6-butyltetrahydro-2H-pyran-2-one

Endpoint summary

Description of key information

A DEREK assessment, DPRA assay and KeratinoSens^TMassay were performed in accordance withSection 8.3 of Annex VII of Regulation (EC) No 1907/2006 as amended in Commission Regulation (EU) 2016/1688 of 20 September 2016 andthe strategy presented in ECHA Guidance on information requirements and chemical safety assessment Chapter R.7a. The studies were performed with substance analogue Delta octalactone, the rationale to read across the data are attached in Section 13.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation, other

Remarks:

In silico assessment

Type of information:

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

Adequacy of study:

weight of evidence

Justification for type of information:

The rationale to read across the data is attached in Section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Run / experiment:

other: Delta Octalactone

Parameter:

other: Prediction on skin sensitization

Remarks on result:

no indication of skin sensitisation

Other effects / acceptance of results:

Delta Octalactone does not contain any unclassified or misclassified features and is consequently predicted to be a non-sensitizer.

Interpretation of results:

study cannot be used for classification

Remarks:

(study is part of a weight of evidence approach and is not used for classification on its own)

Conclusions:

DEREK NEXUS version 6.0.1 did not yield any alerts for skin sensitization for the test item. Additionally, Delta Octalactone does not contain any unclassified or misclassified features and is consequently predicted to be a non-sensitizer. As Delta nonalactone has shared chemical structures, the result applies to Delta nonalactone as well.

Reference 2

Endpoint:

skin sensitisation: in chemico

Type of information:

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

Adequacy of study:

weight of evidence

Justification for type of information:

The rationale to read across the data is attached in Section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Run / experiment:

other: Cysteine Reactivity Assay

Parameter:

other: Mean SPCC depletion(%)

Value:

1.2

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Remarks:

CV between reference controls: 0.8%

Positive controls validity:

valid

Remarks:

Mean percentage SPCC: 74.0% ± 0.2%.

Remarks on result:

other: SD: 0.3%

Key result

Run / experiment:

other: Lysine Reactivity Assay

Parameter:

other: Mean percentage SPCC:

Value:

2.5

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Remarks:

CV between reference controls: 1.3%

Positive controls validity:

valid

Remarks:

Mean percentage SPCL: 53.2% ± 1.8%.

Remarks on result:

other: SD: 0.7%

Other effects / acceptance of results:

All acceptability criteria were met and therefore the DPRA was considered to be valid.
See Table 2 & 3 "any other information on results incl. tables" for acceptibility criteria.

Table 2: Acceptability of the Direct Peptide Reactivity Assay (DPRA)

	Cysteine reactivity assay		Lysine reactivity assay
	Acceptability criteria	Results for SPCC	Acceptability criteria	Results for SPCL
Correlation coefficient (r^2) standard calibration curve	>0.99	0.996	>0.99	0.997
Mean peptide concentration RC-A samples (mM)	0.50 ± 0.05	0.508 ± 0.006	0.50 ± 0.05	0.498 ± 0.007
Mean peptide concentration RC-C samples (mM)	0.50 ± 0.05	0.505 ± 0.005	0.50 ± 0.05	0.498 ± 0.004
CV (%) for RC samples B and C	<15.0	0.8	<15.0	1.3
Mean peptide depletion cinnamic aldehyde (%)	60.8-100	74.0	40.2-69.0	53.2
SD of peptide depletion cinnamic aldehyde (%)	<14.9	0.2	<11.6	1.8
SD of peptide depletion for the test item (%)	<14.9	0.3	<11.6	0.7

RC = Reference Control; CV = Coefficient of Variation; SD = Standard Deviation.

Table 3: SPCC and SPCL Depletion, DPRA Prediction and Reactivity Classification for the Test Item

Test item	SPCC depletion		SPCL depletion		Mean of SPCC and SPCL depletion	DPRA prediction and reactivity classification
	Mean	± SD	Mean	± SD		Cysteine 1:10 / Lysine 1:50 prediction model
Tetrahydro6propyl-2Hpyran-2-one (delta octalactone)	1.2%	±0.3%	2.5%	±0.7%	1.9%	Negative: No or minimal reactivity

SD = Standard Deviation.

Interpretation of results:

other: Study cannot be used for classification independently, but in a WoE for the end point Skin Sensitisation

Conclusions:

Delta octalactone was negative in the DPRA and was classified in the “no or minimal reactivity class” when using the Cysteine 1:10 / Lysine 1:50 prediction model. This result is read across to Delta nonalactone.

Reference 3

Endpoint:

skin sensitisation: in vitro

Type of information:

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

Adequacy of study:

weight of evidence

Justification for type of information:

The rationale to read across the data is attached in Section 13.

Reason / purpose for cross-reference:

read-across source

Positive control results:

The EC1.5 of the positive control was between 26 and 125 μM (59 μM and 46 μM in experiment 1 and 2, respectively). A dose related response was observed and the induction at 250 μM was higher than 2-fold (3.98-fold and 4.59-fold in experiment 1 and 2, respectively).

