5-methyl-5-phenylhexan-3-one

Endpoint summary

Description of key information

Skin sensitisation with Damascol up to 30% (OECD TG 429): not sensitising. In addition, information from an analogue is used which is tested up to 100% without indication of skin sensitisation. Based on these results Damascol is non sensitising up to 100%.

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:

The study was conducted between 13 September 2004 and 29 November 2004.

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

In accordance with GLP conditions, but tested only up to 30%

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

maximum concentration tested was 30%

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

other: CBA/J

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Jackson Laboratories, Bar Harbor, ME 04609, US
- Age at study initiation: 11 weeks at start of dosing
- Weight at study initiation: 18 to 26 g at the outset of the study (Day 1)
- Housing: 5 animals/cage (randomly allocated)
- Diet (e.g. ad libitum): ad libitum (Certified Rodent Chow 7012C)
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.1-26.7
- Humidity (%): 30-53
- Air changes (per hr): No data
- Photoperiod (hrs dark / hrs light): 12/12

Vehicle:

other: Diethyl phthalate/ Ethanol 3:1

Concentration:

7.5%, 15% and 30% (w/v)

No. of animals per dose:

5

Details on study design:

MAIN STUDY

EXPERIMENTAL PHASE
Groups of five mice were treated with the test item at concentrations of 7.5%, 15% and 30% w/v in DEP/EtOH. No justification on the choice of vehicle is provided. The doses were chosen on the basis that these are typical concentrations used for fragrances. The mice were treated by daily application of 25 µl of the appropriate concentration of the test item to the dorsal surface of both ears 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. The positive control animals were similarly treated to the test animals except that 25 µl of the positive control item, Hexylcinnamaldehyde [HCA], at a concentration of 35% v/v. On day 6, all mice were injected i.v. with 250 µl of sterile saline containing 20µCi of 3H-thymidine.

OBSERVATIONS
- Clinical Observations: All animals were observed before dosing and once post-dose on Day 1 to 3. After this observations continued on a daily basis on Days 4, 5 and 6. Any signs of toxicity or signs of ill health during the test were recorded. The animals were also examined daily for erythema and edema on the site of application.
- Bodyweights: The bodyweight of each mouse was recorded on Day 1 (prior to dosing) and Day 6 (prior to termination).

TERMINATIOIN
Five hours following the administration of 3HTdR all mice were killed by carbon dioxide asphyxiation. For each individual animal of each group the draining auricular lymph nodes were excised and processed. A single cell suspension of the lymph node cells for each individual animal was prepared. The lymph node cells were rinsed with PBS and precipitated with 5% trichloroacetic acid during night. The lymph node cells suspension was transferred to a centrifuge tube and thereafter, the pellets were resuspended in 1 ml TCA and transferred to scintillation fluid vials for the measurement of the radioactive material.

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. Increases in the radioactivity compared to the vehicle control were recorded as stimulation indices (SI). Individual DPM values were analyzed with log values. Dunett's test was used to determine significance when required.

Positive control results:

The positive control item, Hexylcinnamaldehyde, gave a Stimulation Index of 7.11 which was statistically significant when compared to the vehicle control group.

Key result

Parameter:

EC3

Test group / Remarks:

All test groups

Remarks on result:

other: up to 30% alll SI results are < 3

Parameter:

SI

Value:

0.89

Test group / Remarks:

7.5% (w/v)

Parameter:

SI

Value:

0.8

Test group / Remarks:

15% (w/v)

Parameter:

SI

Value:

1.12

Test group / Remarks:

30% (w/v)

Cellular proliferation data / Observations:

CELLULAR PROLIFERATION DATA
Mean DPM (+/- SEM) were:
- Vehicle control: 233 +/- 44
- 7.5%: 207 +/- 39
- 15%: 187 +/- 18
- 30%: 260 +/- 7

DETAILS ON STIMULATION INDEX CALCULATION
Stimulation Index = dpm/lymph node test item treated group / dpm/lymph node vehicle control.
- 7.5%: SI = 0.89
- 15%: SI = 0.8
- 30%: SI = 1.12

EC3 CALCULATION
A dose-response relationship was not observed. A calculation of the EC3 value was not performed because no test concentrations produced a S.I. of 3 or higher.

