N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

Skin sensitizing

The skin sensitizing potential of 77PD was evaluated in a limited documented guinea pig maximization assay (Bayer AG 1980). Fifteen guinea pigs were treated with the test substance 77PD; a concurrent negative control (15 animals) was also included. Intradermal induction was done with 1% test substance in lutrol (polyethylenglycol 400). The second induction was done one week later with 2% test substance solved in polyethylenglycol. Animals were treated for 48 hours under occlusive conditions. All animals (pre-treated animals and control animals) were challenged two weeks later with 12.5 % and 25 % test substance solved in polyethylenglycol. The animals were treated for 24 hours under occlusive conditions. Readings were done 24 hours and 48 hours after challenge. The authors concluded that the test substance was sensitizing. However, positive skin reactions were noted in both pre-treated animals and control animals; whereas pre-treated animals reacted with a dermatitis which was more intense than in control animals (average grading score: 0.9 to 2.0 vs. 0.3 to 0.9 control). The authors stated that the dermatitis seen in pre-treated animals and control animals was supported by histological examinations (no data given). Considering the results discussed under chapter skin irritation the test substance 77PD was not skin irritating; thus a primary skin irritating effects could be excluded. However, data from a more recent study (skin irritation study Bayer AG 1990) indicated difficulties in skin erythema evaluation because of the intensive red colour of the test item; thus the positive skin reactions indicated for the negative control, may be rather artificial.

The skin sensitizing potential of 77PD was evaluated in another limited documented guinea pig assay (Stasenkova 1970). White guinea pigs were treated with the test substance, which was applied as a 50 % paste on the skin (no additional data given). The paste was applied daily for 20 days onto the shaved back. No market irritation of the skin was observed during repeated applications. A concurrent negative control was also included. The animals were challenged with 10 %, 20 %, 30 %, 50 % and 100% test substance. The test substance was applied (from 100% to 10%) to a new area of the back, starting with the highest concentration to the lowest concentration from tail to head. A market reddening of the skin of pre-treated animals and control animals was observed only at 100 % test substance. The authors suggested a low or even no allergic potential of the test substance.

In another limited publication (only secondary literature) slight sensitizing effects in guinea pigs of 77PD were reported (McCormick 1972).

In addition, other limited documented sensitizing studies also reported slight skin sensitizing effects of 77PD in guinea pigs (DuPont Chem 1992)

Several early Repeated Insult Patch tests (modified Schwartz Method and Shelanski Method) were performed with human volunteers (Monsanto Co.1961, 1963, 1964, 1974). However the study documentation is limited especially concerning the test samples tested (rubber mixture or rubber master sample) and should only be used for supporting reasons. Some study results indicated that the test article caused no primary irritation and no allergic response, while other study results were positive for sensitization

Migrated from Short description of key information:
There are several animal data for the sensitizing potential of 77PD from different data sources available; but the data are limited in documentation and also have some deficiencies concerning the study design and are not comparable with current guideline studies. However, in a weight of evidence approach the data indicate a rather moderate skin sensitizing potential of 77PD. This is in line with the available limited human data, which also indicate a rather moderate skin sensitizing potential. This is in line with the already existing self-classification as skin sensitizer

Justification for classification or non-classification

The test substance CBS is classified as skin sensitizer according to the classification criteria 67/548/EWG and regulation no. 1272/2008 (GHS).