Key result

Run / experiment:

other: 1

Parameter:

other: Imax

Value:

1.17

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Run / experiment:

other: 2

Parameter:

other: Imax

Value:

1.12

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Other effects / acceptance of results:

- In both experiments, no precipitation was observed at the start and end of the incubation period in the 96-well plates.
- In both experiments, the test item showed no toxicity. The viability of the cells was higher than 70% at all test concentrations and therefore no IC30 and IC50 values could be calculated.
- No luminescence activity induction compared to the vehicle control was observed at any of the test concentrations after treatment with the test item in both experiments. The Imax were 1.17 and 1.12 in experiment 1 and experiment 2, respectively. From these Imax values, no EC1.5 could be calculated.


Both experiments passed the acceptance criteria:
- The luciferase activity induction obtained with the positive control, Ethylene dimethacrylate glycol, was above the threshold of 1.5-fold in at least one concentration.
- The EC1.5 of the positive control was between 5 and 125 μM (26 μM and 46 μM in experiment 1 and 2, respectively). A dose related response was observed and the induction at 250 μM was higher than 2-fold (3.98-fold and 4.59-fold in experiment 1 and 2, respectively).
- Finally, the average coefficient of variation of the luminescence reading for the negative (solvent) control DMSO was below 20% (12% and 10% in experiment 1 and 2, respectively).

Table 1 Overview Luminescence Induction and Cell Viability of the test item in Experiment 1 and 2

Concentration (µM)	0.98	2.0	3.9	7.8	16	31	63	125	250	500	1000	2000
Exp 1 luminescence	1.13	1.00	1.06	1.14	1.17	1.14	1.12	1.15	1.09	0.95	0.90	0.80
Exp 1 viability (%)	98.9	106.6	99.5	96.6	98.2	91.1	93.2	89.3	95.2	101.8	103.7	95.7
Exp 2 luminescence	1.09	0.83	1.00	1.08	1.10	1.12	1.12	1.11	1.02	1.03	1.06	0.88
Exp 2 viability (%)	115.4	122.4	99.8	102.3	100.6	97.8	95.8	95.1	96.7	98.3	97.9	102.5

Table 2 Overview Luminescence Induction and Cell Viability Positive Control EDMG in Experiment 1 and 2

Concentration (µM)	7.8	16	31	63	125	250
Exp 1 luminescence	1.22	1.28	1.60^***	1.86^***	2.67^***	3.98^***
Exp 1 viability (%)	98.7	94.7	107.5	110.8	110.9	106.5
Exp 2 luminescence	1.03	1.13	1.31	1.72^***	2.32^***	4.59^***
Exp 2 viability (%)	105.6	109.2	106.2	107.2	107.1	69.7

^***p<0.001 Student’s t test

Table 3 Overview EC_1.5, I_max, IC₃₀ and IC₅₀ Values

	EC1.5(µM)	Imax	IC30(µM)	IC50(µM)
Test item Experiment 1	NA	1.17	NA	NA
Test item Experiment 2	NA	1.12	NA	NA
Pos Control Experiment 1	26	3.98	NA	NA
Pos Control Experiment 2	46	4.59	NA	NA

NA = Not applicable

Interpretation of results:

study cannot be used for classification

Remarks:

This study is part of a weight of evidence approach on which the classification is based.

Conclusions:

The test item showed no toxicity (no IC30 and IC50 value) and no biologically relevant induction of the luciferase activity (no EC1.5 value) was measured at any of the test concentrations two independent experiments. The maximum luciferase activity induction (Imax) was 1.17-fold and 1.12-fold in experiment 1 and 2 respectively. The test item is classified as negative in the KeratinoSens(TM) assay since negative results (<1.5-fold induction) were observed at test concentrations up to 2000 μM.
Based on the outcome of this KeratinoSens™ assay performed according to OECD guideline and GLP principles, Tetrahydro-6propyl-2H-pyran-2-one (delta octalactone) is classified as negative (no activation of the antioxidant/electrophile responsive element (ARE)-dependent pathway in keratinocytes) under the experimental conditions described in this report. This result is read across to Delta nonalactone.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

For skin sensitization, substance analogue Delta octalactone was tested. The conclusion on this endpoint was drawn following a weight-of-evidence approach:

1.    DEREK NEXUS version 6.0.1 did not yield any alerts for skin sensitization for Delta octalactone. It is of note that the substance does not contain any unclassified or misclassified features and is consequently predicted to be a non-sensitizer.

2.    Delta octalactone was negative in the DPRA and was classified in the “no or minimal reactivity class” when using the Cysteine 1:10 / Lysine 1:50 prediction model.  

3.    Delta octalactone was classified as negative in a KeratinoSens™ assay (no activation of the antioxidant/electrophile responsive element (ARE)-dependent pathway in keratinocytes).

Based on this data-set it is concluded that there are no indications that Delta octalactone has skin sensitizing properties. This result is read across to Delta nonalactone.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

The available data are considered sufficient to conclude that Delta nonalactone does not have to be classified for skin sensitizing properties according to Regulation 1272/2008 and amendments.