Hydroquinone

H302: Harmful if swallowed [Warning Acute toxicity, oral]

H317: May cause an allergic skin reaction [Warning Sensitization, Skin]

H318: Causes serious eye damage [Danger Serious eye damage/eye irritation]

H341: Suspected of causing genetic defects [Warning Germ cell mutagenicity]

H351: Suspected of causing cancer [Warning Carcinogenicity]

H400: Very toxic to aquatic life [Warning Hazardous to the aquatic environment, acute hazard]

P203, P261, P264, P264+P265, P270, P272, P273, P280, P301+P317, P302+P352, P305+P354+P338, P317, P318, P321, P330, P333+P317, P362+P364, P391, P405, and P501 (click each P-code to see the statement)

This chemical does not meet GHS hazard criteria for < 0.1% (1 of 2485) of reports.

H302+H312 (17.7%): Harmful if swallowed or in contact with skin [Warning Acute toxicity, oral; acute toxicity, dermal]

H302 (99.7%): Harmful if swallowed [Warning Acute toxicity, oral]

H312 (17.7%): Harmful in contact with skin [Warning Acute toxicity, dermal]

H317 (> 99.9%): May cause an allergic skin reaction [Warning Sensitization, Skin]

H318 (99.9%): Causes serious eye damage [Danger Serious eye damage/eye irritation]

H341 (99.9%): Suspected of causing genetic defects [Warning Germ cell mutagenicity]

H351 (> 99.9%): Suspected of causing cancer [Warning Carcinogenicity]

H400 (> 99.9%): Very toxic to aquatic life [Warning Hazardous to the aquatic environment, acute hazard]

H410 (21.2%): Very toxic to aquatic life with long lasting effects [Warning Hazardous to the aquatic environment, long-term hazard]

Aggregated GHS information provided per 2485 reports by companies from 36 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Reported as not meeting GHS hazard criteria per 1 of 2485 reports by companies.

There are 35 notifications provided by 2484 of 2485 reports by companies with hazard statement code(s).

Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website.

H340: May cause genetic defects [Danger Germ cell mutagenicity]

H370: Causes damage to organs [Danger Specific target organ toxicity, single exposure]

H373: May causes damage to organs through prolonged or repeated exposure [Warning Specific target organ toxicity, repeated exposure]

H410: Very toxic to aquatic life with long lasting effects [Warning Hazardous to the aquatic environment, long-term hazard]

P203, P260, P261, P264, P264+P265, P270, P272, P273, P280, P301+P317, P302+P352, P305+P354+P338, P308+P316, P317, P318, P319, P321, P330, P333+P317, P362+P364, P391, P405, and P501 (click each P-code to see the statement)

H316: Causes mild skin irritation [Warning Skin corrosion/irritation]

H336: May cause drowsiness or dizziness [Warning Specific target organ toxicity, single exposure; Narcotic effects]

P203, P260, P261, P264+P265, P271, P280, P304+P340, P305+P354+P338, P317, P318, P319, P332+P317, P403+P233, P405, and P501 (click each P-code to see the statement)

H315: Causes skin irritation [Warning Skin corrosion/irritation]

H319: Causes serious eye irritation [Warning Serious eye damage/eye irritation]

H360: May damage fertility or the unborn child [Danger Reproductive toxicity]

H372: Causes damage to organs through prolonged or repeated exposure [Danger Specific target organ toxicity, repeated exposure]

P203, P260, P261, P264, P264+P265, P270, P272, P280, P301+P317, P302+P352, P305+P351+P338, P308+P316, P318, P319, P321, P330, P332+P317, P333+P317, P337+P317, P362+P364, P405, and P501 (click each P-code to see the statement)

Fresh air, rest. Artificial respiration may be needed. Refer for medical attention.

Remove contaminated clothes. Rinse and then wash skin with water and soap.

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

Rinse mouth. Induce vomiting (ONLY IN CONSCIOUS PERSONS!). Refer for medical attention .

Signs and Symptoms of Acute Hydroquinone Exposure: Signs and symptoms of acute exposure to hydroquinone may be severe and include dyspnea (shortness of breath), a sense of suffocation, increased respiratory rate, and respiratory failure. Pallor (paleness of the skin), cyanosis (blue tint to skin and mucous membranes), and cardiovascular collapse may occur. Neurologic effects include headache, tinnitus (ringing in the ears), dizziness, delirium, muscle twitching, tremor, and convulsions. Nausea, vomiting, and the production of green to brown-green urine may also occur. Hydroquinone may be irritating and corrosive to the skin, eyes, and mucous membranes. Jaundice (yellow tint to skin) may be noticed.

Emergency Life-Support Procedures: Acute exposure to hydroquinone may require decontamination and life support for the victims. Emergency personnel should wear protective clothing appropriate to the type and degree of contamination. Air-purifying or supplied-air respiratory equipment should also be worn, as necessary. Rescue vehicles should carry supplies such as plastic sheeting and disposable plastic bags to assist in preventing spread of contamination.

Inhalation Exposure:

1. Move victims to fresh air. Emergency personnel should avoid self-exposure to hydroquinone.

2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer oxygen or other respiratory support.

3. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.

4. Transport to a health care facility.

Dermal/Eye Exposure:

1. Remove victims from exposure. Emergency personnel should avoid self- exposure to hydroquinone.

3. Remove contaminated clothing as soon as possible.

4. If eye exposure has occurred, eyes must be flushed with lukewarm water for at least 15 minutes.

5. Wash exposed skin areas twice with soap and water.

6. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.

7. Transport to a health care facility.

Ingestion Exposure:

1. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer oxygen.

2. IMMEDIATELY give the victims water or milk: children up to 1 year old, 125 mL (4 oz or 1/2 cup); children 1 to 12 years old, 200 mL (6 oz or 3/4 cup); adults, 250 mL (8 oz or 1 cup). Water or milk should be given only if victims are conscious and alert.

