Nickel
This page draws on the EFSA CONTAM 2020 update of the nickel risk assessment (EFSA Ni 2020), the ATSDR 2024 Toxicological Profile for Nickel (ATSDR Ni 2024), the NTP 15th Report on Carcinogens nickel chapter (NTP 15th RoC 2021), the EPA Ecological Soil Screening Levels for nickel (EPA Eco-SSL Ni 2007), and the LGC final report on nickel release from piercing post assemblies (LGC 2003).
Chapter-level cross-metal toxicology context for nickel toxicokinetics, contact dermatitis, nickel carbonyl poisoning, carcinogenicity, epigenetic effects, and treatment is connected from Ufelle & Barchowsky 2021.
Overview
The toxicology of nickel splits sharply by route: inhalation exposure to nickel compounds (particularly soluble salts and certain insoluble forms in occupational settings) produces lung and nasal cancer, and the US National Toxicology Program classifies nickel compounds as a class as known human carcinogens (NTP 15th RoC); dietary exposure to nickel produces non-cancer endpoints, primarily reproductive and developmental effects at chronic exposure and systemic contact dermatitis at acute exposure in nickel-sensitized individuals (EFSA 2020). The EFSA CONTAM Panel 2020 update established a chronic TDI of 13 µg Ni/kg b.w./day and an acute reference using a LOAEL of 4.3 µg Ni/kg b.w. for eczematous flare-up reactions in nickel-sensitized humans, applying a margin-of-exposure approach for the acute case (EFSA 2020).
Dietary nickel sources are broadly distributed across the food supply: cocoa products, nuts, legumes (especially beans), oats, whole grains, and certain leafy vegetables carry the highest concentrations (EFSA 2020). Drinking water is a meaningful additional source (EFSA 2020).
At a glance
Three facts that matter most for a consumer trying to interpret nickel exposure.
First, once a person is nickel-sensitized, very low oral nickel doses (4.3 µg/kg body weight, the EFSA acute LOAEL) can produce eczematous flare-up reactions called systemic contact dermatitis (EFSA 2020).
Second, dietary nickel exposure routinely exceeds the EFSA chronic TDI of 13 µg/kg/day in significant fractions of the European population, particularly among consumers of cocoa products, oat products, legume-heavy diets (including chickpea, soy, lentil), and certain leafy vegetables (EFSA 2020). Drinking water can be a meaningful additional contributor in some regions (EFSA 2020). The EFSA finding that exposure routinely exceeds the TDI is a regulatory-level acknowledgment that current dietary nickel exposure is at or above what the agency considers safe for chronic intake (EFSA 2020).
Third, the carcinogenic risk from nickel is dominantly an occupational inhalation concern (refining, electroplating, stainless steel manufacture), not a dietary concern (NTP 15th RoC). NTP and IARC classify nickel compounds as known human carcinogens based on lung and nasal cancer in occupational cohorts inhaling nickel dust and fume (NTP 15th RoC); dietary nickel intake at typical levels has not been associated with cancer outcomes (NTP 15th RoC). Consumers concerned about nickel cancer risk should attend to occupational exposure if relevant; for dietary nickel, the operative concerns are reproductive/developmental and (for sensitized individuals) acute dermatitis flare-ups (EFSA 2020).
Toxicology
The EFSA 2020 chronic TDI of 13 µg Ni/kg b.w./day is anchored on a BMDL10 of 1.3 mg Ni/kg b.w./day for increased post-implantation loss in rats. Reproductive and developmental endpoints (post-implantation loss, decreased fetal weight, reduced viability) are the most sensitive chronic endpoints and dominate the dietary risk assessment. The chronic TDI was lowered substantially from prior values in the 2020 EFSA update.
For acute oral nickel exposure, EFSA 2020 identified eczematous flare-up reactions in nickel-sensitized humans (systemic contact dermatitis) as the critical effect. A BMDL could not be derived from the available human-volunteer studies; the LOAEL of 4.3 µg Ni/kg b.w. was selected as the reference point, with a margin-of-exposure approach using MOE ≥ 30 as the threshold for low health concern (EFSA 2020).
Carcinogenic effects of nickel compounds are documented in occupational inhalation cohorts (nickel refinery workers, stainless steel and nickel-alloy production, electroplating) (NTP 15th RoC). Lung and nasal cancer are the primary tumor sites (NTP 15th RoC). The NTP 15th Report on Carcinogens (2021) classifies nickel compounds as a class as known human carcinogens (since the 10th RoC, 2002); metallic nickel as reasonably anticipated to be a human carcinogen (since the 1st RoC, 1980); and explicitly reviewed nickel alloys without recommending listing. Dietary nickel intake at typical levels has not been associated with cancer outcomes in epidemiological studies; the cancer risk from nickel is operationally an inhalation/occupational concern (NTP 15th RoC).
The dermal-contact pathway is separate from dietary nickel. LGC 2003 evaluates nickel sensitisation and allergic contact dermatitis from piercing post assemblies, including release from stainless steel into artificial sweat, urine, and blood plasma. The report is important for nickel sensitisation context, but it is not a food occurrence source and does not supply ppb values for infant formula, baby foods, or other Category 1 food rows.
Ufelle & Barchowsky 2021 supports the same route-gating principle at textbook level: nickel is characterized as a dietary/background exposure for the general population, an occupational inhalation concern for lung and nasal cancers, and a dermal immune concern for sensitized individuals. It does not supply food occurrence concentrations.
Typical exposure routes
Dietary intake is the dominant route for the general non-occupationally-exposed population (EFSA 2020). Inhalation of airborne nickel is occupational (smelting, refining, electroplating, stainless steel manufacture, fluid-flux welding) and produces the cancer endpoints rather than the dietary endpoints (NTP 15th RoC).
Once sensitized, individuals are susceptible to systemic contact dermatitis from oral nickel doses well below the EFSA chronic TDI (EFSA 2020).
