Uranium is a naturally occurring element whose best-documented human exposure is drinking groundwater from uranium-rich rock, with kidney tubule changes the main health signal in the cited evidence.
- Role: A naturally occurring element listed among minor toxic metals; chemical kidney toxicity, rather than radiation, is described as its major health effect.
- Main exposure: Drinking water from wells in uranium-rich bedrock and arid groundwater, produce grown near a uranium mine, and inhaled uranium dust at work.
- Key distinction: Natural uranium in drinking water differs from the depleted uranium used in laboratory toxicology studies; isotope ratios tell them apart.
This page draws on 9 peer-reviewed studies and 2 other cited sources. The complete citation list is at the bottom of the page.
Overview
Uranium is listed among minor toxic metals for which toxicity has been described 1. That textbook chapter does not provide a detailed uranium subsection 1.
Uranium occurs naturally in the earth’s crust and in surface water and groundwater, and it is highly soluble in soft, slightly alkaline bicarbonate water under oxidizing conditions, which is why wells drilled into uranium-rich granite can carry very high levels 2. The human evidence on this page comes mainly from groundwater used for drinking in Finland, Kazakhstan and India 2 3 4. Animal and occupational studies reviewed by Finnish investigators point to chemical kidney toxicity, rather than a radiation hazard, as the major health effect of uranium 2.
Two forms recur in the cited work. Natural uranium is what people drink in well water; its isotope ratios distinguish it from fallout or industrial material 3. Depleted uranium, with a lower uranium-235 share, appears here only in laboratory toxicology studies 5 6 7.
Toxicology
Kidney
In 325 people in southern Finland who had drunk water from drilled bedrock wells for an average of 13 years, urinary uranium was associated with higher fractional excretion of calcium and phosphate, markers of proximal tubule function 2. Each 1 µg/mmol creatinine increase in urinary uranium was linked to a 1.5% (95% CI 0.6 to 2.3) rise in calcium fractional excretion and a 13% (1.4 to 25) rise in phosphate fractional excretion 2. Phosphate fractional excretion was significantly higher at water uranium above 300 µg/L than below 2 µg/L 2. The association showed no clear threshold, while creatinine clearance and urinary albumin, which reflect glomerular function, were not associated with exposure 2. The authors state that the clinical and public health relevance of these changes is not easily established 2.
Bone
In long-term exposure, uranium accumulates in bone and kidney, and the uranyl ion is thought to exchange with calcium at the surface of bone mineral 8. In 288 adults from the same Finnish well-water cohort, there was a suggestion that the bone resorption marker CTx (p = 0.05) and osteocalcin (p = 0.19) rose with uranium exposure in men, with no similar pattern in women 8. The authors conclude that bone may be a target of uranium’s chemical toxicity in humans and that more detailed evaluation is needed 8.
Cellular mechanisms
Early laboratory work showed that uranyl nitrate binds reversibly to proteins and inhibits glucose fermentation and oxidation in living yeast, an effect the authors attributed to binding at the protein layer of the cell membrane 9. In Atlantic salmon exposed for 48 hours to 0.25 to 1.0 mg/L depleted uranium in water, liver gene responses pointed to mitochondrial function and oxidative stress pathways, although no micronuclei or plasma stress changes were found 6. A preprint that has not been peer reviewed reports reduced movement and delayed hatching in zebrafish larvae at 18 ppb depleted uranium, with lower cellular reductive capacity that did not depend on reactive oxygen species 7.
Inhalation and the brain
Rats that inhaled a uranium tetraoxide aerosol for 30 minutes had higher uranium than controls in every brain region tested 4 hours later, with the highest levels in the olfactory bulbs and a front-to-back gradient 5. Microscopy located uranium along olfactory neuron dendrites, between epithelial cells and in olfactory nerve bundles, consistent with direct nose-to-brain transport 5. The study used a single 30-minute exposure and reported no functional neurological outcomes 5.
