Reaction mass of Benzenepropanal, 4-ethyl-α,α-dimethyl- and 3-(2-ethylphenyl)-2,2-dimethylpropanal

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:

guideline study

Justification for type of information:

Information is used for read across to Floralozone

Cross-reference

Reason / purpose for cross-reference:

read-across: supporting information

Reference

Skin sensitisation using read across from Cyclamen aldehyde (tested in OECD TG 429): EC3 22.3%: skin sensitising

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

A HRIPT study in which Floralozone is tested at 3.5% is available. This information is considered insufficient to fulfil the REACH requirements. Therefore LLNA information from Cyclamen aldehyde (CAS #103-95-7) is used for read across to Floralozone. In this section first the LLNA of Cyclamen aldehyde is summarised, thereafter the HRIPT study with Floralozone and finally the full read across justification.

Cyclamen aldehyde (103 -95 -7) LLNA (OECD TG 429

The skin sensitisation potential of the substance has been tested in a study similar to OECD TG 429: Local Lymph Node Assay method. At 1, 2.5, 10, 25 and 50% were 1.4, 1.34, 1.84, 3.26 and 5.16, respectively. Reliable negative control was included. The test substance could elicit a SI ≥ 3. An EC3 has been derived resulted in an EC3 of 22.3%.A NOEC of 10% is derived. Based on the results, the substance was considered to be a sensitiser.

HRIPT (with Floralozone)

One hundred twelve subjects participated in evaluating the potential of 3.5% w/w test material in EtOH:DEP (1:3) to elicit dermal irritation and/or induce sensitization. The test material was applied under an occlusive patch to the upper back of each subject and was allowed to remain in direct skin contact for a period of 24 hours. Patches were applied to the same site for a total of 9 applications during the Induction Period. The sites were graded for dermal irritation 24 hours after removal of the patches and 48 hours after removal. Following a 2-week rest period, challenge patches were applied to previously untreated test sites on the back. After 24 hours, the patches were removed and evaluated. The test sites were re-evaluated at 48 and 72 hours. One hundred eight subjects completed the study. The test material did not demonstrate a potential for elicit dermal irritation or sensitization under the test conditions.

Assessing the sensitisation potential of Floralozone (CAS #67634-14-4 and #67634-15-5) using Cyclamen aldehyde (CAS #103-95-7)

Introduction and hypothesis for the analogue approach for skin sensitisation

Floralozone is an ethyl substituted phenyl-propyl aldehyde,to which a dimethyl group is attached to the alpha position.In accordance with Article 13 of REACH, lacking information can be generated by applying alternative methods such asin vitrotests, QSARs, grouping and read-across. In this case read across will be used for assessing the skin sensitising potential of Floralozone using Cyclamen aldehyde as an analogue. This analogue has a similar molecular structure compared to Floralozone and therefore information from Cyclamen aldehyde can be used to determine the skin sensitising potential of Floralozone (see data matrix).

Hypothesis:Floralozone (target) has similar sensitisation potential compared to Cyclamen aldehyde (source) resulting in a similar skin sensitising effect because both molecular structures are similar.

Available information:For Floralozone aHRIPT test with 3.5% substance is available. In this study no skin sensitisation was observed, the REACH requirements cannot be fulfilled with this information. For the analogue Cyclamen aldehyde a Local Lymph Node Assay is available which result can be used forFloralozone. The assay was performed equivalent to OECD TG 429: Local Lymph Node Assay method. The study was assigned reliability 1.

2. Target chemical and source chemical(s)

Chemical structures of the target and the source are shown in the data matrix (see also the attached document in IUCLID section 7.4).

3. Purity / Impurities

Floralozone contains two constituents that are isomers, where CAS# 67634-15-5 (para) is present at 60-75% and CAS# 67634-14-4 (ortho) is present at 20-30%. Cyclamen aldehyde contains one main constituent present at ca. 100%.As a result it is not expected that the impurities of the source and target chemicals affect the read-across justification.

4. Analogue approach justification

According to Annex XI 1.5 read across can be used to replace testing when the similarity can be based on a common backbone and a common functional group. When using read across the result derived should be applicable for C&L and/or risk assessment and it should be presented with adequate and reliable documentation.