4. Vomiting may be induced with syrup of Ipecac. If elapsed time since ingestion of hydroquinone is unknown or suspected to be greater than 30 minutes, do not induce vomiting and proceed to Step

5.Ipecac should not be administered to children under 6 months of age.Warning: Ingestion of hydroquinone may result in sudden onset of seizures or loss of consciousness. Syrup of Ipecac should be administered only if victims are alert, have an active gag-reflex, and show no signs of impending seizure or coma. If ANY uncertainty exists, proceed to Step

5.The following dosages of Ipecac are recommended: children up to 1 year old, 10 mL (1/3 oz); children 1 to 12 years old, 15 mL (1/2 oz); adults, 30 mL (1 oz). Ambulate (walk) the victims and give large quantities of water. If vomiting has not occurred after 15 minutes, Ipecac may be readministered. Continue to ambulate and give water to the victims. If vomiting has not occurred within 15 minutes after second administration of Ipecac, administer activated charcoal.

5. Activated charcoal may be administered if victims are conscious and alert. Use 15 to 30 g (1/2 to 1 oz) for children, 50 to 100 g (1-3/4 to 3-1/2 oz) for adults, with 125 to 250 mL (1/2 to 1 cup) of water.

6. Promote excretion by administering a saline cathartic or sorbitol to conscious and alert victims. Children require 15 to 30 g (1/2 to 1 oz) of cathartic; 50 to 100 g (1-3/4 to 3-1/2 oz) is recommended for adults.

7. Transport to a health care facility. (EPA, 1998)

(General first aid procedures)

Eye: Irrigate immediately - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately.

Skin: Water flush - If this chemical contacts the skin, flush the contaminated skin with water. Where there is evidence of skin irritation, get medical attention.

Breathing: Respiratory support

Swallow: Medical attention immediately - If this chemical has been swallowed, get medical attention immediately.

Wear self-contained (positive pressure if available) breathing apparatus and full protective clothing.

For small fires use dry chemical, carbon dioxide, water spray or foam. Move container from fire area if you can do so without risk. This compound is a slight fire or explosion hazard. (EPA, 1998)

Use water spray, powder, foam, carbon dioxide.

To fight fire, use water, carbon dioxide, dry chem ... .

If material on fire or involved in fire: Extinguish fire using agent suitable for type of surrounding fire (Material itself does not burn or burns with difficulty). Use water in flooding quantities as fog. Apply water from as far a distance as possible. Keep run-off water out of sewers and water sources.

Suitable extinguishing media: Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.

Advice for firefighters: Wear self contained breathing apparatus for fire fighting if necessary.

Special hazards arising from the substance or mixture: Carbon oxides

Excerpt from ERG Guide 171 [Substances (Low to Moderate Hazard)]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids.

SPILL: Increase the immediate precautionary measure distance, in the downwind direction, as necessary.

FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2024)

Personal protection: particulate filter respirator adapted to the airborne concentration of the substance. Do NOT let this chemical enter the environment. Sweep spilled substance into covered sealable containers. Carefully collect remainder. Then store and dispose of according to local regulations.

Environmental Considerations: Land spill: Dig a pit, pond, lagoon, holding area to contain liquid or solid material. Cover solids with a plastic sheet to prevent dissolving in rain or fire fighting water. Dike surface flow using soil, sand bags, foamed polyurethane, or foamed concrete. Absorb bulk liquid with fly ash, cement powder, or commercial sorbents. /SRP: If time permits, pits, ponds, lagoons, soak holes, or holding areas should be sealed with an impermeable flexible membrane liner./

Environmental Considerations: Water spill: Use natural barriers or oil spill control booms to limit spill travel. Use natural deep water pockets, excavated lagoons, or sand bag barriers to trap material at bottom. Remove trapped material with suction hoses.

Environmental Considerations: Air spill: Apply water spray or mist to knock down vapors.

Accidental Release Measures. Personal precautions, protective equipment and emergency procedures: Use personal protective equipment. Avoid dust formation. Avoid breathing vapours, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Avoid breathing dust. Environmental precautions: Prevent further leakage or spillage if safe to do so. Do not let product enter drains. Discharge into the environment must be avoided. Methods and materials for containment and cleaning up: Pick up and arrange disposal without creating dust. Sweep up and shovel. Keep in suitable, closed containers for disposal.

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal and plant life; and conformance with environmental and public health regulations.

The following wastewater treatment technologies have been investigated for Hydroquinone: Concentration process: Reverse osmosis.

The following wastewater treatment technologies have been investigated for Hydroquinone: Concentration process: Activated carbon.

Hydroquinone is a waste chemical stream constituent which may be subjected to ultimate disposal by controlled incineration.

For more Disposal Methods (Complete) data for HYDROQUINONE (6 total), please visit the HSDB record page.

Work clothing that becomes wet or significantly contaminated should be removed and replaced.

Workers whose clothing may have become contaminated should change into uncontaminated clothing before leaving the work premises.

The worker should immediately wash the skin when it becomes contaminated.

SRP: The scientific literature for the use of contact lenses by industrial workers is inconsistent. The benefits or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses. However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye. In those specific cases, contact lenses should not be worn. In any event, the usual eye protection equipment should be worn even when contact lenses are in place.

For more Preventive Measures (Complete) data for HYDROQUINONE (11 total), please visit the HSDB record page.

Excerpt from ERG Guide 171 [Substances (Low to Moderate Hazard)]:

Do not touch or walk through spilled material. Stop leak if you can do it without risk. Prevent dust cloud. For Asbestos, avoid inhalation of dust. Cover spill with plastic sheet or tarp to minimize spreading. Do not clean up or dispose of, except under supervision of a specialist.

SMALL DRY SPILL: With clean shovel, place material into clean, dry container and cover loosely; move containers from spill area.

SMALL SPILL: Pick up with sand or other non-combustible absorbent material and place into containers for later disposal.

LARGE SPILL: Dike far ahead of liquid spill for later disposal. Cover powder spill with plastic sheet or tarp to minimize spreading. Prevent entry into waterways, sewers, basements or confined areas. (ERG, 2024)

Separated from strong bases and food and feedstuffs.

