Gallium is often detected in rural Chinese drinking groundwater and in soil, while the foods tested were mostly below quantification, and no health limit is cited.
- Role: No nutritional role is described. Gallium drugs are studied because they compete with how cells use iron.
- Main exposure: Drinking groundwater is the best measured route, with a median of 8.5 µg/L in 166 rural Chinese wells. Honey and tomato fruit were below quantification.
- Key distinction: A measured concentration is not a risk judgment. The cited studies found no reference dose and no regulatory limit.
This page draws on 11 peer-reviewed studies. The complete citation list is at the bottom of the page.
Overview
Gallium is a technology-critical element used mainly in integrated circuits and optoelectronic devices. Its ionic radius is close to those of aluminum, iron, magnesium, and manganese, so its movement in soil and plants is sometimes compared with those elements 1. No nutritional role is described in the cited literature. Gallium compounds have been studied as drugs because they compete with iron uptake and can inhibit the iron-dependent enzyme ribonucleotide reductase 2.
The other nine papers measure gallium rather than dose it as a drug. They report it in drinking groundwater 3, honey 4, urban garden vegetables 5, human plasma and serum 6 7 8, mining-affected water 9, mining-area soil 10, and river sediment 11. Across those measurements gallium is common in soil, sediment, and rural Chinese groundwater, usually at or below quantification in the foods tested, and present at low or undetectable levels in the blood samples.
Toxicology
The cited evidence does not establish gallium toxicity in people at the concentrations measured in water, food, or blood. A national groundwater assessment could not obtain a reference dose for gallium, or for rubidium, thallium, or thorium, and left those four metals out of its noncancer risk totals 3.
Laboratory data concern a drug, not dietary exposure. In cultured human cells, the organic complex tris(8-quinolinolato)gallium(III), known as KP46, killed four bone-cancer cell lines at low micromolar concentrations and was less toxic to non-malignant lung fibroblasts, which showed no loss of viability up to 5 µM 2. The same paper, summarizing earlier work, states that simple gallium salts (gallium nitrate and gallium chloride) were tested clinically but that unfavorable pharmacokinetic and toxicological properties prevented routine use, and that KP46 has a strong affinity for bone 2. Those clinical statements are background, not new findings.
Three clinical studies report associations, not effects. Serum gallium was slightly higher in patients with renal cell carcinoma than in patients with benign kidney tumors; healthy controls matched the benign-tumor mean 7. Serum gallium also correlated weakly with estimated glomerular filtration rate in that study (r = 0.212, P = 0.034) 7. In a larger chronic kidney disease study, the median was 0 µg/L in both patients and the comparison group, with the comparison group’s upper quartile at 0.02 µg/L 8. Plasma gallium did not differ by cognitive status in a small Taiwanese sample 6.
| Study / location | Material / design | Metal species | Value (units and basis) | n | Interpretation / limitation |
|---|---|---|---|---|---|
| 2, Vienna (laboratory) | Human osteosarcoma cell lines, 72 h MTT assay | KP46 (organic gallium complex) | IC50 1.204 to 3.830 µM (mean of three experiments) | 4 cell lines | Drug-level cell toxicity; not an exposure benchmark |
| 2, Vienna (laboratory) | Non-malignant human lung fibroblasts, 72 h MTT assay | KP46 | IC50 9.01 µM; no viability loss up to 5 µM | 1 culture | Single comparison cell type |
| 7, Mianyang, China, March 2021 to June 2022 | Serum, kidney tumor case-control, ICP-MS | Total gallium | Mean 1.13 ± 0.16 µg/L (renal cell carcinoma), 1.04 ± 0.18 µg/L (benign tumors), 1.04 ± 0.18 µg/L (healthy controls); F = 4.453, P = 0.013 | 57, 43, and 50 | Association only; small difference |
| 6, Taiwan | Plasma, control vs amnestic mild cognitive impairment vs Alzheimer’s disease | Total gallium | Median (1st, 3rd quartile) 0.071 (0.047, 0.095), 0.059 (0.024, 0.071), and 0.036 (0.035, 0.036) µg/L; age-adjusted P = 0.173 and 0.248 vs control | 9, 23, and 8 | No significant group difference; Alzheimer’s group is small |
| 8, Shenyang, China, November 2021 to August 2022 | Serum, chronic kidney disease vs health-exam comparison group | Total gallium | Median (IQR) 0 (0, 0) µg/L in patients and 0 (0, 0.02) µg/L in the comparison group; P < 0.001 | 443 and 100 | Both medians sit at the detection floor; values below the detection limit were replaced with half the limit in the analysis |
Typical exposure routes
Drinking water is the best quantified route in the cited evidence. In 166 groundwater samples from wells used for drinking in 28 Chinese provinces, municipalities, and autonomous regions, collected in July of 2016, February of 2017, and July of 2017, gallium was reported as a median to maximum of 8.5 to 89 µg/L, with a detection frequency above 90 percent 3. Some of those provinces were not sampled. The paper does not give a mean or a lower percentile in the main text.
