Overview
Gold (Au) occupies an unusual position in the food safety literature. Rather than appearing primarily as a contaminant, gold features overwhelmingly as an analytical reagent: gold nanoparticles (AuNPs), gold nanoclusters, and gold nanoflowers are engineered platforms for detecting other hazards including heavy metals, mycotoxins, antibiotics, pesticides, and foodborne pathogens. The 16 papers ingested for this deposit reflect that distribution: 14 describe AuNP-based biosensors validated in food matrices, and 2 characterize potentially toxic element contamination in South African soils near gold mine tailings, where gold is the mining context rather than the measured analyte. Ufelle & Barchowsky 2021 adds a chapter-level toxicological note that gold is listed among metals that can provoke immune reactions and has historical therapeutic applications.
No food occurrence data for gold as a dietary contaminant are contributed by any source in this deposit. This page documents the analytical role of gold in food safety science and the environmental contamination context associated with gold mining operations.
Toxicological context
Ufelle & Barchowsky 2021 names gold in two chapter-level contexts within the metals toxicology chapter: as one of the metals capable of provoking immune reactions, and in connection with the historical and therapeutic use of metal compounds. The chapter does not include a dedicated gold subsection, so these references represent the outer boundary of what this textbook source contributes. No dose-response data, mechanism of toxicity, or regulatory limits for gold in food are provided by any source in this deposit.
Gold nanoparticles as food safety sensing platforms
The dominant finding from this evidence deposit is that gold nanoparticles and their structural variants serve as versatile analytical platforms across multiple food safety target classes. The core mechanism is gold’s strong surface plasmon resonance, which shifts measurably in wavelength when AuNPs aggregate or are etched, and the ease with which gold surfaces can be functionalized with aptamers, antibodies, molecularly imprinted polymers, or redox mediators.
Heavy metal detection
Peng et al. 2018 demonstrated that methionine-capped gold nanoclusters detect cadmium ion with an LOD of 0.1 µg/L in spiked skim milk powder, with recoveries of 91.2 to 103.8%. Yoon et al. 2021 developed d-penicillamine-functionalized AuNPs as a dual colorimetric probe for simultaneous detection of mercury ion (LOD 0.5 nM) and arsenite ion (LOD 0.7 nM) in spiked drinking water, achieving recoveries of 95 to 104%. Shinde et al. 2017 validated casein peptide-functionalized AuNPs for aluminum ion detection (LOD 20 ppb) in drinking water and an ionic drink at one-tenth the WHO guideline value. Yu et al. 2016 applied a Fenton-like etching mechanism using concave gold nanocubes to detect cobalt ions with an LOD of 0.3 nM in river and pond water. In each case, gold is the analytical instrument and the other metal is the target analyte.
Mycotoxin and foodborne toxin detection
Argoubi et al. 2024 developed a ferrocene-tethered AuNP aptasensor for ochratoxin A validated in spiked roasted coffee bean extracts and French wine, achieving an LOD of 0.011 ng/mL, well below the EU maximum levels of 10 µg/kg in roasted coffee and 2 µg/L in wine. Mondal et al. 2018 demonstrated an anti-SEB DNA aptamer conjugated to 13 nm AuNPs for staphylococcal enterotoxin B detection in spiked commercial whole milk, apple juice, and pomegranate juice at LOD 0.5 ng/mL spectrometric, with recoveries of 88 to 96%. Argoubi et al. 2015 reported a cauliflower-shaped AuNP platform on screen-printed carbon electrodes validated for hydrogen peroxide in honey (LOD 0.66 µM) and human IgG in serum (LOD 0.11 ng/mL), illustrating the multipurpose character of AuNP electrode architectures.
Antibiotic and pesticide residue monitoring
Ali et al. 2021 validated a graphene oxide-gold nanoflower modified screen-printed electrode for chloramphenicol residues (LOD 1 nM) across spiked milk, honey, egg, and poultry feed, relevant to veterinary drug surveillance in animal-derived foods. Surya et al. 2020 developed a chitosan-gold nanoparticle molecularly imprinted polymer electrode for ciprofloxacin (LOD 0.21 µmol/L) validated in spiked milk, tap water, and mineral water, with the note that the sensor requires pre-concentration to reach the EU MRL for ciprofloxacin in bovine milk. Liu et al. 2018 reported an anti-aggregation AuNP assay for metsulfuron-methyl herbicide (LOD 0.05 mg/L) validated in spiked agricultural irrigation water, tap water, and well water.
