N-isopropyl-N'-phenyl-p-phenylenediamine

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

Non-human information

The skin sensitizing potential of IPPD was evaluated with the guinea pig maximization test. For induction treatment groups of 20 female guinea pigs were intradermally injected with 0.5 % IPPD in olive oil with complete FCA followed one week later by cutaneous application of 1 % IPPD in petrolatum. According to the grading system of Magnusson and Kligman 10 and 70 %, respectively, of the guinea pigs challenged by epicutaneous application of 0.05 and 0.5 % IPPD in petrolatum reacted positive. The sensitizing potential was classified as low for the 0.05 % and high for the 0.5 % challenge concentration. 90 % of animals sensitized to IPPD showed cross-sensitization to 0.05 % N-phenyl-N' cyclohexyl-p-phenylenediamine (CPPD) in vaseline. Animals sensitized to p-phenylenediamine (PPD) or to N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD) showed also cross-sensitization to IPPD (Herve-Bazin 1977).

The skin sensitizing potential of IPPD was confirmed in a more recent guinea pig maximization test and local lymph node assay (Yamano 2009). Female Hartley guinea pigs challenged with 50 ppm (0.005%) and 5000 ppm (0.5%) IPPD showed positive skin reactions (4/4). Moreover, female BALB/c mice treated with IPPD showed a significant increase in the Stimulation Index (SI: 1.3, 1.68, 3.23, 3.99, at 0.01%, 0.03%, 0.1 % and 0.3 %, respectively) at a non-irritant dose-range and thus was considered to be a positive skin sensitizer in the local lymph node assay.

In addition, the positive response of IPPD was confirmed in another local lymph node assay (Ikarashi 1993). IPPD induced an increase in the stimulation index of 3.85 at a concentration of 0.5%.

Human information

The skin sensitizing potential of IPPD was evaluated in several Repeated Insult Patch tests with human volunteers. IPPD applied 50 % w/v in dimethylphthalate on the upper arm of 50 volunteers induced visible skin changes in 11 of 50 individuals (Monsanto Co. 1976). In another Repeated Insult Patch test, performed with 1 % IPPD in petrolatum, 12 subjects of 82 patched volunteers were deemed to be sensitized (Monsanto Co. 1978).

In addition, a number of publications have reported patients who show a positive reaction when patch tested with IPPD (for review see OECD SIDS 2000).

Migrated from Short description of key information:
The skin sensitisation potential of IPPD was evaluated in guinea pigs, mice and in studies with human volunteers. IPPD was sensitizing in guinea pigs and mice and was found to induce dermal sensitizing in humans; in consequence, existing classification with R 43/skin sensitizer category 1 is confirmed. According to criteria published in REACH guidance document chapter R. 8, IPPD was categorised as strong skin sensitizer.

Justification for classification or non-classification

The test substance IPPD is classified as skin sensitizer according to regulation no. 1272/2008 (GHS).