Food sources
Primary occurrence data from Flyvholm et al. 1984 (2,221 food samples reviewed from the post-1969 AAS or PIXE literature, plus Danish National Food Institute analyses) establishes the foundational Ni-content rank order for foods. The ten highest-Ni foods by weighted mean concentration are:
| Rank | Food | Mean Ni (µg/g) | Range (µg/g) | n |
|---|---|---|---|---|
| 1 | Cocoa | 9.8 | 8.2-12 | 7 |
| 2 | Soy beans | 5.2 | 4.7-5.9 | 3 |
| 3 | Soy products | 5.1 | 1.08-7.8 | 7 |
| 4 | Walnuts | 3.6 | (single sample) | 1 |
| 5 | Peanuts | 2.8 | 1.6-4.9 | 2 |
| 6 | Oats | 2.3 | 0.33-4.8 | 37 |
| 7 | Buckwheat | 2.0 | 1.3-2.8 | 3 |
| 8 | Bitter (dark) chocolate | 1.9 | 1.3-2.7 | 7 |
| 9 | Hazelnuts | 1.8 | 0.66-3.3 | 12 |
| 10 | Dried legumes | 1.7 | 0.52-3.3 | 17 |
Notable lower-ranked foods include almonds (1.3 µg/g, n=5), pistachios (0.8 µg/g, n=1), milk chocolate (0.7 µg/g, n=11), whole wheat (0.33 µg/g, n=85), and white bread (0.27 µg/g, n=65). Within the modeled Danish average diet (2,099 g/person/day excluding drinking water), Flyvholm estimated 150 µg Ni/day total dietary intake, of which oatmeal alone contributed 14.1 µg/day at a striking load factor F = 24 (the highest single-food load factor in the diet). Wheat flour contributed 14.7 µg/day at F = 1.9, potatoes 24.4 µg/day at F = 2.0, and fats including margarine 4.2 µg/day at F = 5.8. Replacing average-diet items with high-Ni foods can push intake to 900 µg/day or more, well within the 600 to 5,600 µg per oral provocation range that triggers hand-eczema flare in nickel-sensitive patients.
| Matrix | Nickel concern |
|---|---|
| Cocoa and chocolate products | Highest-Ni food category at 9.8 µg/g cocoa, 1.9 µg/g bitter chocolate, 0.7 µg/g milk chocolate (Flyvholm 1984; EFSA 2020) |
| Oats and oat products | Elevated at 2.3 µg/g; oatmeal carries the highest dietary load factor F=24 in the Danish average diet (Flyvholm 1984; EFSA 2020) |
| Legumes (beans, chickpeas, lentils, soy) | Plant-family-level efficient Ni accumulators; soybeans 5.2 µg/g, soy products 5.1 µg/g, dried legumes 1.7 µg/g (Flyvholm 1984; EFSA 2020) |
| Nuts (walnuts, peanuts, hazelnuts, almonds, pistachios) | Elevated; walnuts 3.6 µg/g, peanuts 2.8 µg/g, hazelnuts 1.8 µg/g, almonds 1.3 µg/g, pistachios 0.8 µg/g (Flyvholm 1984; EFSA 2020) |
| Drinking water (in some regions) | Variable; cold tap water mean 9 µg/L (Danish data) but post-8-hour stagnation can reach 490 µg/L; corrosion of Ni-containing plumbing (Flyvholm 1984; EFSA 2020) |
EFSA 2020 subsequently confirmed Flyvholm’s rank ordering and found that mean dietary nickel exposure across European Member States routinely exceeds the chronic TDI of 13 µg/kg b.w./day, particularly among toddlers and other children, and among adults consuming legume-heavy or cocoa-heavy diets.
What this means for food choice
For consumers without diagnosed nickel sensitivity: dietary nickel exposure routinely exceeds the EFSA TDI, which is a regulatory finding rather than a personal-action signal. The reproductive and developmental endpoints driving the TDI matter most for women planning pregnancy and for child consumers; for adult men outside the reproductive window, the chronic TDI exceedance is less consequential at the individual level than the population level.
For consumers with diagnosed nickel-sensitivity contact dermatitis: the acute LOAEL of 4.3 µg Ni/kg b.w. corresponds to approximately 300 µg total daily nickel for a 70 kg adult (EFSA 2020).
Regulatory limits
| Jurisdiction / Body | Type | Value | Page |
|---|---|---|---|
| EFSA (EU) | Chronic dietary TDI | 13 µg Ni/kg b.w./day | efsa-nickel-tdi |
| EFSA (EU) | Acute oral LOAEL (sensitized) | 4.3 µg Ni/kg b.w.; MOE ≥ 30 for low concern | efsa-nickel-tdi |
| EU | Nickel Directive 94/27/EC (skin-contact items, as described in LGC 2003) | 0.5 µg Ni/cm2/week release-rate limit for direct/prolonged skin contact; 0.05% m/m content limit for post assemblies; LGC recommendation: 0.2 µg/cm2/week migration limit for all post assemblies | eu-nickel-directive-94-27-ec |
| US NTP | 15th Report on Carcinogens | Ni compounds: known human carcinogen; metallic Ni: reasonably anticipated | NTP 15th RoC 2021 |
| US EPA | Ecological Soil Screening Levels | Threshold values for ecological-risk screening at hazardous waste sites | EPA Eco-SSL Ni 2007 |
| US ATSDR | MRLs (multiple by route and duration) | See profile | ATSDR Ni 2024 |
What the reference values mean in practice
The two EFSA reference points operate together as the dietary nickel benchmark: the chronic TDI of 13 µg/kg/day for general-population reproductive/developmental risk, and the acute LOAEL of 4.3 µg/kg b.w. for nickel-sensitized contact dermatitis flare-up. For a 70-kilogram adult, the chronic TDI corresponds to 910 µg Ni/day; the acute LOAEL corresponds to 300 µg per single dose; the MOE of 30 for “low concern” sets the practical acute target at approximately 10 µg Ni in a single sitting for a sensitized individual.
Typical European dietary nickel intakes routinely exceed the chronic TDI (EFSA 2020).
For the population question: the EFSA finding that mean dietary nickel exposure exceeds the TDI is a regulatory signal that population-level nickel intake reduction is warranted, not that any individual at typical exposure faces a defined acute health threat (EFSA 2020). The TDI is a health-protective threshold for chronic intake assuming lifetime exposure; brief exceedance is not an acute danger (EFSA 2020).
Testing
Nickel food occurrence values require food-matrix analytical methods and ppb basis matching. By contrast, dermal contact-product nickel release is commonly expressed as µg/cm2/week. The EN 1811 nickel-release method discussed in LGC 2003 is therefore relevant to piercing posts and skin-contact articles, not to food concentration cells.