Mining can release gallium to water. Around artisanal gold mining in Marmato, Colombia, the authors state that gallium was detectable and that concentrations were elevated in mining-affected waters, and they attribute it to substitution in the zinc sulfide mineral sphalerite 9. The main text prints no gallium concentration.
Gallium is abundant in soils and sediments relative to plant tissue. Soils at a selenium mine in Enshi, China, held 27.76 ± 1.81 mg/kg in the control, 20.1 ± 2.24 mg/kg at the lower selenium level, and 10.24 ± 3.59 mg/kg at the higher selenium level 10. Bottom sediments of the Biała Przemsza River in a Polish zinc and lead mining district averaged 11.8 mg/kg, with a maximum of 25.6 mg/kg 11. Most of that sediment gallium was in the residual mineral fraction. The largest share in the more mobile amorphous iron and aluminum hydroxide fraction was 7 percent 11.
Human blood is a measured internal marker, not an intake. The serum and plasma values above are single blood draws. They do not identify which food or water supplied the gallium.
| Study / location | Material / design | Metal species | Value (units and basis) | n | Interpretation / limitation |
|---|---|---|---|---|---|
| 3, rural China, 2016 to 2017 | Groundwater used for drinking, ICP-MS | Total gallium | Median to maximum 8.5 to 89 µg/L; detection frequency above 90 percent | 166 wells | Main text gives median and maximum only; full distribution is in a supplement |
| 11, Biała Przemsza River, Poland | Bottom sediment, ICP-MS | Total gallium | Average 11.8 mg/kg (11,800 µg/kg); maximum 25.6 mg/kg at site BP3 | several sites and seasons | Mining-affected river; mostly residual, so not readily mobile |
| 10, Enshi, China | Mining-area soil, ICP-MS | Total gallium | 27.76 ± 1.81, 20.1 ± 2.24, and 10.24 ± 3.59 mg/kg (control, low selenium, high selenium) | 30 samples collected for the microbial work; chemistry group size not stated | Soil, not food; gallium was lower where selenium was higher |
Food sources
Few foods in the cited evidence contain measurable gallium. Gallium was analyzed in 61 honey samples from eight regions of Romania and was not detected in any of them 4. The results column is labeled µg/kg. The footnote prints a quantification limit of 0.04 µ/L for the gallium isotope measured, so the non-detect cannot be restated as a honey concentration in µg/kg without a dilution factor the paper does not apply.
In Vienna urban gardens, gallium in tomato fruit parts (skin, pulp, and seeds) was below the quantification limit, together with beryllium, iron, cobalt, nickel, silver, thallium, lead, and uranium 5. Numeric gallium mass fractions for other garden tissues are in a supplement that is not restated here.