Microbiological and other contaminant screening
Zheng et al. 2019 used AuNPs as mass-loading signal amplifiers in a microcantilever array biosensor for simultaneous culture-free detection of six foodborne bacterial pathogens in spiked pasteurized milk at LOD 1 to 9 cells/mL. Farshchi et al. 2024 applied gold nanoflowers in a colorimetric assay for acetaldehyde detection, exploiting AuNP surface catalysis. Plaisen et al. 2018 validated an AuNP colorimetric method for bromide in rice, illustrating applicability to inorganic halogen residues in a staple food matrix. Li et al. 2018 demonstrated a lateral flow immunochromatographic strip using AuNPs for polymyxin B antibiotic residues in spiked raw milk at LOD 0.5 µg/L.
Environmental context: gold mining and soil contamination
Two papers characterize potentially toxic element contamination around South African gold mining operations. Neither paper measures gold concentrations; both document co-contamination plumes from tailings.
Okereafor et al. 2019 sampled agricultural soil near a decommissioned gold mine dump in Ekurhuleni, Gauteng, reporting maximum soil concentrations (mg/kg dry weight) of arsenic 118.4, chromium 183.3, lead 1,019.0, zinc 1,802.0, and manganese 2,170.0, among other elements. These values substantially exceed typical agricultural soil background concentrations and illustrate the PTE contamination footprint of gold mine tailings on surrounding farmland.
Makhadi et al. 2026 extended this characterization to the Welkom Goldfield in Free State, South Africa, finding that arsenic, chromium, and uranium ranked as moderately to heavily polluted at certain sites by geoaccumulation index. Lead and uranium ranged from unpolluted to strongly contaminated depending on proximity to tailings dams. Surface water quality was also assessed, with elevated sulfate and other anions consistent with acid mine drainage. These findings are relevant to understanding how gold mining landscapes generate secondary PTE exposure pathways for nearby agricultural communities.
What remains uncertain
No source in this deposit provides food occurrence data for gold itself, whether as ionic gold, gold compounds, or gold nanoparticles ingested through food. The scale and mechanism of dietary gold exposure from food additives, food contact materials, edible gold leaf (E175), or incidental contamination is not documented here. The two South African soil studies do not extend their findings to crop uptake, dietary exposure estimates, or bioavailability assessments. The immune reaction mechanism referenced by Ufelle & Barchowsky 2021 is stated at the chapter level only, with no dose, population, or mechanistic detail available from this source. Future ingest focused on therapeutic gold compounds, gold nanoparticle food safety (intentional food additive use and consumer exposure), and agricultural uptake near mining operations would substantially strengthen this page.
Frequently asked questions
Does the Heavy Metal Index have detailed information on gold in food or consumer products?
Not yet. This page is a source-map stub, and the one source cited does not provide a dedicated gold subsection, so the page currently carries only source-map context rather than gold-specific findings. As the page notes, substantive gold-specific expansion awaits a dedicated ingest.
Why is gold mentioned in the toxicology literature at all?
According to Ufelle & Barchowsky 2021, gold is named in two chapter-level contexts: as one of the metals that can provoke immune reactions, and in connection with the historical and therapeutic use of metal compounds. The source discusses these only at a chapter level rather than in a dedicated gold section.
Can gold trigger immune or allergic reactions?
Ufelle & Barchowsky 2021 lists gold among metals that can provoke immune reactions. The page does not provide further detail on the mechanism, dose, or affected populations, because the underlying chapter treats gold only in passing.
Has gold historically been used in medicine or therapy?
The cited source, Ufelle & Barchowsky 2021, references gold in the context of the historical and therapeutic use of metal compounds. The page does not elaborate on specific therapeutic applications beyond noting this context.
Sources
- Ufelle & Barchowsky 2021 : Ufelle AC, Barchowsky A, 2021. Toxic Effects of Metals, Ch 23 in Casarett & Doull’s Essentials of Toxicology, 4th ed.
- Peng et al. 2018 : Peng X et al., 2018. Methionine-capped gold nanoclusters for cadmium detection in milk powder. Sensors (Basel).
- Yoon et al. 2021 : Yoon J et al., 2021. Dual colorimetric probe for mercury and arsenic using d-penicillamine-functionalized AuNPs. RSC Advances.
- Argoubi et al. 2015 : Argoubi W et al., 2015. Cauliflower-shaped AuNP multipurpose biosensing platform on SPCE. Beilstein J Nanotechnol.
- Argoubi et al. 2024 : Argoubi W et al., 2024. AuNP aptasensor for ochratoxin A in coffee and wine. RSC Advances.
- Mondal et al. 2018 : Mondal K et al., 2018. Label-free aptamer-AuNP colorimetric biosensor for staphylococcal enterotoxin B. Front Microbiol.