Radiological dose
Studies that modeled radiological dose from drinking well water found values below the 100 µSv per year reference cited by the authors: 1.0 to 18.7 µSv per year for adults near the Semipalatinsk test site 3, and mean annual ingestion doses of 49.30 and 56.34 µSv per year for infants aged 0 to 6 and 7 to 12 months in arid western India 4. In the Indian study the modeled chemical hazard quotient had a mean of 0.78, below unity 4.
Typical exposure routes
Drinking water (water) from private or community wells is the best-documented route in the cited evidence 2 3 4. In Finland, about one-seventh of the population was reported to use drinking water above 2 µg/L, and some wells reach 12,000 µg/L 2. Around the Semipalatinsk test site, isotope ratios showed that elevated well-water uranium was natural and came from rock weathering, not test fallout 3. In western India, dissolution of the uranium vanadate mineral carnotite, water-rock interaction and evaporation drove enrichment, and high-uranium groundwater was saline sodium chloride water with high dissolved solids 4.
| Study / location | Material / design | Metal species | Value (units and basis) | n | Interpretation / limitation |
|---|---|---|---|---|---|
| 2, southern Finland | Drilled-well drinking water, cross-sectional, 1999 | total uranium | median 28 µg/L (IQR 6 to 135; max 1,920) | 325 | Wells selected to span a wide exposure range, so not a population prevalence |
| 2, southern Finland | Daily intake from drilled-well water | total uranium | median 39 µg/day (IQR 7 to 224) | 325 | Intake derived from reported water volume and measured concentration |
| 8, southern Finland | Drilled-well drinking water, bone marker subcohort | total uranium | median 27 µg/L (IQR 6 to 116) | 288 | Subset of the same cohort, not an independent sample |
| 3, Semipalatinsk region, Kazakhstan | Drinking well water, alpha spectrometry | uranium-238 | 0.3 to 28.7 µg/L (3.6 to 356 mBq/L) | 35 | Few wells per settlement; mass converted from activity by the authors |
| 3, Irtysh River, Kazakhstan | River surface water, comparison | uranium-238 | 2.5 to 3.0 µg/L | not stated | Single river comparison |
| 4, western Rajasthan and northern Gujarat, India | Groundwater from wells, tube-wells and taps, LED fluorimetry | total uranium | 0.6 to 260 µg/L, mean 24.0 µg/L | 265 | Abstract and results disagree on the share above 30 µg/L |
Food grown near a uranium mine is a second route documented here, at low wet-weight levels (see Food sources) 10. Inhalation of uranium dust is described as the main cause of contamination in nuclear occupational activities 5. Surface soil around a prospective uranium mine in Inner Mongolia had a mean uranium-238 activity of 25.81 Bq/kg dry weight before mining began, below the Chinese and world means cited by the authors 11.
Food sources
The only food measurements in the cited evidence come from produce grown within 25 km of the Tummalapalle uranium mine in Andhra Pradesh, India 10. Uranium was the lowest-concentration element of 13 measured, ranging from 1.7 to 27.6 µg/kg wet weight across 72 samples, and the median intake from 100 g a day of these vegetables and fruits was estimated at 0.6 µg per day 10. No site away from the mine was sampled, so the study cannot show whether the mine raised produce uranium 10.
| Study / location | Material / design | Metal species | Value (units and basis) | n | Interpretation / limitation |
|---|---|---|---|---|---|
| 10, Tummalapalle, India | Tomato, core and buffer zones | total uranium | 2.7 and 4.1 µg/kg, wet weight (zone means) | not stated | Per-group n not reported; no distant control |
| 10, Tummalapalle, India | Green chilli (peppers), core and buffer zones | total uranium | 8.0 and 4.4 µg/kg, wet weight (zone means) | not stated | Highest vegetable mean, core zone |
| 10, Tummalapalle, India | Bitter gourd (vegetables), core and buffer zones | total uranium | 4.4 and 4.4 µg/kg, wet weight (zone means) | not stated | No zone difference |
| 10, Tummalapalle, India | Banana, core and buffer zones | total uranium | 16.4 and 5.3 µg/kg, wet weight (zone means) | not stated | Highest mean of all crops, core zone, wide SD |
| 10, Tummalapalle, India | Papaya (fruit), core and buffer zones | total uranium | 6.8 and 10.6 µg/kg, wet weight (zone means) | not stated | Buffer zone higher than core zone |
| 10, Tummalapalle, India | Sweet lime (fruit), core and buffer zones | total uranium | 5.4 and 4.0 µg/kg, wet weight (zone means) | not stated | Low and similar between zones |
The cited evidence does not establish uranium levels in staple foods, infant foods or market baskets, and it does not compare food with drinking water as a share of total intake.
