Choline hydrogen carbonate

Skin sensitisation

Administrative data

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: Well-documented Guideline study according GLP, but performed on formulation of Choline chloride with structural analogue (Chlorocholine chloride).

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1998

Report date:

1998

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

adopted 1992-07-17

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Version / remarks:

Directive 96/54/EEC

Deviations:

no

GLP compliance:

yes

Remarks:

including compliance statement

Type of study:

guinea pig maximisation test

Test material

Test material information

Constituent 1

Reference substance name:

Chlormequat chloride 460 g/L, Choline chloride 320 g/L

IUPAC Name:

Chlormequat chloride 460 g/L, Choline chloride 320 g/L

Test material form:

other: liquid

Details on test material:

- Name of test material (as cited in study report): Chlormequat chloride 460 g/L, Choline chloride 320 g/L
- Substance type: formulation of two read-across substances
- Physical state: liquid
- Composition of test material, percentage of components: Chlormequat chloride 460 g/L, Choline chloride 320 g/L
- Storage condition of test material: room temperature in the dark
- Other: Description: extremely pale yellow liquid

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

male

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: David Hall Limited, Burton-on-Trent, Staffordshire, UK
- Age at study initiation: approx. 8 - 12 weeks
- Weight at study initiation: 312 - 393 g
- Housing: singly or in pairs in solid-floor polypropylene cages furnished with woodflakes
- Diet (e.g. ad libitum): Guinea Pig FD1 Diet, Special Diets Services Limited, Witham, Essex, UK; ad libitum
- