(3E)-dec-3-en-2-one

Endpoint summary

Description of key information

The potential of (3E)-dec-3-en-2-one (target substance) to induce skin sensitisation was evaluated in a suitablein vivotest method conducted according to OECD test guideline 406 (Buehler method). Based on the results, the target substance is not considered to be a contact sensitizer. Therefore, no classification is warranted in accordance with the CLP regulation 1272/2008.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-04-16 to 2009-07-24

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes

Type of study:

Buehler test

Justification for non-LLNA method:

The Buehler test is an accepted method for hazard identification of skin sensitising substances as recommended in "ECHA guidance R.7a: Endpoint specific guidance".

Species:

guinea pig

Strain:

Hartley

Remarks:

albino

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Received from Elm Hill Breeding Labs, Chelmsford, MA on April 15, 29 and May 6, 2009 (Preliminary Irritation Group) and April 22, 2009 (Test and Naive Control Groups).
- Females nulliparous and non-pregnant: yes
- Age at study initiation: Young adult
- Weight at study initiation: 318-412 g
- Housing: Animals were group housed in suspended stainless steel caging with mesh floors or plastic perforated bottom caging. Litter paper was placed beneath the cage and was changed at least three times a week.
- Diet: Pelleted Purina Guinea Pig Chow #5025
- Water: Filtered tap water was supplied ad-libitum by an automatic water dispensing system.
- Acclimation period: 5-7 days
- Indication of any skin lesions: On the day before initiation, the fur of a group of animals was removed by clipping the dorsal area and flanks. After clipping and prior to initiation, the animals were weighed and the skin was checked for any abnormalities. Only healthy naive animals (not previously tested) without preexisting skin irritation were selected for test.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-22
- Humidity (%): 42-74
- Air changes (per hr): not reported
- Photoperiod (hrs dark / hrs light): 12 / 12
- IN-LIFE DATES: 17th April - 28th May 2009

Route:

epicutaneous, occlusive

Vehicle:

other: mineral oil

Concentration / amount:

100%, 75% / 0.4 mL

Day(s)/duration:

three times per week for three weeks

Adequacy of induction:

highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

other: mineral oil (HNIC)

Concentration / amount:

1% / 0.4 mL

Day(s)/duration:

27 days after first induction

Adequacy of challenge:

highest non-irritant concentration

No. of animals per dose:

- Preliminary Irritation Group: 8
- Test Group: 20
- Naive Control Group: 10

Details on study design:

PRELIMINARY IRRITATION TESTING:
A group of animals was used to determine the highest non-irritating concentration (HNIC) of the test substance prior to the challenge dose. The fur was removed by clipping the dorsal area and flanks of each guinea pig. This area was divided into four test sites (two sites on each side of the midline) on each animal. The test substance was applied neat (100%) and also diluted with mineral oil to yield w/w concentrations of 75%, 50%, 25%, 12%, 6%, 3%, and 1%. Each concentration was applied (0.4 mL each) to a test site using an occlusive 25 mm Hill Top Chamber. The sites were wrapped with non-allergenic Durapore adhesive tape. After 6 hours of exposure, the chambers were removed and the test sites were gently cleansed of any residual test substance. Approximately 24 hours after application, each site was evaluated for local reactions (erythema) according to the scoring system described below under section "Main Study". From these results, the HNIC (the highest concentration that produced responses in 4 guinea pigs no more severe than two scores of 0.5 and two scores of zero) was established and used for challenge. The HNIC selected for the challenge phase was 1% w/w mixture in mineral oil.

MAIN STUDY
A. PREPARATION AND SELECTION OF ANIMALS
On the day before initiation, the fur of a group of animals was removed by clipping the dorsal area and flanks. After clipping and prior to initiation, the animals were weighed and the skin was checked for any abnormalities. Only healthy naive animals (not previously tested) without pre-existing skin irritation were selected for test. Animals were re-clipped prior to each dose.

B. INDUCTION EXPOSURE
Three times each week for three weeks, four-tenths of a milliliter of the undiluted test substance or a 75% w/w mixture of the test substance in mineral oil was applied to the left side of each test animal using an occlusive 25 mm Hill Top Chamber. The chambers were secured in place and wrapped with non-allergenic Durapore adhesive tape to avoid dislocation of the chambers and to minimize loss of the test substance. After the 6-hour exposure period, the chambers were removed and the test sites were gently cleansed of any residual test substance. Approximately 24 and 48 hours after each induction application, readings were made of local reactions (erythema) according to the scoring system below :
- 0 no reaction
- 0.5 very faint erythema, usually non-confluent*
- 1 faint erythema, usually confluent
- 2 moderate erythema
- 3 severe erythema with or without edema
*Very faint erythema is not considered a positive reaction

B. CHALLENGE EXPOSURE
Twenty-seven days after the first induction dose, four-tenths of a milliliter of a 1% w/w mixture of the test substance in mineral oil (HNIC) was applied to a naive site on the right side of each animal as a challenge dose, using the procedures described above. These sites were evaluated for a sensitization response (erythema) approximately 24 and 48 hours after the challenge application according to the system described above.

OTHER:
Individual body weights of the animals were recorded prior to initiation and again on the day after challenge.

Challenge controls:

10 guinea pigs from the same shipment were maintained under identical environmental conditions and were treated with the HNIC of the test substance at challenge only. These animals constituted the "naive control" group.

Positive control substance(s):

yes

Remarks:

alpha-hexylcinnamaldehyde Technical (HCA) - historical data

Positive control results:

INDUCTION PHASE:
Historical Positive Control Animals (100% HCA): Very faint erythema (0.5) was noted for six often positive control sites at various intervals during the induction phase.

