Lithium bis(trifluoromethylsulfonyl)imide

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:

experimental study

Adequacy of study:

key study

Study period:

Report date: 2002-07-11

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study performed according to OECD Guideline and EU Method and according to GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

At the time of testing (2002), the LLNA method was just adopted as new OECD Guideline and not yet identified as the standard information requirement.
For this reason the use of the guinea pig maximisation test (GPMT) was considered te be acceptable.

Species:

guinea pig

Strain:

Hartley

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River .Laboratories, Saint-Aubin-lès-Elbeuf, France.
- Age at study initiation: On day 1, the animals of the main test were 1 - 3 months old.
- Weight at study initiation: On day 1, the animals of the main test had a mean body weight ± standard deviation of 367 ± 19 g for the males and 359 ± 20 g for the females.
- Housing: The animals were housed individually in polycarbonate cages with stainless steel lid (48 cm x 27 cm x 20 cm) equipped with a polypropylene bottle.
- Diet (e.g. ad libitum): The animals had free access to 106 pelleted diet (UAR, Villemoisson, Epinay-sur-Orge, France).
- Water (e.g. ad libitum): Drinking water filtered by a FG Millipore membrane (0.22 micron) was provided ad libitum.
- Acclimation period: At least 5 days before the beginning of the study.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 2°C
- Humidity (%): 30 to 70%
- Air changes (per hr): Approximately 12 cycles/hour of filtered, non-recycled air
- Photoperiod (hrs dark / hrs light): 12 h/12 h

IN-LIFE DATES: From: 6 December 2001 To: 26 April 2002

Route:

intradermal and epicutaneous

Vehicle:

physiological saline

Concentration / amount:

Induction exposure: 0.1% (w/w) in 0.9% NaCl (intradermal injection), 50% (w/w) in 0.9% NaCl (topical application)
Fisrt challenge exposure: 50% (w/w) in 0.9% NaCl (topical application)
Second challenge exposure: 10% (w/w) in 0.9% NaCl (topical application)

Route:

epicutaneous, semiocclusive

Vehicle:

physiological saline

Concentration / amount:

Induction exposure: 0.1% (w/w) in 0.9% NaCl (intradermal injection), 50% (w/w) in 0.9% NaCl (topical application)
Fisrt challenge exposure: 50% (w/w) in 0.9% NaCl (topical application)
Second challenge exposure: 10% (w/w) in 0.9% NaCl (topical application)

No. of animals per dose:

Number of animals in test group: 20 (10 males and 10 females)
Number of animals in negative control group: 10 (5 males and 5 females) for the fisrt challenge exposure and 10 (5 males and 5 females) for the second challenge exposure

Details on study design:

RANGE FINDING TESTS: Based on the results of the preliminary test at 25%, 10%, 5%, 1% and 0.1% (w/w), the test substance concentration of 0.1% (w/w) was selected for intradermal induction in the main study.
For epidermal applications, the test substance concentration of 50% (w/w) was chosen for the topical application of the induction phase (day 8). For the first challenge application (day 22), the chosen concentration was 50% (w/w). For the second challenge application (day 40), the chosen concentration was 10% (w/w).

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2 (one intradermal and one cutaneous)
- Type of epicutaneous induction: Occlusive
- Sodium lauryl sulfate application: No
- Exposure period: 48 hours (cutaneous induction)
- Test groups:
> injections with 50% (v/v) FCA (Freund Complete Adjuvant) in 0.9% NaCl, or test item at 0.1% (w/w) in 0.9% NaCl, or test item at 0.1% (w/w) in the mixture FCA/0.9% NaCl (50/50, v/v)
> cutaneous application: test item at the concentration of 50% (w/w) in vehicle
- Control group:
> injections with 50% (v/v) FCA in 0.9% NaCl, or 0.9% NaCl alone, or vehicle at 50% (w/v) in a mixture FCA/0.9% NaCl (50/50, v/v)
> cutaneous application: vehicle alone
- Site: each side dorsal skin of the interscapular region (i.e. 3 pairs of sites)
- Frequency of applications: once
- Duration: 8 days (total duration of the induction period)
- Concentrations: 0.1% (w/w) in 0.9% NaCl (intradermal), 50% (w/w) in 0.9% NaCl (topical application)

