Toxno Substance Profile
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Substance Name

Oxalic acid
Identification Number: CASRN | 144-62-7

  Substance Attributes


  • Metabolic Interference or Disruption

    Interferes with human metabolism. This can be a very serious thing. Some of these interference mechanics are well established. However, often long term effects and health consequences remain largely unknown. Additionally an emerging area of concern and one that is not currently studied, is the combined synergistic effects these metabolically disrupting chemicals have on human health.


    Metabolic interference happens when the substance produces highly reactive and often damaging intermediates during detoxification or when the substance binds to specific enzymes, important structural groups on molecules, receptors and membranes or targets DNA or mimics key nutrients.

  • Exposure Produces Health Symptoms

    Symptoms maybe short term or long term depending on the exposure duration and intensity and effects areas like Cardiovascular, Gastrointestinal, Cognition, Fatigue. A substance with this attribute may cause an allergic skin reaction, serious eye irritation, allergy or asthma symptoms or breathing difficulties if inhaled.

These attributes are ONLY based on peer-reviewed evidence. See link to Data Sources below. Everyone benefits from knowing this stuff. Please Share.



  • CATEGORIES: Household Toxin | Industrial/Workplace Toxin | Plant Toxin | Food Toxin | Natural Toxin | Indirect Additives Used in Food Contact Substances | Inert Pesticide Ingredient USA - Food Use Permitted | A Hazardous Substance that may be found in the Australian Workplace
  • SUBSTANCE LINEAGE: Organic Compounds | Organic Acids and Derivatives | Carboxylic Acids and Derivatives | Dicarboxylic Acids and Derivatives | Dicarboxylic Acids and Derivatives
  • SYNONYMS: Ammonium oxalate | Ethane-1,2-dioate | Ethane-1,2-dioic acid | Ethanedioate | Ethanedioic acid | Ethanedioic acid dihydrate | Ethanedionate | Ethanedionic acid | Kyselina stavelova | Oxaalzuur | Oxalate | Oxalic acid 2-Hydrate | Oxalic acid anhydrous | Oxalic acid diammonium salt | Oxalic acid dihydrate
  • DESCRIPTION: Oxalic acid is a dicarboxylic acid. It is a colorless crystalline solid that dissolves in water to give colorless, acidic solutions. In terms of acid strength, it is much stronger than acetic acid. Oxalic acid, because of its di-acid structure can also act as a chelating agent for metal cations. About 25% of produced oxalic acid is used as a mordant in dyeing processes. It is also used in bleaches, especially for pulpwood. Oxalic acid's main applications include cleaning (it is also found in baking powder) or bleaching, especially for the removal of rust. Oxalic acid is found in a number of common foods with members of the spinach family being particularly high in oxalates. Beat leaves, parsley, chives and cassava are quite rich in oxalate. Rhubarb leaves contain about 0.5% oxalic acid and jack-in-the-pulpit (Arisaema triphyllum) contains calcium oxalate crystals. Bacteria naturally produce oxalates from the oxidation of carbohydrates. At least two pathways exist for the enzyme-mediated formation of oxalate in humans. In one pathway, oxaloacetate (part of the citric acid cycle) can be hydrolyzed to oxalate and acetic acid by the enzyme oxaloacetase. Oxalic acid can also be generated from the dehydrogenation of glycolic acid, which is produced by the metabolism of ethylene glycol. Oxalate is a competitive inhibitor of lactate dehydrogenase (LDH). LDH catalyses the conversion of pyruvate to lactic acid oxidizing the coenzyme NADH to NAD+ and H+ concurrently. As cancer cells preferentially use aerobic glycolysis, inhibition of LDH has been shown to inhibit tumor formation and growth. However, oxalic acid is not particularly safe and is considered a mild toxin. In particular, it is a well-known uremic toxin. In humans, ingested oxalic acid has an oral lowest-published-lethal-dose of 600 mg/kg. It has been reported that the lethal oral dose is 15 to 30 grams. The toxicity of oxalic acid is due to kidney failure caused by precipitation of solid calcium oxalate, the main component of kidney stones. Oxalic acid can also cause joint pain due to the formation of similar precipitates in the joints.
  • COMMENTS:

    From Safe Work Australia and the Hazardous Substances Information System (HSIS) in Australia:

    Harmful in contact with skin. Harmful if swallowed | General Health Hazard | A Hazardous Substance that may be found in the Australian Workplace. Check with your employer or health and safety officer. Stay informed and become aware of the dangers that surround you. This chemical is included on the list of recognised hazardous chemicals from the Safe Work Australia - Hazardous Substances Information System (HSIS) that is based on the Globally Harmonised System of Classification and Labelling of Chemicals (GHS)

    Work Health and Safety (WHS) Regulations are the basis for hazardous chemicals regulations in Commonwealth, State and Territory jurisdictions in Australia. Under the model WHS Regulations, manufacturers and importers of substances, mixtures and articles supplied for use in workplaces are required to determine whether they are hazardous to health and safety before supply. The model WHS Regulations mandate that the hazards of a chemical as determined by the Globally Harmonised System of Classification and Labelling of Chemicals (GHS) must be included in safety data sheets and on labels. There are transitional arrangements in place for moving to the GHS-based system.