Regulatory limits
The cited papers quote drinking-water values rather than food limits. The provisional WHO guideline for uranium in drinking water is 30 µg/L, and India’s Atomic Energy Regulatory Board set a radiological limit of 60 µg/L in 2004, while the Bureau of Indian Standards has set no limit 4 (WHO drinking-water guidelines). The United States EPA maximum contaminant level for uranium in drinking water is 30 µg/L 7 (US EPA drinking-water standards).
Earlier WHO values were lower. At the time of the Finnish kidney study, WHO had proposed a guideline value of 2 µg/L based on animal experiments in the absence of human data, and proposed guideline values ranged from 2 to 100 µg/L 2. A restrictive proposed WHO guideline of 15 µg/L from the third edition was used as the comparison for Kazakh well water 3. The Finnish authors suggested that the safe concentration may lie within the proposed range of 2 to 30 µg/L 2.
For chemical toxicity, the Indian study compared its lifetime average daily dose (mean 0.47 µg/kg body weight per day) with reference doses of 0.6 µg/kg per day from WHO and 4.4 µg/kg per day from the Atomic Energy Regulatory Board 4. For radiological dose, the reference value cited for drinking water is 100 µSv per year 3. The cited evidence does not establish any maximum level for uranium in food.
Testing
Inductively coupled plasma mass spectrometry (ICP-MS) was used for uranium in water and urine, with detection limits of 0.0004 µg/L in water and 0.002 µg/L in urine, split-sample checks and inter-laboratory comparison 2. It was also used for produce digested in nitric and perchloric acids 10 and for rat brain tissue 5. Other methods in the cited work are alpha-particle spectrometry after radiochemical separation with a uranium-232 yield tracer 3, LED fluorimetry of uranyl complexes with a detection limit of 0.2 ppb 4, and gamma spectrometry that infers uranium-238 activity in soil from a thorium-234 line 11.
Urinary uranium tracks drinking-water uranium closely: in the Finnish cohort the correlation between water and urine concentrations was 0.85, and each additional 1 µg of daily intake was associated with 0.21 ng/mmol creatinine more uranium in urine 2. Isotope ratios identify the source of uranium: a uranium-235 to uranium-238 activity ratio near 0.046 marked natural uranium in Kazakh wells 3, and a uranium-235 share of 0.4% rather than 0.7% confirmed that brain uranium in exposed rats came from depleted test material 5.
Microbiome effects
The cited evidence does not establish effects of uranium on the gut or other human microbiomes. The only microbial work cited is a 1948 laboratory study showing that uranyl nitrate inhibits glucose metabolism in yeast and some bacteria, which says nothing about microbial communities in people 9.
Vulnerable populations
Infants had the highest modeled annual ingestion doses from groundwater in arid western India, with means of 49.30 µSv per year at 0 to 6 months and 56.34 µSv per year at 7 to 12 months 4. People who rely on private drilled wells in uranium-rich bedrock form the exposed group in the Finnish studies 2. In the bone study, the suggested effect was seen in men but not in women 8. Workers in nuclear fuel-cycle operations, mines and dismantling are described as exposed through airborne uranium particles 5. The cited evidence does not establish effects in pregnancy; pregnant women were excluded from the Finnish kidney study 2.
