Cerium and lanthanum reach food crops from soil and from deliberate agricultural use, and lanthanum is also given orally as a phosphate binder, but measured food levels in the cited evidence are sparse and mostly experimental.
- Role: Non-essential elements used as plant growth stimulants, as phosphate binders in medicine and cat feed, and in water treatment materials, sensors and catalysts.
- Main exposure: Crops grown on rare earth-bearing soils or treated with rare earth inputs, and deliberate oral lanthanum carbonate use in kidney disease.
- Key distinction: Cerium and lanthanum findings are reported separately, and cerium oxide nanoparticles, dissolved cerium and lanthanum salts behave differently in plants and animals.
This page draws on evidence from EFSA, together with 26 peer-reviewed studies. The complete citation list is at the bottom of the page.
Overview
This page covers two rare earth elements, cerium and lanthanum, and keeps every element-level finding labeled by element. Cerium is described as the most abundant rare earth element in the earth’s crust 2, and lanthanum and cerium are among the more abundant rare earths, with average crustal values given as 39.0 mg/kg for lanthanum and 66.5 mg/kg for cerium 3.
Most of the cited evidence is experimental. It shows that both elements are applied to crops as growth stimulants or seed treatments, that crops take them up mainly into roots and leaves, and that lanthanum is used as an oral phosphate binder in people with kidney disease and in cat food 4 5 6 1. Direct measurements of either element in market food are limited to a single method-development study 7.
Neither element has an established oral reference dose in the cited evidence. One modeling study had to borrow surrogate values from nine other rare earth elements to interpret cerium intake from carrots 8.
Toxicology
Lanthanum
In rats exposed to lanthanum chloride in drinking water at 0.25%, 0.5% or 1% from gestation through 28 days after weaning, offspring showed impaired spatial learning, dose-dependent lanthanum accumulation in the hippocampus, neuronal damage and increased apoptosis 9. These concentrations are far above any food exposure described in the cited evidence.
In rats with surgically reduced kidney function fed 0.5% lanthanum as lanthanum carbonate for four weeks, alanine transaminase was higher than in other groups 10. The European Food Safety Authority feed panel confirmed lanthanum carbonate octahydrate as safe for cats at up to 7.5 g/kg of complete feed, based on post-market reports showing an adverse event incidence of 0.0003% in cats, mostly digestive signs in animals that already had kidney disease 1. The same opinion records that the additive was negative in genotoxicity tests and showed no systemic effects in a 90-day study, while inhalation caused some persistent lung effects in rats 1.
For aquatic life, the seven-day lethal concentration for half of Daphnia magna was 403.67 µg/L lanthanum, while delayed maturity responded at 0.26 µg/L (10% effect) 11. In catfish fed mycotoxin-contaminated diets, adding 200 or 400 mg/kg lanthanum chloride improved growth and blood measures rather than causing harm 12.
In plants, lanthanum at 0.5 mM and above raised reactive oxygen species and lipid peroxidation in rice roots, while lower concentrations raised antioxidant enzyme activity 13.
Cerium
Rats with reduced kidney function fed 1.31% cerium oxide for four weeks showed lower serum phosphate without a rise in liver enzymes; this study was funded by a pharmaceutical company and did not measure cerium in tissues 10. Zebrafish embryos exposed to a titanium dioxide nanocomposite containing 3% cerium oxide at up to 20 mg/L showed no developmental toxicity, although heart rate changed at 1 mg/L and above 14.
In a hospital case-control study in Fujian, China, oral cancer patients had lower serum cerium than controls (median 0.57 versus 2.27 µg/L), and serum cerium at or above the control median was associated with lower adjusted odds of oral cancer (odds ratio 0.60, 95% CI 0.43 to 0.84) 2. Blood was drawn after diagnosis, so the disease may have affected serum cerium; the study does not show a protective effect.
Plants show a low-dose stimulation and high-dose inhibition pattern. Foliar cerium at 5 mg/L promoted soybean growth and grain quality while 50 mg/L inhibited growth 5, and cerium oxide nanoparticles at 2000 mg/kg in sand reduced maize seedling biomass 15.
