Sodium 2-sulphonatoethyl laurate

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Not conducted under GLP. The method used is equivalent to OECD 406, but with reduced animal numbers (10 test, 8 control). Test item is identified as Fenopon AC78; which is Sodium Cocoyl Isethionate. Read-across is based upon a commonality of functional groups, constituents, breakdown products and metabolic pathways. A detailed justification is appended in Section 13.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

yes

Remarks:

Reduced animal numbers (10 test, 8 control)

Principles of method if other than guideline:

The method is intended to follow closely that described by Magnusson and Kligman (1,2).
1. Magnusson, B. and Kligman, A.M. 1969. The Identification of Contact Allergens by "Animal Assay. The Guinea Pig Maximisation Test.
2. Magnusson, B. and Kligman, A.M. 1970. Allergic Contact Dermatitis in the Guinea Pig. Identification of Contact Allergens. Thomas, Springfield, Illinois.

GLP compliance:

no

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

An LLNA study was not performed because there is an existing reliable study for skin sensitisation using the Guinea Pig Maximisation test method.

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: SEAC
- Age at study initiation: no details
- Weight at study initiation: ~320g
- Housing: no details
- Diet (e.g. ad libitum): R12 pellets, hay, cabbage, ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: no details


ENVIRONMENTAL CONDITIONS
No details


IN-LIFE DATES: From: 1978-08-28 To: 1978-11-14

Route:

intradermal and epicutaneous

Vehicle:

other: Physiological saline (for intradermal induction) and 80% distilled water and 20% PEG (for epicutaneous induction & challenge).

Concentration / amount:

A - Intradermal induction - 0.15% test substance (with physiological saline as solvent) suitably non-irritant concentration for injection.
B - Epicutaneous induction - 2.0 % test substance (with 80% distilled water and 20% PEG 400 as solvent) suitably irritant concentration.
C - Epicutaneous challenge - 5.0% test substance (with 80% distilled water and 20% PEG 400 as solvent) suitably non-irritant concentration.

Route:

epicutaneous, semiocclusive

Vehicle:

other: Physiological saline (for intradermal induction) and 80% distilled water and 20% PEG (for epicutaneous induction & challenge).

Concentration / amount:

A - Intradermal induction - 0.15% test substance (with physiological saline as solvent) suitably non-irritant concentration for injection.
B - Epicutaneous induction - 2.0 % test substance (with 80% distilled water and 20% PEG 400 as solvent) suitably irritant concentration.
C - Epicutaneous challenge - 5.0% test substance (with 80% distilled water and 20% PEG 400 as solvent) suitably non-irritant concentration.

No. of animals per dose:

10 Test animals (six females and 4 males)
4 Treated control animals (females) in Challenge 1 (only).
4 Untreated control animals (males) in all challenges.

Details on study design:

RANGE FINDING TESTS:
Intradermal injection: 4 previously untreated guinea pigs (males) weighing approximately 320g were each injected intradermally on the clipped flanks with 0.1 ml aliquots of a range of concentrations of test substance in a suitable solvent. 24 hours later the reactions are examined for size (2 largest diameters) erythema and oedema. The concentration which produces a definite irritation reaction (10 x 10 mm, pale pink, with or without oedema) is selected as the intradermal injection induction concentration.

Topical application (for neck induction and flank challenge): 8mm diameter filter paper (Whatman 3MM patches), in 11mm "Fintest" aluminium patch test cups (Epitest Ltd), are saturated with a range of concentrations of test substance in a suitable solvent and the cups applied to the shaved flanks of 4 previously untreated guinea pigs of the same sex and weighing approximately 450g. The patches are held in place by adhesive plaster (Poroplast) wound around the trunk. 24 hours later the patches are removed, the reaction sites being examined 24 and 48 hours subsequently. The reactions are scored for irritation on a scale from 0 to +++. The concentration giving definite irritation (~+/- ) is selected for shoulder induction. The highest non-irritant concentration is chosen for sensitization challenge.

Challenge controls:

At every challenge in the test, 4 previously untreated control animals (male and weighing approximately the same as the test animals) were treated the same as the test animals, but without any induction treatment.
For each animal, an 8 mm diameter filter paper patch in an 11 mm aluminium patch test cup soaked in the test solvent (distilled water and PEG 400) was applied to the shaved flank. The patch was held in place for 24 hours by adhesive plaster wound around the trunk. The treatment sites were examined for evidence of sensitization 24 and 48 hours after removal of the patches.

Positive control substance(s):

not specified

Positive control results:

No data.