B. CHALLENGE EXPOSURE
- No. of exposures: 2
- Day(s) of challenge: Day 22 and day 40
- Type of epicutaneous induction: Occlusive
- Exposure period: 24 hours
- Test groups: The filter paper of a chamber (Finn Chamber®) was fully-loaded with the test item at the concentration of 50% (w/w) in 0.9% NaCl and was then applied to a clipped area of the skin of the posterior right flank of all animals for the first challenge or of the median left flank for the second challenge.
- Control group: The vehicle was applied under the same experimental conditions to the skin of the posterior left flank for the first challenge or of the median right flank for the second challenge.
- Concentrations: 50% (w/w) in 0.9% NaCl for the first challenge or 10% (w/w) in 0.9% NaCl for the second challenge
- Evaluation: 24 and 48 hours after patch removal

As equivocal cutaneous reactions were noted, a second challenge application was performed after a rest period of 17 days.
For this new challenge application, a new control of ten animals (5 males and 5 females), which was free from any previous treatment, was introduced.

C. OTHER
- Scoring of cutaneous reactions: Before the second challenge application and 24 and 48 hours after removal of the dressing of each challenge application, both flanks of the treated and control animals were observed in order to evaluate cutaneous reactions, according to the following scale:
> no visible change: 0
> discrete or patchy erythema: 1
> moderate and confluent erythema: 2
> intense erythema: 3
Any observed oedema was recorded and any other lesions were noted.
- Clinical examinations: The animals were observed at least once a day during the study in order to check for clinical signs and mortality.
- Body weight: The animals were weighed individually on the day of allocation into the groups, on the first day of the study (day 1), on day 25, on day 39 (group 3) and on the last day of the study (day 43).
- Necrospy: At the end of the study, all the animals were killed by carbon dioxide asphyxiation. No necropsy was performed.
- Skin samples: At the end of the study, skin samples were taken from the posterior left and right flanks of the animal showing skin reactions (male n°144 of the treated group). The samples were preserved in 10% buffered formalin.
- Microscopic examination: No histological examination was performed.

Positive control substance(s):

yes

Remarks:

Mercaptobenzothiazole

Positive control results:

Mercaptobenzothiazole was tested in the same conditions as described above. The positive control was not included in the study, but put in an other report as regularly controlled.
Under the experimental conditions of this study and according to the Magnusson and Kligman method, the reference item Mercaptobenzothiazole at the concentration of 20% (w/w) induced positive skin sensitization reactions in 100% guinea pigs and thus, the sensitivity of the guinea-pigs strain from the same source was considered satisfactory.

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

50 %

No. with + reactions:

19

Total no. in group:

20

Clinical observations:

Discrete to severe erythema in 19/20 animals and a dryness of the skin in all animals

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

50 %

No. with + reactions:

20

Total no. in group:

20

Clinical observations:

Discrete to severe erythema and a dryness of the skin, sometimes associated with oedema and/or brownish area

Reading:

rechallenge

Hours after challenge:

24

Group:

test chemical

Dose level:

10 %

No. with + reactions:

1

Total no. in group:

20

Clinical observations:

discrete erythema and a dryness of the skin in 1/20 animal

Reading:

rechallenge

Hours after challenge:

48

Group:

test chemical

Dose level:

10 %

No. with + reactions:

1

Total no. in group:

20

Clinical observations:

Discrete erythema in addition to a dryness of the skin and to a brownish area in 1/20 animal

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

50 %

No. with + reactions:

9

Total no. in group:

10

Clinical observations:

Discrete or moderate erythema in 9/10 animals and a dryness of the skin in all animals

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

50 %

No. with + reactions:

10

Total no. in group:

10

Clinical observations:

Discrete or moderate erythema and a dryness of the skin, sometimes associated with oedema and/or brownish area

Reading:

rechallenge

Hours after challenge:

24

Group:

negative control

Dose level:

10 %

No. with + reactions:

0

Total no. in group:

10

Reading:

rechallenge

Hours after challenge:

48

Group:

negative control

Dose level:

10 %

No. with + reactions:

0

Total no. in group:

10

Clinical examinations:

No clinical signs and no deaths were observed during the main test.

Body weight:

The body weight gain of the treated animals was similar to that of controls.

Challenge phase - scoring of cutaneous reactions:

On removal of the dressing, no residual test item was observed.