Typical exposure routes
Soil to crop. Both elements are present in agricultural soils, and higher levels are reported near rare earth mining waste (see the soil table under Food sources) 3 16. Crops tend to hold cerium in roots: in two pot-grown species, root cerium rose up to about 16,000 µg/kg dry weight while leaf cerium stayed far lower 17. Barley grown in soil with 500 or 1000 mg/kg cerium oxide nanoparticles did not have significantly more kernel cerium than controls 18.
Agricultural inputs applied to crops. Lanthanum chloride has been applied to aromatic rice at 12 kg/ha in field trials 4, to konjac 19 and as an amino acid chelate to rice seedlings 20. Cerium nitrate has been sprayed on soybean leaves 5, cerium oxide nanoparticles used to prime rice seed 21, and a cerium-doped titanium dioxide spray applied to bok choy to break down an insecticide 22. None of these studies measured the element in the harvested food, except that foliar cerium on soybean moved to grain at less than 5% of the leaf concentration 5.
Deliberate oral use. Lanthanum carbonate is taken as a phosphate binder by people with chronic kidney disease, at 500 mg three times daily in one Indian trial 6. Cerium oxide has been tested in rats as an alternative binder 10. In animal feed, lanthanum carbonate is authorized in the EU for cats 1, and lanthanum chloride has been tested in catfish diets 12.
Water treatment materials. Cerium- and lanthanum-based sorbents can release small amounts of the element into treated water: 0.015 to 0.062 mg/L cerium from a cerium oxide lignin sorbent across pH 4 to 9 23, and about 3% of the lanthanum from a lanthanum-modified activated carbon 24. These are laboratory tests, not measurements of drinking water.
Food sources
The only market food measurements in the cited evidence come from one method-development study in Bangladesh, which analyzed one sample of each food five times 7. Its cerium values (7.5 to 21.8 mg/kg, basis not stated) are far higher than the 0.50 mg/kg dry weight measured in control barley kernels in Italy 18, and they have not been reproduced in the cited evidence. Foods covered include carrot, wheat, corn, rice, potatoes, spinach, cabbage and mango.
Experimental studies show that carrots grown with cerium can carry most of it in the peel, so that peeling cut projected intake roughly 10-fold to 100-fold 8. Lanthanum accumulates in tea plant leaves, the harvested part of Camellia sinensis, with clear differences between cultivars 25; leaf values are shown only graphically. Foliar cerium on soybean moved little into the grain 5, and cerium oxide in soil did not raise cerium in barley, a cereal grain 18.
Measured results: food and human samples
| Study / location | Material / design | Metal species | Value (units and basis) | n | Interpretation / limitation |
|---|---|---|---|---|---|
| 7 Chittagong and Rajshahi, Bangladesh | Market foods; fluorescence method checked against ICP-OES | Ce (total) | Carrot 21.8; mango 16.8; wheat 12.8; potato 11.5; rice 10.1; spinach 9.8; corn 9.5; cabbage 7.5 mg/kg (basis not stated) | 1 sample each, 5 analyses | Method demonstration; single samples; not representative |
| 18 Udine, Italy | Barley kernels, pot trial; control and soil with 500 or 1000 mg/kg cerium oxide nanoparticles | Ce (total) | 0.50, 1.03 and 0.70 mg/kg dry weight (means) | 5 per treatment | No significant difference from control; high variability |
| 8 USA, greenhouse | Carrots in sand culture with cerium oxide nanoparticles or ionic cerium up to 500 mg/kg | Ce (nanoparticle or ionic) | Maximum 65.8 (nanoparticle) and 126.9 (ionic) mg/kg fresh weight | 4 to 5 per treatment | Deliberately extreme exposures; not market food |
| 17 Udine, Italy | Diplotaxis tenuifolia leaves, pot trial with 200 mg/kg cerium oxide nanoparticles | Ce (total) | Control 145; 50 nm particles 1,044 µg/kg dry weight | 4 | Wild species; leaf values highly variable |
