Toxno Substance Profile
Evidence-based data. We have more than 25,000 profiles on Toxno.
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Substance Name

Hydroquinone
Identification Number: CASRN | 123-31-9

  Substance Attributes


  • Carcinogenic Properties

    Accumulating evidence points to cancer potential. Exercise caution with this substance, explore your exposure routes and consider complete avoidance. See further details under Toxins.

  • Birth/Developmental

    Known to effect development of fetus.

  • 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.

  • Toxic to Wildlife

    May kill plants, fish, birds or other animals and insects or may be very toxic to aquatic life with long lasting effects. This then effects delicate environmental ecology and food supply in ways we don't fully understand yet.

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



  • CATEGORIES: Cigarette Toxin | Household Toxin | Pollutant | Airborne Pollutant | Food Toxin | Synthetic Toxin | Indirect Additives Used in Food Contact Substances | Inert Pesticide Ingredient USA - Non Food Use Only | A Hazardous Substance that may be found in the Australian Workplace
  • SUBSTANCE LINEAGE: Organic Compounds | Benzenoids | Benzene and Substituted Derivatives | Phenols and Derivatives | Hydroquinones
  • SYNONYMS: 1,4-Benzenediol | 1,4-Dihydroxy-benzeen | 1,4-Dihydroxy-benzol | 1,4-Dihydroxybenzen | 1,4-Diidrobenzene | 4-Hydroxyphenol | a-Hydroquinone | alpha-Hydroquinone | b-Quinol | Benzene-1,4-diol | Benzohydroquinone | Benzoquinol | beta-Quinol | Dihydroquinone | Dihydroxybenzene | Hydrochinon | Hydrochinone | Hydroquinol | Hydroquinole | Hydroquinone for synthesis | Hydroquinone gr | Hydroquinoue | Idrochinone | Melanex | p-Benzenediol | p-Dihydroxybenzene | p-Dioxobenzene | p-Dioxybenzene | p-Hydroquinone | p-Hydroxybenzene | p-Hydroxyphenol | Phiaquin | Quinol | Solaquin forte
  • DESCRIPTION: Hydroquinone, also benzene-1,4-diol, is an aromatic organic compound which is a type of phenol. Hydroquinone is commonly used as a biomarker for benzene exposure. The presence of hydroquinone in normal individuals stems mainly from direct dietary ingestion, catabolism of tyrosine and other substrates by gut bacteria, ingestion of arbutin containing foods, cigarette smoking, and the use of some over-the-counter medicines. In human medicine, hydroquinone is used as a topical application in skin whitening to reduce the color of skin. In 2006, the United States Food and Drug Administration revoked its previous approval of hydroquinone and proposed a ban on all over-the-counter preparations. The FDA stated that hydroquinone cannot be ruled out as a potential carcinogen. This conclusion was reached based on the extent of absorption in humans and the incidence of neoplasms in rats in several studies where adult rats were found to have increased rates of tumours, including thyroid follicular cell hyperplasias, anisokaryosis, mononuclear cell leukemia, hepatocellular adenomas and renal tubule cell adenomas. Numerous studies have revealed that hydroquinone can cause exogenous ochronosis, a disfiguring disease in which blue-black pigments are deposited onto the skin, if taken orally; however, skin preparations containing the ingredient are administered topically. The FDA has classified hydroquinone currently as a safe product, as currently used. (Wikipedia)
  • COMMENTS:

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

    Suspected of causing cancer. Suspected of causing genetic defects. Harmful if swallowed. Causes serious eye damage. May cause an allergic skin reaction. Very toxic to aquatic life | Chronic Health Hazard Environmental Hazard 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: C6H6O2
  • DATA SOURCES: DATA SOURCES: ARTICLE 4 | CPDB | T3DB | PubChem | IARC | 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:
  • POSSIBLE HEALTH CONSEQUENCES:
  • ACTION OF TOXIN:
  • TOXIN SITES OF ACTION IN CELL: "Cytoplasm", "Extracellular"
  • Additional Exposure Routes: Hydroquinone has a variety of uses principally associated with its action as a reducing agent which is soluble in water. It is a major component in most photographic developers where, with the compound Metol, it reduces silver halides to elemental silver. In human medicine, hydroquinone is used as a topical application in skin whitening to reduce the color of skin.

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  Exposure Routes

These are the Exposure Routes we have so far for this substance. There are almost certainly more. We update this section regularly. The number of chemicals with 2 or more nastiness attributes in an exposure route is shown in orange. They grey badge shows the total amount of chemicals within the exposure route.


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