CHALLENGE PHASE:
Historical Positive Control Animals (100% HCA): Three of ten positive control animals exhibited signs of a sensitization response (faint erythema) 24 hours after challenge. Similar indications persisted at one of these sites through 48 hours. Very faint erythema (0.5) was noted for most other sites following challenge.

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

0.4 mL of a 1% w/w mixture of the test substance in mineral oil

No. with + reactions:

7

Total no. in group:

20

Clinical observations:

Very faint erythema (score 0.5) in seven animals

Remarks on result:

no indication of skin sensitisation

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

0.4 ml of 1% w!w mixture of the test substance in mineral oil

No. with + reactions:

1

Total no. in group:

20

Clinical observations:

Very faint erythema (score 0.5) in one animal

Remarks on result:

no indication of skin sensitisation

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

0.4 ml of 1% w!w mixture of the test substance in mineral oil

No. with + reactions:

1

Total no. in group:

10

Clinical observations:

very faint erythema (score 0.5) was observed in one animal

Remarks on result:

no indication of skin sensitisation

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

0.4 ml of 1% w!w mixture of the test substance in mineral oil

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

no indication of skin sensitisation

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

100% HCA - historical data

No. with + reactions:

9

Total no. in group:

10

Clinical observations:

Three of ten positive control animals exhibited signs of a sensitization response (faint erythema) 24 hours after challenge. Six of ten positive control animals exhibited very faint erythema (score 0.5)

Remarks on result:

positive indication of skin sensitisation

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Dose level:

100% HCA - historical data

No. with + reactions:

7

Total no. in group:

10

Clinical observations:

Faint erythema (score 1) was noted in one animal and very faint erythema (score 0.5) was noted in six animals

Remarks on result:

positive indication of skin sensitisation

Results of Challenge Phase:

- Test Animals (1% w/w mixture of the test substance in mineral oil): Very faint erythema (0.5) was noted for seven of twenty test sites 24 hours after challenge. Similar irritation persisted at one site through 48 hours.

- Naive Control Animals (1% w/w mixture of the test substance in mineral oil): Very faint erythema (0.5) was noted for one of ten naive control sites 24 hours after challenge. Irritation was clear from this site by 48-hours.

- Historical Positive Control Animals (100% HCA): Three of ten positive control animals exhibited signs of a sensitization response (faint erythema [1]) 24 hours after challenge. Similar indications persisted at one of these sites through 48 hours. Very faint erythema (0.5) was noted for most other sites following challenge.

- Historical Naive Control Animals (100% HCA): Very faint erythema (0.5) was noted for one naive control site 24 hours after challenge. Irritation cleared from the affected site by 48 hours.

Table 1: Sensitisation response

	Sensitisation response indices
	Incidence of positive response*		Severity**
	24 hours	48 hours	24 hours	48 hours
Test animals	0/20	0/20	0.18	0.03
Naive control animals	0/10	0/10	0.05	0.00

* Animals with erythema scores greater than 0.5.

** Sum of the erythema scores divided by the number of animals evaluated.

Interpretation of results:

GHS criteria not met

Conclusions:

Based on the results from an in vivo skin sensitisation test (Buehler test), the test item (3E)-dec-3-en-2-one is not considered to be a contact sensitiser.

Executive summary:

A dermal sensitization test (Buehler, OECD 406) was conducted with guinea pigs to determine the potential of (3E)-dec-3-en-2-one to produce sensitization after repeated topical applications. The undiluted test substance or a 75% w/w mixture of the test substance in mineral oil was topically applied to twenty healthy test guinea pigs, three times each week for a three-week induction period. Twenty-seven days after the first induction dose, a challenge dose (0.4 mL) of the test substance at its highest non-initating concentration (HNIC, detennined in the preliminary irritation screen to be a 1% w/w mixture in mineral oil) was applied to a naive site on each guinea pig. A naive control group (ten animals) was maintained under the same environmental conditions and treated with the test substance at challenge only. Approximately 24 and 48 hours after each induction and challenge dose, the animals were scored for erythema. Only very faint erythema (score 0.5) was observed in test and negative control animals after the challenge phase.

Based on the results of this study, the test substance is not considered to be a contact sensitiser. Furthermore the positive response observed in the historical positive control validation study with alpha hexylcinnamaldehyde technical (HCA) validates the test system used in this study.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

A dermal sensitization test (OECD 406, Buehler Method) was conducted with guinea pigs to determine the potential of (3E)-dec-3-en-2-one to produce sensitization after repeated topical applications. The undiluted test substance or a 75% w/w mixture of the test substance in mineral oil was topically applied to twenty healthy guinea pigs, three times each week for a three-week induction period. Twenty-seven days after the first induction dose, a challenge dose (0.4 mL) of the test substance at its highest non-initiating concentration (HNIC, determined in the preliminary irritation screen to be a 1% w/w mixture in mineral oil) was applied to a naive site on each guinea pig. A naive control group (ten animals) was maintained under the same environmental conditions and treated with the test substance at challenge only. Approximately 24 and 48 hours after each induction and challenge dose, the animals were scored for erythema. Only very faint erythema (score 0.5) were observed in test animals and negative control group after the challenge phase. Therefore, based on the results of this study, the test substance is not considered to be a contact sensitizer and no classification is warranted in accordance with the CLP regulation 1272/2008.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

In an in vivo skin sensitisation study conducted in according to OECD test guideline 406 (Buehler Method), the target substance was tested negative for skin sensitisation. Based on the results, classification for skin sensitisation is not warranted.