| 2 Fujian, China | Serum, hospital case-control study | Ce (total) | Controls median 2.27 µg/L; oral cancer cases 0.57 µg/L | 650 controls; 324 cases | Post-diagnosis sampling; source of cerium unknown |
| 7 Chittagong, Bangladesh | Human blood, urine and milk from individual patients and one mother | Ce (total) | Blood 152.5 to 430.0; urine 42.8 to 110.8; milk 58.6 ng/L | 1 per person | Single patient samples; not a population survey |
Measured results: soils
| Study / location | Material / design | Metal species | Value (units and basis) | n | Interpretation / limitation |
|---|---|---|---|---|---|
| 3 Sichuan, China | Farmland topsoil near the Maoniuping rare earth tailings | La and Ce (total) | La about 29.0; Ce about 67.6 mg/kg | Composite sample | One site; values reported as approximate |
| 16 Jiangsu, China | Rice field topsoils from three cities | La (total) | 46.93, 47.37 and 32.78 mg/kg dry soil | 1 per site | Background values for a microcosm study |
| 5 Shenyang, China | Experimental field topsoil | Ce (total) | 41.22 plus or minus 3.65 mg/kg | Not stated | Pot experiment soil |
| 7 Chittagong, Bangladesh | Industrial, agricultural, roadside and marine surface soils | Ce (total) | 21.8 to 135.8 mg/kg | 10 sites | Method demonstration |
Regulatory limits
The cited evidence contains no food or drinking water limit for cerium or lanthanum. No oral reference dose for cerium was available to the authors of the carrot modeling study, who used the median of nine other rare earth elements (5 µg/kg body weight per day) as a surrogate; against that value, carrot cerium of 1.0 mg/kg fresh weight in one serving would reach the surrogate for a 13 kg child 8.
For lanthanum, the European Food Safety Authority confirmed the EU feed authorization of lanthanum carbonate octahydrate for adult cats at 1.5 to 7.5 g/kg of complete feed. The opinion excluded consumer and environmental safety from its scope, and recorded additive impurity results of arsenic below 2, cadmium below 1, lead below 1 and mercury below 0.2 mg/kg 1.
Testing
Total cerium and lanthanum in serum, grain, plant tissue and soil were measured by ICP-MS in the cited studies. The Fujian serum study reported a detection limit of 0.0003 µg/L for cerium with recovery of 89.1% to 92% for rare earth standards 2, and the barley study a detection limit of 1 µg/L in digest solution with 97% average recovery on a tomato leaves reference material 18. Single-particle ICP-MS distinguished cerium oxide particles from dissolved cerium in plant tissue 17.
A spectrofluorimetric method for cerium reported a detection limit of 0.1 ng/L in solution and gave food results close to ICP-OES 7; see also fluorescence methods. Sequential extraction separates exchangeable, carbonate-bound, oxide-bound, organic and residual soil fractions of both elements 3.
None of the human or food studies determined cerium oxidation state; the Fujian authors note their method could not distinguish cerium valence 2. In marine sediment, X-ray absorption spectroscopy showed cerium held as cerium-phosphate clusters around fish-bone apatite 26.
Microbiome effects
The cited evidence does not address the human gut microbiome. In rice field soils from Jiangsu, China, adding lanthanum chloride inhibited methane consumption to a degree that depended on soil pH and origin, and methane-oxidizing communities shifted toward Methylobacter, Methylosarcina and Methylocystis while keeping function over time 16. This is soil ecology evidence and does not support statements about gut effects.
Vulnerable populations
People with chronic kidney disease taking lanthanum carbonate receive deliberate, sustained oral lanthanum doses (500 mg three times daily in one trial), which is a distinct exposure from food 6; the cited trial did not measure lanthanum in the body. In a rat model of reduced kidney function, lanthanum carbonate raised alanine transaminase 10.