- Ali et al. 2021 : Ali A et al., 2021. Graphene oxide-gold nanoflower modified SPE for chloramphenicol detection. RSC Advances.
- Zheng et al. 2019 : Zheng F et al., 2019. AuNP-amplified microcantilever biosensor for six foodborne bacteria. Front Chem.
- Yu et al. 2016 : Yu CJ et al., 2016. Concave gold nanocubes for cobalt ion colorimetric sensing. RSC Advances.
- Shinde et al. 2017 : Shinde S et al., 2017. Surface functionalized AuNPs as spectral probe for aluminum detection. Nanomaterials (Basel).
- Plaisen et al. 2018 : Plaisen S et al., 2018. AuNP colorimetric method for bromide in rice. RSC Advances.
- Li et al. 2018 : Li S et al., 2018. AuNP lateral flow strip for polymyxin B in raw milk. Nanomaterials (Basel).
- Surya et al. 2020 : Surya SG et al., 2020. Chitosan-AuNP molecularly imprinted polymer sensor for ciprofloxacin. RSC Advances.
- Farshchi et al. 2024 : Farshchi F et al., 2024. Gold nanoflower colorimetric assay for acetaldehyde. RSC Advances.
- Liu et al. 2018 : Liu W et al., 2018. AuNP anti-aggregation sensor for metsulfuron-methyl herbicide. Sensors (Basel).
- Okereafor et al. 2019 : Okereafor U et al., 2019. Trace metals in farming area near gold mine dump, Ekurhuleni, South Africa. Data in Brief.
- Makhadi et al. 2026 : Makhadi R et al., 2026. Geochemical assessment of soil and water around Welkom Goldfield tailings. Environ Geochem Health.
References
Works cited in this page’s text, in first-appearance order. See Sources for this page’s source inventory. Each title links to a source record with bibliographic details, reported findings, and document provenance.
- Toxic Effects of Metals (Chapter 23), in Casarett & Doull’s Essentials of Toxicology, Fourth EditionTextbook
- Methionine-Capped Gold Nanoclusters as a Fluorescence-Enhanced Probe for Cadmium(II) SensingPeer-reviewed
- A dual colorimetric probe for rapid environmental monitoring of Hg(2+) and As(3+) using gold nanoparticles functionalized with d-penicillaminePeer-reviewed
- A Spectral Probe for Detection of Aluminum (III) Ions Using Surface Functionalized Gold NanoparticlesPeer-reviewed
- Etching-induced morphological evolution of concave gold nanocubes for enhanced colorimetric sensing of cobalt ions based on Fenton-like reactionsPeer-reviewed
- Enhanced sensitivity in electrochemical detection of ochratoxin A within food samples using ferrocene- and aptamer-tethered gold nanoparticles on disposable electrodesPeer-reviewed
- Highly Sensitive Colorimetric Biosensor for Staphylococcal Enterotoxin B by a Label-Free Aptamer and Gold NanoparticlesPeer-reviewed
- Optimized design of a nanostructured SPCE-based multipurpose biosensing platform formed by ferrocene-tethered electrochemically-deposited cauliflower-shaped gold nanoparticlesPeer-reviewed
- N-Hydroxysuccinimide crosslinked graphene oxide-gold nanoflower modified SPE electrode for sensitive detection of chloramphenicol antibioticPeer-reviewed
- A chitosan gold nanoparticles molecularly imprinted polymer based ciprofloxacin sensorPeer-reviewed
- Visual and Colorimetric Sensing of Metsulfuron-Methyl by Exploiting Hydrogen Bond-Induced Anti-Aggregation of Gold Nanoparticles in the Presence of MelaminePeer-reviewed
- Simultaneous and Ultrasensitive Detection of Foodborne Bacteria by Gold Nanoparticles-Amplified Microcantilever Array BiosensorPeer-reviewed
- Identification of acetaldehyde based on plasmonic patterns of a gold nanostructure conjugated with chromophore and H(2)O(2): a new platform for the rapid and low-cost analysis of carcinogenic agents by colorimetric affordable test strip (CATS)Peer-reviewed
- Robust colorimetric detection based on the anti-aggregation of gold nanoparticles for bromide in rice samplesPeer-reviewed
- A Rapid and Semi-Quantitative Gold Nanoparticles Based Strip Sensor for Polymyxin B Sulfate ResiduesPeer-reviewed
- Dataset on assessment of pollution level of selected trace metals in farming area within the proximity of a gold mine dump, Ekuhurleni, South AfricaPeer-reviewed
- Geochemical assessment of soil and water around abandoned gold mine tailings dams: evidence from the Welkom Goldfield, South AfricaPeer-reviewed
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