Registration Dossier

Administrative data

Description of key information

Not skin sensitiser.

Key value for chemical safety assessment

Skin sensitisation

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

The skin sensitization potential of Basic Brown 022 was assessed by a weight of evidence approach, relying on both in vitro and in vivo studies.

A test using the KeratinoSens™ method (ARE-Nrf2 Luciferase Test Method) was run according to OECD guideline 442D.

The test was run in 2 independent runs using 12 doses between 2000 µM to 1 µM; there was cytotoxicity induced (viability < 70 %) by test item in KeratinoSens™ cells compared to the solvent/vehicle control at several concentrations in both tests. In the first run the IC30 and IC50 values were 185 µM and 209 µM while in the second run 179 µM and 204 µM respectively. However, induction did not exceed the threshold of 1.5 -fold at any concentrations compared to negative controls, thus both runs were concluded to be negative.

A further in vitro test, h-CLAT, was run according to OECD guideline 442E. The potential for inducing expression of THP-1 cell surface markers CD86 and CD54 associated with the activation of dendritic cells (DC) in the skin sensitisation reactions was assessed.

The extent of cytotoxicity induced on THP-1 cells by test item was studied in 2 dose finding tests. In the main test, 8 doses were used in each independent run between 163 and 45 µg/ml.

No increase of CD54 expression was observed when the dose-levels of test item were compared with the negative control; increase in CD86 marker expression (RFI) is ≥ 150 % compared to the respective negative controls in at least one tested dose (with > 50 % of cell viability) in each independent run, test item prediction is considered as positive.

Based on these results, test item was considered as positive under testing conditions.

Due to conflicting results, a further test was planned.

As Basic Brown 022 is a metal complex, a DPRA according to OECD 442C could not be performed. Similarly, a in vivo LLNA according to OECD 429 could not be run.

Consequently, a Buehler test on Guinea pig according to OECD guideline 406 was run.

A concentration of 100 mg in 0.1 ml was used for induction and challenge phase of main study, based on a pre-study.

The main study comprised a vehicle control group and a treatment group. Main study included 3 inductions on day 0, 7 and 14 and challenge on day 28.

Test substance was applied topically under occlusive bandage and removed after 6 hours. During induction phase, skin reactions were observed approximately at 1 and 24 hours post removal of test patches; during challenge phase, skin reactions were observed approximately at 24 and 48 hours post removal.

In both induction and challenge phase, no skin reactions were observed in vehicle control and treatment group animals.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

According to the CLP Regulation (EC 1272/2008), skin sensitiser means a substance that will lead to an allergic response following skin contact.

Conflicting results in vitro did not allow to draw a conclusion on the skin sensitising potential.

Based a Buehler assay, classification in cat. 1A and 1B is as follows:

- cat. 1A: ≥ 15 % responding at ≤ 0,2 % topical induction dose or ≥ 60 % responding at > 0,2 % to ≤ 20 % topical induction dose

- cat. 1B: ≥ 15 % to < 60 % responding at > 0,2 % to ≤ 20 % topical induction dose or ≥ 15 % responding at > 20 % topical induction dose.

As no positive response was seen after induction and challenge, Basic Brown 022 was considered as not skin sensitising and not classified within the CLP Regulation.