.", "quote": "Cd concentrations in cacao nibs were 10 to 28 times higher than those measured in the topsoil, demonstrating substantial bioconcentration.", "extracted_at": "2026-05-31" }, { "record_id": "blommaert2022-cd-cacao-translocation#1", "cite_key": "blommaert2022-cd-cacao-translocation", "source_page": "wiki/sources/blommaert2022-cd-cacao-translocation.md", "record_type": "driver", "crop": "cocoa", "metal": "Cd", "supply_chain_stage": "cultivation", "region": "BE", "parent_geology": null, "factor": "root retention and xylem loading (plant physiology control point)", "direction": "modulates", "intervention": null, "intervention_class": null, "effect_direction": null, "effect_magnitude": null, "comparator": null, "conditions": { "season": null, "water_regime": null, "input": null, "soil_ph": null }, "evidence_tier": "C", "study_design": "mechanism study (stable Cd isotope fractionation + LA-ICP-MS mapping)", "confounders": "Isotope-fractionation inference of transporter selectivity is indirect; pot experiment under greenhouse conditions; alternative explanations include differential binding to organic acids in roots vs. shoot tissue rather than transporter-mediated selectivity per se.", "what_would_confirm": "Comparative field or pot trials of cacao genotypes with known differences in root-to-shoot Cd translocation (e.g., contrasting xylem-loading transporter expression), measuring nib Cd against matched soil Cd, to quantify how much variation in nib Cd is explained by the xylem-loading step.", "transferability": "The xylem-loading-as-control-point concept already underpins low-Cd cultivar selection in rice and durum wheat; identifies the same lever for cacao breeding and rootstock selection.", "summary": "Roots retain lighter Cd isotopes and the xylem-loading step controls how much Cd reaches the harvestable bean, identifying root retention and xylem loading as the key physiological control points for nib Cd.", "quote": "Isotope fractionation patterns indicated that roots are a key compartment for Cd retention and that the xylem loading step is a critical control point for how much Cd reaches the harvestable bean.", "extracted_at": "2026-05-31" }, { "record_id": "blommaert2022-cd-cacao-translocation#2", "cite_key": "blommaert2022-cd-cacao-translocation", "source_page": "wiki/sources/blommaert2022-cd-cacao-translocation.md", "record_type": "driver", "crop": "cocoa", "metal": "Cd", "supply_chain_stage": "cultivation", "region": "BE", "parent_geology": null, "factor": "Cd speciation in plant tissue (organic-acid and thiol ligand binding)", "direction": "modulates", "intervention": null, "intervention_class": null, "effect_direction": null, "effect_magnitude": null, "comparator": "absence of phosphate/sulfide mineral speciation", "conditions": { "season": null, "water_regime": null, "input": null, "soil_ph": null }, "evidence_tier": "C", "study_design": "mechanism study (XANES/EXAFS speciation on lyophilized plant tissue)", "confounders": "Single greenhouse pot system; XAS speciation can shift with sample preparation (lyophilization may alter labile ligand environments); does not by itself demonstrate which intervention class would disrupt the chelation pathway in vivo.", "what_would_confirm": "Targeted intervention trials (e.g., foliar or rhizosphere amendments that compete for thiol/organic-acid ligands, or genotypes with altered phytochelatin synthesis) measured against nib Cd, to confirm that disrupting chelation-based transport actually lowers bean Cd.", "transferability": "Identifies chelation-based transport as a transferable lever class — relevant to Cd in rice, leafy greens, and tobacco where thiol- and organic-acid-mediated transport is similarly implicated.", "summary": "Cd in cacao tissues is primarily bound to organic acids and thiol ligands consistent with active chelation-based transport, pointing to chelation pathways as a mechanistic intervention target.", "quote": "XAS revealed that Cd in cacao tissues is primarily bound to organic acids and thiol ligands rather than to phosphate or sulfide minerals, consistent with an active chelation-based transport mechanism.", "extracted_at": "2026-05-31" }, { "record_id": "blommaert2022-cd-cacao-translocation#3", "cite_key": "blommaert2022-cd-cacao-translocation", "source_page": "wiki/sources/blommaert2022-cd-cacao-translocation.md", "record_type": "intervention", "crop": "cocoa", "metal": "Cd", "supply_chain_stage": "soil", "region": null, "parent_geology": null, "factor": null, "direction": null, "intervention": "soil screening and origin selection (sourcing from low-Cd soils)", "intervention_class": "input-control", "effect_direction": "reduces", "effect_magnitude": null, "comparator": "sourcing without soil-Cd screening, including from 40–100 mg Cd/kg South American cocoa-growing soils", "conditions": { "season": null, "water_regime": null, "input": null, "soil_ph": null }, "evidence_tier": "B", "study_design": "implication drawn from a mechanism / pot bioconcentration study", "confounders": "Bioconcentration factor was measured in a pot experiment under greenhouse conditions; real-world soil-Cd-to-nib transfer is also modulated by cultivar, rootstock, soil pH, organic matter, and climate, so soil screening alone may not predict nib Cd precisely.", "what_would_confirm": null, "transferability": "Origin-screening as the highest-leverage lever transfers to other crops with strong soil-to-edible-tissue Cd transfer (e.g., rice, leafy greens, sunflower, durum wheat).", "summary": "Given 10–28× soil-to-nib bioconcentration, soil screening and origin selection are framed as the highest-leverage mitigation levers for Cd in cocoa.", "quote": "Soil screening and origin selection remain the highest-leverage mitigation levers; this paper supports that framing.", "extracted_at": "2026-05-31" } ] }