Microbiome effects
Nickel is an essential cofactor for at least five distinct virulence-associated enzyme systems in human and animal pathogens, documented in Maier and Benoit 2019 (University of Georgia, Center for Metalloenzyme Studies). The pathogen-Ni-virulence systems span gastric, urinary-tract, and central-nervous-system infections, with Helicobacter pylori as the canonical Ni-dependent gastric pathogen: H. pylori uses [NiFe] hydrogenases for H2-utilization-driven host colonization and uses urease for gastric pH neutralization, and both Ni-enzyme systems are required for the translocation of the carcinogenic CagA toxin into host epithelial cells. Salmonella enterica Typhimurium hydrogenases are characterized as host-colonization factors. Proteus mirabilis urease drives urolithiasis pathogenesis. Staphylococcus species ureases participate in soft-tissue infections. Cryptococcus genus urease enables blood-brain-barrier penetration in meningeal cryptococcosis. The pathogen Ni-uptake, Ni-storage, and Ni-maturation enzyme machinery is sophisticated enough to balance Ni availability against Ni toxicity.
Host nutritional immunity (calprotectin-mediated Ni and Zn sequestration) is the principal evolutionary counter to pathogen Ni acquisition (Maier and Benoit 2019). This is the mechanism through which the host gut starves invading pathogens of Ni; dietary Ni loading that overwhelms calprotectin’s sequestering capacity is a candidate pathway by which heavy-metal exposure perturbs pathogen virulence beyond its direct host-toxicity endpoints. The EFSA chronic TDI of 13 µg Ni/kg b.w./day is calibrated against direct host endpoints (reproductive/developmental) and does not address this microbiome-and-pathogenesis axis.
Nickel-microbiome interactions in non-pathogen contexts are documented in Yang et al. 2023 (Environmental Pollution n=109 Chinese cohort): occupational Ni exposure correlates with elevated serum uric acid via diminished uric-acid-lowering bacteria (Lactobacillus and related taxa) in the gut microbiome, with intestinal purine-to-uric-acid degradation impaired by Ni-driven microbiota perturbation. The Yang 2023 cohort-level human evidence complements the Maier and Benoit 2019 mechanistic pathogen-Ni-virulence review.
Cross-cutting metal-microbiome reviews Coryell et al. 2019, Zhu et al. 2024, and Ghosh et al. 2024 contextualize the Ni-microbiome interaction within the broader heavy-metal-and-microbiota literature. See nickel-microbial-pathogenesis for the dedicated synthesis page that crosswalks to WikiBiome.
Vulnerable populations
| Population | Basis |
|---|---|
| Nickel-sensitized individuals | Acute systemic contact dermatitis flare-up at very low oral nickel doses (4.3 µg/kg b.w. LOAEL) (EFSA 2020) |
| Frequent consumers of cocoa, oats, legumes, nuts | Chronic dietary exposure routinely exceeds the 13 µg/kg/day TDI (EFSA 2020) |
| Pregnant women | Reproductive/developmental endpoint anchors the TDI; pregnancy is the most sensitive life stage (EFSA 2020) |
| Children and toddlers | Higher per-kg dietary intake; routine TDI exceedance documented in EFSA 2020 |
| Workers in nickel-related occupations | Inhalation exposure to nickel compounds (refining, electroplating, stainless steel manufacture) (NTP 15th RoC) |
If you are in one of these groups
For pregnant women: the EFSA reproductive/developmental endpoint anchoring the chronic TDI applies most directly to this population (EFSA 2020). The TDI itself incorporates uncertainty factors for inter-individual variability; brief exceedance is not an acute danger, but sustained exceedance during pregnancy is the regulatory concern that drove the TDI’s lowering (EFSA 2020).
App-layer integration
Machine-readable takeaways from this synthesis for the Heavy Metal Index consumer app pipeline.
The reference-value structure for nickel is bimodal: a chronic TDI (13 µg Ni/kg b.w./day for general-population reproductive risk) and an acute LOAEL with MOE approach (4.3 µg Ni/kg b.w. for sensitized-individual dermatitis). The app should benchmark against the chronic TDI for non-sensitized users and against the acute LOAEL with MOE ≥ 30 for users flagged as nickel-sensitized.
Pediatric multipliers for nickel are through body-weight scaling. EFSA 2020 documents routine TDI exceedance in toddlers and children at the population level.
Structured outputs:
- Acute LOAEL (sensitized, oral): 4.3 µg Ni/kg b.w. (EFSA 2020).
- Acute MOE threshold for low concern: ≥ 30 (EFSA 2020).
- Chronic TDI: 13 µg Ni/kg b.w./day (EFSA 2020).
- High-Ni food categories for app dietary calculation: cocoa, chocolate, nuts (cashews, hazelnuts), oats, legumes (soy, chickpea, lentil, bean), leafy vegetables (spinach, lettuce), shellfish (EFSA 2020).
For nickel-sensitized users, the app should provide a “low-nickel diet” mode flagging high-nickel foods and offering substitutions. For non-sensitized users, the chronic TDI benchmark is the primary signal.
Open questions
Two load-bearing open questions for nickel:
First, the population-level TDI exceedance reported by EFSA 2020 is a regulatory finding without a clear individual-level intervention pathway. Reducing dietary nickel below the TDI through ordinary food choice is difficult given nickel’s broad distribution across plant foods and beverages. Whether this constitutes a population-health concern warranting policy intervention beyond the existing EU Nickel Directive on skin-contact items is an open question the wiki tracks as the regulatory landscape develops.
Second, the relationship between dermal sensitization (the gateway exposure for many sensitized individuals) and dietary flare-up tolerance is mechanistically established but quantitatively variable across sensitized populations. Whether an HMT&C or analogous certification program targeting “low nickel” finished products would meaningfully serve sensitized consumers depends on individual-level threshold variation that the literature has not fully characterized.
Third, LGC 2003 shows why dermal/contact-material evidence must be route-gated inside the wiki: a robust release-rate page for piercing post assemblies can coexist with Category 1 food data gaps without letting a skin-contact migration limit masquerade as a food occurrence value.
Systemic Nickel Allergy Syndrome (SNAS) and the low-nickel diet
Systemic Nickel Allergy Syndrome (SNAS) is the clinical bridge between contact-allergy (the most-recognized nickel endpoint) and a much broader spectrum of systemic disease triggered by dietary nickel. SNAS affects approximately 20 percent of nickel allergic-contact-dermatitis patients and is defined by three diagnostic criteria per Braga et al. 2013: positive patch test to nickel, symptom improvement on a low-nickel diet, and positive oral nickel challenge (gold standard: double-blind placebo-controlled). The Braga 2013 BraMa-Ni structured low-nickel diet (~50 µg Ni/day, nutritionally balanced) achieves 94.4 percent sensitivity and 93.3 percent specificity for SNAS diagnosis, dramatically outperforming conventional forbidden-foods lists (51.1 percent / 44.2 percent).