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

5.0% test substance (with 80% distilled water and 20% PEG 400 as solvent)

No. with + reactions:

1

Total no. in group:

10

Clinical observations:

None

Remarks on result:

other: 1st challenge

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

5.0% test substance (with 80% distilled water and 20% PEG 400 as solvent)

No. with + reactions:

2

Total no. in group:

10

Clinical observations:

None

Remarks on result:

other: 1st challenge

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

5.0% test substance (with 80% distilled water and 20% PEG 400 as solvent)

No. with + reactions:

2

Total no. in group:

10

Clinical observations:

None

Remarks on result:

other: 2nd challenge

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

5.0% test substance (with 80% distilled water and 20% PEG 400 as solvent)

No. with + reactions:

1

Total no. in group:

10

Clinical observations:

None

Remarks on result:

other: 2nd challenge

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

5.0% test substance (with 80% distilled water and 20% PEG 400 as solvent)

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

None

Remarks on result:

no indication of skin sensitisation

Remarks:

3rd challenge

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

5.0% test substance (with 80% distilled water and 20% PEG 400 as solvent)

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

None

Remarks on result:

no indication of skin sensitisation

Remarks:

3rd challenge

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

5.0% test substance (with 80% distilled water and 20% PEG 400 as solvent)

No. with + reactions:

2

Total no. in group:

10

Clinical observations:

None

Remarks on result:

other: 4th challenge

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

5.0% test substance (with 80% distilled water and 20% PEG 400 as solvent)

No. with + reactions:

1

Total no. in group:

8

Clinical observations:

At this fourth challenge, two test animals died due to neck lesions from the induction procedure. The mortalities were not due to the topical challenge.

Remarks on result:

other: 4th challenge

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

5.0% test substance (with 80% distilled water and 20% PEG 400 as solvent)

Remarks on result:

other: Some reactions were seen in the control animals. Details are not available.

Remarks:

Challenge No. 1, 2, 3 & 4

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

5.0% test substance (with 80% distilled water and 20% PEG 400 as solvent)

Remarks on result:

other: Some reactions were seen in the control animals. Details are not available.

Remarks:

Challenge No 1, 2, 3 & 4

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Remarks on result:

other: Not specified

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Remarks on result:

other: Not specified

Interpretation of results:

not sensitising

Conclusions:

1 out of 8 guinea pigs sensitised after 4 challenges
The test item is not classified as a skin sensitiser based on the result of this study.

Executive summary:

The Guinea Pig Maximizatin Test (GPMT), performed according to the Magnusson and Kligman method, was used. The animals weighed approximately 320 grams. The GPMT method involves induction in Guinea pigs by intradermal injections of both test substance and Freunds complete adjuvant. The induction process is supplemented seven days later by test substance applied to the shoulder injection sites and occluded by patch. Fourteen days later the animals were challenged by occluded patch on one flank. In this particular study, three subsequent challenges were then performed.

Three additional challenges were performed after the initial challenge. After the first challenge, 1 of 10 animals had a faint/very faint reaction at 24 hours and 2 of 10 animals showed the same reaction at 48 hours. After the second challenge, 2 of 10 animals had a faint/very faint reaction at 24 hours and 1 of 10 possibly showed the same reaction at 48 hours. After the third challenge, no animals showed any reactions. After the fourth challenge, 1 of 8 animals had a faint/very faint reaction at 24 hours with a further 1 of 8 with possible reactions, and 1 of 8 animals showed the same reaction at 48 hours. At this fourth challenge, two test animals died due to neck lesions from the induction procedure. The mortalities were not due to the topical challenge. Interpretation of the results is difficult due to the number of faint/very faint erythema reactions observed following each challenge. Some reactions were also seen in the control animals. Comparing the reactions at 24 hours versus 48 hours and the reproducibility of responses at each challenge, there is some evidence that one (and perhaps two) of the animals may have been weakly sensitized. However, the amount of background irritation in control animals and the weak responses in the test animals point towards this study being inconclusive.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

There is no skin sensitisation study available for lauric acid 2-sulfoethyl ester, sodium salt (sodium lauroyl isethionate) CAS No 7381-01-3. 

There are however studies on the source chemical coco fatty acids 2-sulphoethyl ester sodium salt CAS No 61789 -32 -0, which are Klimisch 2 and were carried out according to the OECD guideline 406 under GLP , as described in the Unilever reports SSM780397 and SSM830078.

The two Magnusson and Kligman studies were conducted using 10 guinea pigs per study; faint responses were observed in these studies, but not sufficient to be considerd potential for sensitisation.

In the first of the Mangusson and Kligman studies (Unilever Skin Sensitisation SSM780397) performed in 1978, a 0.15% intradermal induction dose and a 2% epicutaneous induction dose was used followed by 5% Coco fatty acids 2-sulfoethyl ester, sodium salt CAS No 61789 -32 -0,

in the challenge doses. Several challenge doses were used due to a low level of faint responses being observed in 1 or 2 animals, but no responses were seen at one re-challenge at both 24 and 48 hours.