Keep well closed and protected from light.

Plug tight and store in a place away from direct sunlight.

Conditions for safe storage, including any incompatibilities: Keep container tightly closed in a dry and well-ventilated place. Air and light sensitive.

2.0 [mg/m3]

20 [mg/m3]

50 [mg/m3]

2 mg/m³ [15 minutes]

C 2 mg/m3 [15-minute]

TWA 2 mg/m3

50 mg/m3 (NIOSH, 2024)

50.0 [mg/m3]

Excerpts from Documentation for IDLHs: Human data: It has been reported that 5 to 12 grams is the lethal oral dose [Zeidman and Deutel 1945]. [Note: An oral dose of 5 to 12 grams is equivalent to a worker being exposed to 3,333 to 8,000 mg/m3 for 30 minutes, assuming a breathing rate of 50 liters per minute and 100% absorption.]

50 mg/cu m.

50 mg/m³

50 mg/m3

See: 123319

1.0 [mg/m3]

8 hr Time Weighted Avg (TWA): 1 mg/cu m, dermal sensitization.

Excursion Limit Recommendation: Excursions in worker exposure levels may exceed 3 times the TLV-TWA for no more than a total of 30 minutes during a work day, and under no circumstances should they exceed 5 times the TLV-TWA, provided that the TLV-TWA is not exceeded.

A3; Confirmed animal carcinogen with unknown relevance to humans.

1 mg/m³ [2007]

skin absorption (H); sensitization of skin (SH); carcinogen category: 2; germ cell mutagen group: 3A

A harmful contamination of the air will not or will only very slowly be reached on evaporation of this substance at 20 °C.

The substance is severely irritating to the eyes. The substance is irritating to the skin and respiratory tract.

Repeated or prolonged contact with skin may cause dermatitis. Repeated or prolonged contact may cause skin sensitization. The substance may have effects on the eyes and skin. This may result in discolouration of the conjunctiva and cornea and skin depigmentation. This substance is possibly carcinogenic to humans.

Excerpt from NIOSH Pocket Guide for Hydroquinone:

Skin: PREVENT SKIN CONTACT - Wear appropriate personal protective clothing to prevent skin contact.

Eyes: PREVENT EYE CONTACT - Wear appropriate eye protection to prevent eye contact.

Wash skin: WHEN CONTAMINATED - The worker should immediately wash the skin when it becomes contaminated.

Remove: WHEN WET OR CONTAMINATED - Work clothing that becomes wet or significantly contaminated should be removed and replaced.

Change: DAILY - Workers whose clothing may have become contaminated should change into uncontaminated clothing before leaving the work premises.

Provide: EYEWASH (>7%) - Eyewash fountains should be provided in areas where there is any possibility that workers could be exposed to the substances; this is irrespective of the recommendation involving the wearing of eye protection. (>7%) (NIOSH, 2024)

Wear appropriate personal protective clothing to prevent skin contact.

Wear appropriate eye protection to prevent eye contact.

Eyewash fountains should be provided in areas where there is any possbility that workers could be exposed to the substance; this is irrespective of the recommendation involving the wearing of eye protection. (>7%)

Respirator Recommendations: Up to 50 mg/cu m [Table#1668]

For more Personal Protective Equipment (PPE) (Complete) data for HYDROQUINONE (11 total), please visit the HSDB record page.

NIOSH/OSHA

Up to 50 mg/m3 :

(APF = 25) Any powered, air-purifying respirator with a high-efficiency particulate filter./

(APF = 50) Any air-purifying, full-facepiece respirator with an N100, R100, or P100 filter.

Click here for information on selection of N, R, or P filters. 

(APF = 50) Any supplied-air respirator that has a tight-fitting facepiece and is operated in a continuous-flow mode

Hydroquinone appears as light colored crystals or solutions. May irritate the skin, eyes and mucous membranes. Mildly toxic by ingestion or skin absorption.

Large Crystals; Other Solid; Dry Powder; Liquid

Light-tan, light-gray, or colorless crystals; [NIOSH]

COLOURLESS CRYSTALS.

Light-tan, light-gray, or colorless crystals.

White crystals

Monoclinic prisms (sublimation); needles from water; prisms from methanol

Light-tan, light-gray, or colorless crystals

Odorless

A slightly bitter taste in aqueous solutions

545 to 549 °F at 760 mmHg (EPA, 1998)

285-287 °C

286.00 to 288.00 °C. @ 760.00 mm Hg

285 °C @760 [mm Hg]

338 to 340 °F (EPA, 1998)

170-171 °C

MP: 173 °C; BP 288 °C

Heat of fusion at melting point = 2.71X10+7 J/kmol

172.3 °C

329 °F (EPA, 1998)

329 °F (CLOSED CUP)

165 °C (329 °F) (Closed cup)

329 °F (165 °C) (Closed cup)

329 °F (Molten)

10 to 50 mg/mL at 68 °F (NTP, 1992)

6.72g/L at 20 deg C

In water, 72,000 mg/L at 25 °C

In water, 6.72 g/L at 20 °C. Also water solubility = 3.85 g/L at 0 °C; 5.12 g/L at 10 °C; 5.40 g/L at 15 °C; 8.76 g/L at 30 °C; 11.5 g/L at 40 °C; 25/9 g/L at 60 °C; 46.8 g/L at 80 °C; 66.4 g/L at 100 °C

7% soluble in water at 25 °C

Grams of hydroquinone per 100 g solvent (30 °C); ethanol 46.4; acetone 28.4; water 8.3; benzene 0.06; tetrachloromethane 0.01

For more Solubility (Complete) data for HYDROQUINONE (6 total), please visit the HSDB record page.