Young children have the highest projected cerium intake per unit body weight from a given carrot concentration, because the same serving is divided by a smaller body mass 8. Developmental exposure through gestation and nursing affected learning in rat offspring at high drinking-water doses of lanthanum chloride 9. The cited evidence does not establish effects at dietary exposure levels for any population.
Mitigation
Peeling root vegetables. Peeling carrots grown with cerium reduced projected cerium intake roughly 10-fold to 100-fold, because most cerium stayed in the peel 8.
Soil amendment. Mixing compost from kiwifruit branches and sheep manure into farmland soil near rare earth tailings lowered the mobile fraction of lanthanum from 13.8% to 4.3% of the total and of cerium from 8.1% to 2.9% at the highest compost ratio after 28 days, with a 10% ratio suggested as practical 3. Part of the decline reflected dilution, and crop uptake was not tested.
Material design for water treatment. Coating lanthanum nanorods with carbon greatly reduced lanthanum leakage into water compared with uncoated material 27.
Food processing steps other than peeling are not established in the cited evidence.
Open questions
- No survey of cerium or lanthanum in market foods with a stated moisture basis and adequate sample numbers; the only market values are single samples from one method paper.
- No lanthanum measurements in any harvested food, including rice, konjac and tea from fields treated with lanthanum.
- No oral reference dose, tolerable intake or food limit for cerium or lanthanum in the cited evidence; Regulatory limits could cite only a cat feed authorization.
- No population dietary intake estimate for either element.
- No human absorption, distribution or excretion data for dietary cerium or lanthanum, and no measurement of body lanthanum in people taking lanthanum carbonate.
- No evidence on cerium oxidation state or nanoparticle form in foods.
- No study of either element on the human gut microbiome.
- No evidence on whether soil amendment lowers crop uptake, or on processing steps other than peeling.
What remains uncertain
The cited evidence is dominated by experiments that add cerium or lanthanum at high concentrations to plants, soils, animals or water. These show where the elements go and what high doses do, but they do not describe ordinary dietary exposure. The single set of market food values comes from a method paper with one sample per food and much higher values than control grain measured elsewhere, so the typical cerium content of foods remains unknown.
Human data are limited to one case-control study of serum cerium, in which the inverse association with oral cancer may reflect the disease itself, and one clinical trial of lanthanum carbonate that did not measure lanthanum. Animal toxicity findings come from drinking water or diet concentrations far above food levels, and one of the rat feeding studies was industry funded.
Cerium oxide nanoparticles, dissolved cerium and lanthanum salts behaved differently in the studies cited, and results for one form or element should not be transferred to another.
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.
- Assessment of the application for renewal of authorisation of Lantharenol (lanthanum carbonate octahydrate) for catsGovernment
- Association Between Rare Earth Element Cerium and the Risk of Oral Cancer: A Case-Control Study in Southeast ChinaPeer-reviewed
- Kiwifruit branch compost reduces the bioavailability of the rare earth elements lanthanum and cerium in agricultural soilsPeer-reviewed
- Lanthanum (La) improves growth, yield formation and 2-acetyl-1-pyrroline biosynthesis in aromatic rice (Oryza sativa L.)Peer-reviewed
- Genome-Wide DNA Methylation Analysis of the Toxicological Responses to Foliar Cerium Application in SoybeanPeer-reviewed
- Efficacy of Lanthanum Carbonate and Sevelamer Carbonate as Phosphate Binders in Chronic Kidney Disease: A Comparative Clinical StudyPeer-reviewed