    The GHS Hazardous Chemical Information List contains chemicals classified by an authoritative source (such as the European Commission or NICNAS) in accordance with the Globally Harmonized System of Classification and Labelling of Chemicals (the GHS). This list contains the vast majority of chemicals currently in HSIS. This list and its detail are regularly updated by Work Safe Australia. The model Work Health and Safety (WHS) Regulations require chemicals to be classified in accordance with the Globally Harmonised System of Classification and Labelling of Chemicals (GHS). However transitional arrangements allow use of classification information in HSIS derived from the Approved Criteria until the 31 December 2016.
  • toxin chemical structure pubchem
  • FORMULA: C2H2O4
  • DATA SOURCES: DATA SOURCES: ARTICLE 4 | T3DB | PubChem | FDA Indirect Food Additives | EPA USA - Pesticide Inerts | Safe Work Australia - Hazardous Substances Information System (HSIS)
  • LAST UPDATE: 28/04/2018

  Health Associations

Mostly focused on Health Implications of Long Term Exposure to this substance

  • SYMPTOMS: Oxalic acid poisoning symptoms include weakness, burning in the mouth, death from cardiovascular collapse, on the respiratory system, throat – burning in the throat, abdominal pain, nausea, vomiting, diarrhea, convulsions, and coma.
  • POSSIBLE HEALTH CONSEQUENCES: Because it binds vital nutrients such as calcium, long-term consumption of foods high in oxalic acid can be problematic. Healthy individuals can safely consume such foods in moderation, but those with kidney disorders, gout, rheumatoid arthritis, or certain forms of chronic vulvar pain (vulvodynia) are typically advised to avoid foods high in oxalic acid or oxalates. The calcium oxalate precipitate (better known as kidney stones) obstruct the kidney tubules. Conversely, calcium supplements taken along with foods high in oxalic acid can cause calcium oxalate to precipitate out in the gut and drastically reduce the levels of oxalate absorbed by the body (by 97% in some cases.) Chronically high levels of oxalic acid are associated with at least 2 inborn errors of metabolism including: Type I primary hyperoxaluria and Primary hyperoxaluria. Oxalate stones in primary hyperoxaluria tend to be severe, resulting in relatively early kidney damage (before age 20), which impairs the excretion of oxalate leading to a further acceleration in accumulation of oxalate in the body. After the development of renal failure patients may develop oxalate deposits in the bones, joints and bone marrow. Severe cases may develop haematological problems such as anaemia and thrombocytopaenia. The deposition of oxalate in the body is sometimes called "oxalosis" to be distinguished from "oxaluria" which refers to oxalate in the urine. | Oxalic acid is not metabolized but excreted in the urine.
  • ACTION OF TOXIN: The affinity of divalent metal ions is sometimes reflected in their tendency to form insoluble precipitates. Thus in the body, oxalic acid also combines with metals ions such as Ca2+, Fe2+, and Mg2+ to deposit crystals of the corresponding oxalates, which irritate the gut and kidneys. (2) Therefore the toxicity of oxalic acid is due to kidney failure caused by precipitation of solid calcium oxalate, the main component of kidney stones. Oxalic acid can also cause joint pain due to the formation of similar precipitates in the joints. Ingestion of ethylene glycol results in oxalic acid as a metabolite that can also cause acute kidney failure. | Oxalic acid binds to the prothrombin promoter, inhibiting the formation of thromboxane B2 from arachidonic acid. (A218)(A219)
  • TOXIN SITES OF ACTION IN CELL: "Cytoplasm", "Extracellular", "Mitochondria", "Peroxisome"
  • Additional Exposure Routes: Oxalic acid and oxalates are abundantly present in many plants, most notably fat hen (lamb's quarters), sorrel, and Oxalis species. The root and/or leaves of rhubarb and buckwheat are listed being high in oxalic acid.[8] Other edible plants that contain significant concentrations of oxalic acid include—in decreasing order—star fruit (carambola), black pepper, parsley, poppy seed, amaranth, spinach, chard, beets, cocoa, chocolate, most nuts, most berries, and beans. (L618)

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  Exposure Routes

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