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CHLORINE DIOXIDE

5.1 - Oxidizer 6.1 - Poison
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The Chemical Identifier fields include common identification numbers, the NFPA diamond U.S. Department of Transportation hazard labels, and a general description of the chemical. The information in CAMEO Chemicals comes from a variety of data sources.
CAS Number UN/NA Number
  • 10049-04-4   (CHLORINE DIOXIDE)
  • 70377-94-5   (hydrate)
DOT Hazard Label USCG CHRIS Code
  • Oxidizer
  • Poison
none
NIOSH Pocket Guide International Chem Safety Card
Chlorine dioxideexternal_link
NFPA 704
data unavailable
General Description
Chlorine dioxide hydrate, frozen is an orange colored solid, appearing as a block of ice, with a faint odor of chlorine. It may only be shipped in the frozen state and then only by private or contract motor carrier. The melting point of the hydrate is around 30°F. If it should thaw and further warm up, chlorine dioxide gas is given off. The gas is toxic by inhalation. The gas and liquid are violently decomposed by organic materials. The gas will decompose explosively at temperatures below the boiling point of water. It is used to bleach wood pulp, fats and oils; in processing flour, and for water purification.

Chlorine dioxide is a yellow to reddish gas or a red-brown liquid below 52 deg. F. with an unpleasant odor similar to chlorine.

The Hazard fields include special hazard alerts air and water reactions, fire hazards, health hazards, a reactivity profile, and details about reactive groups assignments and potentially incompatible absorbents. The information in CAMEO Chemicals comes from a variety of data sources.
Reactivity Alerts
  • Explosive
  • Strong Oxidizing Agent
  • Water-Reactive
Air & Water Reactions
Decomposes in water, products likely to include gaseous Cl2 (Lewis 2000).

Reacts with water to produce toxic and corrosive fumes of chlorine. Based on a scenario where the chemical is spilled into an excess of water (at least 5 fold excess of water), half of the maximum theoretical yield of Chlorine gas will be created in 0.14 minutes. Experimental details are in the following: "Development of the Table of Initial Isolation and Protective Distances for the 2008 Emergency Response Guidebook", ANL/DIS-09-2, D.F. Brown, H.M. Hartmann, W.A. Freeman, and W.D. Haney, Argonne National Laboratory, Argonne, Illinois, June 2009.
Fire Hazard
Excerpt from ERG Guide 143 [Oxidizers (Unstable)]:

May explode from friction, heat or contamination. These substances will accelerate burning when involved in a fire. May ignite combustibles (wood, paper, oil, clothing, etc.). Some will react explosively with hydrocarbons (fuels). Containers may explode when heated. Runoff may create fire or explosion hazard. (ERG, 2024)
Health Hazard
Excerpt from ERG Guide 143 [Oxidizers (Unstable)]:

TOXIC; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance may cause severe injury, burns or death. Fire may produce irritating and/or toxic gases. Toxic fumes or dust may accumulate in confined areas (basement, tanks, hopper/tank cars, etc.). Runoff from fire control or dilution water may cause environmental contamination. (ERG, 2024)
Reactivity Profile
CHLORINE DIOXIDE is a powerful oxidizer of low stability. Explodes violently on the slightest provocation as gas or liquid even below -100°C by impact [Sidgwick, 1950, 1203; Stedman, R. F., Chem Eng. News, 1951, 29, p. 5030]. Mixtures with carbon monoxide, methane, ethane, propane, ethylene or butadiene always explode spontaneously. Concentrations of greater than 10% in air are explosive. Severe explosion hazard when heated to 100°C. Sensitive to shock and sunlight. Explodes on contact with mercury, potassium hydroxide, phosphorus, phosphorus pentachloride, sulfur, difluoramine, trifluoramine, sugar. Very sensitive to the presence of any easily oxidized material. These may, even in minute quantities, trigger a decomposition. Materials such as rubber, hydrocarbons, carbon, iron, rust, reactive metals, and organics such as sawdust have all caused problems. [Inorganic Chemistry Handbook]. Emits highly toxic fumes of chlorine gas upon decomposition. Can react violently with fluorine, reducing reagents or finally dispersed organic matter [Bretherick, 5th ed., 1995, p. 1292].
Belongs to the Following Reactive Group(s)
Potentially Incompatible Absorbents

Use caution: Liquids with this reactive group classification have been known to react with the absorbents listed below. More info about absorbents, including situations to watch out for...

