(carboxylatomethyl)hexadecyldimethylammonium

Endpoint summary

Description of key information

Both in-vitro methods used suggested that this substance should be classified as a skin sensitiser.

Cetyl betaine is essentially the same molecule as lauryl betaine but with an extra C4 in the alkyl chain so it is likely that the toxicology of the two species will be very similar. Hence, it is assessed that the skin sensitisation response for cetyl would be similar to lauryl.

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:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Type of study:

activation of keratinocytes

Justification for non-LLNA method:

Skin sensitisers have been reported to induce genes that are regulated by the antioxidant response element (ARE). The KeratinoSensTM test is a method for which validation studies have been completed followed by an independent peer review conducted by the European Union Reference Laboratory for Alternatives to Animal Testing (EURL ECVAM). The KeratinoSensTM test method was considered scientifically valid to be used as part of an IATA (Integrated Approach to Testing and Assessment), to support the discrimination between skin sensitisers and non-sensitisers for the purpose of hazard classification and labelling. The method cannot be used on its own, neither to sub-categorise skin sensitisers into subcategories 1A and 1B as defined by the UN GHS, for authorities implementing these two optional subcategories, nor to predict potency for safety assessment decisions. However, depending on the regulatory framework a positive result may be used on its own to classify a chemical into UN GHS category 1.

Specific details on test material used for the study:

Test Item Name
ColaTeric LAB-70UP; (1-Dodecanaminium, N-(carboxymethyl)-N,N-dimethyl-, inner salt)
Supplier Code:Not provided
Supplier batch/lot number: 55880C17
CAS number: 683-10-3
Purity: 33.7%
Active Expiry Date: 10 Mar 2019 (from Cofa)
Physical sate: Liquid, clear
Storage Conditions: Standard (10-49˚C, closed container)
Solvent: 1% DMSO in cell culture medium Administration method
In cell culture medium
Concentrations tested (μg/ml)
200, 100, 50, 25, 12.5, 6.25, 3.13, 1.56, 0.78, 0.39, 0.20, 0.10

Key result

Parameter:

other: EC1.5 value

Remarks:

Luciferase measurements and MTT viability testing were performed. The sensitisation potential of ColaTeric LAB-70UP; was quantified by calculating 2 parameters known as the EC1.5 and the IMAX value.

Value:

9.09

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

positive indication of skin sensitisation

The human skin sensitisation potential of ColaTeric LAB-70UP; (Lauryl betaine (C12)) was assessed using validated in vitro method: the KeratinoSensTM test to determine keratinocyte activation. The method was adapted to animal product-free conditions by XCELLR8 and reference chemicals described in the guideline and in the performance standards were used to confirm the reliability, accuracy, sensitivity and specificity values. The adapted method showed full concordance with the Validated Reference Method (VRM) – the KeratinoSensTM standard protocol. Clarification from the European Chemicals Agency (ECHA) says that data using the adapted method may be used in REACH submissions, provided that the Performance Standards data, demonstrating equivalence with the VRM, is included in the dossier.

In this study, ColaTeric LAB-70UP; (Lauryl betaine (C12) was classified as a sensitiser to human skin.

The sensitisation potential of was quantified by calculating 2 parameters known as the EC1.5 and the IMAX value.

Lauryl betaine caused luciferase induction >1.5 in all 3 repetitions. The respective EC1.5 value were calculated as 31.72μg/ml for repetition 1; 61.87 μg/ml for repetition 2 and 9.09μg/ml for repetition 3. Therefore, ColaTeric LAB-70UP; (Lauryl betaine (C12)) was classified as a sensitiser.

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Conclusions:

Cetyl betaine is essentially the same molecule as lauryl betaine but with an extra C4 in the alkyl chain so it is likely that the toxicology of the two species will be very similar. Hence, it is assessed that the skin sensitisation response for cetyl would be similar to lauryl.

Reference 2

Endpoint:

skin sensitisation: in vitro

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

other: OECD Test Guideline 442E: human Cell Line Activation Test (h-CLAT)

Version / remarks:

adopted 29 Jul 2016. The study was performed using the h-CLAT method as detailed in OECD TG 442E and also in EURL ECVAM DB-ALM Protocol No. 158 (Issued 01 Jul 2015). Methodology is detailed in an XCellR8 SOP (L0094) that covers the h-CLAT. Study data is collected using XCellR8 internal protocols (IPs).

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

other: In Vitro human Cell Line Activation Test (h-CLAT) method according to OECD Test Guideline 442E.

Specific details on test material used for the study:

Supplier Colonial Chemical
Test Item Name ColaTeric LAB-70UP; (1-Dodecanaminium, N-(carboxymethyl)-N,N-dimethyl-, inner salt)
Supplier Code Not provided
Supplier Batch/Lot Number 55880C17
CAS Number 683-10-3
Purity 30-32%
Expiry Date 10 Mar 2019 (from CofA)
Physical State Liquid, Clear
Storage Conditions Standard (10-49˚C, closed container)
Solubility Water

Positive control results:

The CV75 (2,4-dinitrochlorobenzene (DNCB)) dose informs the dosing range selected for the CD54/86 (Nickel Sulphate) expression assay. However, in this case the highest possible dose was used which was equal to 5mg/ml (5000µg/ml). Note that Runs 4 and 5 used the same top dose however the dilution factor was adjusted (1 in 1.2 changed to 1 in 1.5) to give a greater dilution range with lower concentrations (below 1mg/ml at dilutions 5-8). This was due to low overall cell numbers observed when using high concentrations of the test item.

Key result

Parameter:

other: EC200

Value:

452

Vehicle controls validity:

valid

Positive controls validity:

valid

Remarks on result:

positive indication of skin sensitisation

Key result

Parameter:

other: EC150

Value:

469

Vehicle controls validity:

valid

Positive controls validity:

valid

Remarks on result:

positive indication of skin sensitisation

As Runs 2 and 3 were invalid, a repeat run was carried out (Run 4). As Run 4 was not concordant with the result from Run 1, a final run (Run 5) was required to determine the test item classification. Runs 4 and 5 were both valid and concordant. As can be seen from the data, the expression of CD54 as measured by the RFI crossed the threshold (RFI ≥200) at 6/8 concentrations used in Run 4 and 7/8 in Run 5 (yellow highlighted cells). The expression of CD86 as measured by the RFI, crossed the threshold (RFI ≥150) at 6/8 concentrations used in Run 4 and 8/8 in Run 5 (green highlighted cells). As the CD54/CD86 expression crossed the threshold for both CD54 and CD86 at non-cytotoxic concentrations, the test item is classified as a Sensitiser. Cell viability did not fall below 50% at any of the test item concentrations and therefore the result is deemed to be valid.  

For ColaTeric LAB-70UP; (1-Dodecanaminium, N-(carboxymethyl)-N,N-dimethyl-, inner salt) the dose that gave 75% cell viability could not be determined and therefore the maximal dose was used (5 mg/ml). The EC200 and EC150 values for CD54 and CD86 expression were 452 and 469 respectively, therefore,ColaTeric LAB-70UP; (1-Dodecanaminium, N-(carboxymethyl)-N,N-dimethyl-, inner salt)was classified as aSensitiseras per the prediction model

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Conclusions:

Cetyl betaine is essentially the same molecule as lauryl betaine but with an extra C4 in the alkyl chain so it is likely that the toxicology of the two species will be very similar. Hence, it is assessed that the skin sensitisation response for cetyl would be similar to lauryl.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

Cetyl betaine (C16) and Lauryl betaine (C12) are very closely related chemical structures. The parent compound, betaine, is a naturally occurringN-trimethylated amino acid.

The individual betaines differ only in chain length. They are generally UVCB substances being manufactured from naturally occurring plant and animal sources.

 The Cosmetic Ingredient Review Expert Panel reviewed the product use, formulation and safety data of eleven alkyl betaines, as used in cosmetics. (Final report issued 2014-04-04)

The Panel concluded that the common core chemical structure, similar functions and concentrations in cosmetics, and the predicted physicochemical properties enabled grouping these ingredients and reading across the available toxicological data to support the safety assessment of each individual compound in the entire group.

Therefore it is assessed that it is acceptable to apply the results of this test to cetyl betaine

Justification for classification or non-classification

Cetyl betaine (C16) and Lauryl betaine (C12) are very closely related chemical structures. The parent compound, betaine, is a naturally occurringN-trimethylated amino acid.

The individual betaines differ only in chain length. They are generally UVCB substances being manufactured from naturally occurring plant and animal sources.

 The Cosmetic Ingredient Review Expert Panel reviewed the product use, formulation and safety data of eleven alkyl betaines, as used in cosmetics. (Final report issued 2014-04-04)

The Panel concluded that the common core chemical structure, similar functions and concentrations in cosmetics, and the predicted physicochemical properties enabled grouping these ingredients and reading across the available toxicological data to support the safety assessment of each individual compound in the entire group.

So based on read-across to this study report for lauryl betaine, it is assessed that cetyl betaine will have a similar response in this test