First challenge application: scoring of skin reaction

Sex	Animal number	Control group 1
		24 hours		48 hours
		LF	RF	LF	RF
Male	121	0	2/S	0	2/S/Oe
	122	0	2/S	0	2/S/Oe
	123	0	1/S	0	1/S
	124	0	1/S	0	2/S/Oe/Zb
	125	0	2/S	0	2/S/Oe
Female	136	0	1/S	0	2/S/Oe/Zb
	137	0	1/S	0	2/S/Oe/Zb
	138	0	LS	0	2/S/Zb
	139	0	2/S	0	2/S
	140	0	1/S	0	2/S/Zb
Sex	Animal number	Treated group 2
		24 hours		48 hours
		LF	RF	LF	RF
Male	126	0	2/S	0	2/Oe/Zb
	127	0	1/S	0	3/S
	128	0	2/S	0	2/S/Oe/Zb
	129	0	3/S	0	2/S/Oe/Zb
	130	0	0/S	0	1/S/Oe
	131	0	2/S	0	3/S/Oe/Zb
	132	0	1/S	0	2/S/Oe
	133	0	1/S	0	2/S
	134	0	2/S	0	3/S/Oe/Zb
	135	0	2/S	0	2/S/Oe/Zb
Female	141	0	1/S	0	2/S/Oe/Zb
	142	0	1/S	0	2/S/Oe
	143	0	1/S	0	2/S/Oe/Zb
	144	0	1/S	0	2/S/Oe/Zb
	145	0	2/S	0	3/S/Oe/Zb
	146	0	2/S	0	2/S/Oe/Zb
	147	0	1/S	0	2/S/Oe
	148	0	2/S	0	2/S/Oe/Zb
	149	0	2/S	0	3/S/Oe/Zb
	150	0	3/S	0	3/S/Oe/Zb

LF: left flank (vehicle)

RF: right flank (test item at the concentration of 50% (w/w))

S: dryness of the skin

Oe: oedema

Zb: brownish area on the treatment site

In the control group, at the 24-hour reading, a discrete or moderate erythema (grade 1 or 2) was observed in 9/10 animals; a dryness of the skin, marked enough to mask evaluation of erythema in 1/10 animals, was noted in all the animals. In the treated group, a discrete to severe erythema (grades 1 to 3) was noted in 19/20 animals. A dryness of the skin was recorded in all the animals.

At 48-hour reading, a discrete or moderate erythema (grade 1 or 2) was observed in all the animals of the control group and a discrete to severe erythema (grades 1 to 3) was noted in all the animals of the treated group.

A dryness of the skin, sometimes associated with oedema and/or brownish area was recorded in most of the animals of both groups.

In order to determine whether the observed cutaneous reactions are attributable to delayed contact hypersensitivity or to an irritant effect of the test item, a second challenge application was performed. For this second challenge, a lower concentration of 10% (w/w) was chosen.

Second challenge application: scoring of skin reaction

Sex	Animal number	Control group 3
		Before treatement		24 hours		48 hours
		LF	RF	LF	RF	LF	RF
Male	181	0	0	0	0	0	0
	182	0	0	0	0	0	0
	183	0	0	0	0	0	0
	184	0	0	0	0	0	0
	185	0	0	0	0	0	0
Female	186	0	0	0	0	0	0
	187	0	0	0	0	0	0
	188	0	0	0	0	0	0
	189	0	0	0	0	0	0
	190	0	0	0	0	0	0
Sex	Animal number	Treated group 2
		Before treatement		24 hours		48 hours
		LF	RF	LF	RF	LF	RF
Male	126	0	0	0	0	0	0
	127	0	0	0	0	0	0
	128	0	0	0	0	0	0
	129	0	0	0	0	0	0
	130	0	0	0	0	0	0
	131	0	0	0	0	0	0
	132	0	0	0	0	0	0
	133	0	0	0	0	0	0
	134	0	0	0	0	0	0
	135	0	0	0	0	0	0
Female	141	0	0	0	0	0	0
	142	0	0	0	0	0	0
	143	0	0	0	0	0	0
	144	0	0	1/S	0	1/S/Zb	0
	145	0	0	0	0	0	0
	146	0	0	0	0	0	0
	147	0	0	0	0	0	0
	148	0	0	0	0	0	0
	149	0	0	0	0	0	0
	150	0	0	0	0	0	0

LF: left flank (test item at the concentration of 10% (w/w))

RF: right flank (vehicle)

S: dryness of the skin

Zb: brownish area on the treatment site

In the animals of the control group, no cutaneous reactions were observed at both reading.

In the treated group, only a discrete erythema (grade 1) in addition to a dryness of the skin and to a brownish area at the 48 -hour reading, was noted in 1/20 animals, at both readings.

The cutaneous reactions observed in 1/20 animals of the treated group, which were of higher incidence and severity than those recorded in the animals of the control group, were attributed to delayed contact hypersensitivity.