Structural similarities and differences:Floralozone and Cyclamen aldehyde have the same phenyl-propyl aldehyde backbone and the same functional group: the aldehyde. The difference is that Floralozone has two methyl groups on the alpha position next to the aldehyde and Cyclamen aldehyde has one. Floralozone has an ethyl group on the para-position of the phenyl group while Cyclamen aldehyde has an isopropyl group. These differences are not expected to have a different skin sensitisation potential. Also the para versus the ortho position of the ethyl group in Floralozone is not expected to make a difference in skin sensitisation potential.

Toxico-kinetic similarities and differences:For skin sensitisation the dermal absorption is of secondary importance. Cyclamen aldehyde has a very similar log Kow compared to Floralozone: 3.9 and 4.1, respectively.

Toxico-dynamic aspect: Reactivity:Floralozone and Cyclamen aldehyde contain the same reactive groups and no difference in reactivity is to be expected. 

Experimental data similarity and difference:The skin and eye irritation endpoints are other local endpoints for which reactivity is a key parameter. Both substances are irritating to the skin and not irritating to the eyes supporting the similarity in reactivity.

Uncertainty of the prediction:There is no remaining uncertainty, in view of similarities in structure, and reactivity, as presented above the read across is justified.

5. Data matrix

The relevant information on physico-chemical properties and toxicological characteristics are presented in the Data matrix in Table 1.

6. Conclusions per endpoint for C&L and dose descriptor

When using read across the result derived should be applicable for C&L and/or risk assessment and be presented with adequate and reliable documentation.

Cyclamen aldehyde is an analogue for Floralozone. Cyclamen aldehyde is a skin sensitizer in an LLNA test and has an EC3 of 22.3 and a NOEC of 10%. In view of the close similarity with Floralozone the same values can be used.

Final conclusion on hazard, C&L and risk characterization:

Floralozone has EC3 of 22.3 and a NOEC of 10% based on analogue information. Therefore it has to be classified for skin sensitization and a NOEC will be used for the risk characterization.

Data matrix for assessing the skin sensitisation of Floralozone using read across from Cyclamen aldehyde

Common names	Floralozone	Cyclamen aldehyde
Chemical structures
CAS no	67634-14-4 and 67634-15-5	103-95-7
Smiles	O=CC(Cc1c(cccc1)CC)(C)C and O=CC(Cc1ccc(cc1)CC)(C)C	CC(C)c1ccc(cc1)CC(C)C=O
Molecular weight	190	190
Appearance	Liquid	Liquid
Physico-chemical data
Melting point, °C	-20	-50
Boiling point, °C	260	234
Vapour pressure, Pa	0.43	0.3
Water solubility, mg/l	40	66
Log Kow	4.1	3.91
Human health
Skin irritation/corrosion	irritating (OECD 439)	irritating (similar to OECD 404)
Eye irritation/corrosion	not irritating (OECD 438)	not irritating (similar to OECD 405)
Skin sensitisation	EC3 derived by read across	Skin sensitiserEC3 of 22.3%. (OECD TG 429)
	HRIPT: 3.5% no sensitisation

 

 

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The substance is not a respiratory sensitizer because there are no human data that indicate respiratory sensitisation. In addition the potential for respiratory sensitisation of the substance is assessed using the integrated evaluation strategy for respiratory sensitisation data in the ECHA guidance (R7A, Fig. 7.3-2).

1)           The substance is a moderate skin sensitizer;

2)           The substance does not belong to the di-isocyanates;

3)           The substance has not structural alerts or is structurally related to chemicals causing respiratory sensitization as presented in Table R.7.3-1 in the ECHA guidance of 2008 or those provided in the following document: http://ec.europa.eu/health/scientific_committees/docs/annex6_respiratory.pdf

Using this ITS in the ECHA guidance it can be concluded that the substance is not a respiratory sensitizer.

According to EU CLP (EC No. 1272/2008 and its updates) the substance is classified as a skin sensitiser category 1B with the following H phrased: H319: May cause an allergic skin reaction. The substance does not need to be classified and labelled when using the information on respiratory sensitisation in accordance with EU CLP (Regulation (EC) No. 1272/2008 and its updates).