Wild plants on uncontaminated soil in St. Petersburg took up only a small share of soil gallium. At one site, rhizosphere soil held 6.55 ± 0.33 mg/kg under couch grass and 7.32 ± 0.73 mg/kg under plantain. Roots held 1.52 ± 0.45 and 0.46 ± 0.14 mg/kg, and leaves held 0.058 ± 0.010 and 0.14 ± 0.05 mg/kg 1. Those figures are mg/kg after the plants were washed and air dried to constant weight. The same paper cites other work for a plant range of 0.001 to 0.30 mg/kg on uncontaminated soils, mostly in crops such as rice and wheat, and a soil range of 3 to 300 mg/kg 1. Those ranges are background citations, not new measurements, and the plants in the study are weeds, not foods.
| Study / location | Material / design | Metal species | Value (units and basis) | n | Interpretation / limitation |
|---|---|---|---|---|---|
| 4, Romania | Honey, eight regions, ICP-MS | Total gallium | Not detected in any sample. Footnote quantification limit 0.04 µ/L; table unit µg/kg | 61 | One food, one country; the two units are not reconciled in the paper |
| 5, Vienna | Tomato fruit skin, pulp, and seeds | Total gallium | Below the quantification limit | see paper | Numeric tissue values are in the supplement |
| 1, St. Petersburg, site 1 | Wild plant leaves, air dried to constant weight | Total gallium | 0.058 ± 0.010 mg/kg couch grass (58 ± 10 µg/kg); 0.14 ± 0.05 mg/kg plantain (140 ± 50 µg/kg) | 3 to 6 plants per sampling | Weeds, not food crops |
Regulatory limits
The cited evidence does not state any food, drinking water, or supplement limit for gallium, and it does not state a tolerable intake. The groundwater risk assessment explicitly found no reference dose for gallium in the databases it searched 3.
Testing
ICP-MS is the method used for gallium in every concentration study cited here: groundwater, honey, garden vegetables, wild plants, serum, plasma, mining water, mining soil, and river sediment 3 4 5 1 7 6 8 9 10 11. The drug study measured cell viability, not gallium content 2.
Quality checks differ. The plant study compared results with two certified plant reference materials and found differences under 10 percent 1. In that study, gallium in rhizosphere soil changed by about 20 percent during a day, and gallium in roots changed by more than two times, so the hour of sampling can move the result 1. In the Marmato water study, indium measured alongside gallium may have been an artifact because indium was the ICP-MS internal standard; the authors do not say that about gallium 9. The kidney tumor study used germanium as the internal standard for gallium 7.
Microbiome effects
The cited evidence does not establish any effect of gallium on the human gut microbiome. In selenium-impacted mining soils, gallium was one of several elements positively correlated with bacterial community composition, and a random forest model placed it among the top predictors of bacterial diversity 10. That is a soil correlation. Gallium moved with many other elements, so the analysis does not show that gallium itself changed the community.
Vulnerable populations
The cited evidence does not identify a group with a demonstrated health risk from gallium. Rural households using untreated groundwater had the highest measured water concentrations in this set 3, and communities near the Marmato workings are the group the mining study describes as exposed 9. Neither paper links those concentrations to a health outcome. The clinical studies enroll people with kidney tumors, chronic kidney disease, or cognitive impairment. They do not show that gallium caused those conditions 7 8 6.
Mitigation
Washing lettuce significantly reduced gallium on the leaves, along with beryllium, aluminum, vanadium, nickel, and thallium, which is consistent with a surface-bound fraction 5. The paper does not give the size of that reduction in the main text. The cited evidence does not describe a water treatment or a soil treatment that removes gallium.
Open questions
- No regulatory limit, guidance value, or reference dose for gallium is cited.
- Dietary intake has not been estimated. The foods with a gallium result are honey, all below quantification, and tomato fruit, also below quantification.
- Toxicity at the measured water, food, and blood levels is not established. The only dose data are drug concentrations in cells.
