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Description of key information

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

Based upon studies in animals and in humans (table 7.4.1 below), Sodium Pyrithione is not classified as sensitizing. In two GLP studies compliant to OECD 406, [references, ESPTF 6015-001 ;, ESPTF 6015-002], it was determined that Sodium Pyrithione is non-sensitizing.


Table 7.4.1             Summary of sensitisation



Number of animals sensitised/total number of animals



Guinea pig (female)

OECD 406, 1992: Skin Sensitisation,
Directive 96/54/EC, B.6.

Guinea Pig Maximisation Test.

Test material Sodium Pyrion powder (>92.5%)


Non sensitising


3 females were administered intra-dermally with Freund`s adjuvant, the test substance (50 % w/w) was applied epicutaneously to the sites of the intradermal injections. 7 days later 4 concentrations of the test substance (50 %, 25 %, 10 % and 1 %) were administered epicutaneously to the flanks of the animals. The duration of the exposure was 24 hours. Skin reactions were severe erythema at 50 %, very slight erythema at 25 % and no reaction at 10 % and 1 %.

After the challenge exposure, 2/20 animals of the test substance group had positive skin reactions 24 h after the end of the exposures. No adverse skin reactions were observed in the control animals. Therefore 2/20 animals of the test substance group (10 %) were regarded as sensitised, which is below the threshold of 30 % for classification as a sensitising substance.

Key Study


ESPTF 6015-001


Weiss-Fuchs U (2002)



Guinea pig



US EPA 81-6, which complies with OECD 406 (Buehler method). GLP (self certification by the laboratory).


Test material: Sodium Omadine® solution (43.7%).

2/10 , 3/10



Induction A: Scores for erythema were generally severe on the intradermal sites dosed with FCA and FCA/test article mixture and mild to severe on the sites dosed with test article only.

Induction B: Erythema was mild to severe following a 48 hour exposure to a 10% dilution of test article.

Challenge: Following a 24 hour exposure to a 5% dilution of the test article, mild erythema was observed in 2/10 (20%) animals 24.5 hours post does. At 48 hours, 3/10 (30%) animals had mild erythema.


ESPTF 6015-002




The information contained within this robust summary document comes from studies which are in the ownership of Arch Chemicals Inc. and which are protected in several regions globally. This information may not be used for any purpose other than in support of the Chemical safety Report submitted by Arch Chemicals Inc. under RegulationEC 1907/2006.

Justification for classification or non-classification