72.0 mg/mL at 25 °C

Solubility in water, g/100ml at 15 °C: 5.9

1.332 at 59 °F (EPA, 1998) - Denser than water; will sink

1.330 g/cu cm at 20 °C

Density of "saturated" air = 1.011 (150 °C) (air = 1) ... Crystals remain relatively stable in air if dry ... Reacts with molecular oxygen undergoing autooxidation in aqueous media

Relative density (water = 1): 1.3

1.332 at 59 °F

1.358 @ 20°C

3.81 (EPA, 1998) - Heavier than air; will sink (Relative to Air)

Darkens on exposure to air and light. Miscible in water. Solutions become brown in air due to oxidation. Oxidation is very rapid in the presence of alkali.

Phenols and Cresols

Acids, Weak

CSL00016

ACROLEIN + HYDROQUINONE

Warning - This reagent combination was observed internally to build significant pressure, resulting in the failure of a sealed tube apparatus. Please consider using a solvent such as Xylenes or running the reaction at lower temperature.

Gas Under Pressure

ALDEHYDE

User-Reported

CSL00017

HYDROQUINONE + METHYL ACRYLATE

HYDROQUINONE is a slight explosion hazard when exposed to heat. Incompatible with strong oxidizing agents. Also incompatible with bases. It reacts with oxygen and sodium hydroxide. Reacts with ferric salts (NTP, 1992). Hot and/or concentrated NaOH can cause hydroquinone to decompose exothermically at elevated temperature. (NFPA Pub. 491M, 1975, 385)

Strong oxidizers, alkalis.

Accidental mixing of the hot crude hydroquinone with concn sodium hydroxide solution led to extensive exothermic decomposition.

Violent reaction with NaOH.

Incompatible materials: Strong bases, strong oxidizing agents

Crude hydroquinone was pumped into a sodium hydroxide storage tank by mistake. The hyrdoquinone liquor at 85 °C decomposed rapidly in the presence of the sodium hydroxide resulting in overflow of the tank and evolution of a considerable amount of heat.

Strong oxidizers, alkalis

The CIR Expert Panel concluded that hydroquinone is safe at concentrations of less than or equal to 1% for cosmetic formulations designed for discontinuous, brief use followed by rinsing from the skin and hair. Hydroquinone is safe for use in nail adhesives and in artificial nail coatings, as a polymerization inhibitor, that are cured by LED light. Hydroquinone is unsafe for use in other leave-on cosmetic products.

The ingredient is unsafe for use in cosmetics

IDENTIFICATION AND USE: Hydroquinone (HQ) is an aromatic compound in the form of light tan to gray crystals. It is a high-volume commodity chemical used as a reducing agent, antioxidant, polymerization inhibitor, chemical stabilizer, chemical intermediate, and photographic reducer and developer. It is also used in skin lighteners, in cosmetics, hair dye, glue, and a medication to treat dyschromias. HUMAN EXPOSURE: A great deal of research has been conducted with HQ because it is a metabolite of benzene. In workers engaged in the manufacture, HQ dust oxidizes to brown benzoquinone. This material causes pigmentation of the eye and, in some cases, permanent corneal damage. There are reported cases of keratitis and discoloration of the conjunctiva among men exposed to concentrations ranging from 10 to 30 mg of vapor or dust of HQ per cubic meter of air. Ingestion of 1 g by an adult has caused dizziness, sense of suffocation, increased rate of respiration, vomiting, pallor, muscular twitching, headache, dyspnea, cyanosis and collapse and eventually death due to respiratory failure. Upon ingestion urine is green or brownish-green in color and continues to darken on standing. Five hundred forty-four (544) crewmen aboard a large USA Navy vessel developed GI disease characterized by acute onset of nausea, vomiting, abdominal cramps, and diarrhea which was found to be due to hydroquinone contamination of the chilled water system by automatic photo developing machines on the ship. HQ is only weakly positive in in vivo chromosomal assays when expected human exposure routes are used. Chromosomal effects are increased significantly when parenteral or in vitro assays are used. Hydroquinone impairs several leukocyte cell functions, which alter the immune response. It evokes pro-inflammatory properties in endothelial cells that are triggered by the enhancement of NF-kappaB nuclear translocation-dependent gene transcription. Parenteral administration of HQ is associated with changes in several hematopoietic and immunologic endpoints. This toxicity is more severe when combined with parenteral administration of phenol. It is likely that oxidation of HQ within the bone marrow compartment to the semiquinone or p-benzoquinone (BQ), followed by covalent macromolecular binding, and is critical to these effects. Bone marrow and hematologic effects are generally not characteristic of HQ exposures in animal studies employing routes of exposure other than parenteral. Enhanced Ras signaling increases both hydroquinone-mediated growth inhibition in yeast and genotoxicity in mammalian hematopoietic suggesting that HQ toxicity is modulated by Ras signaling and individuals with abnormal Ras signaling could be more vulnerable to developing myeloid diseases after exposure. Hydroquinone also increases proliferation of CFU-GM progenitor cells in mice with Nf1 null bone marrow relative to WT, the same cell type associated with benzene-associated leukemia. It is confirmed animal carcinogen with unknown relevance to humans. ANIMAL STUDIES: In cancer bioassays, HQ has reproducibly produced renal adenomas in male rats. The mechanism of tumorigenesis is unclear but probably involves a species-, strain-, and sex-specific interaction between renal tubule toxicity and an interaction with the chronic progressive nephropathy that is characteristic of aged male rats. Mouse liver tumors (adenomas) and mononuclear cell leukemia (female rat) have also been reported following HQ exposure, but their significance is uncertain. Various tumor initiation/promotion assays with HQ have shown generally negative results. In two-year studies in rats of each sex given hydroquinone in deionized water by gavage, nearly all male rats and most female rats in all vehicle control and dosed groups had nephropathy. The severity of this disease was judged to be greater in high dose male rats. The data on the effect of HQ on development are conflicting, with several studies reporting minimal to no treatment -related effects on duration of gestation, mean litter size, fetal viability, or lactation index in rats fed diets containing HQ. However, one study reports that female rats fed 0.5 g of hydroquinone in their diet during pregnancy had higher rates of fetal resorption than controls (100% versus 41% of the dams), and a greater number of the total implantations were resorbed (27% versus 11%). HQ was not mutagenic in Salmonella typhimurium strains TA98, TA100, TA1535, or TA1537 with or without exogenous metabolic activation. It induced trifluorothymidine resistance in mouse L5178Y/TK lymphoma cells in the presence or absence of metabolic activation, and induced sister chromatid exchanges in Chinese hamster ovary cells both with or without exogenous metabolic activation and caused chromosomal aberrations in the presence of activation. HQ also induced aneuploidy in yeast by delaying the cell cycle at the G2/M transition.