- The Marmato paper describes gallium in mining water as elevated and does not print a concentration.
- Garden vegetable concentrations other than the tomato non-detect are in a supplement and are not on this page.
- Whether soil gallium changes microbes, or only travels with other elements, is not resolved.
What remains uncertain
Each matrix on this page rests on one study. The groundwater median of 8.5 µg/L and the maximum of 89 µg/L come from rural China in 2016 and 2017 and may not describe other supplies. The honey non-detect is one country and one food, and the paper’s quantification limit is not in the same unit as the results column.
Without a toxicity benchmark, these concentrations cannot be read as a risk or as a clearance. The renal cell carcinoma mean is 1.13 µg/L and the other two group means are 1.04 µg/L, from one hospital, and the chronic kidney disease medians are both zero. Cell-line toxicity at micromolar drug concentrations does not translate into a level of everyday exposure.
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.
- Temporal Variability of Gallium in Natural PlantsPeer-reviewed
- Distinct activity of the bone-targeted gallium compound KP46 against osteosarcoma cells - synergism with autophagy inhibitionPeer-reviewed
- Occurrence and Health Risks of Organic Micro-Pollutants and Metals in Groundwater of Chinese Rural AreasPeer-reviewed
- Comprehensive Elemental Profiling of Romanian Honey: Exploring Regional Variance, Honey Types, and Analyzed Metals for Sustainable Apicultural and Environmental PracticesPeer-reviewed
- Compost amendment in urban gardens: elemental and isotopic analysis of soils and vegetable tissuesPeer-reviewed
- A Metallomic Approach to Assess Associations of Plasma Metal Levels with Amnestic Mild Cognitive Impairment and Alzheimer’s Disease: An Exploratory StudyPeer-reviewed
- Diagnostic performance of serum vitamin D metabolites and 14 inorganic elements in early prediction of kidney neoplasmPeer-reviewed
- Comparative mathematical modeling of causal association between metal exposure and development of chronic kidney diseasePeer-reviewed
- The impact of artisanal gold mining, ore processing and mineralization on water quality in Marmato, ColombiaPeer-reviewed
- Microbial diversity and community assembly in heavy metal-contaminated soils: insights from selenium-impacted mining areasPeer-reviewed
- Assessment of contamination, mobility and application of selected technology-critical elements as indicators of anthropogenic pollution of bottom sedimentsPeer-reviewed
Sources
- Daily variation of gallium in wild plants and soil (2023; peer-reviewed): measured gallium in couch grass, plantain, dandelion, and rhizosphere soil in St. Petersburg.
- Anticancer gallium compound KP46 in osteosarcoma cells (2017; peer-reviewed): in vitro cytotoxicity of an organic gallium drug; no dietary or environmental concentrations.
- Organic micropollutants and metals in rural Chinese groundwater (2020; peer-reviewed): gallium in 166 drinking-water wells, and no reference dose.
- Elemental profile of Romanian honey (2024; peer-reviewed): gallium not detected in 61 honeys.
- Elements in urban garden soils and vegetables (2024; peer-reviewed): tomato fruit below quantification; washing reduced gallium on lettuce.
- Plasma metals in mild cognitive impairment and Alzheimer’s disease (2022; peer-reviewed): plasma gallium by cognitive status in 40 adults.
- Serum elements and vitamin D in kidney tumors (2026; peer-reviewed): serum gallium in renal cell carcinoma, benign kidney tumors, and healthy controls.
- Serum metals and chronic kidney disease (2024; peer-reviewed): serum gallium at the detection floor in patients and a comparison group.
- Artisanal gold mining and water quality in Colombia (2021; peer-reviewed): gallium described in mining-affected water, with no concentration in the main text.
- Soil microbes in selenium mining soils (2025; peer-reviewed): soil gallium and a correlation with soil bacteria.
- Technology-critical elements in Polish river sediments (2024; peer-reviewed): sediment gallium concentration and low mobility.
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