Chlorine dioxide

Appearance / physical state / colour

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

appearance / physical state / colour

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Information comes from the description of the test sample in an experimental GLP study; no specific guideline is required, however temperature and pressure are not specified, and no certificate of analysis is provided, which cannot allow full reliability score.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline required

GLP compliance:

yes

Physical state at 20°C and 1013 hPa:

liquid

Key result

Form:

liquid

Colour:

yellow

Executive summary:

A 2 ⁰/₀₀ aqueous solution of chlorine dioxide was tested in a GLP study for acute toxicity. The sample is described as a yellow solution.

Reference 2

Endpoint:

appearance / physical state / colour

Type of information:

other: secondary source

Adequacy of study:

other information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Justification for type of information:

No specific guideline is required, however data comes from an online compilation and toxicological profiles citing other data sources, and therefore cannot be considered as fully reliable. However, please note that all secondary sources are considered as peer reviewed.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Principles of method if other than guideline:

No data.

Physical state at 20°C and 1013 hPa:

gaseous

Remarks:

at room temperature [1]

Form:

gas

Colour:

Yellow to reddish-yellow gas at room temperature [1, 3].
Solid chlorine dioxide is a yellowish-red crystalline mass; liquid is reddish-brown. [1]
Yellow to red gas or a red-brown liquid (below 52 degrees F). [2]

Odour:

other: Pungent, distinctive from chlorine [1]. Unpleasant odor similar to chlorine and nitric acid [2].

Executive summary:

The HSDB database provides a peer-reviewed description for the three physical states of Chlorine dioxide. At room temperature, the substance is a yellow to reddish-yellow gas, with characteristic odor. The ATSDR peer reviewed profile cites one of the same original reference.

Reference 3

Endpoint:

appearance / physical state / colour

Type of information:

other: handbook data

Adequacy of study:

other information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Justification for type of information:

No specific guideline is required, however data comes from a handbook, and
therefore cannot be considered as fully reliable (no purity stated). Please note also that the data source is cited among "reference books containing peer reviewed physico-chemical data" in the ECHA guidance document on information requirements (R7a).

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Principles of method if other than guideline:

No data.

Physical state at 20°C and 1013 hPa:

gaseous

Form:

gas

Colour:

orange-green

Substance type:

inorganic

Executive summary:

The peer-reviewed CRC Handbook of Chemistry and Physics describes the substance Chlorine dioxide as an orange-green gas.

Reference 4

Endpoint:

appearance / physical state / colour

Type of information:

other: secondary source

Adequacy of study:

other information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Justification for type of information:

No specific guideline is required, however data comes from a review using secondary data sources, and therefore cannot be considered as fully reliable.

Reason / purpose for cross-reference:

reference to same study

Principles of method if other than guideline:

No data.

Physical state at 20°C and 1013 hPa:

gaseous

Remarks:

at room temperature

Form:

gas

Colour:

Greenish yellow to orange gas at room temperature

Odour:

pungent

Executive summary:

The international CICAD review describes the substance Chlorine dioxide as a greenish yellow to orange gas at room temperature with a characteristic pungent chlorine-like odour.

Reference 5

Endpoint:

appearance / physical state / colour

Type of information:

other: publication

Adequacy of study:

other information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Justification for type of information:

No specific guideline is required, however data comes from a publication using secondary data sources regarding physico-chemical properties, and therefore cannot be considered as fully reliable.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Physical state at 20°C and 1013 hPa:

gaseous

Form:

gas

Colour:

Chlorine dioxide is a yellowish-green gas which approaches an orange-red as its concentration increases.

Odour:

other: disagreeable, irritating odor somewhat similar to chlorine

Executive summary:

The publication provides, as a secondary source, some physico-chemical properties for chlorine dioxide. The substance is described as a yellow-green gas, turning to orange-red when concentration increases, with a chlorine-like odor.

Reference 6

Endpoint:

appearance / physical state / colour

Type of information:

other: secondary source

Adequacy of study:

other information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Justification for type of information:

No specific guideline is required, however data comes from a sheet with no reference to data sources, and therefore cannot be considered as fully reliable.

Reason / purpose for cross-reference:

reference to same study

Principles of method if other than guideline:

No data.

Physical state at 20°C and 1013 hPa:

gaseous

Form:

gas

Colour:

red-yellow

Odour:

pungent

Executive summary:

The ICSC describes the substance Chlorine dioxide as a red-yellow gas, with pungent odour.

Reference 7

Endpoint:

appearance / physical state / colour

Type of information:

other: secondary source

Adequacy of study:

other information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Justification for type of information:

Data comes from a book dedicated to chlorine dioxide, compiling very numerous literature references, but few experimental details are provided. However, for the present endpoint, no specific guideline is required, therefore data can be assigned as reliable, with the restriction that there is no information on the purity of the substance.

Reason / purpose for cross-reference:

reference to same study

Physical state at 20°C and 1013 hPa:

gaseous

Form:

gas

Colour:

At ambient temperatures, chlorine dioxide is a yellow-green gas. As the concentration increases, the color becomes more reddish.

Odour:

other: similar to chlorine

Executive summary:

The Simpson's book, dedicated to chlorine dioxide, states that the substance is a yellow-green gas at ambient temperature, becoming more red when the concentration increases, and with a chlorine/ozone-like odor.

Description of key information

Solution of chlorine dioxine generated in-situ at less than 2% in water

(as registered): Yellow liquid with a chlorine-like odour.

Key value for chemical safety assessment

Physical state at 20°C and 1013 hPa:

liquid

Form:

liquid

Colour:

yellow

Additional information

The substance as registered is always generated in situ as a gas dissolved in water, with concentration not exceeding 2%. An experimental study was conducted on a diluted aqueous solution (2 ⁰/₀₀); the test item is described as a yellow solution. The same appearance is anticipated for the substance as registered. Due to high volatility of the substance, the odour is expected to be perceptible, if not in closed systems. This data is considered as key data for CSA purpose.

Other information : Literature data was found on chlorine dioxide (not registered as such). It is a gas at ambient temperature and pressure, with chlorine-like pungent odour. The colour is green-yellow to orange-red depending on concentration.