No significant toxicity has been found with the topical use of the hydroquinone cream.

Some studies report malignancies in animals treated for an extended period with large oral doses.

Hydroquinone in the Environment

In the environment, hydroquinone is a chemical and can be toxic in human and industrial activities by promoting the generation of reactive oxygen species, oxidative stress, and hence the potential for DNA damage. It is a major benzene metabolite and is known to be hepatotoxic and carcinogenic in these settings. Some studies suggest it can promote tumor cell growth and suppress the immune response. It is used in photography and is present in dyes, paints, varnishes oils, and motor fuels. In its oxidized form, it is more toxic and less degradable. It demonstrates high toxicity to aquatic organisms and rodents and may induce leukemia, renal tubular cell tumors, and liver cancer. It has also been found to influence immune cell responses and cause an increase in an allergic reaction by increasing interleukin-4 production and immunoglobulin E levels.

Hydroquinone

Evaluation: There is inadequate evidence in humans for the carcinogenicity of hydroquinone. There is limited evidence in experimental animals for the carcinogenicity of hydroquinone. Overall evaluation: Hydroquinone is not classifiable as to its carcinogenicity to humans (Group 3).

A3; Confirmed animal carcinogen with unknown relevance to humans.

The authors of this detailed review cover hydroquinone's potential for carcinogenicity and its possible mode of carcinogenic action. They proposed and evaluated a nongenotoxic mode of action that involves the exacerbation of chronic progressive nephropathy (CPN), a spontaneously occurring rodent renal disease. Their conclusion is that the increased incidence of renal tubule adenomas in hydroquinone-dosed male rats is without human consequence.

Group 3: Not classifiable as to its carcinogenicity to humans

Volume 15: (1977) Some Fumigants, the Herbicides 2,4-D and 2,4,5-T, Chlorinated Dibenzodioxins and Miscellaneous Industrial Chemicals

Volume Sup 7: Overall Evaluations of Carcinogenicity: An Updating of IARC Monographs Volumes 1 to 42, 1987; 440 pages; ISBN 92-832-1411-0 (out of print)

Volume 71: (1999) Re-evaluation of Some Organic Chemicals, Hydrazine and Hydrogen Peroxide (Part 1, Part 2, Part 3)

TR-366: Toxicology and Carcinogenesis Studies of Hydroquinone (CASRN 123-31-9) in F344/N Rats and B6C3F1 Mice (Gavage Studies) (1989 )

10/03/88

Some Evidence

No Evidence

Under the conditions of these 2-year gavage studies, there was some evidence of carcinogenic activity of hydroquinone for male F344/N rats, as shown by marked increases in tubular cell adenomas of the kidney. There was some evidence of carcinogenic activity of hydroquinone for female F344/N rats, as shown by increases in mononuclear cell leukemia. There was no evidence of carcinogenic activity of hydroquinone for male B6C3F1 mice administered 50 or 100 mg/kg in water by gavage. There was some evidence of carcinogenic activity of hydroquinone for female B6C3F1 mice, as shown by increases in hepatocellular neoplasms, mainly adenomas.

Administration of hydroquinone was associated with thyroid follicular cell hyperplasia in both male and female mice and anisokaryosis, multinucleated hepatocytes, and basophilic foci of the liver in male mice.

3, not classifiable as to its carcinogenicity to humans. (L135)

◉ Summary of Use during Lactation

Topical hydroquinone has not been studied during breastfeeding. Although hydroquinone is not contraindicated during breastfeeding, some experts feel that long-term use of hydroquinone should not be used in nursing mothers. If hydroquinone is used, ensure that the infant's skin does not come into direct contact with the areas of maternal skin that have been treated and the infant does not ingest the product from the mother's skin.

◉ Effects in Breastfed Infants

Relevant published information was not found as of the revision date.

◉ Effects on Lactation and Breastmilk

The substance can be absorbed into the body by inhalation, through the skin and by ingestion.

inhalation, ingestion, skin and/or eye contact

Cough. Laboured breathing.

Redness.

Redness. Pain. Blurred vision.

Dizziness. Headache. Nausea. Shortness of breath. Convulsions. Vomiting. Ringing in the ears.

irritation eyes: conjunctivitis; keratitis (inflammation of the cornea); central nervous system excitement; colored urine, nausea, dizziness, suffocation, rapid breath; muscle twitching, delirium; collapse; skin irritation, sensitization, dermatitis

Eyes, skin, respiratory system, central nervous system

Methemoglobinemia - The presence of increased methemoglobin in the blood; the compound is classified as secondary toxic effect

Skin Sensitizer - An agent that can induce an allergic reaction in the skin.

ACGIH Carcinogen - Confirmed Animal.

Adverse Effects Include

* Irritation

EC50; Species: Chlorococcales (Green algae); Conditions: freshwater, static; Concentration: 17000 ug/L for 24 hr; Effect: physiology; assimilation efficiency /formulation/

EC50; Species: Dunaliella tertiolecta (Green algae); Conditions: freshwater, static, 24 °C, pH 6.8, salinity 2.348%, ; Concentration: 29250 ug/L for 24 hr; Effect: population, decreased photosynthesis /formulation/

EC50; Species: Selenastrum capricormutum (algae); Concentration: 0.335 mg/L for 72 hr; Effect: growth /Conditions of bioassay not specified in source examined/

EC50; Species: Daphnia magna (Water flea) age 6-24 hr; Conditions: freshwater, static, 20 °C, pH > or =7.0; Concentration: 320 ug/L for 24 hr (95% confidence interval: 270-380 ug/L); Effect: intoxication, immobilization /formulation/

For more Ecotoxicity Values (Complete) data for HYDROQUINONE (22 total), please visit the HSDB record page.