Mitigation
The cited evidence does not establish how well any treatment removes uranium from water or food. The Finnish kidney study excluded households that had effective equipment for removing uranium from their well water, but it reports no removal performance 2.
Open questions
- Uranium in staple foods, infant foods, bottled water and total diets is not covered by the cited evidence.
- No cited study compares food and drinking water as shares of total uranium intake.
- Removal of uranium by household water treatment, municipal treatment or food processing is not established.
- Whether the proximal tubule changes linked to drinking-water uranium progress to clinical kidney disease is not established.
- Bone effects in humans rest on one cross-sectional analysis with borderline significance and a sex difference that is not explained.
- Effects of uranium on the gut microbiome are not established.
- Effects in pregnancy and early childhood are not measured; infant evidence is limited to modeled doses.
- Whether a uranium mine raises uranium in nearby produce is not established, because the produce study had no distant control site.
- Food limits for uranium are not stated in the cited evidence.
Frequently asked questions
In which foods and beverages has uranium actually been measured?
The sources mapped on this page report uranium occurrence across a wide range of foods and beverages, including commercial milk and infant formulas (Largueza et al. 2026, Almeida et al. 2022), ready-to-eat baby purees (Henríquez-Hernández et al. 2023), rice (Gama et al. 2025), coffee beans (Albals et al. 2021), and edible seaweeds (Mosusu 2023). The page catalogs these as occurrence sources; it does not yet synthesize concentration values.
Is uranium in drinking water something researchers track?
Yes. Several sources mapped here assess uranium in drinking water, including a global review of heavy metals in drinking water (Olowoyo et al. 2026), a US contaminants review (Levin et al. 2024), and analyses of uranium in US community water systems (Ravalli et al. 2022, Martinez-Morata et al. 2022). The page lists these as occurrence and exposure sources rather than summarizing their findings.
Do any regulators set limits or monitoring programs for uranium in food or water?
The regulatory sources mapped here address uranium in several ways. The WHO drinking-water guidelines derive guideline values for uranium among other contaminants (WHO 2022), the FDA runs a compliance program covering uranium surveillance in food and foodware (FDA 2025) and includes uranium in its Total Diet Study (FDA 2022), and Hong Kong’s Centre for Food Safety sets maximum levels for uranium as one of its metallic contaminants (Centre for Food Safety 2019). This page does not reproduce the specific limit values.
Are infants and pregnant women covered in the uranium literature here?
Yes. The mapped sources include uranium in infant formula and baby purees, infant birth-cohort dietary exposure (Signes-Pastor et al. 2022), infant serum levels alongside gut microbiota (Yan et al. 2025), human breast milk (Bzikowska-Jura et al. 2024), and maternal soil ingestion during pregnancy (Lawluvi et al. 2026). These are listed as exposure and occurrence sources; the page does not yet draw conclusions about risk to these groups.
How is uranium measured in these food and water studies?
Several of the mapped studies measure uranium by ICP-MS, including analyses of baby purees (Henríquez-Hernández et al. 2023) and coffee beans (Albals et al. 2021). The FDA Total Diet Study documentation records uranium measurement limits of detection and QA/QC parameters by food category (FDA 2022), and a state-of-the-science review addresses uranium exposure biomarkers in blood, urine, and tissue (Martinez-Morata et al. 2023).
What remains uncertain
The human toxicology evidence cited here rests on two cross-sectional analyses of one Finnish well-water cohort 2 8. They show associations with kidney tubule markers and, less firmly, bone turnover markers, not disease. Mechanistic work in yeast, fish, rats and a zebrafish preprint points to cell-membrane, mitochondrial and olfactory-transport pathways, but the exposures and forms of uranium in those studies differ from natural uranium in drinking water 9 6 7 5.
Occurrence data cover groundwater in three countries and one produce survey near a uranium mine 2 3 4 10. None of these studies was designed to estimate typical population intake, and the guideline values quoted on this page come from study authors citing guideline editions that have changed over time 2 3 4.
