Trisodium bis[2-hydroxy-5-nitro-3-[[2-oxo-1-[(phenylamino)carbonyl]propyl]azo]benzenesulphonato(3-)]cobaltate(3-)

Endpoint summary

Description of key information

An increase in cell proliferation of drain in glymphnodes, statistically significant at all concentrations and dose correlated, was observed in all treatment groups.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 442B (Skin Sensitization: Local Lymph Node Assay: BrdU-ELISA)

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Type of study:

other: evaluation of dermal effects

Justification for non-LLNA method:

no data

Species:

mouse

Strain:

CBA:JN

Sex:

female

Details on test animals and environmental conditions:

Age at order: 7 to 8 weeks old
Supplier: Charles River Italia S.p.A., Calco (Lecco),Italy
Breeder: CharlesRiverFrance Laboratories, Domaine des Oncins B.P. 0109,F69592 L’ARBRES LE CEDEX,France
Date of arrival: 19 May 2016
Weight range at arrival: 20 to 22 grams
Acclimatisation period: At least 5 days
Veterinary health check: During acclimatisation period
Animals per cage: Up to 5 during acclimatisation;1/cage during the study
Housing: Polysulphone solid bottomed cages measuring 35.5×23.5×19 cm with nesting material
Cage control: Daily inspected and changed as necessary (atleasttwice/week)
Water: drinking water supplied to each cage via a water bottle
Water supply: ad libitum
Diet: 4RF21(Mucedola S.r.l.,Via G.Galilei,4, 20019,Settimo Milanese(MI)Italy)
Diet supply: ad libitum throughout the study
Room lighting: Artificial (fluorescenttubes), daily light/dark cycle of 12/12 hours
Air changes: Approximately 15 to 20 air changes per hour
Temperature range: 22°C ± 2°C
Relative humidity range: 55%±15%

Vehicle:

dimethyl sulphoxide

Concentration:

25, 10, 5 % w/w

No. of animals per dose:

2 for each dose

Details on study design:

- 5-bromo-2-deoxyuridine (BrdU) treatment: The animals were treated intraperitoneally, on Day 5 (once only), with 0.5 mL/animal of a solution of BrdU at a concentration of 10 mg/mL in physiological saline(0.9%NaCl),usinga plastic graded syringe

Positive control substance(s):

other: Acetone / olive oil 4:1 v/v

Statistics:

Differences between each treated group and the concurrent negative control group (individual BrdU labelling indices) were assessed by Dunnett’s test. The homogeneity of the data was verified by Bartlett’s test before Dunnett’s test. If data were found to be inhomogeneous, a Modifiedt test (Cochran and Cox) was applied.

Positive control results:

In the group treated with the positive control item, a Stimulation Index of 2.61was calculated. As it was greater than 2, the study was regarded as valid.

Parameter:

SI

Value:

> 5

Test group / Remarks:

low, mid and high dose

Remarks on result:

other: dermal effects

Preliminary test:

Five concentrations [25 (maximum feasible concentration), 10, 5, 2.5 and 1% w/w in dimethylsulfoxide] were tested in the preliminary phase,in order to identify a non toxic and minimally irritant concentration and avoid false positive results. No signs of toxicity (significant clinical signs or body weight losses) were observed at the tested concentrations. According to the results of the irritations creening, the concentration of 25% w/w was judged to be not irritant.

Main assay:

In the main assay, the test item was topically administered at the concentrations of 25, 10 and 5% (w/w), in dimethylsulfoxide. No mortality nor clinical signs were recorded in any animal. Changes in body weight observed during the study were with in the expected range for this strain and age of animals. An increase in cell proliferation of draining lymphnodes, statistically significant and correlated with the dose was observed in low, mid-and high dose group. The calculated Stimulation Indices (SI) were 5.85, 5.86 and 6.34, respectively at the low, mid- and high dose levels [5,10 and 25%, respectively]. The above results indicate that the test item may elicit a sensitisation response in mice following dermal exposure, since in mid- and high dose groups the Stimulation Index was greater than 1.6.

Interpretation of results:

Category 1B (indication of skin sensitising potential) based on GHS criteria

Conclusions:

An increase in cell proliferation of drain in glymphnodes, statistically significant at all concentrations and dose correlated, was observed in all treatment groups.

Executive summary:

Based on the criteria indicated in Regulation (EC) No. 1272/2008, the tested substance is to be considered as skin sensitizer.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

Based on the criteria indicated in Regulation (EC) No. 1272/2008, the tested substance is to be considered as skin sensitizer.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the criteria indicated in Regulation (EC) No. 1272/2008, the tested substance is to be considered as skin sensitizer.