Interpretation of results:

not sensitising

Conclusions:

Under these experimental conditions and according to the maximization method of Magnusson and Kligman, the test item BIS TRIFLUOROMETHANESULFONIMIDE LITHIUM induces contact hypersensitivity in 1/20 (5%) guinea pigs.

Executive summary:

The potential of the test item Bis trifluoromethanesulfonimide lithium (TFSILi) to induce delayed contact hypersensitivity was evaluated in guinea pigs according to the maximization method of Magnusson and Kligman and to OECD No. 406 and EC B.6 guidelines and in compliance with the principles of Good Laboratory Practice Regulations.

Thirty guinea pigs were allocated to two groups: a control group of five males and five females and a treated group of ten males and ten females.

On day 1, three pairs of intradermal injections were performed in the interscapular region of all animals:

• Freund's complete adjuvant (FCA) diluted to 50% (v/v) with 0.9% NaCl (both groups),

• test item at the chosen concentration in the chosen vehicle (treated group) or vehicle alone (control group),

• test item at the chosen concentration in a mixture FCA/0.9% NaCl (50/50, v/v) (treated group) or vehicle at the concentration of 50% (w/v) in a mixture FCA/0.9% NaCl (50/50, v/v) (control group).

On day 8, the test item (treated group) or the vehicle (control group) was applied topically to the same site, which was then covered by an occlusive dressing for 48 hours.

On day 22, all animals of both groups were challenged by a cutaneous application of the test item to the right flank. The left flank served as control and received the vehicle only. The test item and vehicle were maintained under an occlusive dressing for 24 hours.

Skin reactions were evaluated approximately 24 and 48 hours after removal of the dressing.

As equivocal cutaneous reactions were noted, a second challenge application of the test itel was performed on day 40 using the original treated group and a new control group of ten animals (five males and five females) which was free from any previous treatment. The second challenge application was performed under the same experimental conditions as for the first one, except that the test item and the vehicle were applied to the left and right flanks, respectively.

Test item concentration were as follow:

Induction (treated group)

- intradermal injections (day 1): TFSILi at the concentration of 0.1% (w/w) in 0.9% NaCl,

- topical application (day 8): TFSILi at the concentration of 50% (w/w) in 0.9% NaCl.

First challenge (all groups)

- topical application (day 22): TFSILi at the concentration of 50% (w/w) in 0.9% NaCl.

Second challenge (all groups)

- topical application (day 40): TFSILi at the concentration of 10% (w/w) in 0.9% NaCl.

At the end of the study, animals were killed without examination of internal organs.

Skin samples were taken from the challenge application sites of the animal showing skin reactions.

No histological examination was performed.

No clinical signs and no deaths were noted during the main study.

After the first challenge application:

In the control group, at the 24-hour reading, a discrete or moderate erythema was observed in 9/10 animals; a dryness of the skin, marked enough to mask evaluation of erythema in 1/10 animals, was noted in all the animals. In the treated group, a discrete to severe erythema was noted in 19/20 animals. A dryness of the skin was recorded in all the animals.

At 48-hour reading, a discrete or moderate erythema was observed in all the animals of the control group and a discrete to severe erythema was noted in all the animals of the treated group.

A dryness of the skin, sometimes associated with oedema and/or brownish area was recorded in most of the animals of both groups.

After the second challenge application:

In the animals of the control group, no cutaneous reactions were observed at both reading.

In the treated group, only a discrete erythema in addition to a dryness of the skin and to a brownish area at the 48 -hour reading, was noted in 1/20 animals, at both readings.

The cutaneous reactions observed in 1/20 animals of the treated group, which were of higher incidence and severity than those recorded in the animals of the control group, were attributed to delayed contact hypersensitivity.

Under these experimental conditions and according to the maximization method of Magnusson and Kligman, the test item Bis trifluoromethanesulfonimide lithium induces delayed contact hypersensitivity in 1/20 (5%) guinea pigs.

However, TFSILi should not be considered as a skin sensitizer and should not be classified according to the EU criteria.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Three reliable studies are available for skin sensitization. Two studies were selected as a key study, one LLNA and one Magnusson and Klingman test of reliability 1 according to Klimisch (Pelcot, 2002e and Parcell, 1993). The third one was selected as supporting study, of reliability 2 (Prinsen, 1997). Based on the results of the three studies, TFSILi is considered as not sensitising to skin. Therefore, no classification according to Regulation (EC) 1272/2008 is required.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the experimental data, Bis trifluoromethanesulfonimide lithium is not classified as sensitising to skin according to the CLP regulation 1272/2008 criteria and to the Directive 67/548/EEC criteria.