1-(3,5-Dichloro-4-fluoro-phenyl)-2,2,2-trifluoro-ethanone

Endpoint summary

Description of key information

LLNA:

A study was performed to assess the skin sensitization potential of the test item in the CBA/Ca strain mouse following topical application to the dorsal surface of the ear according to OECD 429.

The Stimulation Index (SI) was determined to be 2.10, 3.81, 13.27 for concentration of 5%, 10% and 25% w/w, respectively. The concentration of test item expected to cause a 3 fold increase in radioactive incorporation (EC3 value) was calculated to be 8%.

The test item was considered to be a sensitizer under the conditions of the test.

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

Study period:

From 2014-05-20 to 2014-07-02

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

22 July 2010

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Specific details on test material used for the study:

Batch No.: CPFOA1301
Purity: 98.5%

Species:

mouse

Strain:

CBA/Ca

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: supplied by Harlan Laboratories UK Ltd.
- Females nulliparous and non-pregnant: yes
- Age at study initiation: eight to twelve weeks
- Weight at study initiation: 15 to 23 g
- Housing: individually housed in suspended solid floor polypropylene cages furnished with softwood woodflakes.
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least five days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 to 25 °C
- Humidity (%): 30 to 70%
- Air changes (per hr): approximately fifteen changes per hour
- Photoperiod (hrs dark / hrs light): twelve hours continuous light (06.00 to 18.00) and twelve hours darkness.

Vehicle:

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

Concentration:

25%, 10% or 5% w/w in acetone/olive oil (4:1 v/v)

No. of animals per dose:

5

Details on study design:

PRE-SCREEN TESTS:
- Compound solubility: Acetone/olive oil (4:1 v/v) was chosen as it produced the highest concentration that was suitable for dosing.
- Result: A preliminary screening test was performed using four mice, one mouse per test item concentration. The mice were treated by daily application of 25 μL of the test item at concentrations of 50%, 25%, 10% or 5 v/v in acetone/olive oil 4:1, to the dorsal surface of each ear for two consecutive days (Days 1 and 2). The surviving mice were similarly treated with the test item at concentrations of 25%, 10% or 5 v/v in acetone/olive oil 4:1, on the following day (Day 3).
The animal treated with the test item at a concentration of 50% v/v in acetone/olive oil 4:1 was humanely killed, post dose on Day 2, due to the occurrence of clinical signs of toxicity that exceeded the moderate severity limit set forth in the UK Home Office Project Licence. Signs of systemic toxicity noted in this animal were prostration, ptosis, labored respiration and hypothermia. Very slight erythema on both ears and body weight loss were also noted in this animal. No signs of systemic toxicity, visual local skin irritation or irritation indicated by an equal to or greater than 25% increase in mean ear thickness were noted in the surviving animals.
Based on this information the dose levels selected for the main test were 25%, 10% and 5% v/v in acetone/olive oil 4:1.

MAIN STUDY
- Test Item Formulation:
The test item was formulated within two hours of being applied to the test system.
- Test Item Administration:
Groups of five mice were treated with thee test item at concentrations of 25%, 10% or 5% w/w in acetone/olive oil 4:1. The mice were treated by daily application of 25 μL of the appropriate concentration of the test item to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). The test item formulation was administered using an automatic micropipette and spread over the dorsal surface of the ear using the tip of the pipette.
A further group of five mice received the vehicle alone in the same manner.
- 3H-Methyl Thymidine Administration:
Five days following the first topical application of the test item or vehicle (Day 6) all mice were injected via the tail vein with 250 μL of phosphate buffered saline (PBS) containing 3H-methyl thymidine (3HTdR: 80 μCi/mL, specific activity 2.0 Ci/mmoL) giving a total of 20 μCi to each mouse.
- Observations:
Clinical Observations: All animals were observed twice daily on Days 1, 2 and 3 and on a daily basis on Days 4, 5 and 6. Any signs of toxicity or signs of ill health during the test were recorded.
Body Weights: The body weight of each mouse was recorded on Day 1 (prior to dosing) and Day 6 (prior to termination).
- Terminal Procedures: Five hours following the administration of 3HTdR all mice were killed by carbon dioxide asphyxiation followed by cervical separation.
- Criteria used to consider a positive response:
The test item will be regarded as a sensitizer if at least one concentration of the test item results in a threefold or greater increase in 3HTdR incorporation compared to control values.

Positive control substance(s):

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

Statistics:

Data was processed to give group mean values for disintegrations per minute and standard deviations where appropriate. Individual and group mean disintegrations per minute values were assessed for dose response relationships by analysis of homogeneity of variance followed by one
way analysis of variance (ANOVA). In the event of a significant result from the ANOVA, pairwise comparisons were performed between control and treated groups. For homogenous datasets Dunnett's Multiple Comparison test was used and for non-homogenous datasets Dunnett's T3 Multiple Comparison Method was used.

Positive control results:

α-Hexylcinnamaldehyde, tech., 85% was considered to be a sensitizer (SI=12.76 at a concentration of 25% v/v in acetone/olive oil 4:1) under the conditions of the test.

Parameter:

SI

Value:

2.1

Test group / Remarks:

5% w/w in acetone/olive oil 4:1

Parameter:

SI

Value:

3.81

Test group / Remarks:

10% w/w in acetone/olive oil 4:1

Parameter:

SI

Value:

13.27

Test group / Remarks:

25% w/w in acetone/olive oil 4:1

Cellular proliferation data / Observations:

- Clinical Observations and Mortality Data:
There were no deaths. No signs of systemic toxicity were noted in the test or control animals during the test.
- Body Weight:
Body weight changes of the test animals between Day 1 and Day 6 were comparable to that observed in the corresponding control group animals over the same period.

The concentration of test item expected to cause a 3 fold increase in 3HTdR incorporation (EC3 value) was calculated to be 8%.

Interpretation of results:

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

Conclusions:

The test item was considered to be a sensitizer under the conditions of the test.

Executive summary:

A study was performed to assess the skin sensitization potential of the test item in the CBA/Ca strain mouse following topical application to the dorsal surface of the ear according to OECD 429.

Following a preliminary screening test in which no clinical signs of toxicity were noted at a concentration of 25% w/w, this concentration was selected as the highest dose investigated in the main test of the Local Lymph Node Assay. Three groups, each of five animals, were treated with 50 μL (25 μL per ear) of the test item as a solution in acetone/olive oil 4:1 at concentrations of 25%, 10% or 5% w/w. A further group of five animals was treated with acetone/olive oil 4:1 alone.

The Stimulation Index (SI) was determined to be 2.10, 3.81, 13.27 for concentration of 5 %, 10% and 25% w/w, respectively. The concentration of test item expected to cause a 3 fold increase in radioactive incorporation (EC3 value) was calculated to be 8%.

The test item was considered to be a sensitizer under the conditions of the test.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Skin sensitisation:

in vivo: LLNA, SI max: 13.27 > 3, sensitising, EC3 value: 8% > 2%

 

Respiratory sensitisation:

No data available, not minimum required data.

 

Classification:

Skin: The stimulation indexes were above 3 in all tested concentrations in the murine local lymph node assay (OECD 429). Based on criteria Table 3.4.4 from Regulation (EC) 1272/2008 and amendments, the substance has to be classified as Category 1B for skin sensitiser.