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
- Renal Effects of Uranium in Drinking WaterPeer-reviewed
- Uranium isotopes in well water samples as drinking sources in some settlements around the Semipalatinsk Nuclear Test Site, KazakhstanPeer-reviewed
- Tracing geochemical sources and health risk assessment of uranium in groundwater of arid zone of IndiaPeer-reviewed
- Evaluation of the Nose-to-Brain Transport of Different Physicochemical Forms of Uranium after Exposure via Inhalation of a UO4 Aerosol in the RatPeer-reviewed
- Hepatic transcriptomic profiling reveals early toxicological mechanisms of uranium in Atlantic salmon (Salmo salar)Peer-reviewed
- Environmentally relevant depleted uranium exposure damages mitochondria, decreases cytosolic reductive capacity, and increases global DNA damage accumulation through a ROS-independent mechanism involving slingshot protein phosphatase 1b enrichmentPreprint
- Bone as a Possible Target of Chemical Toxicity of Natural Uranium in Drinking WaterPeer-reviewed
- Regulatory Mechanisms of Cellular Respiration I. The Role of Cell Membranes: Uranium Inhibition of Cellular RespirationPeer-reviewed
- Trace metals in vegetables and fruits cultivated around the surroundings of Tummalapalle uranium mining site, Andhra Pradesh, IndiaPeer-reviewed
- Assessment of Radioactive Materials and Heavy Metals in the Surface Soil around the Bayanwula Prospective Uranium Mining Area in ChinaPeer-reviewed
- Essential and Potentially Toxic Elements in Commercial Milk Formulas: Health Risk Assessment Through a Systematic Review and Meta-analysisPeer-reviewed
- Toxic Metals and Metalloids in Infant Formulas Marketed in Brazil, and Child Health Risks According to the Target Hazard Quotients and Target Cancer RiskPeer-reviewed
- Concentration of Essential, Toxic, and Rare Earth Elements in Ready-to-Eat Baby Purees from the Spanish MarketPeer-reviewed
- Assessing trace elements in soils and rice: insights from the Baixo Vouga Lagunar (Portugal)Peer-reviewed
- Multi-element determination of essential and toxic metals in green and roasted coffee beans: A comparative study among different origins using ICP-MSPeer-reviewed
- Heavy metal contents in some edible seaweeds (Wakame, Kombu) in JapanThesis
- Heavy Metals Burden in Drinking Water: Global Patterns, Sources, and Public Health ImplicationsReview
- Drinking water quality in the United States: a review of contaminants, regulations, and health implicationsPeer-reviewed
- Sociodemographic inequalities in uranium and other metals in community water systems across the USA, 2006–11: a cross-sectional studyPeer-reviewed
- Nationwide geospatial analysis of county racial and ethnic composition and public drinking water arsenic and uraniumPeer-reviewed
- Compliance Program Guidance Manual: Toxic Elements in Food and Foodware, and Radionuclides in Food – Import and Domestic (Program 7304.019)Government
- Total Diet Study Report: Fiscal Years 2018-2020 Elements DataGovernment
- Guidelines on the Food Adulteration (Metallic Contamination) (Amendment) Regulation 2018Government
- Dietary Exposure to Essential and Non-essential Elements During Infants’ First Year of Life in the New Hampshire Birth Cohort StudyPeer-reviewed
- Association between infants’ serum levels of 26 metals and gut microbiota: a hospital-based cross-sectional study in ChinaPeer-reviewed
- Essential and non-essential element concentrations in human milk samples and the assessment of infants’ exposurePeer-reviewed
- Maternal geophagy in Ghana: a mini review of toxicological, microbial, nutritional, and radiological exposure pathwaysPeer-reviewed
- FY2018-FY2020 TDS Elements Analytical Results KeyGovernment
- A State-of-the-Science Review on Metal BiomarkersPeer-reviewed
Sources
Source records associated with this topic. Inclusion does not establish that every finding applies to this product or ingredient. References above identify works cited in the text.
