Registration Dossier

Administrative data

Description of key information

2-(2H-Benzotriazol-2-yl)-4-methylphenol the substance was reported to be sensitizing in a guinea pig maximization test (Hagemann 1992) performed under GLP and following the procedure of OECD testing guideline 406. The tested sample was a commercial product of more than 98% purity. Concentrations were 5% in arachis oil for intradermal induction and 20 or 30% in vaseline for epidermal challenge. With 20% challenge, 16 and 18 of 20 animals showed skin reactions after 24 and 48h, respectively. This is consistent with reports on single incidences of contact allergy (Kaniwa 1991, Arisu 1992, Bjoerkner 1997, DeGroot 1983 and Niklasson 1989) and with literature publications on further animal tests (Yamono 1993, Ikarashi 1994a and b). Two repeated insult patch tests with volunteers performed in the 1960s did not result in skin sensitization (Welch 1960 and Kligman 1964). Secondary information on the safety of use in cosmetics is available (Anonymous 2008).

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:

The key study for skin sensitization (Hagemann 1992) was chosen because it was performed with a well-characterized test material at adequately high concentrations, according to the OECD testing guideline 406 and under GLP. In this study, 2-(2H-benzotriazol-2-yl)-4-methylphenol was reported to be sensitizing after intradermal induction with 5% in arachis oil and challenge at 20 or 30% in vaseline.

Sensitization in guinea pigs was also indicated in an English abstract of a Japanese publication (Yamano 1993). Published data for mice is available on results combining a local lymph node assay with intraperitoneal induction treatment and the mouse ear swelling test (Ikarashi 1994a and b). 2-(2H-Benzotriazol-2-yl)-4-methylphenol was found to be sensitizing in the MEST but not in the LLNA. However, for these investigations, neither positive control nor historical control data is reported and the applied concentrations of up to 2% and the number of animals used are very low. Therefore, this data is considered to be of limited use for hazard assessment.

Single incidences of contact allergy in consumers have been reported (Kaniwa 1991, Arisu 1992, Bjoerkner 1997, DeGroot 1983 and Niklasson 1989). In a repeated insult patch test with 25 male volunteers receiving five induction doses, no incidence of sensitization was observed (Kligman 1964). Also no contact dermatitis was observed in another HRIPT with 59 subjects that received 24-hour patch exposures to 0.2% of the test solution three times weekly - for three weeks, followed by a similar challenge exposure in the sixth week (Welsh 1960).

The substance was handled by the cosmetics industry under the name of Drometrizole and secondary information on sensitizing properties is published in the “Amended final report of the safety assessment of Drometrizole as used in cosmetics” (Anonymous 2008): It is stated that the substance was negative for sensitization in two Magnusson-Kligman maximization tests in guinea pigs. In addition, it is referred to a 3-year clinical therapeutic trial conducted to evaluate the effectiveness of two UV absorbing preparations containing up to 5% Drometrizole, in which two hypersensitivity reactions were observed during 445 applications. It is also referred to clinical tests of cosmetic products containing 0.03% to 1.0% Drometrizole which produced no irritation, sensitization, photosensitization, or phototoxicity in a total of 436 subjects.

Investigation of the structural formula using the QSAR tool DEREK identified the 4-methylphenol as a structural alert for sensitization (Ciba 2009).

Overall, the substance is considered to meet the criteria for classification as a skin sensitizer.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

The available experimental test data are reliable and suitable for classification purposes under Regulation 1272/2008. As a result the substance is considered to be classified as a skin sensitizer of moderate potency (GHS Cat 1B) under Regulation (EC) No. 1272/2008.