/AQUATIC SPECIES/ Sea bass (Dicentrarchus labrax) were injected intraperitoneally once (single dose) or three times (fractionated dose) with phenol or OH-phenols (hydroquinone, resorcinol, and pyrocatechol). On the basis of the lethal doses, OH-phenols were more toxic than phenol, and pyrocatechol was the most powerful compound. Hematological, metabolic and antioxidant blood parameters were measured 3 days after the end of the treatment. Metabolic variations as specific effects on erythrocytes were revealed and differences between single and fractionated doses were observed. OH-phenols-treated fish showed disorders in the metabolic toxicity indicators as hypoglycemia, low blood urea nitrogen level (BUN) and decrease of alkaline phosphatase activity (ALP).

9.00e+00

3.80e+01

1.30e+00

5.00e+01

8.70e-04

6.00e-02

4.00e-02

Volatile

9.00e+02

3.80e+03

1.30e+02

The substance is very toxic to aquatic organisms.

Hydroquinone's production and use as a chemical intermediate, glue and hair dye ingredient, and administration as a skin depigmentor may result in its release to the environment through various waste streams. Hydroquinone occurs naturally in several arthropods and assorted species of plants. If released to air, a vapor pressure of 2.4X10-5 mm Hg at 25 °C indicates hydroquinone will exist in both the vapor and particulate phases in the atmosphere. Vapor-phase hydroquinone will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 17 hrs. Particulate-phase hydroquinone will be removed from the atmosphere by wet and dry deposition. Hydroquinone contains chromophores that absorb at wavelengths >290 nm and, therefore, may be susceptible to direct photolysis by sunlight. If released to soil, hydroquinone is expected to have moderate mobility based upon an estimated Koc of 240. Volatilization from moist soil surfaces is not expected to be an important fate process based upon an estimated Henry's Law constant of 4.7X10-11 atm-cu m/mole. Hydroquinone is not expected to volatilize from dry soil surfaces based upon its vapor pressure. Hydroquinone was found to biodegrade in the coupled units test, the Zahn-Wellens test, the MITI test, the Sturm test, the AFNOR test, the OECD screening test and the closed bottle test, indicating that biodegradation may be an important environmental fate process in soil and water, although its biodegradation is likely to be strongly concentration-dependent. It may be inhibitory at high concentration. If released into water, hydroquinone is expected to adsorb to suspended solids and sediment based upon the estimated Koc. Volatilization from water surfaces is not expected to be an important fate process based upon this compound's estimated Henry's Law constant. An estimated BCF of 3 suggests the potential for bioconcentration in aquatic organisms is low. Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions (pH 5 to 9). Aqueous hydroquinone showed 75% decomposition after 44 hours of UV photooxidation. Occupational exposure to hydroquinone may occur through inhalation and dermal contact with this compound at workplaces where hydroquinone is produced or used. Monitoring/use data indicate that the general population may be exposed to hydroquinone via inhalation of wood or cigarette smoke, ingestion of certain foods and dermal contact with consumer products containing hydroquinone. (SRC)

Hydroquinone occurs naturally in several arthropods and assorted species of plants. It is present in the African plant Noogoora burr (Xanthium pungens) at concentrations high enough to poison pigs and cattle. It is formed as a by-product of metabolism in several bacteria and marine species(1). Hydroquinone occurs naturally, as a conjugate with beta-D-glucopyranoside, in the leaves, bark and fruit of a number of plants, especially the ericaceous shrubs such as the cranberry, cowberry, bearberry and blueberry(2,3). Its presence may be an important factor in fire-blight resistance in the pear, and it may also play an important part in the defense mechanisms of a number of insects, including the bombadier beetle and the earwig(2).

Hydroquinone's production and use as an intermediate for chemical conversion to inhibitors used to stabilize monomers, paints, varnishes, motor oils, fuels, as a rust inhibitor in cooling towers(1), in glue and hair dye formulations(2), and as a depigmentor(3) to gradually lighten age spots, liver spots, freckles or hyperpigmentation that can occur as a result of pregnancy or use of oral contraceptives(4) may result in its release to the environment through various waste streams(SRC). It may also be released to the environment in the effluent coal-gasification condensate water(5) and cigarette smoke(1).

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 240(SRC), determined from a strucure estimation method(2), indicates that hydroquinone is expected to have moderate mobility in soil(SRC). Volatilization of hydroquinone from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 4.7X10-11 atm-cu m/mole(SRC), derived from its vapor pressure, 2.4X10-5 mm Hg(3), and water solubility, 7.2X10+4 mg/L(4). Hydroquinone is not expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(3). The compound may be removed from soil by oxidation processes(5,6) or by direct photolysis on the surface(7,8). In a survey of standardized tests, hydroquinone was found to biodegrade in the coupled units test, the Zahn-Wellens test, the MITI test, the Sturm test, the AFNOR test, the OECD screening test and the closed bottle test, although its biodegradation is likely to be strongly concentration-dependent. It may be inhibitory at high concentration(9,10).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 240(SRC), determined from a structure estimation method(2), indicates that hydroquinone is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(3) based upon an estimated Henry's Law constant of 4.7X10-11 atm-cu m/mole(SRC), derived from its vapor pressure, 2.4X10-5 mm Hg(4), and water solubility, 7.2X10+4 mg/L(5). According to a classification scheme(6), an estimated BCF of 3(SRC), from its log Kow(7) and a regression-derived equation(2), suggests the potential for bioconcentration in aquatic organisms is low(SRC). In a survey of standardized tests, hydroquinone was found to biodegrade in the coupled units test, the Zahn-Wellens test, the MITI test, the Sturm test, the AFNOR test, the OECD screening test and the closed bottle test, although its biodegradation is likely to be strongly concentration-dependent. It may be inhibitory at high concentration(8,9).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), hydroquinone, which has a vapor pressure of 2.4X10-5 mm Hg at 25 °C(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase hydroquinone is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 17 hrs(SRC), calculated from its rate constant of 2.3X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase hydroquinone may be removed from the air by wet and dry deposition(SRC). The water solubility of hydroquinone, 72,000 mg/L at 25 °C(4), indicates that it may undergo atmospheric removal by wet deposition processes(SRC). It may also be removed from the atmosphere by a gas-phase reaction with nitrate radicals, an important nighttime oxidant(3). Hydroquinone contains chromophores that absorb at wavelengths >290 nm(5) and, therefore, may be susceptible to direct photolysis by sunlight(SRC).