  • Cellulose-Based Absorbents
  • Mineral-Based & Clay-Based Absorbents
  • Expanded Polymeric Absorbents
  • Dirt/Earth

The Response Recommendation fields include isolation and evacuation distances, as well as recommendations for firefighting, non-fire response, protective clothing, and first aid. The information in CAMEO Chemicals comes from a variety of data sources.
Isolation and Evacuation
Excerpt from ERG Guide 143 [Oxidizers (Unstable)]:

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: See ERG Table 1 - Initial Isolation and Protective Action Distances on the UN/NA 9191 datasheet.

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)
Firefighting
Excerpt from ERG Guide 143 [Oxidizers (Unstable)]:

SMALL FIRE: Use water. Do not use dry chemicals or foams. CO2 or Halon® may provide limited control.

LARGE FIRE: Flood fire area with water from a distance. Do not move cargo or vehicle if cargo has been exposed to heat. If it can be done safely, move undamaged containers away from the area around the fire. Do not get water inside containers: a violent reaction may occur.

FIRE INVOLVING TANKS, RAIL TANK CARS OR HIGHWAY TANKS: Cool containers with flooding quantities of water until well after fire is out. Dike runoff from fire control for later disposal. ALWAYS stay away from tanks in direct contact with flames. For massive fire, use unmanned master stream devices or monitor nozzles; if this is impossible, withdraw from area and let fire burn. (ERG, 2024)
Non-Fire Response
Excerpt from ERG Guide 143 [Oxidizers (Unstable)]:

Keep combustibles (wood, paper, oil, etc.) away from spilled material. Do not touch damaged containers or spilled material unless wearing appropriate protective clothing. Use water spray to reduce vapors or divert vapor cloud drift. Prevent entry into waterways, sewers, basements or confined areas.

SMALL SPILL: Flush area with large amounts of water.

LARGE SPILL: DO NOT CLEAN-UP OR DISPOSE OF, EXCEPT UNDER SUPERVISION OF A SPECIALIST. (ERG, 2024)
Protective Clothing
Excerpt from NIOSH Pocket Guide for Chlorine dioxideexternal link:

Skin: PREVENT SKIN CONTACT (LIQUID) - If this chemical is in liquid form, wear appropriate personal protective clothing to prevent skin contact.

Eyes: PREVENT EYE CONTACT (LIQUID) - If this chemical is in liquid form, wear appropriate eye protection to prevent eye contact.

Wash skin: WHEN CONTAMINATED (LIQUID) - If this chemical is in liquid form, the worker should immediately wash the skin when it becomes contaminated.

Remove: WHEN WET (FLAMMABLE) - Work clothing that becomes wet should be immediately removed due to its flammability hazard (i.e., for liquids with a flash point <100°F).

Change: No recommendation is made specifying the need for the worker to change clothing after the workshift.

Provide:
• EYEWASH (LIQUID) - Eyewash fountains should be provided (when this chemical is in liquid form) 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.
• QUICK DRENCH (LIQUID) - Facilities for quickly drenching the body should be provided (when this chemical is in liquid form) within the immediate work area for emergency use where there is a possibility of exposure. [Note: It is intended that these facilities provide a sufficient quantity or flow of water to quickly remove the substance from any body areas likely to be exposed. The actual determination of what constitutes an adequate quick drench facility depends on the specific circumstances. In certain instances, a deluge shower should be readily available, whereas in others, the availability of water from a sink or hose could be considered adequate.] (NIOSH, 2024)
DuPont Tychem® Suit Fabrics
No information available.
First Aid
Excerpt from NIOSH Pocket Guide for Chlorine dioxideexternal link:

Eye: IRRIGATE IMMEDIATELY (LIQUID) - If this chemical in liquid form 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: SOAP WASH IMMEDIATELY (LIQUID) - If this chemical in liquid form contacts the skin, immediately wash the contaminated skin with soap and water. If this chemical penetrates the clothing, immediately remove the clothing, wash the skin with soap and water, and get medical attention promptly.

Breathing: RESPIRATORY SUPPORT - If a person breathes large amounts of this chemical, move the exposed person to fresh air at once. If breathing has stopped, perform artificial respiration. Keep the affected person warm and at rest. Get medical attention as soon as possible.

Swallow: MEDICAL ATTENTION IMMEDIATELY (LIQUID) - If this chemical in liquid form has been swallowed, get medical attention immediately. (NIOSH, 2024)

The Physical Property fields include properties such as vapor pressure and boiling point, as well as explosive limits and toxic exposure thresholds The information in CAMEO Chemicals comes from a variety of data sources.