The low-nickel diet has substantial clinical-trial evidence across a remarkable range of conditions. In dermatitis, Kaaber et al. 1978 (the foundational paper) found 9 of 17 oral-Ni-challenge-positive patients improved during 6-week low-Ni diet, with 7 of 9 flaring on return to normal diet. Veien et al. 1993 enrolled 90 nickel-sensitive patients and documented 64.4 percent short-term benefit, with 72.7 percent of responders sustaining improvement at 1-2 years follow-up. In IBS, Rizzi et al. 2017 found that nickel-sensitive IBS patients had intestinal permeability 2.7-fold elevated versus controls (5.91 percent vs 2.20 percent 51Cr-EDTA excretion) and that all GI symptoms except vomiting improved on a low-Ni diet. In GERD, Yousaf et al. 2021 documented 95 percent symptom-severity reduction (19 of 20 refractory GERD patients) at 8 weeks, with response independent of patch-test status. In recurrent aphthous stomatitis, Pacor et al. 2003 showed 45.7 percent of nickel-sensitive RAS patients had positive DBPC oral Ni challenge, with 21 of 32 improving on nickel-free diet (and 92.6 percent of the 380-patient RAS cohort reported chocolate/cocoa-aggravated symptoms, reinforcing the cocoa-as-high-nickel matrix). In endometriosis, Borghini et al. 2020 found 90.3 percent Ni allergic contact mucositis prevalence in endometriosis patients with GI symptoms, and a 3-month low-Ni diet significantly improved all 15 GI symptoms, all 7 extra-intestinal symptoms, and gynecological symptoms (dysmenorrhea, dyspareunia, pelvic pain). In H. pylori eradication, Campanale et al. 2014 showed a nickel-free diet added to standard triple therapy nearly doubled eradication rate (84.6 percent vs 46.2 percent, p<0.01) — direct in-vivo confirmation that disabling H. pylori’s nickel-dependent urease and hydrogenase translates to clinical pathogen-clearance, consistent with the Maier and Benoit 2019 mechanism review.
Oral hyposensitization is an emerging alternative to lifelong dietary adherence. Minelli et al. 2010 enrolled 36 SNAS patients in a graduated oral nickel sulphate protocol (sub-nanogram to microgram doses over ~6 months) and documented both clinical improvement and significant cytokine reductions: IFN-gamma -55.3 percent, IL-13 -58.6 percent, IL-5 -31.2 percent. The dual-pathway downregulation (Th1 plus Th2) is consistent with classical oral-tolerance induction mechanisms.
Clinical population implications
The clinical-trial cluster above expands the population for whom dietary nickel matters substantially beyond the EFSA TDI’s reproductive/developmental endpoint and the EFSA acute LOAEL’s contact-allergy framing:
| Clinical condition | Population scale | Low-Ni-diet evidence |
|---|---|---|
| Nickel allergic contact dermatitis | 8-19 percent of adults; 13-18 percent of women | Kaaber 1978, Veien 1993 |
| SNAS (subset of ACD) | ~20 percent of ACD patients | Braga 2013, Minelli 2010 |
| Refractory GERD | Subset of the ~20 percent adult prevalence; response not patch-test-gated | Yousaf 2021 |
| IBS with Ni sensitization | Subset of the ~10 percent adult IBS prevalence | Rizzi 2017 |
| Recurrent aphthous stomatitis with Ni reactivity | Subset of the 5-25 percent lifetime RAS prevalence | Pacor 2003 |
| Endometriosis with GI / extra-intestinal symptoms | 90.3 percent Ni ACM prevalence in symptomatic subset | Borghini 2020 |
| H. pylori infection on triple therapy | Global; H. pylori colonizes ~50 percent of humans | Campanale 2014 |
The implication for HMTc Ni threshold rationale: the EFSA TDI framework calibrates against direct host endpoints in healthy populations. The clinical-trial cluster documents that dietary nickel modulates clinically meaningful endpoints across a population substantially larger than the EFSA framework recognizes, and that intervention via reduced dietary intake produces measurable response in most of these populations. Population-level Ni-threshold setting should reference this body of evidence as it does the EFSA TDI.
Sources
Auto-generated from source-page frontmatter. The “Used on this page for” column is populated by the orchestrator’s POPULATE-SOURCE-LEGEND action; pending entries appear as *[awaiting synthesis]*.