CLINICAL OBSERVATIONS:
One mouse in the group treated with the test article at 15% was found dead on day 5. A necropsy revealed no gross lesions. All other mice survived and did not show signs of toxicity. The lymph nodes of all animals which were treated with the test item were normal in size and appearance. At termination both ears were measured. There was one statistically significant different in the ear measurement in the group treated with the test article at a dose of 7.5%. This slight decrease was not considered to be biologically significant.

BODY WEIGHTS
Body weight changes of the test animals between Day 1 and Day 6 were comparable to those observed in the corresponding control group animals over the same period.

Interpretation of results:

other: not sensitising

Remarks:

based on CLP criteria (EC 1272/2008 and its updates)

Conclusions:

Under the conditions of this test, Damascol did not elicit a Stimulation Index of greater than 3 and was therefore not considered to be a sensitiser up to 30%. Therefore, the substance does not need to be classified as skin sensitiser in accordance with the criteria outlined in Annex I of the CLP Regulation (1272/2008/EC and its updates).

Executive summary:

The skin sensitisation potential of the test substance has been tested according to OECD TG 429 (Local Lymph Node Assay) and under GLP conditions. The positive control showed a statistically significant induction of the stimulation index as compared to the vehicle control. At doses of 7.5, 15 and 30% (w/v) Damascol, the following Stimulation Index (SI) values were found, respectively: 0.89, 0.80 and 1.12. As these SI values are all below 3 and no EC3 value could be calculated, the substance was not considered to be a skin sensitiser under the conditions of this test. Therefore, the substance does not need to be classified as skin sensitiser up to 30%.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

For assessing the skin sensitisation of Damascol information on the substance itself is available in which the substance was tested up to 30%. To assess the skin sensitisation up to 100% information from an analogue is used. The justification for the read across is also presented. The information below is presented in this order. Overall it can be concluded that Damascol is not a skin sensitiser.

Damascol LLNA up to 30%

In the key study, the skin sensitisation potential of Damascol has been tested according to OECD TG 429 (Local Lymph Node Assay) under GLP conditions. At doses of 7.5, 15 and 30% (w/v), the following Stimulation Index (SI) values were found, respectively: 0.89, 0.80 and 1.12. As these SI values are all below 3 and no EC3 value could be calculated, the substance was not considered to be a skin sensitiser under the conditions of this test. This result is supported by an available Local Lymph Node Assay (OECD TG 429, GLP) for the read-across substance 4-phenylbutan-2-one. Treatment with 25, 50 and 100% (w/v) of the test substance showed Stimulation Index (SI) values of 1.6, 1.5 and 1.6 respectively. Based on this results, 4-phenylbutan-2-one was not found to be a skin sensitiser and an EC3 value could not be calculated.

4 -phenylbutan-2 -one skin sensitisation LLNA up to 100%

The skin sensitisation potential of the substance 4-phenylbutan-2-one has been tested according to OECD TG 429 (Local Lymph Node Assay) under GLP conditions. The test was considered valid as the positive control showed an EC3 value of 13.0. Treatment with 25, 50 and 100% (w/v) of the test substance showed Stimulation Index (SI) values of 1.6, 1.5 and 1.6 respectively. Based on this results, 4-phenylbutan-2-one was not found to be a skin sensitiser and an EC3 value could not be calculated.

Damascol and its non-sensitising properties using read across from 4-phenylbutan-2-one

Introduction and hypothesis for the read across

For Damascol skin sensitisation data are available up to a concentration of 30%. Therefore additional information is used in accordance with Article 13 of REACH where it is said thatlacking information should be generated whenever possible by means other than vertebrate animal tests, i.e. applying alternative methods such as in vitro tests, SARs, grouping and read-across.

Hypothesis:Damascolis not expected to have sensitising properties based on information on the substance (up to 30%) and based on closely related analogue information (tested up to 100%).