AEROBIC: Hydroquinone at a concentration of 0.05 mg/L underwent 7.5% removal in 5 days when inoculated with an activated sludge seed(1,2). Sewage sludge activated to phenol was found to oxidize hydroquinone(3,4). Pure culture oxidation of hydroquinone produced 1,4-benzoquinone, 2-hydroxy-1,4-benzoquinone and beta-ketoadipic acid(5). In a screening study using a sewage seed, hydroquinone had a 5 day theoretical BOD of 25.3%(6). Hydroquinone at an initial concentration of 200 mg/L COD underwent 54.2% removal (less than 120 hours) using a thickened adapted activated sludge under aerobic conditions(7). Activated sludges adapted to aniline, phenol or m-cresol were found to biodegrade hydroquinone under aerobic conditions(8). It was listed as undergoing rapid biodegradation in a commercial activated sludge unit under aerobic conditions(9).

AEROBIC: Hydroquinone at an initial concentration of 500 mg/L underwent 3%, 4% and 25% theoretical oxidation when inoculated with an activated sewage sludge seed acclimated to phenol(1,2), benzoic acid and catechol(1). Hydroquinone underwent a 5 day theoretical biological oxygen demand (BOD) of 53% when inoculated with a settled raw wastewater seed(3). It was found to biodegrade when inoculated with an activated sludge acclimated to resorcinol, but not to m-nitrobenzenesulfonate sodium salt(4). Hydroquinone underwent a 5 day theoretical BOD of 37% under aerobic conditions(5). Hydroquinone was completely removed by an activated sludge in 15 days(6). An activated sewage sludge was found to oxidize hydroquinone(7). Hydroquinone, present at 100 mg/L, reached 95% of its theoretical BOD in 2 weeks using an activated sludge inoculum at 30 mg/L in the Japanese MITI test(8-11).

AEROBIC: Hydroquinone applied at a concentration of 500 mg/kg degraded in 1 day on a hard, carbonaceous woody loam at 19 °C(1,2). Bacteria from soil and related environments raised on a wide variety of different phenolic compounds were found to utilize 95% of 300 ppm hydroquinone within 1 to 2 days under aerobic conditions(3). In a survey of standarized tests, hydroquinone was found to biodegrade in the coupled units test, the Zahn-Wellens test, the MITI test, the Sturm test, the AFNOR test, the OECD screening test and the closed bottle test, although its biodegradation is probably strongly concentration dependent and it may be inhibitory at high concentration(4,5).

ANAEROBIC: In a 500 mg/L fixed-bed reactor, degradation of hydroquinone at concentrations ranging from 0.55 g/L to 2.2 g/L was complete at a flow rate of 170 mL/hr using a mixed microbial seed under anaerobic conditions(1). It was listed as a compound which should be amenable to biological degradation in wastewater treatment by anaerobic biotechnology(2). Hydroquinone was listed as a compound metabolized by enriched methane cultures from a sewage sludge(3). Methanogenic organisms isolated from freshwater sediment and sewage sludge were found to degrade hydroquinone under anaerobic conditions(4).

The rate constant for the vapor-phase reaction of hydroquinone with photochemically-produced hydroxyl radicals has been estimated as 2.3X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 17 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). The half-life for oxidation of hydroquinone by alkylperoxy radicals (present in sunlit waters) in organic solvents is 12 min(2) and at 90 to 95 °C under a UV lamp in aqueous media, 25% photooxidation occurred after 10 hours, 50% after 23 hours, and 75% at 44 hours(3). Autoxidation at 25 °C exhibited half-lives of 111 hours at pH 7.0, 41 hours at pH 8.0, and 0.8 hours at pH 9.0(4). Hydroquinone may also undergo a nighttime reaction with nitrate radicals, which is a facile reaction for similarly substituted phenols(1). Laboratory oxidation of hydroquinone with manganese dioxide is thought to be representative of oxidants commonly present in soil. The result of this test was loss of substrate, indicating that this may be a method of abiotic removal of hydroquinone in soil(5). At pH <9, hydroquinone was found to be oxidized to quinone in the presence of smectite, an isomorphically substituted clay mineral, indicating that oxidation may occur in soil(6).

Hydroquinone is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(1). Hydroxyquinone contains chromophores that absorb at wavelengths >290 nm(1) and, therefore, is susceptible to direct photolysis by sunlight(SRC). When irradiated at 290 nm, 100 ng/g hydroquinone, adsorbed to silica gel, underwent 57.4% photomineralization after 17 hrs(2,3). Photolysis of hydroquinone in water by natural sunlight produced superoxide anion, and ultimately, hydrogen peroxide(4). Laboratory irradiation of a 1.0 mM aqueous hydroquinone solution for 5 hrs produced >42 uM oxidant (superoxide radical anion, aqueous electrons or hydrogen peroxide)(5,6). Photolysis of hydroquinone in dilute aqueous solutions and in the presence of oxygen produced quinone through semiquinonic radicals intermediates(7,8). Hydroquinone was oxidized to unidentified colored products when oxygen was bubbled through an aqueous solution(9).

An estimated BCF of 3 was calculated in fish for hydroquinone(SRC), using a log Kow of 0.59(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC). A bioaccumulation factor of 40 was measured using Golden ide fish (Leuciscus idus melanotus) exposed for 3 days to 0.05 mg/L hydroquinone(4,5). Experimental 24-hour bioaccumulation factors in alga were 40 and 65 for hydroquinone(4-6).

