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Description of key information

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available
Additional information:

The substance is classified as highly corrosive (R35) according to Annex 1, Directive 67/548/EEC. Therefore, the testing of sensitising properties is not necessary according to Regulation (EC) No. 1907/2006, Annex VII, column 2.

SOCl2 is hydrolyzed rapidly and completely by water in an exothermic reaction with formation of HCl and SO2. Therefore the toxicity of the hydroysis products(HCl and SO2) is also considered and compared with thionyl dichloride.

For HCl there are no studies available that have been performed recently or under national/international guidelines, and in compliance with GLP (OECD SIDS for HCl). However, both guinea pig maximization test (1% HCl in EtOH [undefined concentration] was used in both sensitization and challenge phase) and mouse ear swelling test (MEST; 1% HCl in 70% EtOH for sensitization phase, 5% HCl for challenge phase was used) showed negative result. The concentration levels used were expected to refer to “not irritating (1%)” and “slightly irritating (5%)”.

In conclusion, from the data of HCl a sensitisation potential of SOCl2 is not expected.

For SO2 animal studies are not available, scientifically not justified and technically not feasible according standard protocols due to technical reasons because SO2 is a gaseous substance at room temperature under normal pressure.

In conclusion, from the data of HCl a sensitisation potential of SOCl2 is not expected.

SO2 is readily soluble in water and is converted on the moist mucosa to sulfurous acid (H2SO3). In a further oxidation step sulfurous acid is metabolized to sulfuric acid. Excess sulfate is excreted via urine.

Chloride and the conversion products of SO2 are normal body constituents. Therefore a sensitisation potential can be excluded and a classification for skin/respiratiory sensitisation is not justified.


Migrated from Short description of key information:
Waiving: Test substance is classified as highly corrosive

Justification for selection of skin sensitisation endpoint:
No valid study for sensitization for thionyl chloride (SOCl2) is available.
SOCl2 is hydrolyzed rapidly and completely by water in an exothermic reaction with formation of HCl and SO2. Therfore the toxicity of the hydroysis products is also considered.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available
Additional information:

The substance is classified as highly corrosive (R35) according to Annex 1, Directive 67/548/EEC. Therefore, the testing of sensitising properties is not necessary according to Regulation (EC) No. 1907/2006, Annex VII, column 2.

SOCl2 is hydrolyzed rapidly and completely by water in an exothermic reaction with formation of HCl and SO2. Therefore the toxicity of the hydroysis products (HCl and SO2) is also considered and compared with thionyl dichloride.

Hydrogen chloride will rapidly dissociate and its effects are thought to be a result of pH change (local deposition of H+) rather than effects of hydrogen chloride/hydrochloric acid. Chloride is a normal constituent of the blood and the excess is expected to be excreted into the urine.

SO2 is readily soluble in water and is converted on the moist mucosa to sulfurous acid (H2SO3). In a further oxidation step sulfurous acid is metabolized to sulfuric acid. Excess sulfate is excreted via urine.

Chloride and the conversion products of SO2 are normal body constituents. Therefore a sensitisation potential can be excluded and a classification for skin/respiratiory sensitisation is not justified.

No studies are available for respiratory sensitisation.


Migrated from Short description of key information:
Waiving: Test substance is classified as highly corrosive

Justification for classification or non-classification

The substance is classified as highly corrosive (R35) according to Annex 1, Directive 67/548/EEC. Therefore, the testing of sensitising properties is not necessary according to Regulation (EC) No. 1907/2006, Annex VII, column 2.

Hydrogen chloride will rapidly dissociate and its effects are thought to be a result of pH change (local deposition of H+) rather than effects of hydrogen chloride/hydrochloric acid. Chloride is a normal constituent of the blood and the excess is expected to be excreted into the urine.

SO2 is readily soluble in water and is converted on the moist mucosa to sulfurous acid (H2SO3). In a further oxidation step sulfurous acid is metabolized to sulfuric acid. Excess sulfate is excreted via urine.

Chloride and the conversion products of SO2 are normal body constituents. Therefore a sensitisation potential can be excluded and a classification for skin/respiratiory sensitisation is not justified.

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