Available information:Damascol has been tested in an LLNA in which no sensitisation (Stimulation Index < 3) was observed up to 30% concentration (Reliability 2 because of too low test concentrations). The source chemical 4-phenylbutan-2-one has been tested in a well conducted LLNA in which no sensitisation (Stimulation Index < 3) was observed up to 100% concentration (Reliability 1 based on the information as such).

Target and Source chemical(s):The information on Damascol and the analogue information from 4-phenylbutan-2-one are presented in the data matrix.

Purity / Impurities

The purity and impurities of the target chemical do not indicate skin sensitisation potential other than indicated by the parent substance. The impurities are all below < 10%.

Analogue justification

According REACH Annex XI an analogue approach and structural alert information can be used to replace testing when information from different sources provides sufficient evidence to conclude that this substance has or does not have a particular dangerous property. The result derived should be applicable for C&L and/or risk assessment and be presented with adequate and reliable documentation. In addition, to the information on Damascol up to 30% for the structurally related 4-phenylbutan-2-one a well conducted LLNA test (OECD TG 429) is available, showing the absence of skin sensitising potential up to 100%.

Analogue selection:According to ECHA guidance (RAAF, 2015) a clear documentation is needed on the selection of potential source substances. The substance was selected because the chemical structure is very similar to Damascol and for this substance LLNA information is available up to 100%.

Structural similarities and differences:The structural differences between 4-phenylbutan-2-one and Damascol are a longer alkyl chain (including a methyl group adjacent to the ketone) and a dimethylated quaternary carbon on the latter. These differences will not influence the reactivity of the ketone functional group. Therefore the information from 4-phenylbutan-2-one can be used for read-across to Damascol.

Toxico-kinetics:The skin absorption characteristics will be similar to both substances based on both substances being liquids and similar molecular weights. The water solubility and log Kow are slightly lower and higher respectively for Damascol due to the additional two methyl groups in the alkyl chain.

Toxico-dynamics: Both parent substances are not expected to have protein binding properties (OECD Toolbox, data not shown). Also after reduction of the ketone, becoming an alcohol, not protein binding properties are expected. Both substances will not be pre or prohaptens.

Based on the above justification, read-across from 4-phenylbutan-2-one to Damascol is possible for the skin sensitisation endpoint.

Remaining uncertainties:There are no remaining uncertainties because 4-phenylbutan-2-one is structurally a very close analogue to Damascol.

In the ECHA guidance (RAAF, 2015) terminology it receives a score of 5 (acceptable with high confidence), because therationale for the selection of the analogues is clearly documented (vide supra) and there is supporting evidence provided (vide infra).

Data matrix

The relevant information on physico-chemical properties and toxicological characteristics are presented in the Data Matrix below.

Conclusions for the endpoint for C&L

When using read across the result derived should be applicable for C&L and/or risk assessment, cover an exposure period duration comparable or longer than the corresponding method and be presented with adequate and reliable documentation.

It is shown that Damascol is not a skin sensitiser up to 30% and that based on analogue information it can be concluded that Damascol has no skin sensitising properties up to 100%.

Final conclusion on hazard, C&L: Damascol is not sensitising, and it does not need to be classified and labelled for sensitisation according to EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008 and its updates

Data matrix with information on Damascol and 4-phenylbutan-2-one to assess theskin sensitising properties of Damascol.

Common name	Damascol	4-phenylbutan-2-one
CAS	4927-36-0	2550-26-7
Chemical structure
Empirical formula	C13H18O	C10H12O
Physico-chemical properties
Molecular weight	190.29	148.21
Appearance	Liquid	Liquid
Vapour pressureat 25˚C (Pa)	1.98 (measured)	4 (Episuite)
Water solubility at 20˚C (mg/L)	95 (measured)	1625 (Episuite)
Log Kow	3.5 (measured)	2.0 (Episuite)
Human health
Skin sensitisation animal test	LLNA not sensitising up to 30% Read across to assess 100% exposure	LLNA not sensitising up to 100%

 

Justification for classification or non-classification

Damascol is not a skin sensitiser based on the information of the substance as such up to 30% and based on additional information of an analogue tested up to 100% in accordance with the criteria outlined in Annex I of the CLP Regulation (1272/2008/EC and its updates).