| # | Citation | Year | Type | Used on this page for |
|---|---|---|---|---|
| 1 | Balzani et al. 2026. Metals and Metalloids Accumulation and Biomagnification in Three Commercially Important Fishes from a Turkish Brackish Lake, Environmental Science and Pollution Research | 2026 | Peer-reviewed | Ni concentrations in fish muscle (n=27) |
| 2 | Ccopi et al. 2026. Bioaccumulation of heavy metals in high Andean crops of the Peruvian Andes: comparative evaluation between irrigated and dry systems, Journal of Agriculture and Food Research | 2026 | Peer-reviewed | Ni concentrations in quinoa (n=218) |
| 3 | Marcelino et al. 2026. Monitoring trace minerals and heavy metals in liver of free-living large herbivores in the Netherlands, Frontiers in Veterinary Science | 2026 | Peer-reviewed | Ni data: A twenty-year post-mortem monitoring programme at the Oostvaardersplassen (OVP) nature reserve in the Netherlands measured 13 trace elements and heavy metals by ICP-MS in the li… |
| 4 | Rodríguez-Rodríguez et al. 2026. Trace Element Content in Tomato Fruit Grown with Sargassum-Based Biofertilizer, Agronomy | 2026 | Peer-reviewed | Ni concentrations in fruit by ICP-MS |
| 5 | WHO 2026. GEMS/Food Contaminants database heavy-metal exports, GEMS/Food Contamination Monitoring and Assessment Programme | 2026 | Government dataset | WHO GEMS/Food contaminants database: global Ni occurrence monitoring data across food commodities |
| 6 | Zhang et al. 2026. Trace metal pollution and ecological effects on five crops around a typical manganese mining area in Chongqing, China, Scientific Reports | 2026 | Peer-reviewed | Ni data: Zhang and colleagues measured nine trace metals (Mn, Cd, Cu, Zn, Ni, Pb, As, Cr, Sb) in roots, stems, leaves, shells, and edible grain/tuber portions of five crops (rice, maize,… |
| 7 | Abeslami et al. 2025. Mineral Profile and Heavy Metal Content of Seven Monofloral and Multifloral Honeys from Eastern Morocco, Molecules | 2025 | Peer-reviewed | Ni concentrations in honey by ICP-MS |
| 8 | Asadi et al. 2025. Human health risk assessment of arsenic and potentially toxic elements exposure in bread and wheat flour in Northeast Iran, PLoS ONE | 2025 | Peer-reviewed | Ni concentrations and health risk assessment in bread (n=270) |
| 9 | Asmoay et al. 2025. Geochemical characterization and health risk assessment of groundwater in Wadi Ranyah, Saudi Arabia, using statistical and GIS-based models, Applied Water Science | 2025 | Peer-reviewed | Ni data: Seventy-seven groundwater samples from Wadi Ranyah, the primary water source for communities in the Al-Baha region of Saudi Arabia, were analyzed for physicochemical properties,… |
| 10 | Erol et al. 2025. Safety and Nutritional Profile of Traditional Turkish Cheeses: A Comprehensive Study on Their Mineral Content, Heavy Metal Contamination, and Health Risks of Aho, Golot, and Telli, Food Science & Nutrition | 2025 | Peer-reviewed | Ni concentrations and health risk assessment in cheese (n=30) by ICP-MS |
| 11 | Fan et al. 2025. Occurrence, exposure and health risk assessment of heavy metals in green tea samples cultivated in Hangzhou area, Scientific Reports | 2025 | Peer-reviewed | Ni concentrations and health risk assessment in green tea (n=120) by ICP-MS |
| 12 | Godja et al. 2025. Screen-Printed Gold Electrode for Nickel(II) Detection in Deep Eutectic Solvent Media | 2025 | Peer-reviewed | Ni data: Godja et al. |
| 13 | Ibrahim et al. 2025. Dietary Exposure and Health Risk Assessment of Selected Toxic and Essential Metals in Various Flavored Dairy Products, Biological Trace Element Research | 2025 | Peer-reviewed | Ni concentrations and health risk assessment in milk (n=180) by ICP-MS |
| 14 | Lin et al. 2025. LINE-1 DNA methylation mediates smoking-related risk in site-specific urothelial carcinoma: a Taiwan case-control study, Archives of Toxicology | 2025 | Peer-reviewed | Ni blood biomonitoring in Taiwanese adults: whole-blood concentrations in urothelial carcinoma case-control study |
| 15 | Naccari et al. 2025. Study of Toxic Metals and Microelements in Honey as a Tool to Support Beekeeping Production and Consumer Safety, Foods 2025, 14, 1986 | 2025 | Peer-reviewed | Ni concentrations in honey (n=38) by ICP-MS |
| 16 | Naz et al. 2025. Trace elements in fish species from the Punjnad headworks: bioaccumulation and human health risk assessment, PLoS ONE | 2025 | Peer-reviewed | Ni concentrations and health risk assessment in fish muscle (n=27) |
| 17 | Nour et al. 2025. Nutritional and heavy metal composition of seaweeds from the coast of Djibouti, Food Science and Nutrition | 2025 | Peer-reviewed | Ni concentrations in seaweed (n=6) by ICP-MS |
| 18 | Price et al. 2025. Forging biofilms: metal-induced microbial responses in biofilm formation, Journal of Bacteriology | 2025 | Peer-reviewed | Ni induction of bacterial biofilm formation: microbial resistance and food-safety implications |
| 19 | Uthayarajan et al. 2025. Quality and sources of food and water consumed by people with chronic kidney disease of unknown etiology in Sri Lanka: a systematic review, Environmental Science and Pollution Research | 2025 | Peer-reviewed | [awaiting synthesis] |
| 20 | Weldegebriel et al. 2025. Toxic metal contamination and health risk assessment of packaged fruit juices for children in Gondar city, Ethiopia, Scientific Reports | 2025 | Peer-reviewed | Ni concentrations and health risk assessment in fruit juices (n=80) |
| 21 | Yan et al. 2025. Association between infants’ serum levels of 26 metals and gut microbiota: a hospital-based cross-sectional study in China, Frontiers in Microbiology 16:1669475 | 2025 | Peer-reviewed | Infant serum Ni and gut microbiota composition associations, hospital-based cross-sectional study |
| 22 | Adelusi et al. 2024. Heavy Metal Contamination of Dairy Cattle Feed in the Free State and Limpopo Provinces of South Africa, Food Science & Nutrition | 2024 | Peer-reviewed | Ni concentrations in dairy products (n=70) by ICP-MS |
| 23 | Alinezhad et al. 2024. Heavy metals contamination in pasteurized and sterilized cow’s milk: a systematic review, PLOS ONE | 2024 | Peer-reviewed | Systematic review of Ni in milk: synthesised occurrence, health effects, and exposure data |
| 24 | ATSDR 2024. Toxicological Profile for Nickel, U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry | 2024 | Government report | ATSDR toxicological profile for nickel: exposure routes, health effects, dose-response, and MRL derivation |