In the second Magnusson and Kligman study (Unilever Skin Sensitisation SSM830078) performed in 1994 a 0.2% intradermal induction dose and a 2.5% epicutaneous induction dose was used followed by 1% Coco fatty acids 2-sulfoethyl ester, sodium salt CAS No 61789 -32 -0,

in the challenge dose. Again in this study two additional challenge doses were applied and inconsistent observations of faint/very faint reactions were seen in one or two guinea pigs, with the exception of the first re-challenge dose where no responses were seen. Additionally in a genuine sensitization reaction it would be expected that an increase in reactions would be observed at 48 hours when compared to the 24 hour readings and this was not observed in this study.

It is concluded that based on the weight of evidence, there is no convincing evidence that any animals had been sensitized in the two studies, therefore Coco fatty acids 2-sulfoethyl ester, sodium salt CAS No 61789 -32 -0,

is not a skin sensitizer in Guinea pigs. Read-across from the source chemical,Coco fatty acids 2 -sulfoethyl ester, sodium salt CAS no 61789 -32 -0 to the target chemical is considered to be justified based upon a commonality of functional groups, constituents, breakdown products and metabolic pathways.

Therefore we consider these study endpoint results as sufficiently conservative to be taken account of in the risk assessment of lauric acid 2-sulfoethyl ester, sodium salt (sodium lauroyl isethionate) CAS No 7381-01-3.

Migrated from Short description of key information:

Assessment of the sensitisation potential of lauric acid 2-sulfoethyl ester, sodium salt (sodium lauroyl isethionate) CAS No 7381-01-3 is based upon read-across to coco fatty acids 2-sulphoethyl ester sodium salt CAS No 61789 -32 -0. There are two valid guinea pig skin sensitization studies available for coco fatty acids 2-sulphoethyl ester sodium salt CAS No 61789-32-0; Magnusson and Kligman studies carried out according to the OECD guideline 406 under GLP conditions using 10 test and four control guinea pigs per study.  Faint responses were observed in the Magnusson and Kligman studies however there was no clear evidence of potential for skin sensitisation.

Justification for selection of skin sensitisation endpoint:

Determination of sensitisation potential is based upon read across to two guinea pig skin sensitization studies available for coco fatty acids 2-sulphoethyl ester sodium salt.  These studies were performed using the Magnusson and Kligman test. The Klimisch 2 study Skin sensitization, SSM780397 has been selected as the key study.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

Based upon read-across to coco fatty acids 2-sulfoethyl ester, sodium salt CAS No 61789 -32 -0, which was found not to be a skin sensitiser when tested in two valid OECD 406 studies,we conclude that lauric acid 2-sulfoethyl ester, sodium salt (sodium lauroyl isethionate) CAS No 7381-01-3

is unlikely to possess any significant potential for respiratory sensitisation. The physical form of

lauric acid 2-sulfoethyl ester, sodium salt (sodium lauroyl isethionate) CAS No 7381-01-3

as a solid with a low vapour pressure means inhalation exposure will be minimal. Based on this information it is not considered to be likely to be a respiratory sensitiser.

Migrated from Short description of key information:

There is no standard validated animal test available to detect respiratory sensitisers.  However as a general rule all respiratory sensitisers are also skin sensitisers.  Therefore in the absence of human evidence of respiratory sensitization potential, skin sensitization data will be used to indicate the possibility of respiratory sensitisation.

Justification for selection of respiratory sensitisation endpoint:

There is no standard validated animal test available to detect respiratory sensitisers.

Justification for classification or non-classification

The justification for classification of lauric acid 2-sulfoethyl ester, sodium salt (sodium lauroyl isethionate) CAS No 7381-01 -3 for sensitisation potential is based upon read-across to two

guinea pig skin sensitization studies available for coco fatty acids 2-sulphoethyl ester sodium salt, CAS No 61789 -32 -0 performed using the Magnusson and Kligman test.   Both the Magnusson and Kligman studies showed some inconsistent faint or very faint reactions in 1 or 2 out of 10 Guinea pigs, but no reactions on some challenges, however the positive indications seen were not sufficinet to classify the substance as a skin sensitiser As a general rule all respiratory sensitisers are also skin sensitisers. Therefore in the absence of human evidence of respiratory sensitization potential, skin sensitization data will be used to indicate the possibility.The weight of evidence is that Coco fatty acids 2-sulfoethyl ester, sodium salt is not a skin sensitizer and therefore not classified as either a skin or respiratory sensitiser.