- A highly sensitive and selective spectrofluorimetric method for the determination of cerium at pico-trace levels in some real, environmental, biological, soil, food and bone samples using 2-(alpha-pyridyl)-thioquinaldinamidePeer-reviewed
- Projected Dietary Intake of Zinc, Copper, and Cerium from Consumption of Carrot (Daucus carota) Exposed to Metal Oxide Nanoparticles or Metal IonsPeer-reviewed
- Lanthanum Chloride Causes Neurotoxicity in Rats by Upregulating miR-124 Expression and Targeting PIK3CA to Regulate the PI3K/Akt Signaling PathwayPeer-reviewed
- Evaluation of cerium oxide as a phosphate binder using 5/6 nephrectomy model ratPeer-reviewed
- Sublethal and lethal toxicity assessment of lanthanum and gadolinium to Daphnia magna in a 7-day test methodPeer-reviewed
- Effects of Dietary Lanthanum Chloride on Growth Performance, Hematology and Serum Biochemistry of Juvenile Clarias gariepinus Catfish Fed Diets Amended with Mixtures of Aflatoxin B1 and Fumonisin B1Peer-reviewed
- Lanthanum regulates the reactive oxygen species in the roots of rice seedlingsPeer-reviewed
- Toxicity of Titanium Dioxide-Cerium Oxide Nanocomposites to Zebrafish Embryos: A Preliminary EvaluationPeer-reviewed
- Divergent effects of cerium oxide nanoparticles alone and in combination with cadmium on nutrient acquisition and the growth of maize (Zea mays)Peer-reviewed
- Unraveling the impact of lanthanum on methane consuming microbial communities in rice field soilsPeer-reviewed
- Influence of Cerium Oxide Nanoparticles on Two Terrestrial Wild Plant SpeciesPeer-reviewed
- Effects of Cerium and Titanium Oxide Nanoparticles in Soil on the Nutrient Composition of Barley (Hordeum vulgare L.) KernelsPeer-reviewed
- Glucomannan Accumulation Induced by Exogenous Lanthanum in Amorphophallus konjac: Insights from a Comparative Transcriptome AnalysisPeer-reviewed
- Lanthanum(III)-amino acid chelate mitigates copper(II) stress in rice (Oryza sativa)Peer-reviewed
- An Analysis of the Different Salt-Tolerance Mechanisms in Rice Cultivars Induced by Cerium Oxide NanoparticlesPeer-reviewed
- Photocatalytic degradation of dimethoate in Bok choy using cerium-doped nano titanium dioxidePeer-reviewed
- Cerium oxide nanoparticle functionalized lignin as a nano-biosorbent for efficient phosphate removalPeer-reviewed
- Chromium(VI) Removal from Water by Lanthanum Hybrid Modified Activated Carbon Produced from Coconut ShellsPeer-reviewed
- Proteomic Analysis Reveals the Association between the Pathways of Glutathione and alpha-Linolenic Acid Metabolism and Lanthanum Accumulation in Tea PlantsPeer-reviewed
- Cerium occurs as cerium-phosphate clusters around bioapatite nanocrystals in deep-sea sedimentsPeer-reviewed
- Synchronous, efficient and fast removal of phosphate and organic matter by carbon-coated lanthanum nanorodsPeer-reviewed
Sources
- Projected cerium intake from carrots (2016; peer-reviewed): modeled cerium intake from experimentally grown carrots, surrogate reference dose and peeling effect.
- Serum cerium and oral cancer in Fujian (2021; peer-reviewed): serum cerium in 974 adults and an inverse association with oral cancer.
- Lanthanum carbonate feed additive for cats (2019; government-report): EU authorized feed range and target-animal safety conclusion.
- Cerium in barley kernels (2016; peer-reviewed): kernel cerium under soil cerium oxide nanoparticle treatment.
- Compost and soil lanthanum and cerium (2025; peer-reviewed): soil totals near rare earth tailings and compost reduction of mobile fractions.
- Spectrofluorimetric cerium method (2019; peer-reviewed): detection method and single-sample cerium values in Bangladeshi foods, fluids and soils.
- Cerium oxide as a phosphate binder in rats (2022; peer-reviewed): four-week dietary cerium oxide and lanthanum carbonate in rats; industry funded.
- Lanthanum carbonate in kidney disease (2023; peer-reviewed): clinical oral lanthanum carbonate dose and phosphate outcomes.
- Lanthanum chloride neurotoxicity in rats (2020; peer-reviewed): developmental drinking-water exposure, brain accumulation and learning deficits.