| 25 | Bruno et al. 2024. Mineral composition in mussel Mytilus galloprovincialis and clam Tapes decussatus from Faro Lake of Messina: risk assessment for human health, Frontiers in Toxicology | 2024 | Peer-reviewed | [awaiting synthesis] |
| 26 | Canadian Food Inspection Agency 2024. T-4-93 – Safety standards for fertilizers and supplements, Canadian Food Inspection Agency (CFIA) | 2024 | Regulation | Canadian fertilizer heavy metal standards (T-4-93): maximum Ni in fertilizer inputs and agronomic contamination controls |
| 27 | Eccles et al. 2024. Non-invasive biomonitoring of polar bear feces can be used to estimate concentrations of metals of concern in traditional food, PLOS ONE | 2024 | Peer-reviewed | [awaiting synthesis] |
| 28 | Gupta et al. 2024. Assessment of human health risks posed by toxic heavy metals in Tilapia fish (Oreochromis mossambicus) from the Cauvery River, India, Frontiers in Public Health | 2024 | Peer-reviewed | [awaiting synthesis] |
| 29 | Kim et al. 2024. Nutrients and non-essential metals in darkibor kale grown at urban and rural farms: a pilot study, PLOS ONE | 2024 | Peer-reviewed | Ni concentrations in leafy vegetables (n=42) |
| 30 | Kovacik et al. 2024. Microelements, Fatty Acid Profile, and Selected Biomarkers in Grass Carp (Ctenopharyngodon idella) Muscle Tissue: Seasonal Variations and Health Risk Assessment, Research (journal not specified in text; published online 9 May 2024) | 2024 | Peer-reviewed | State-of-the-science review on metal biomarkers: Ni measurement matrices (blood, urine, hair) for exposure assessment |
| 31 | Meli et al. 2024. Chemical characterization of baby food consumed in Italy, PLOS ONE | 2024 | Peer-reviewed | Ni concentrations in baby food |
| 32 | Owusu et al. 2024. Assessment of Heavy Metal Contamination in Lettuce and Spring Onion Cultivated at Anthropogenic Activity Sites in the Kumasi Metropolis, Ghana, Environmental Health Insights | 2024 | Peer-reviewed | [awaiting synthesis] |
| 33 | Toledo et al. 2024. Essential and Toxic Elements in Infant Cereal in Brazil: Exposure Risk Assessment, International Journal of Environmental Research and Public Health 21(4):381 | 2024 | Peer-reviewed | Ni concentrations and health risk assessment in infant rice cereal (n=18) |
| 34 | Zhu et al. 2024. Toxic and essential metals: metabolic interactions with the gut microbiota and health implications, Frontiers in Nutrition 11:1448388 | 2024 | Peer-reviewed | Ni and gut microbiome: taxa-level effects, functional consequences, and disease-process links |
| 35 | Amarh et al. 2023. Health risk assessment of some selected heavy metals in infant food sold in Wa, Ghana, Heliyon | 2023 | Peer-reviewed | Ni concentrations and health risk assessment in infant/baby food (n=22) |
| 36 | El-Batal et al. 2023. Effect of selenium nanoparticles on heavy metal accumulation in carrot (Daucus carota) irrigated with wastewater, Biologia | 2023 | Peer-reviewed | Ni data: El-Batal et al. |
| 37 | Henríquez-Hernández et al. 2023. Concentration of Essential, Toxic, and Rare Earth Elements in Ready-to-Eat Baby Purees from the Spanish Market, Nutrients 15(14):3251 | 2023 | Peer-reviewed | Ni concentrations in ready-to-eat baby purees (n=159) by ICP-MS |
| 38 | Kamaly et al. 2023. Health risk assessment of metals in chicken meat and liver in Egypt, Environmental Science and Pollution Research | 2023 | Peer-reviewed | [awaiting synthesis] |
| 39 | Kazeminia et al. 2023. Heavy metals and their adverse effects: sources, risks, and strategies to reduce accumulation in tea herb — a systematic review, Carpathian Journal of Food Science and Technology | 2023 | Peer-reviewed | Systematic review of Ni in tea herb: synthesised occurrence, health effects, and exposure data |
| 40 | Marriott et al. 2023. Considerations for environmental biogeochemistry and food security for aquaculture around Lake Victoria, Kenya, Environmental Geochemistry and Health | 2023 | Peer-reviewed | [awaiting synthesis] |
| 41 | Martinez-Morata et al. 2023. A State-of-the-Science Review on Metal Biomarkers, Current Environmental Health Reports, Vol. 10, No. 3, pp. 215-249 | 2023 | Peer-reviewed | State-of-the-science review on metal biomarkers: blood, urine, and tissue matrices for Ni exposure assessment |
| 42 | Milani et al. 2023. Trace Elements in Soy-Based Beverages: A Comprehensive Study of Total Content and In Vitro Bioaccessibility, International Journal of Environmental Research and Public Health | 2023 | Peer-reviewed | Ni data: This A-tier peer-reviewed paper is the first promoted Category 5 occurrence source for the soy-based plant-milk row. |
| 43 | Myat et al. 2023. Arsenic and heavy metal contents in white rice samples from rainfed paddy fields in Yangon division, Myanmar—Natural background levels?, PLoS ONE | 2023 | Peer-reviewed | [awaiting synthesis] |
| 44 | Romero-Crespo et al. 2023. Heavy metals in soils and crops in a mining area of Ecuador, Environmental Geochemistry and Health | 2023 | Peer-reviewed | Ni data: Romero-Crespo et al. |
| 45 | Salmani et al. 2023. Comparison of Essential and Toxic Metals Levels in some Herbal Teas: a Systematic Review, Biological Trace Element Research | 2023 | Review | Systematic review of Ni in black tea: synthesised occurrence, health effects, and exposure data |
| 46 | Suomi et al. 2023. Cumulative risk assessment of the dietary heavy metal and aluminum exposure of Finnish adults, Environmental Science and Pollution Research | 2023 | Peer-reviewed | [awaiting synthesis] |
| 47 | Wang et al. 2023. Heavy metal(loid)s in agricultural soil from main grain production regions of China: Bioaccessibility and health risks to humans, Science of the Total Environment | 2023 | Peer-reviewed | Ni concentrations and health risk assessment in grain crops (n=509) |
| 48 | Wang et al. 2023. Spatial distribution, sources, and risks of heavy metals in soil from industrial areas of Hangzhou, eastern China, Environmental Earth Sciences | 2023 | Peer-reviewed | Ni exposure in industrial settings: occupational biomonitoring and community health context |
| 49 | Yang et al. 2023. Nickel exposure induces gut microbiome disorder and serum uric acid elevation, Environmental Pollution, Vol. 324, 121349 | 2023 | Peer-reviewed | Occupational Ni exposure, gut microbiome dysbiosis, and serum uric acid elevation: mechanistic links from Environmental Pollution study |
