3-(heptyloxy)propane-1,2-diol

Endpoint summary

Description of key information

DPRA: Negative

KeratinoSens: Positive

h-CLAT: Negative

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation: in vitro

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

21 November 2019 - 17 December 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

In the interest of sound science and animal welfare, a sequential testing strategy is recommended to minimise the need of in vivo testing. One of the validated in vitro skin sensitization tests is the h-CLAT test, which is recommended in international guidelines (e.g. OECD).

Qualifier:

according to guideline

Guideline:

other: OECD 442E In vitro skin sensitisation: human cell line activation test (h-CLAT)

Version / remarks:

2017

Deviations:

no

GLP compliance:

yes

Type of study:

activation of dendritic cells

Justification for non-LLNA method:

The purpose of this study was to evaluate the ability of Saskine 70 to activate the dendritic cells. Activation of these cells can lead to skin sensitisation.

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature, protected from light

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: Test substance was dissolved in DMSO. Highest concentration: 500 mg/mL (stock solution). Compound concentration in the wroking solution (culture medium) 1000 µg/mL

Details on the study design:

CONTROLS
Vehicle control: DMSO

REFERENCE ITEMS
Dinitrochlorobenzene (DNCB)
Concentration: 4 µg/mL in DMSO
CAS: 97-00-7

Nickel sulfate (NiSO4)
Concentration: 100 µg/mL in PBS
CAS: 10101-97-0

Lactic acid (LA)
Concentration: 1000 µg/mL in 0.9% NaCl
CAS: 50-21-5

TEST SYSTEM
Cell type: THP-1 cells
Source: American type culture collection
Batch: 61077351
Culture conditions: 37 °C, 5% CO2, humidified atmosphere
Culture medium: RPMI-1640, supplemented with 10% Foetal calf serum, 100 units/mL penicillin and 100 µg/ml streptomycin.
Seeding densitiy for testing: 0.2 x E6* (pre-cultured for 72 hours)
*The cell seeding specifications have been modified from the protocol outlined in the guidelines. However, the protocol has been established and validated by Eurosafe as the density is optimal in this condition not exceeding 1 x E6 cells/mL after amplification.

CYTOTOXICITY ASSAYS
Eight concentrations of test item were prepared by a two-fold serial dilution from a maximum final concentration of 1000 µg/mL or lower, depending on its solubility limit.
On the day of testing, cells were harvested and suspended in fresh culture medium at 2 x E6 cells/mL. Then, THP-1 cells were distributed into a 24 well flat-bottom plate with 500 µL (1 x E6 cells/well) with various concentrations of test item for 24 ± 0.5 hours at 37 °C. After incubation, cells were stained with 7-AAD (5 µg/mL) and analysed with flow cytometry to measure cell viability.

Log CV75 = ((75-c) x Log (b) - (75-a) x Log (d))/(a-c)
a = minimum value of cell viability over 75%
c = maximum value of cell viability below 75%
b and d are the concentrations showing the value of cell viability a and c respectively.

ACTIVATION TEST
Each activation test was performed on eight concentrations: 25.1, 30.1, 36.2, 43.4, 52.1, 62.5, 75.0, 90 µg/mL
Top concentration was considered to be be the limit of cytotoxicity based on the cell toxicity assays.
THP-1 cells were plated at 1 X E6 cells/mL/well in 24 well plates and treated for 24 ± 0.5 hours at 37 °C ± under 5 ± 1% CO2. After treatment cells were washed twice with Fb buffer. After washing, blocking the cells with Fb buffer containing 0.01% (w/v) globulin was not performed due to low expression of Fc receptors by THP-1 cells.

Cells were stained for 30 min at 4 °C with the following antibodies: anti-human CD54, anti-human CD86, fluorescein isothiocyanate (FITC) labelled-mouse IgG1 using the manufacturer's recommended dilutions. Then, the cells were stained with 7-AAD for at least 30 min at 4 °C. After washing once and resuspension with Fb, Fluorescence intensities of the THP-1 cell surface markers were analysed by flow cytometry on 10000 living cells.

DATA ANALYSIS AND INTERPRETATION
Relative fluorescence intensity (RFI):
RFI = ((MFI of test item treated cells - MFI of test item treated isotype control cells) / (MFI of vehicle control cells - MFI of vehicle isotype control cells)) x 100
MFI: mean fluorescence intensity

Effective concentration (EF):
EC150 (CD86) = Bconcentration + ((150 - BRFI)/(ARFI-BRFI) x (Aconcentration - Bconcentration))
EC200 (CD54) = Bconcentration + ((200 - BRFI)/(ARFI-BRFI) x (Aconcentration - Bconcentration))

Aconcentration: lowest concentration in µg/mL, with RFI > 150 (CD86) or 200 (CD54)
Bconcentration: highest concentration in µg/mL, with RFI < 150 (CD86) or 200 (CD54)
ARFI: RFI at the lowest concentration with RFI > 150 (CD86) or 200 (CD54)
BRFI: RFI at the highest cncentration with RFI < 150 (CD86) or 200 (CD54)

ACCEPTACE CRITERIA
- In the positive control (DNCB) (performed in all activation experiments) and (NiS04) (performed only in an activation experiment): RFI values of both CD86 and CD54 must be over the positive criteria (CD54 ≥ 200% and CD86 ≥ 150%). The cell viability must be more than 50%.
- In the negative control (LA) {performed only in an activation experiment): RFI values of both CD86 and CD54 must be under the positive criteria (CD54 < 200% and CD86 < 150%). The cell viability must be more than 50%.
- In the vehicle control(medium, 0.9% NaCI, DMSO, Ethanoletc.): Cell viability must be more than 90%. In the solvent/vehicle control, RFI values of both CD86 and CD54 must not exceed the positive criteria (CD86 ≥ 150% and CD54 ≥ 200%) compared to the medium control. The MFI ratio of both CD86 and CD54 to isotype control must be > 105%.
- In the test item: Cell viability must be more than 50% in at least four tested concentrations in each run.

EVALUATION CRITERIA
The positive criteria are described as following:
RFI of CD54 ≥ 200% and/or RFI of CD86 ≥ 150% of their respective control, at any tested concentration.

Positive control results:

Experiment 2 (cell viability ≥ 70%):
- CD54: RFI (%) = 1913
- CD86: RFI (%) = 383
Experiment 3 (cell viability ≥ 70%):
- CD54: RFI (%) = 790
- CD86: RFI (%)= 460

Key result

Run / experiment:

other: 1

Parameter:

other: RFI (%)

Remarks:

CD86

Value:

96

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of skin sensitisation

Remarks:

Top dose: 90.0 µg/mL; RFI: 96 %

Key result

Run / experiment:

other: 2

Parameter:

other: RFI (%)

Remarks:

CD86

Value:

90

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of skin sensitisation

Remarks:

Top dose: 90.0 µg/mL; RFI: 140%

Key result

Run / experiment:

other: 1

Parameter:

other: RFI (%)

Remarks:

CD54

Value:

141

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of skin sensitisation

Remarks:

Top dose: 90.0 µg/mL; RFI: 162%

Key result

Run / experiment:

other: 2

Parameter:

other: RFI (%)

Remarks:

CD54

Value:

120

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of skin sensitisation

Remarks:

Top dose: 90.0 µg/mL; RFI: 180%

Other effects / acceptance of results:

- Cytotoxicity was induced on THP-1 cells by Saskine 70. According to this cytotoxic profile CV75: 74.1 μg/mL
- One deviation was observed in experiment 1 with a RFI value of CD86 > 150% for the DMSO control.

ACCEPTANCE CRITERIA
- In the positive control (DNCB) RFI values were above the criteria in experiment 2 and 3 (CD54: 1913 and 383; CD86: 383 and 460).
- In the negative control (LA) (performed only in an activation experiment): RFI values of both CD86 and CD54 were under the positive criteria (CD54: 136 and CD86: 59). The cell viability was 98%.
- In the vehicle control (DMSO): Cell viability was ≥ 97%. In the solvent/vehicle control, RFI values of CD86 was 124 and 100 in experiment 2 and 3 and the RFI values of CD54 were 123 and 123 in experiment 2 and 3 (CD86 ≥ 150% and CD54 ≥ 200%) compared to the medium control. The MFI ratio of both CD86 and CD54 to isotype control must be > 105% (198 and 127, respectively).
- In the test item: Cell viability was more than 50% in at least four tested concentrations in each run.

Interpretation of results:

other: Study can be part of a weight of evidence

Conclusions:

In a h-CLAT test performed according to OECD TG 442E and in accordance with GLP principles, Saskine 70 did not activate dendritic cells and therefore tested negative for skin sensitizing properties under experimental conditions described in this report.

Executive summary:

A h-CLAT test was performed with Saskine 70 according to OECD guideline 442E and in accordance with GLP principles. The study consisted of two seperate experiments. Based on the solvent, negative and positive controls it was concluded that the test conditions were adequate and that the test system functioned properly. Cell viability (CV) was determined to be 75% at a concentration of 74.1 μg/mL. In both experiments, all concentrations tested did not induce a 1.5 or 2-fold increase of CD86 and CD54, respectively. Based on the results, Saskine 70 is not considered to have skin sensitizing properties under the current experimental conditions.

Reference 2

Endpoint:

skin sensitisation: in chemico

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

21 October 2019 - 25 November 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

In the interest of sound science and animal welfare, a sequential testing strategy is recommended to minimise the need of in vivo testing. One of the validated in vitro skin sensitization tests is the DPRA, which is recommended in international guidelines (e.g. OECD).

Qualifier:

according to guideline

Guideline:

OECD Guideline 442C (In Chemico Skin Sensitisation: Direct Peptide Reactivity Assay (DPRA))

Version / remarks:

Version not stated in the study report

Deviations:

no

Principles of method if other than guideline:

Protocol No154 from ECVAM DB ALM

GLP compliance:

yes

Type of study:

direct peptide reactivity assay (DPRA)

Justification for non-LLNA method:

A validated in chemico skin sensitization test is the DPRA assay, which is recommended in international guidelines (e.g. OECD) and mentioned in the ECHA guidance as one of the non-animal tests to be performed as part of weight of evidence.

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature (20°C ± 5°C)
- Solubility of the test substance in the solvent: Assessed before performing the assay. The chose solvent was acetonitrile.

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: Test item was diluted at 100 mM in acetonitrile

Details on the study design:

TEST SYSTEM
Cysteine peptide
- Source: RS Synthesis, LLC
- Reference: Ac RFAACAA-COOH
- Batch number: 180622
- Purity: 94.35%

Lysine peptide
- Source: RS Synthesis, LLC
- Reference: Ac-RFAAKAA-COOH
- Batch number: 180622
- Purity: 93.68%

Incubation
Test item and positive control were incubated in excess with the peptides at 1:10 and 1:50 ratio for cystein and lysine peptides, respectively.
Vials were mixed carefully and then placed in the HPLC system sampler at room temperature (19°C to 27.5°C). HPLC analysis started 24 hours ± 2 hours after addition of the peptides. The samples were checked for homogeneity immediately after addition of the test item solution to the peptide solution, prior to the beginning of the HPLC analysis and at the end of the analysis.

Analysis
The HPLC column was installed and equilibrated at 30 °C with 50% of phase A and 50% of phase B, for at least 20 minutes before use.
After the equilibration phase, 7 µL of each sample are automatically injected and the HPLC analysis was performed with a flow of 0.40 mL per minute according to the sequence described in table 1.
A complete sequence was performed for each sample. The column was re-equilibrated to initial conditions (90% Phase A and 10% of phase B) at least 4 minutes between each injection.
Lysine and cysteine analyses were conducted on seperate days and the test item was freshly prepared for both assays on each day.

POSITIVE CONTROL
Cinnamaldehyde
- Purity: 99.1%
- Batch number: MKBT8955V
- Expiry date: 28/02/2020
- Storage conditions: Room temperature
- Solvent: Acetonitrile

DATA EVALUATION
The depletion rate was calculated for each type of peptide according to the following formula:
Depletion % = (1-(Peptide peak area with the replicate injection/Mean peptide peak area in reference control)x100)
Then, the mean depletion percentage for cysteine and lysine peptides was calculated for the test item and the positive control.

DATA INTERPRETATION
The 6.38% treshold is used in order to differentiatie between non-sensitizers and sensitizers.

Key result

Run / experiment:

other: Lysine Reactivity assay

Parameter:

other: Mean depletion in Lysine Peptide (%)

Value:

2.02

Negative controls validity:

valid

Remarks:

Reference control CV: 0.48%

Positive controls validity:

valid

Remarks:

Mean: 58.64%

Remarks on result:

other: SD = 2.02

Key result

Run / experiment:

other: Cystein Reactivity assay

Parameter:

other: Mean depletion in Cysteine Peptide (%)

Value:

2.34

Negative controls validity:

valid

Remarks:

Reference control CV: 0.47%

Positive controls validity:

valid

Remarks:

Mean: 73.77%

Remarks on result:

other: SD = 1.35

Other effects / acceptance of results:

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: The CV of the 9 controls B and C must be less than 15%.
- Acceptance criteria met for positive control: Lysine: 40.2 < Depletion < 69.4; Cysteine: 60.8 < Depletion < 100
- Acceptance criteria met for variability between replicate measurements: SD Lysine: < 11.6%; SD Cysteine: < 14.9%

Interpretation of results:

other: Study is used as part of Weight of Evidence

Conclusions:

Saskine (TM) 70 shows a mean depletion of 2.02% for Lysine and 2.34% for Cysteine, resulting in an overall average of 2.18%. Based on these results, it can be concluded that the test substance 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.

Executive summary:

An in chemico study was performed according to OECD guideline 442C and in accordance with GLP principles the reactivity of Saskine (TM) 70 towards model synthetic peptides containing either cysteine or lysine was determined to assign the test chemical to one of four reactivity classes used to support the discrimination between skin sensitisers and non skin sensitisers. Following incubation of the test substance with either cysteine or lysine, the relative peptide concentration was determined by High-Performance Liquid Chromatography (HPLC). Acetonitril was found to be an appropriate solvent to dissolve the test substance, and was therefore used in this DPRA study. Cinnamicaldehyde was used as a positive control. All acceptibility criteria were met and therefore, the study was considered to be valid. In the cysteine reactivity assay the test item showed 2.34% depeletion and in the lysine reactivity assay the test item showed 2.02% depletion. The mean depletion was 2.18% and as a result the test item was considered to be negative in the DPRA and classified in the "no or minimal reactivity class" when using the Cysteine 1:10 / Lysine 1:50 prediction model.

Reference 3

Endpoint:

skin sensitisation: in vitro

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

26 March 2018 - 30 April 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

In the interest of sound science and animal welfare, a sequential testing strategy is recommended to minimise the need of in vivo testing. One of the validated in vitro skin sensitization tests is the KeratinoSensTM assay, which is recommended in international guidelines (e.g. OECD).

Qualifier:

according to guideline

Guideline:

OECD Guideline 442D (In Vitro Skin Sensitisation: ARE-Nrf2 Luciferase Test Method)

Version / remarks:

February 2015

Deviations:

no

GLP compliance:

yes

Type of study:

activation of keratinocytes

Justification for non-LLNA method:

The purpose of this study was to evaluate the ability of Saskine 70 to activate the antioxidant/electrophile responsive element (ARE)-dependent pathway. Activation of this pathway can lead to skin sensitisation.

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature (20°C ± 5°C)
- Stability of the test substance in the solvent: Not specified

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: The test item was diluted in DMSO. The stock solution was prepared at 200 mM. The test item was tested at 12 concentrations according to a geometric progression of ratio 2 from 0.98 µM to 2000 µM.

Details on the study design:

Media:
- Maintenance medium: DMEM 1g/L glucose, 9.1% non-heat inactivated foetal calf serum, 0.05% geneticin - stored at 5 °C ± 3 °C
- Seeding medium: DMEM 1 g/L glucose, 9.1% non-heat inactivated foetal calf serum - stored at 5 °C ± 3 °C
- Treatment medium: DMEM 1 g/L glucose, 1% non-heat inactivated foetal calf serum - stored at 5 °C ± 3 °C

CONTROLS
Positve control: Cinnamaldehyde
- Purity: 99.1 %
- Solvent: DMSO
- Final concentrations: 5 concentrations varying between 4 - 64 µM; two repetitions

Negative control: treatment culture medium containing 1% DMSO, 1% Non-heat inactivated foetal calf serum.
- Negative control was prepared just prior to the test and used within the day.
- Two repetitions

TEST SYSTEM
Cells: KeratinoSens maintained according to the current working instruction IL 09. Cells were cultured in maintenance medium at 37 °C, 5% C02 and checked for mycoplasma.
Cells were used at passage 18 in repetition 1 and passage 20 in repetition 2.

Cells suspension were adjusted to a density of 8.10 E4 cells/ml in seeding medium.
125 µL of the cell suspension at 8.10 E4 cells/ml (i.e. 10 E4 cells per well) were distributed in three white plates for the induction measurement and two transparent plates to assess the cytotoxicity. The seeded plates were incubated 24 hours ± 1 hour at 37°C, S% CO2.
The H12 wells were left without cells and allowed the measurement of blanks.

Treatment of the cells:
The test item was diluted in DMSO at 200 mM and a 100-fold dilution series was prepared in a 96-well plate. The 100x DMSO plate was diluted 25 fold in a new plate (4x) in treatment medium.
In the 5 seeded plates, the medium was aspirated and replaced with 150 µL of treatment medium. Then the plate was replicated 5 times: 50 µL from the 4x plate were placed in three white plates and in two transparent plates. The treatment plates were covered with an adhesive plastic foil to prevent evaporation and incubated for 48 hours ± 1 hour (37°C, 5% C02).

Luciferase activity measurement:
After 48 hours, the medium was aspirated and each well was gently washed once with 200 µL of PBS. Then, 100 µL of luciferase substrate (luciferin + ATP + lysing agent) were then added in each well. The plates were incubated at least 15 minutes at room temperature to ensure cells lysis.
The plates were placed in the luminometer then the luciferase activity was measured with an integration time of 2 seconds.

Cell viability assessment with MTT method
After 48 hours, the medium was aspirated and each well was gently washed once with 200 µL of PBS. Then, 225 µL of staining solution diluted at 0.6 mg/ml in treatment medium (from the 5 mg/ml stock solution) were distributed in each well. The plates were covered with an adhesive plastic foil and incubated for 4 hours ± 30 minutes (37°C, 5% C02).
After this contact time, the staining solution was eliminated and the cells were treated with 200 µL of 10% SDS one night in the dark (37°C, 5% C02). After a 10 minutes homogenization, the absorbances were measured at 540 nm.

Positive control results:

The EC1.5 of the positive control was between 2 and 20 μM (9.76 μM and 18.89 μM in repetition 1 and 2, respectively). The induction for cinnamaldehyde at 64 μM is between 2 and 8 (4.26 and 3.45 in repetition 1 and 2, respectively).

Key result

Run / experiment:

other: Repetition 1

Parameter:

Imax [442D]

Value:

165 %

Negative controls validity:

valid

Positive controls validity:

valid

Key result

Run / experiment:

other: Repetition 2

Parameter:

Imax [442D]

Value:

158 %

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

Imax is greater than 1.5, the EC1.5 is less than 1000 μM and viability at the EC1.5 concentration is greater than 70%.

The test substance showed toxicity with an IC70 of 174.65 μM in the first repetition and and IC70 of 227.35 μM in the second repetition. The EC1.5 was 29.19 μM in the first repetition and 94.05 μM in the second repetition.

Both experiments passed the aceptance criteria:
- The luciferase activity induction obtained with the positive control was above the treshold of 1.5-fold in at least one concentration.
- The EC1.5 of the positive control was between 2 and 20 µM (9.76 μM and 18.89 μM in repetition 1 and 2, respectively). A dose response was observed and the induction at 64 µM was between 2 and 8 (4.26 and 3.45 in repetition 1 and 2, respectively).
- Finally, the average coefficient of variation of the luminescence reading for the negative (solvent) control DMSO was below 20% (11.0% and 16.7% in repetition 1 and 2, respectively).

Tabel 1 Positive control

Cinnamaldehyde	4 µM	8 µM	16µM	32 µM	64 µM	EC1.5	Imax
Rep1   Rep2	1.18   1.12	1.43   1.32	1.76   1.44	2.91   1.75	4.26   3.45	9.76   18.89	4.26   3.45
Mean	1.15	1.37	1.60	2.33	3.85	13.58*	3.85

*geometric mean

Tabel 2 control solvent

Control solvent                CV%

controlsolvent

 

Rep1                          11.0

 

Rep2                          16.7

Tabel 3 Test item

	VIABILITY	INDUCTION
	IC70µM	Imax	LinearEC1.5 µM	EC1.5 Lin/Log µM
Rep1   Rep2	174.65   227.35	1.65   1.58	29.19   94.05	28.53   88.68
Mean	-	1.61	-	-
Geometricmean	199.27	-	52.40	50.30

Interpretation of results:

other: Study is used as part of Weight of Evidence

Conclusions:

Based on the outcome of a KeratinoSensTM assay performed according to OECD TG 442D and in accordance with GLP principles, Saskine 70 is tested positive for skin sensitizing properties under the current experimental conditions.

Executive summary:

A KeratinoSens^TM assay was performed with Saskine 70 according to OECD guideline 442D and in accordance with GLP principles. The study consisted of two seperate repetitions. Based on the negative and positive controls it was concluded that the test conditions were adequate and that the test system functioned properly. Saskine 70 showed toxicity with an IC70 of 174.65 μM in the first repetition and an IC70 of 227.35 μM in the second repetition. The induction of luciferase activity (EC1.5) was 29.19 μM in the first repetition and 94.05 μM in the second repetition. The maximum luciferase activity induction (Imax) was 1.65 -fold and 1.58 -fold in repetition 1 and 2, respectively. It is concluded that the KeratinoSens TM assay is valid and that Saskine 70 is considered to have skin sensitizing properties under the current experimental conditions.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The DPRA showed that Saskine™ 70 does not interact with cysteine or lysine moieties and therefore key event 1 of the skin sensitization AOP, a reaction with endogenous skin proteins, is not expected to take place. The KeratinoSensTMassay was positive as a dose-dependent increase in luciferase activity was observed however the applicability of the assay to assess the skin sensitizing properties of this substance is doubted. In the KeratinoSens^TM assay luciferase induction is mediated by the Keap1 (Kelch-like ECH-associated protein 1)-Nrf2 (nuclear factor-erythroid 2-related factor 2)-ARE (antioxidant response element) pathway. Yokota et al. showed that an alkyl glyceryl ether, chimyl alcohol (CAS: 6145-69-3), can act as an agonist for PPAR-γ¹. Both Nrf2 and PPARγ have been shown to play key roles in establishing the cellular antioxidative defence system and direct regulation of the Nrf2 pathway by PPARγ has been described^2,3. It may be possible that this chemical class of alkyl glyceryl ethers may induce Nrf2 via PPAR-γ and thus inadvertently induce luciferase production. Considering Saskine™ 70 is an alkyl glyceryl ether the positive result obtained may well be a false positive result and thus no conclusion on key event 2 can be drawn with sufficient confidence. The h-CLAT performed with Saskine™ 70 showed no increase in CD54 and CD86 in dendritic cells at non-cytotoxic levels and therefore the outcome was concluded to be negative. As a result, the third key event, activation of dendritic cells, is considered negative. Since key event 2 is not assessable but key event 1 and 3 of the skin sensitization AOP tested negative sufficient evidence is presented to conclude thatSaskine™ 70 is unlikely to be a skin sensitizer and is thus not expected to initiate an allergic response following skin contact. This conclusion is supported by a review prepared by Cosmetic Ingredient Review Expert Panel in which the available skin sensitization data for alkyl glyceryl ethers was evaluated. No skin sensitization incidents were reported, and alkyl glyceryl ethers were regarded as safe for use as cosmetic ingredient⁴.

Based on these considerations, it is concluded that Saskine™ 70 does not need to be classified for skin sensitization according to Regulation (EC) No 1272/2008 and related amendments.

 

 

1.       Yokota, M., Yahagi, S., Tokudome, Y., & Masaki, H. (2018).Chimyl alcohol suppresses PGE2 synthesis by human epidermal keratinocytes through the activation of PPAR-γ. Journal of Oleo Science, 67(4), 455–462.https://doi.org/10.5650/jos.ess17157

2.       Lee, C. (2017). Collaborative Power of Nrf2 and PPAR γ Activators against Metabolic and Drug-Induced Oxidative Injury. Oxidative Medicine and Cellular Longevity, 2017.https://doi.org/10.1155/2017/1378175

3.       Polvani, S., Tarocchi, M., & Galli, A. (2012).PPAR and oxidative stress: Con(β) catenating NRF2 and FOXO. PPAR Research, 2012.https://doi.org/10.1155/2012/641087

4.        Cosmetic Ingredient Review. (2011). Final Safety Assessment On the Safety Assessment of Alkyl Glyceryl Ethers As Used in Cosmetics.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the results of the available studies, the substance does not need to be classified for skin sensitizationaccording to Regulation (EC) No 1272/2008 on classification, labelling and packaging of items and mixtures (including all amendments).