- Lanthanum chloride in catfish feed (2022; peer-reviewed): lanthanum chloride as an aquaculture feed additive.
- Lanthanum toxicity to Daphnia (2025; peer-reviewed): aquatic lethal and sublethal effect concentrations.
- Zebrafish and a titanium-cerium nanocomposite (2023; peer-reviewed): embryo toxicity screening of a cerium-containing nanomaterial.
- Foliar cerium in soybean (2026; peer-reviewed): foliar cerium translocation to grain and soil background cerium.
- Cerium oxide and cadmium in maize (2023; peer-reviewed): seedling cerium uptake and dose response.
- Cerium uptake by two wild plants (2021; peer-reviewed): root and leaf cerium after nanoparticle exposure.
- Lanthanum and rice soil methanotrophs (2024; peer-reviewed): paddy soil lanthanum and soil microbial response.
- Cerium in deep-sea sediments (2025; peer-reviewed): off-topic for dietary exposure: marine sediment geochemistry.
- Cerium and rice germination (2018; peer-reviewed): cerium as a plant growth stimulant; no grain data.
- Cerium oxide seed priming in rice (2025; peer-reviewed): nanoceria seed priming; no cerium measurements.
- Lanthanum and aromatic rice (2021; peer-reviewed): field use of lanthanum chloride on rice; no grain lanthanum.
- Lanthanum in rice phytoliths (2018; peer-reviewed): lanthanum binding in plant silica of germinating seeds.
- Lanthanum chelate for rice (2024; peer-reviewed): development of a lanthanum agrochemical.
- Lanthanum and rice root oxidative stress (2016; peer-reviewed): plant stress response to lanthanum.
- Lanthanum and konjac glucomannan (2025; peer-reviewed): lanthanum as a konjac quality input; no residue data.
- Lanthanum in tea plants (2023; peer-reviewed): cultivar differences in tea leaf lanthanum accumulation.
- Cerium-doped titanium dioxide on bok choy (2018; peer-reviewed): cerium-containing spray on a vegetable; no cerium measured.
- Cerium oxide lignin sorbent (2020; peer-reviewed): cerium leaching from a water treatment sorbent.
- Lanthanum-modified activated carbon (2022; peer-reviewed): lanthanum leaching from a water treatment sorbent.
- Carbon-coated lanthanum nanorods (2018; peer-reviewed): carbon coating reduced lanthanum leakage into water.
- Plant-extract cerium oxide nanoparticles (2023; peer-reviewed): off-topic for dietary exposure: in vitro nanomedicine assays.
- Exosome-delivered cerium dioxide (2025; peer-reviewed): off-topic for dietary exposure: experimental nanomedicine.
- Cerium oxide nanoparticles and antidiabetic assays (2026; peer-reviewed): off-topic for dietary exposure: in vitro and docking study.
- Nanoporous cerium oxide antioxidant material (2023; peer-reviewed): off-topic for dietary exposure: materials chemistry.
- Cerium nanogel choline sensor (2024; peer-reviewed): off-topic for dietary exposure: cerium is a sensor component.
- Cerium oxide vanillin sensor (2026; peer-reviewed): off-topic for dietary exposure: cerium is an electrode material.
- Cerium-manganese ozonation catalyst (2025; peer-reviewed): off-topic for dietary exposure: water treatment catalysis.
- Manganese-cerium catalyst on rice husk carbon (2019; peer-reviewed): off-topic for dietary exposure: air pollution control catalysis.
- Lanthanum sulfide herbicide sensor (2023; peer-reviewed): off-topic for dietary exposure: lanthanum is an electrode material.
- Lanthanum-doped barium titanate catalyst (2024; peer-reviewed): off-topic for dietary exposure: antibiotic degradation in water.
- Lanthanum-modified biochar for ammonium (2026; peer-reviewed): off-topic for dietary exposure: wastewater treatment material.
- Lanthanum-modified tea waste biochar for fluoride (2024; peer-reviewed): off-topic for dietary exposure: water treatment material.
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