Bromobenzene

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Remarks:

limited data on results (body weights, local irritation, individual data/readouts)

Justification for type of information:

Please refer to analogue justification provided in IUCLID section 13

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2012

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Version / remarks:

23 July 2010

Deviations:

yes

Remarks:

limited data on results (body weights, local irritation, individual data/readouts)

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Chlorobenzene

EC Number:

203-628-5

EC Name:

Chlorobenzene

Cas Number:

108-90-7

Molecular formula:

C6H5Cl

IUPAC Name:

chlorobenzene

Test material form:

liquid

In vivo test system

Test animals

Species:

mouse

Strain:

CBA

Remarks:

(CBA/CaOlaHsd and CBA/J, not further specified)

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Haraln Winkelmann GmbH, Borchen, Germany or Charles River Laboratories, Sulzfeld, Germany GmbH (not further specified), Sulzfeld, Germany
- Females nulliparous and non-pregnant: Not specified
- Age at study initiation: 6-12 weeks
- Housing: Makrolon type I or II cages
- Diet: Provimi Kliba, (Kliba-Labordiät, Maus/Ratte Haltung 'GLP', SA, Kaiseraugst, Basel, Switzerland), ad libitum
- Water: Tap water, ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24
- Humidity (%): 30 - 70
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (LLNA)

Vehicle:

acetone/olive oil (4:1 v/v)

Concentration:

25, 50 and 100% (undiluted) (no further information available)

No. of animals per dose:

6

Details on study design:

PRE-SCREEN TESTS:
- Ear thickness measurements: conducted in three mice exposed to a concentration of 5% in order to determine skin irritating concentrations. The resultant high concentration and two lower concentrations spaced by a factor of approximately 3 each were selected for the study (if an indication of ear skin irritation was observed, lower concentrations were used). The concentrations tested in the presented study were higher than that defined in the published harmonized minimum performance standards (PS study).

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

eugenol (CAS No 97-53-0)

mercaptobenzothiazole (CAS No 149-30-4)

other: All substances defined as recommended reference substances for the LLNA performance standards defined in OECD TG 429 were tested in the conducted study.

Statistics:

The estimated concentration (EC) for the SI = 1.5 (defined for the non-radioactive evaluation method) or SI = 3 (defined for the standard radioactive LLNA procedure) was calculated by linear regression using the data points directly below and above the threshold or using the two nearest points below or above the SI. Results exceeding these cut-off SIs are considered to indicate biologically relevant signs of lymph node cell proliferation. A substance was considered a sensitizer if at least one concentration tested caused a concentration-dependent statistically significant and/or biologically relevant increase in LNCC, dpm and/or lymph node weight compared with the vehicle control.

Mean values and standard deviations of the measured parameters were calculated for the test and control groups from the individual values. The SIs of lymph node cell cound (LNCC, referred to as "non-radioactive" method, 3H-thymidine incorporation, lymph node weight (LNW) and ear weight were calculated as the ration of the test group mean values divided by those of the vehicle control group. The presence of a skin irritation reaction to topical treatment was determined by whether a greater than 20% increase in ear weight occurred.

Results and discussion

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Remarks:

standard radioactive LLNA

Value:

>= 1.91 - <= 5.3

Test group / Remarks:

25, 50 and 100%

Remarks on result:

other: At the highest concentration tested, increased ear weight was determined. Thus, a positive response due to irritation cannot be excluded.

Results 2

Parameter:

SI

Remarks:

non-radioactive LLNA

Value:

>= 0.97 - <= 1.61

Test group / Remarks:

25, 50 and 100%

Remarks on result:

other: At the highest concentration tested, increased ear weight was determined. Thus, a positive response due to irritation cannot be excluded.

Cellular proliferation data / Observations:

CELLULAR PROLIFERATION DATA:
EC1.5 (non-radioactive method): 79.0

EC3 CALCULATION
EC3 (radioactive method) = 45.6

Any other information on results incl. tables

Interpretation of results:

Chlorobenzene induced a dose-dependent increase in cell count (non-radioactive LLNA) and thymidine incorporation (standard LLNA). Test concentrations of 25, 50 and 100% resulted in SI values of 0.97, 1.34 and 1.61 for cell counts (non-radioactive LLNA) and SI values of 1.91, 3.23 and 5.30 for thymidine incorporation, respectively. In parallel, ear weights were increased by more than 20% at the highest test concentration, which indicates skin irritation. Considering that chlorobenzene is classified as skin irritant (category 2), a false-positive result due to skin irritation cannot be excluded for both evaluation methods. Taking further into account that 1) chlorobenzene revealed negative results in the studies considered for the recommended reference substance list cited in OECD TG 429 and 2) the dose tested are higher than that defined in the published harmonized minimum performance standards, the obtained result is considered as false-positive result. Therefore, chlorobenzene is presumed to be a non-sensitizer in the conducted LLNA test. 

Applicant's summary and conclusion

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation(EC) No. 1272/2008

Conclusions:

CLP: Not classified