| 50 | Zergui et al. 2023. Evaluation of trace metallic element levels in coffee by ICP-MS: a comparative study among different origins, forms, and packaging types and consumer risk assessment, Biological Trace Element Research | 2023 | Peer-reviewed | Ni concentrations and health risk assessment in coffee (n=44) by ICP-MS |
| 51 | FDA 2022. Total Diet Study Report: Fiscal Years 2018-2020 Elements Data, U.S. Food and Drug Administration, Total Diet Study Program | 2022 | Government report | FDA Total Diet Study FY2018-2020: Ni concentrations and estimated dietary exposures across commercial food categories |
| 52 | FDA 2022. FY2018-FY2020 TDS Elements Analytical Results Key, FDA Total Diet Study supporting documentation | 2022 | Government report | FDA TDS FY2018-2020 analytical key: Ni measurement LODs and QA/QC parameters by food category |
| 53 | FDA 2022. FY2018-FY2020 TDS Elements Analytical Results, FDA Total Diet Study | 2022 | Government dataset | FDA Total Diet Study FY2018-2020: Ni concentrations and estimated dietary exposures across commercial food categories |
| 54 | Astolfi et al. 2021. Determination of 40 Elements in Powdered Infant Formulas and Related Risk Assessment, International Journal of Environmental Research and Public Health | 2021 | Peer-reviewed | Ni concentrations and health risk assessment in infant formula (n=22) |
| 55 | Kinuthia et al. 2021. Urban mosquitoes and filamentous green algae: their biomonitoring role in heavy metal pollution in open drainage channels in Nairobi industrial area, Kenya, BMC Ecology and Evolution | 2021 | Peer-reviewed | Ni human biomonitoring: blood/urine/tissue concentrations as exposure indicators |
| 56 | Li et al. 2021. Occurrence, accumulation, and risk assessment of trace metals in tea (Camellia sinensis): A national reconnaissance, Science of the Total Environment | 2021 | Peer-reviewed | Ni concentrations and health risk assessment in tea (n=225) |
| 57 | Marques et al. 2021. Essential and Non-essential Trace Elements in Milks and Plant-Based Drinks, Biological Trace Element Research | 2021 | Peer-reviewed | Ni concentrations in milk and dairy by ICP-MS |
| 58 | Program 2021. Nickel Compounds and Metallic Nickel — 15th Report on Carcinogens, National Toxicology Program, 15th Report on Carcinogens | 2021 | Government report | NTP 15th Report on Carcinogens: nickel carcinogenicity classification (known/reasonably anticipated) and supporting evidence |
| 59 | Ufelle et al. 2021. Toxic Effects of Metals (Chapter 23), in Casarett & Doull’s Essentials of Toxicology, Fourth Edition, Casarett & Doull’s Essentials of Toxicology, Fourth Edition. McGraw Hill Education | 2021 | Textbook chapter | Toxicology reference text on nickel: mechanisms of toxicity, target organs, and clinical manifestations |
| 60 | Uzomah et al. 2021. Chemical Contaminants in Nigerian Fresh and Marine Fish: A Review, Foods | 2021 | Peer-reviewed | Ni concentrations in fish and seafood |
| 61 | Yousaf et al. 2021. The effect of a low-nickel diet and nickel sensitization on gastroesophageal reflux disease: A pilot study, Indian Journal of Gastroenterology 40(2):137-143 | 2021 | Peer-reviewed | Low-Ni-diet clinical trial in refractory GERD and nickel sensitisation: symptom reduction and dietary Ni thresholds |
| 62 | Assefa et al. 2020. Intestinal Microbiome and Metal Toxicity, Current Opinion in Toxicology, Vol. 19, pp. 21-27 | 2020 | Peer-reviewed | Ni and gut microbiome: taxa-level effects, functional consequences, and disease-process links |
| 63 | Borghini et al. 2020. Irritable Bowel Syndrome-Like Disorders in Endometriosis: Prevalence of Nickel Sensitivity and Effects of a Low-Nickel Diet. An Open-Label Pilot Study, Nutrients 12(2):341 | 2020 | Peer-reviewed | Low-Ni-diet intervention in endometriosis with IBS-like symptoms: symptom reduction and nickel allergy prevalence assessment |
| 64 | EFSA 2020. Update of the Risk Assessment of Nickel in Food and Drinking Water, EFSA Journal 2020;18(11):6268 | 2020 | Government report | EFSA 2020 updated risk assessment for Ni: tolerable daily intake of 13 µg/kg bw/day, dose-response, and dietary exposure |
| 65 | Elsheikh et al. 2020. Evaluation of Some Toxic and Essential Trace Elements in Children Foods and Infant Formulae by Using ICP-OES, Asian Journal of Chemistry 32(6):1273-1278 | 2020 | Peer-reviewed | Ni concentrations in powdered infant formula (n=57) |
| 66 | Liu et al. 2020. Genome-wide association studies of ionomic and agronomic traits in USDA mini core collection of rice and comparative analyses of different mapping methods, BMC Plant Biology | 2020 | Peer-reviewed | Ni concentrations in rice and rice products (n=191) |
| 67 | Bakyayita et al. 2019. Assessment of Levels, Speciation, and Toxicity of Trace Metal Contaminants in Selected Shallow Groundwater Sources, Surface Runoff, Wastewater, and Surface Water from Designated Streams in Lake Victoria Basin, Uganda, Journal of Environmental and Public Health | 2019 | Peer-reviewed | Ni in Lake Victoria shallow groundwater wells: levels and speciation in Ugandan drinking and food-preparation water |
| 68 | Chekri et al. 2019. Trace element contents in foods from the first French Total Diet Study on infants and toddlers, Journal of Food Composition and Analysis | 2019 | Peer-reviewed | Ni occurrence data from a Total Diet Study on infants and toddlers: concentrations across food categories |
| 69 | Maier et al. 2019. Role of Nickel in Microbial Pathogenesis, Inorganics 7(7):80 | 2019 | Peer-reviewed | Ni-dependent virulence and microbial pathogenesis: nickel-metalloenzyme systems |
| 70 | Romero-Estevez et al. 2019. Content and the relationship between cadmium, nickel, and lead concentrations in Ecuadorian cocoa beans from nine provinces, Food Control | 2019 | Peer-reviewed | Ni concentrations in cocoa/chocolate by AAS |
| 71 | Ametepey et al. 2018. Determination of heavy metals in selected vegetables from markets in Tamale Metropolis, Ghana, International Journal of Food Contamination | 2018 | Peer-reviewed | Ni concentrations in vegetables (n=75) by AAS |