Note: For Vapor Density and Specific Gravity, comparing the value to 1.0 can tell you if the chemical will likely sink/rise in air or sink/float in fresh water (respectively). Short phrases have been added to those values below as an aid. However, make sure to also consider the circumstances of a release. The Vapor Density comparisons are only valid when the gas escaping is at the same temperature as the surrounding air itself. If the chemical is escaping from a container where it was pressurized or refrigerated, it may first escape and behave as a heavy gas and sink in the air (even if it has a Vapor Density value less than 1). Also, the Specific Gravity comparisons are for fresh water (density 1.0 g/mL). If your spill is in salt water (density about 1.027 g/mL), you need to adjust the point of comparison. There are some chemicals that will sink in fresh water and float in salt water.
Chemical Formula:
  • ClO2.xH2O, ClO2 (gas)
Flash Point: data unavailable
Lower Explosive Limit (LEL): data unavailable
Upper Explosive Limit (UEL): data unavailable
Autoignition Temperature: data unavailable
Melting Point: -74°F (NIOSH, 2024)
Vapor Pressure: greater than 1 atm (NIOSH, 2024)
Vapor Density (Relative to Air): 2.33 (NIOSH, 2024) - Heavier than air; will sink
Specific Gravity: 1.6 (Liquid at 32°F) (NIOSH, 2024) - Denser than water; will sink
Boiling Point: 52°F at 760 mmHg (NIOSH, 2024)
Molecular Weight: 67.5 (NIOSH, 2024)
Water Solubility: 0.3 % at 77°F (NIOSH, 2024)
Ionization Energy/Potential: 10.36 eV (NIOSH, 2024)
IDLH: 5 ppm (NIOSH, 2024)

AEGLs (Acute Exposure Guideline Levels)

Final AEGLs for Chlorine dioxide (10049-04-4)
Exposure Period AEGL-1 AEGL-2 AEGL-3
10 minutes 0.15 ppm 1.4 ppm 3 ppm
30 minutes 0.15 ppm 1.4 ppm 3 ppm
60 minutes 0.15 ppm 1.1 ppm 2.4 ppm
4 hours 0.15 ppm 0.69 ppm 1.5 ppm
8 hours 0.15 ppm 0.45 ppm 0.98 ppm
(NAC/NRC, 2024)

ERPGs (Emergency Response Planning Guidelines)

Chemical ERPG-1 ERPG-2 ERPG-3
Chlorine Dioxide (10049-04-4) NA 0.5 ppm 3 ppm
NA = not appropriate.
(AIHA, 2022)

PACs (Protective Action Criteria)

Chemical PAC-1 PAC-2 PAC-3
Chlorine dioxide (10049-04-4) 0.15 ppm 1.1 ppm 2.4 ppm
(DOE, 2024)

The Regulatory Information fields include information from the U.S. Environmental Protection Agency's Title III Consolidated List of Lists, the U.S. Cybersecurity and Infrastructure Security Agency's Chemical Facility Anti-Terrorism Standards, and the U.S. Occupational Safety and Health Administration's Process Safety Management of Highly Hazardous Chemicals Standard List (see more about these data sources).

EPA Consolidated List of Lists

Regulatory Name CAS Number/
313 Category Code
EPCRA 302
EHS TPQ
EPCRA 304
EHS RQ
CERCLA RQ EPCRA 313
TRI
RCRA
Code
CAA 112(r)
RMP TQ
Chlorine dioxide 10049-04-4 313 1000 pounds
Chlorine oxide (ClO2) 10049-04-4 X 1000 pounds

(EPA List of Lists, 2024)

CISA Chemical Facility Anti-Terrorism Standards (CFATS)

RELEASE THEFT SABOTAGE
Chemical of Interest CAS Number Min Conc STQ Security
Issue
Min Conc STQ Security
Issue
Min Conc STQ Security
Issue
Chlorine dioxide; [Chlorine oxide, (ClO2)] 10049-04-4 1.00 % 1000 pounds toxic ACG APA sabotage/ contamination

(CISA, 2007)

OSHA Process Safety Management (PSM) Standard List

Chemical Name CAS Number Threshold Quantity (TQ)
Chlorine Dioxide 10049-04-4 1000 pounds

(OSHA, 2019)

This section provides a listing of alternate names for this chemical, including trade names and synonyms.
  • CHLORINE DIOXIDE
  • CHLORINE DIOXIDE HYDRATE, [FROZEN]
  • CHLORINE DIOXIDE, HYDRATE
  • CHLORINE DIOXIDE, HYDRATE, FROZEN
  • CHLORINE OXIDE
  • CHLORINE OXIDE (CLO2)
  • CHLORINE PEROXIDE

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