Using a structure estimation method based on molecular connectivity indices(1), the Koc of hydroquinone is estimated as 240(SRC). According to a classification scheme(2), this estimated Koc value suggests that hydroquinone is expected to have moderate mobility in soil. Hydroquinone can exhibit chemisorption to transition metal-containing particulate matter via reaction with the copper oxide/silca surfaces present(3).

The Henry's Law constant for hydroquinone is estimated as 4.7X10-11 atm-cu m/mole(SRC) derived from its vapor pressure, 2.4X10-5 mm Hg(1), and water solubility, 7.2X10+4 mg/L(2). This Henry's Law constant indicates that hydroquinone is expected to be essentially nonvolatile from water and moist soil surfaces(3). Hydroquinone is not expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(1).

Hydroquinone was detected in 3 of 4 samples of effluents of coal-gasification condensate water at a concentration ranging from 1 to 35 mg/L(1). It is typically present in the water of photographic processes(2). Atmospheric emissions in hydroquinone have been associated with the following industries; industrial organics, plastic materials and resins, pharmaceutical preparations, paints and allied products, cyclic crude and intermediates, industrial organics, chemical preparations, petroleum refining, electronic computing equipment, electronic components, and services allied to motion pictures(3). Emission of hydroquinone has been associated with the production of polyvinyl acetate and methyl methacrylate(4). Hydroquinone has been detected in waste ammonia liquor from low temperature carbonization wastes in India at a mean concentration of 33.33 mg/L(5).

Hydroquinone is present in several foods such as wheat products, fruits, and beverages including coffee, teas, beer, and wine(1). Hydroquinone was detected in trace amounts in a mixture of extractable organic substances from New Zealand honeys from unifloral manuka (Leptospermum scoparium) and nodding thistle (Carduus nutans)(2,3).

Hydroquinone occurrence in foods(1).[Table#1672]

Hydroquinone may play an important part in the defense mechanisms of a number of insects, including the bombadier beetle (Carabidae) and the earwig (Forficula auricularia)(1).

Hydroquinone is present at trace levels in cigarette smoke. An estimated 5X10+4 kg of hydroquinone is generated per year during cigarette smoking(1).

Characterization of particulate emissions from fireplace combustion of the most prevalent woods found in the United States revealed the presence of hydroquinone. Smoke samples were collected during a pyrolysis experiment and analyzed by GC/MS. The concentrations were reported in mg/g pyrolysis product/wood weight as follows: 7.609 yellow poplar (Liriodendron tulipifera); 1.621, white ash (Faxinus americana); 1.435, sweetgum (Liquidambar styraciflua); 10.119, mockernut hickory (Carya tomentosa); 0.763, loblolly pine (Pinus taeda); 0.295, slash pine (Pinus elliottii)(1). Combustion of wood in residential fireplaces in the Los Angeles area resulted in hydroquinone emissions of 61.78 mg/kg of pine logs burned and 22.52 mg/kg of oak logs burned; hydroquinone was not detected when burning synthetic logs(2).

Hydroquinone was present at 36.9, 84.2 and 55.3 mg/kg dry wood burned in open, half-closed and closed airflow emissions, respectively, using woodheaters commonly used in central Australia. Higher burn rates (open fair flow) producing much less particle mass per kg wood burned than the low burn rates (closed airflow). Wood used was White gum (Eucalyptus viminalis)(1).

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal and plant life; and conformance with environmental and public health regulations.

The following wastewater treatment technologies have been investigated for Hydroquinone: Concentration process: Reverse osmosis.

The following wastewater treatment technologies have been investigated for Hydroquinone: Concentration process: Activated carbon.

Hydroquinone is a waste chemical stream constituent which may be subjected to ultimate disposal by controlled incineration.

For more Disposal Methods (Complete) data for HYDROQUINONE (6 total), please visit the HSDB record page.

/GUIDE 153: SUBSTANCES - TOXIC and/or CORROSIVE (Combustible)/ Fire or Explosion: Combustible material: may burn but does not ignite readily. When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion hazards. Those substances designated with a (P) may polymerize explosively when heated or involved in a fire. Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated. Runoff may pollute waterways. Substance may be transported in a molten form.

/GUIDE 153: SUBSTANCES - TOXIC and/or CORROSIVE (Combustible)/ Health: TOXIC; inhalation, ingestion or skin contact with material may cause severe injury or death. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.

/GUIDE 153: SUBSTANCES - TOXIC and/or CORROSIVE (Combustible)/ Public Safety: CALL Emergency Response Telephone Number on Shipping Paper first. If Shipping Paper not available or no answer, refer to appropriate telephone number listed on the inside back cover. As an immediate precautionary measure, isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids. Keep unauthorized personnel away. Stay upwind. Keep out of low areas. Ventilate enclosed areas.

/GUIDE 153: SUBSTANCES - TOXIC and/or CORROSIVE (Combustible)/ Protective Clothing: Wear positive pressure self-contained breathing apparatus (SCBA). Wear chemical protective clothing that is specifically recommended by the manufacturer. It may provide little or no thermal protection. Structural firefighters' protective clothing provides limited protection in fire situations ONLY; it is not effective in spill situations where direct contact with the substance is possible.

For more DOT Emergency Guidelines (Complete) data for HYDROQUINONE (8 total), please visit the HSDB record page.

UN 2662; Hydroquinone

No person may /transport,/ offer or accept a hazardous material for transportation in commerce unless that person is registered in conformance ... and the hazardous material is properly classed, described, packaged, marked, labeled, and in condition for shipment as required or authorized by ... /the hazardous materials regulations (49 CFR 171-177)./

Class 9 Poison

Do not transport with food and feedstuffs.

Symbol: Xn, N; R: 22-40-41-43-50-68; S: (2)-26-36/37/39-61

UN Hazard Class: 6.1; UN Pack Group: III