| 72 | Zhang et al. 2018. Accumulation of Heavy Metals in Tea Leaves and Potential Health Risk Assessment: A Case Study from Puan County, Guizhou Province, China, International Journal of Environmental Research and Public Health | 2018 | Peer-reviewed | Ni concentrations and health risk assessment in tea (n=26) by ICP-MS |
| 73 | Akhtar et al. 2017. Determination of aflatoxin M1 and heavy metals in infant formula milk brands available in Pakistani markets, Korean Journal for Food Science of Animal Resources | 2017 | Peer-reviewed | Ni concentrations in infant formula (n=13) |
| 74 | Arévalo-Gardini et al. 2017. Heavy metal accumulation in leaves and beans of cacao (Theobroma cacao L.) in major cacao growing regions in Peru, Science of the Total Environment | 2017 | Peer-reviewed | Ni accumulation in cacao leaves and beans across Peruvian regions: co-occurrence survey with Cd and other metals in cacao supply chain |
| 75 | Chandrangsu et al. 2017. Metal homeostasis and resistance in bacteria, Nature Reviews Microbiology, Vol. 15, pp. 338-350 | 2017 | Peer-reviewed | Bacterial Ni homeostasis and resistance: metalloregulatory systems, efflux transporters, and food-safety context |
| 76 | Kilbo et al. 2017. Health Risk Assessment of PM2.5 and PM2.5-Bound Trace Elements in Thohoyandou, South Africa, International Journal of Environmental Research and Public Health | 2017 | Peer-reviewed | Ni in PM2.5 in Thohoyandou, South Africa: inhalation health risk assessment with carcinogenic Ni characterisation |
| 77 | Rizzi et al. 2017. Irritable Bowel Syndrome and Nickel Allergy: What Is the Role of the Low Nickel Diet?, Journal of Neurogastroenterology and Motility 23(1):101-108 | 2017 | Peer-reviewed | Low-Ni-diet clinical trial in IBS and nickel allergy: symptom reduction and dietary Ni thresholds |
| 78 | Brzezicha-Cirocka et al. 2016. Monitoring of essential and heavy metals in green tea from different geographical origins, Environmental Monitoring and Assessment | 2016 | Peer-reviewed | Ni concentrations in tea infusions (n=41) |
| 79 | FSA 2016. Survey of metals in commercial infant foods, infant formula and non-infant specific foods, UK Food Standards Agency report FS102048 | 2016 | Government report | UK Food Standards Agency 2016 survey: Ni concentrations in infant foods and formula |
| 80 | Li et al. 2015. A comparison of the potential health risk of aluminum and heavy metals in tea leaves and tea infusion of commercially available green tea in Jiangxi, China, Environmental Monitoring and Assessment | 2015 | Peer-reviewed | Ni concentrations and health risk assessment in tea infusions (n=26) by ICP-MS |
| 81 | Campanale et al. 2014. Nickel Free-Diet Enhances the Helicobacter pylori Eradication Rate: A Pilot Study, Digestive Diseases and Sciences 59(8):1851-1855 | 2014 | Peer-reviewed | Low-Ni-diet enhances H. pylori eradication rate: randomised pilot trial, dietary Ni thresholds and clinical response |
| 82 | Lutfullah et al. 2014. Comparative study of heavy metals in dried and fluid milk in Peshawar by atomic absorption spectrophotometry, The Scientific World Journal | 2014 | Peer-reviewed | Ni concentrations in infant formula (n=46) |
| 83 | Braga et al. 2013. Systemic Nickel Allergy Syndrome: Nosologic Framework and Usefulness of Diet Regimen for Diagnosis, International Journal of Immunopathology and Pharmacology 26(3):707-716 | 2013 | Peer-reviewed | Canonical nosologic framework for Systemic Nickel Allergy Syndrome (SNAS): diagnostic criteria and Ni-restricted diet rationale |
| 84 | Pandelova et al. 2012. Ca, Cd, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn contents in baby foods from the EU market: Comparison of assessed infant intakes with the present safety limits for minerals and trace elements, Journal of Food Composition and Analysis | 2012 | Peer-reviewed | Ni concentrations in baby food |
| 85 | Minelli et al. 2010. Oral Hyposensitization to Nickel Induces Clinical Improvement and a Decrease in Th1 and Th2 Cytokines in Patients with Systemic Nickel Allergy Syndrome, International Journal of Immunopathology and Pharmacology 23(1):193-201 | 2010 | Peer-reviewed | Oral Ni hyposensitisation: immunological mechanism (Th1/Th2 shift) and clinical response in SNAS patients |
| 86 | EPA 2007. Ecological Soil Screening Levels for Nickel — Interim Final, OSWER Directive 9285.7-76, U.S. Environmental Protection Agency | 2007 | Government report | EPA ecological soil screening level for nickel: risk-based soil guideline for ecological receptor protection |
| 87 | Limited 2003. Risk of sensitisation of humans to nickel by piercing post assemblies, Final Report submitted under EC Contract ETD/FIF.2001592 | 2003 | Government report | LGC risk assessment of Ni sensitisation from body-piercing jewellery: release rates and LNCD threshold context |
| 88 | Pacor et al. 2003. Results of Double-Blind Placebo-Controlled Challenge with Nickel Salts in Patients Affected by Recurrent Aphthous Stomatitis, International Archives of Allergy and Immunology 131(4):296-300 | 2003 | Peer-reviewed | Double-blind placebo-controlled oral Ni challenge in recurrent aphthous stomatitis patients: dose-response and SNAS diagnostic context |
| 89 | Veien et al. 1993. Low nickel diet: An open, prospective trial, Journal of the American Academy of Dermatology 29(6):1002-1007 | 1993 | Peer-reviewed | Low-Ni-diet clinical trial in nickel-contact dermatitis: symptom reduction and dietary Ni thresholds |
| 90 | Flyvholm et al. 1984. Nickel Content of Food and Estimation of Dietary Intake, Zeitschrift für Lebensmittel-Untersuchung und -Forschung 179(6):427-431 | 1984 | Peer-reviewed | Ni dietary intake estimation across Danish food categories by wet-ashing AAS: foundational food-Ni occurrence dataset |
| 91 | Kirkpatrick et al. 1980. The Trace Element Content of Canadian Baby Foods and Estimation of Trace Element Intake by Infants, Canadian Institute of Food Science and Technology Journal 13(4):154-161 | 1980 | Peer-reviewed | Ni concentrations in baby food (n=330) |
| 92 | Kaaber et al. 1978. Low nickel diet in the treatment of patients with chronic nickel dermatitis, British Journal of Dermatology 98(2):197-201 | 1978 | Peer-reviewed | Low-Ni-diet clinical trial in chronic nickel dermatitis: symptom reduction and dietary Ni thresholds |
| 93 | Kim et al.. Evaluation of selected ultra-trace minerals in commercially available dry dog foods, Veterinary Medicine: Research and Reports | — | Peer-reviewed | Ni concentrations in dry pet food (n=49) |