2,4,7,9-Tetramethyldec-5-yne-4,7-diol, ethoxylated

Endpoint summary

Description of key information

sensitising (Cat 1B); OECD TG 429: S.I. of 1.67, 2.76, and 3.69 at 10, 25, and 50%, EC3 = 31.45%

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that source and target substances have similar toxicological properties because
- they are manufactured from similar precursors under similar conditions
- they share structural similarities with common functional groups: the substances start with an acetylene group as core structure; geminal hydroxyl groups on the alpha carbon atoms; distal to the geminal hydroxyl groups is an isobutyl group (methyl isopropyl); the target substance 2,4,7,9-Tetramethyl-5-decyne-4,7-diol, ethoxylated (1.3) is further functionalised with ethylene oxide and has an ethoxylation degree of 1.3; the source substance 2,4,7,9-Tetramethyl-5-decyne-4,7-diol, ethoxylated (3.8) has an ethoxylation degree of 3.8
- they have similar physicochemical properties and thus, show a similar toxicokinetic behaviour
- they are expected to undergo similar metabolism: oxidation of the terminal methyl groups to result in alcohol, aldehyde and finally the corresponding acid

Therefore, read-across from the existing toxicity, ecotoxicity, environmental fate and physicochemical studies on the source substances is considered as an appropriate adaptation to the standard information requirements of REACH regulation.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
see “Justification for read-across” attached to IUCLID section 13

3. ANALOGUE APPROACH JUSTIFICATION
see “Justification for read-across” attached to IUCLID section 13

4. DATA MATRIX
see “Justification for read-across” attached to IUCLID section 13

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

CBA

Sex:

female

Vehicle:

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

Concentration:

50%
25%
10%

No. of animals per dose:

5 mice

Positive control substance(s):

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

Positive control results:

alpha-Hexylcinnamaldehyde, 85% was considered to be a sensitiser under the conditions of the test.

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: Vehicle: 1817.54 (+/- 657.13) dpm/Animal 10%: 3037.60 (+/-1145.05) dpm/Animal 25%: 5009.25 (+/-639.45) dpm/Animal 50%: 6698.23 (+/-2082.90) dpm/Animal

Key result

Parameter:

SI

Value:

1.67

Test group / Remarks:

10 %

Key result

Parameter:

SI

Value:

2.76

Test group / Remarks:

25 %

Key result

Parameter:

SI

Value:

3.69

Test group / Remarks:

50 %

Parameter:

EC3

Value:

31.45

Interpretation of results:

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

Conclusions:

The test item was considered to be a sensitiser under the conditions of the test (EC3 = 31.45%).

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

Experimental data on the sensitisation potential of 2,4,7,9-Tetramethyl-5-decyne-4,7-diol, ethoxylated (1.3) are not available. However, a LLNA was conducted with the structurally related source substance 2,4,7,9-Tetramethyl-5-decyne-4,7-diol. Since 2,4,7,9-Tetramethyl-5-decyne-4,7-diol is a major component of the target substance 2,4,7,9-Tetramethyl-5-decyne-4,7-diol, ethoxylated (1.3), the results obtained with the source substance are applicable also to the target substance. A justification for read-across is attached to iuclid section 13.

 

In a local lymph node assay according to OECD guideline 429 2,4,7,9-Tetramethyl-5-decyne-4,7-diol in acetone/olive oil (4:1 v/v) was assessed for its possible contact allergenic potential using test item concentrations of 10, 25, 50%.

In this study, Stimulation Indices (S.I.) of 1.67, 2.76, and 3.69 were determined with the test item at concentrations of 10, 25, and 50%, respectively. These results indicate that the test substance could elicit an SI ≥ 3 is therefore regarded as skin sensitiser under the conditions of this study. The data showed a dose-response and an EC3 value of 31.45% was calculated.

Based on these results 2,4,7,9-Tetramethyl-5-decyne-4,7-diol is classified as Category 1B based on CLP, EU GHS (Regulation (EC) No 1272/2008).

 

Based on structural similarity, this outcome is also applied to the target substance 2,4,7,9-Tetramethyl-5-decyne-4,7-diol, ethoxylated (1.3), which is also considered to be sensitising.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

There is no information available for respiratory sensitisation. Therefore, there is a data gap in this respect. However, the data gap cannot be fulfilled with experimental data, since there is no internationally accepted animal model for respiratory sensitisation. In case human data for respiratory sensitisation emerges, this will be taken into account.

Justification for classification or non-classification

Based on reliable, adequate and relevant data, 2,4,7,9-Tetramethyl-5-decyne-4,7-diol, ethoxylated (1.3) is classified as skin sensitiser Category 1B according to regulation (EC) 1272/2008 and labelled with H317: May cause an allergic skin reaction and the signal word “Warning”.