Data source

Reference

Reference Type:

publication

Title:

Human potency predictions for aldehydes using the local lymph node assay

Author:

Basketter DA, Wright Z, Warrick E, Dearman R, Kimber I, Ryan C, Gerberick G, White I

Year:

2001

Bibliographic source:

Contact Dermat 45:89-94

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

not specified

GLP compliance:

not specified

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

1

Reference substance name:

3-p-cumenyl-2-methylpropionaldehyde

EC Number:

203-161-7

EC Name:

3-p-cumenyl-2-methylpropionaldehyde

Cas Number:

103-95-7

Molecular formula:

C13H18O

IUPAC Name:

2‐methyl‐3‐[4‐(propan‐2‐yl)phenyl]propanal

In vivo test system

Test animals

Species:

mouse

Strain:

CBA/Ca

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Olac, Bicester, Oxfordshire, UK)
- Age at study initiation: 6–12 weeks old
- Housing: animals were housed under standard conditions
- Diet: ad libitum
- Water: tap water, ad libitum

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

The test item at concentrations of 1%, 2.5%, 10%, 25%, 50% v/v in vehicle

No. of animals per dose:

Groups of four mice were treated

Details on study design:

MAIN STUDY
Groups of mice were exposed topically on the dorsum of both ears to 25 µL of various concentrations of the test aldehyde, or to the same volume of vehicle (AOO) alone, daily for 3 consecutive days.
5 days after the initiation of exposure, all mice were injected intravenously via the tail vein with 20 µCi of [3H]methyl thymidine in 250 µL of phosphate buffered saline (PBS). After 5 hours mice were killed and the auricular lymph nodes were excised and pooled. A single cell suspension of the lymph node cells was prepared by gentle mechanical disaggregation through a 200 mesh stainless steel gauze. Cells were washed twice with an excess of PBS and precipitated in 5% trichloroacetic acid (TCA) at 4 °C. After 12 hours the pellets were resuspended in 5% TCA (1 mL) and transferred to 10 mL of scintillation fluid (Optiphase ‘‘Hisafe3’’, Wallac, Turku, Finland). Incorporation of 3H-TdR was measured by ß-scintillation counting as disintegration per minute (dpm) per node for each experimental group. In each case, a stimulation index (SI) relative to the concurrent vehicle treated control value was derived.

Positive control substance(s):

not specified

Results and discussion

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

EC3

Remarks:

%

Value:

22.3

Results 2

Key result

Parameter:

other: NOEC / %

Value:

10

Results 3

Parameter:

SI

Value:

1

Remarks on result:

other: Vehicle control

Results 4

Parameter:

SI

Value:

1.4

Remarks on result:

other: Test group 1%

Results 5

Parameter:

SI

Value:

1.34

Remarks on result:

other: Test group 2.5%

Results 6

Parameter:

SI

Value:

1.84

Remarks on result:

other: Test group 10%

Results 7

Parameter:

SI

Value:

3.26

Remarks on result:

other: Test group 25%

Results 8

Parameter:

SI

Value:

5.16

Remarks on result:

other: Test group 50%

Cellular proliferation data / Observations:

DISINTEGRATION PER MINUTE (DPM)
The disintegrations per minute were counted for the substance concentrations 1, 2.5, 10, 25 and 50% were 204, 195, 267, 47 and 750, respectively.

EC3 CALCULATION
The estimated concentration of chemical required to induce an SI of 3 relative to concurrent vehicle treated controls, or EC3 value, was derived by linear interpolation of dose response data. The EC3 value was calculated by interpolating between 2 points on the SI axis, one immediately above, and the other immediately below, the SI value of 3.

Applicant's summary and conclusion

Interpretation of results:

other: skin sensitiser Category 1B

Remarks:

in accordance with CLP (EC 1272/2008 and its updates)

Conclusions:

The SI values calculated for the substance concentrations 1, 2.5, 10, 25 and 50% were 1.4, 1.34, 1.84, 3.26 and 5.16, respectively. These results show that the test substance could elicit a SI ≥ 3. An EC3 has been derived resulted in an EC3 of 22.3%. A NOEC of 10% is derived. The test substance was considered to be a sensitiser under the conditions of the test.

Executive summary:

The skin sensitisation potential of the substance has been tested in a study similar to OECD TG 429: Local Lymph Node Assay method. At 1, 2.5, 10, 25 and 50% were 1.4, 1.34, 1.84, 3.26 and 5.16, respectively. Reliable negative control was included. The test substance could elicit a SI ≥ 3. An EC3 has been derived resulted in an EC3 of 22.3%. A NOEC of 10% is derived. Based on the results, the substance was considered to be a skin sensitiser.