2,2',4'-trichloroacetophenone

Skin sensitisation

Administrative data

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:

other: Well documented study according to international accepted guidelines and GLP compliant.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

2,2',4'-trichloroacetophenone

EC Number:

224-218-2

EC Name:

2,2',4'-trichloroacetophenone

Cas Number:

4252-78-2

Molecular formula:

C8H5Cl3O

IUPAC Name:

2-chloro-1-(2,4-dichlorophenyl)ethan-1-one

Details on test material:

Test item: DICHLOROPHENACYL CHLORIDE
CAS No.: 4252-78-2
Batch No.: T-5427
Colour: beige
Physical state: solid, crystalline powder
Active Ingredient Content (GC): 98.9 %
Storage: on cool and dry place, protected from light

In vivo test system

Test animals

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

Species and strain: CBA/Ca mice
Source: TOXI-COOP ZRT.
Hygienic level at arrival: SPF
Hygienic level during the study: Good conventional
Number of animals: 28 animals/main test (4 animals/treatment group)
Sex: Female, nulliparous, non-pregnant
Age of animals: Young adult mice; 10-11 weeks old (at start of the main test)
Body weight range at starting: 18.4-22.5 g
Animal health: Only healthy animals were used

Acclimatization time: 7 days
Housing during acclimatization period: Grouped caging in small groups
Housing during the test: Grouped caging (4 animals/cage)
Light: 12 hours daily, from 6.00 a.m. to 6.00 p.m.
Temperature: 22 ± 3 °C
Relative humidity: 30 – 70 %

Study design: in vivo (LLNA)

Vehicle:

dimethylformamide

Remarks:

AOO (acetone:olive oil, 4:1) for positive control gropus

Concentration:

The test item was administered at four different concentrations (0.25; 0.1; 0.05; 0.025 % w/v) according to the results of the dose range finding test.

No. of animals per dose:

4 animal/dose

Details on study design:

Selection of test item concentrations was based on the results of a formulation evaluation and also results of preliminary irritation/toxicity tests to find an appropriate solvent and the maximum applicable concentration according to the relevant guidelines. Based on the preliminary test results the test item was examined in the main test at 0.25 %, 0.1 %, 0.05 % and 0.025 % (w/v) concentrations as formulations in the selected vehicle of N,N-Dimethylformamide (DMF). Appropriate positive control (α-Hexylcinnamaldehyde [HCA] in 25 % (w/v) concentration), furthermore two negative control groups dosed with the vehicles of the test and positive control groups, respectively, were employed.
The positive control item (25 % (w/v) HCA in Acetone: Olive oil 4:1 (v/v) mixture, AOO) induced the appropriate stimulation over the control, thus confirming the validity of the assay.

Positive control substance(s):

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

Results and discussion

Positive control results:

The positive control group animals were treated with 25 % (w/v) HCA solution (dissolved in AOO) concurrent to the test item groups. No mortality, cutaneous reactions or signs of toxicity were observed in the positive control group.
Significant lymphoproliferative response (SI ≥ 3) was noted for HCA (SI = 14.9). The results of the positive control item demonstrated appropriate performance of the test in accordance with the relevant guidelines and confirmed validity of the assay.

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Remarks on result:

other: see Remark

Remarks:

The stimulation index (SI = the DPN of a treated (positive control or test item) group divided by the DPN of the respective negative control group) for each treatment group was also calculated. A stimulation index of 3 or greater is an indication of a positive result. Based on the results EC3 value (dose calculated to induce a stimulation index of 3) of the test item was not calculated. Dose-response relationship was evaluated by linear regression. (See Table1 for the values.)

Results 2

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: see Remark

Remarks:

DPM (disintegration per minute) was measured for each treatment group. The measured DPM values were corrected with the background DPM value. The average of the two measured DPM values of 5 % (w/v) TCA solutions was used as the background DPM value. The results were expressed as DPN (DPM divided by the number of pooled lymph nodes). (See Table1 for the values.)

Any other information on results incl. tables

Test Group Name	Measured DPM/group	Group* DPM	DPN (DPN/Node)	Stimulation Index Values
Vehicle control for the positive control: AOO	5753	5718.5	714.8	1.0
Positive control: 25 % HCA in AOO	85009	84974.5	10621.8	14.9
DICHLOROPHENACYL CHLORIDE 0.25 % in DMF	180734	180699.5	22587.4	25.5
DICHLOROPHENACYL CHLORIDE 0.1 % in DMF	145732	145697.5	18212.2	20.6
DICHLOROPHENACYL CHLORIDE  0.05 % in DMF	53398	53363.5	6670.4	7.5
DICHLOROPHENACYL CHLORIDE  0.025 % in DMF	40053	40018.5	5002.3	5.7
Vehicle control for the test item: DMF	7115	7080.5	885.1	1.0

 *Group DPM = measured DPM(group)- average DPM(background)

Applicant's summary and conclusion

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Remarks:

Migrated information: extreme

Conclusions:

In conclusion, under the conditions of the present Local Lymph Node Assay, DICHLOROPHENACYL CHLORIDE (CAS No. 4252-78-2) tested at the maximum applicable (non-toxic, non-irritant) concentration of 0.25 % and at concentrations of 0.1 %, 0.05 % and 0.025 % (w/v) as formulations in an appropriate vehicle (DMF) was shown to have skin sensitization potential.
Based on the results an EC3 < 0.025 % (w/v) was estimated for the test item in this LLNA so DICHLOROPHENACYL CHLORIDE (CAS No. 4252-78-2) is considered to be classified as an extreme skin sensitizer according to the published data.