N,N''-hexane-1,6-diylbis[N'-benzylurea]

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

In a GLP compliant study according to OECD guideline 429 the possible skin sensitisation potential of N,N“-Hexane-1,6-diylbis[N`-benzylurea] was studied (Harlan CCR, 2012). Three groups each of five female mice were treated once daily with the test item at concentrations of 0.5, 1, and 2.5% (w/w) in dimethylformamide by topical application to the dorsum of each ear for three consecutive days. The test item could be suspended in the vehicle. The appropriateness of the used concentrations was previously assessed by a pre-experiment. A control group of five mice was treated with the vehicle (dimethylformamide) only. Five days after the first topical application the mice were injected intravenously into a tail vein with radio-labelled thymidine (³H-methyl thymidine). Approximately five hours after intravenous injection, the mice were sacrificed, the draining auricular lymph nodes were excised, pooled per animal and immediately weighed. Furthermore, after excision of the lymph nodes, both ears of the mice were punched at the apical area using a biopsy punch and were immediately weighed pooled per animal using an analytical balance. Afterwards, single cell suspensions of lymph node cells were prepared from lymph nodes pooled per animal. An aliquot of each cell suspension was used for determination of lymph node cell count. Subsequently the suspensions were washed and incubated with trichloroacetic acid overnight. The proliferative capacity of pooled lymph node cells was determined by the incorporation of ³H-methyl thymidine measured in a β-scintillation counter. All treated animals survived the scheduled study period and no signs of systemic toxicity or local skin irritation were observed. A statistically significant or biologically relevant increase in ear weights was not observed in any treated group in comparison to the vehicle control group. Furthermore, for BALB/c mice, a cutoff-value of 1.1 for the ear weight index was reported for a positive response regarding ear skin irritation. None of the indices determined for the test item treated groups exceeded this threshold. A test item is regarded as a sensitiser in the LLNA if the exposure to one or more test concentration resulted in 3-fold or greater increase in incorporation of ³HTdR compared with concurrent controls, as indicated by the Stimulation Index (S.I.). The estimated concentration of test item required to produce a S.I. of 3 is referred to as the EC3 value. In this study Stimulation Indices (S.I.) of 0.84, 0.89, and 0.92 were determined with the test item at concentrations of 0.5, 1, and 2.5% (w/w) in dimethylformamide, respectively. An EC3 value could not be calculated, since none of the tested concentrations induced a S.I. greater than the threshold value of 3. A statistically significant increase in DPM value, lymph node weights and in lymph node cell count was not observed in any treated group in comparison to the vehicle control group. Furthermore, the cutoff-value of 1.55 for a positive response regarding the lymph node cell count index reported for BALB/c mice was not exceeded in any dose group. The test item N,N“-Hexane-1,6-diylbis[N`-benzylurea] was not a skin sensitiserunder the test conditions of this study.

Migrated from Short description of key information:
LLNA: not sensitizing (Harlan, 2012)

Justification for classification or non-classification

Based on the available data, no classification and labeling is required (according to Directive 67/548/EEC and according to CLP) for skin sensitization.