Recent source records are shown below. Browse the complete evidence table for all source records and their reported findings.
| # | Citation | Year | Type | Used on this page for |
|---|---|---|---|---|
| 1 | Durkalec et al. 2026. From flowers to pollinators: Dietary exposure of honey bees, bumble bees and solitary bees to trace elements across European fields, Journal of Hazardous Materials 514 (2026) 142644 | 2026 | Peer-reviewed | Contribution to this topic remains under review; see the source record for its reported scope. |
| 2 | Hall et al. 2026. Toenail metal concentrations and kidney health among young people at risk of chronic kidney disease of uncertain etiology, Environmental Epidemiology 10: e461 | 2026 | Peer-reviewed | Contribution to this topic remains under review; see the source record for its reported scope. |
| 3 | Kalaniopio et al. 2026. Environmentally relevant depleted uranium exposure damages mitochondria, decreases cytosolic reductive capacity, and increases global DNA damage accumulation through a ROS-independent mechanism involving slingshot protein phosphatase 1b enrichment, bioRxiv preprint 2026.07.02.736169 (posted July 8, 2026; not peer reviewed) | 2026 | Preprint | Contribution to this topic remains under review; see the source record for its reported scope. |
| 4 | Largueza et al. 2026. Essential and Potentially Toxic Elements in Commercial Milk Formulas: Health Risk Assessment Through a Systematic Review and Meta-analysis, Biological Trace Element Research | 2026 | Peer-reviewed | BR/EU/US Al, iAs, tAs, Cd, Co, Cr, Cu, Fe, MeHg, Mn, Ni, Pb, U, Zn occurrence in Systematic review with meta-analysis of 30 observational studies (PRISMA, OSF.IO/2YNKB registered), 18 with pooled meta-analysis data, covering three… (n=30) |
| 5 | Lawluvi et al. 2026. Maternal geophagy in Ghana: a mini review of toxicological, microbial, nutritional, and radiological exposure pathways., Frontiers in Public Health 2026;14:1782963 | 2026 | Peer-reviewed | U exposure from maternal geophagy: soil ingestion pathway and fetal/infant exposure implications |
| 6 | Makhadi et al. 2026. Geochemical assessment of soil and water around abandoned gold mine tailings dams: evidence from the Welkom Goldfield, South Africa, Environmental Geochemistry and Health | 2026 | Peer-reviewed | Contribution to this topic remains under review; see the source record for its reported scope. |
| 7 | Olowoyo et al. 2026. Heavy Metals Burden in Drinking Water: Global Patterns, Sources, and Public Health Implications, Water 18(8): 886 | 2026 | Review | global Pb, Cd, tAs, Cr, Ni, Fe, Cu, Zn, U, Mn, tHg, Sb, Se occurrence in Systematic narrative review; 66 peer-reviewed articles published 2015–2024 (sourced from ScienceDirect, Google Scholar, PubMed) reporting heavy-metal concentrations in… (n=66) |
| 8 | Trimmel et al. 2026. Biomonitoring with bees and bee products: multielement profiles including technology-critical elements, Monatshefte für Chemie - Chemical Monthly (2026) 157:193-205 | 2026 | Peer-reviewed | Contribution to this topic remains under review; see the source record for its reported scope. |
| 9 | Zgavarogea et al. 2026. Traceability and Health Risk Assessment in the Feed-Animal-Milk Chain: A Comparative Evaluation of Traditional and Industrial Dairy Systems in Romania, Foods 2026, 15(16): 2844 | 2026 | Peer-reviewed | Contribution to this topic remains under review; see the source record for its reported scope. |
| 10 | Du et al. 2025. Heavy metal exposures in aerodigestive clinic cohort of infants with reflux or dysphagia, Scientific Reports | 2025 | Peer-reviewed | US tAs, iAs, Pb, tHg, Cd, Sn, Cr, Ni, U occurrence in Infants under 1 year of age with reflux or oropharyngeal dysphagia seen at Boston Children’s Hospital aerodigestive clinic,… (n=56) |
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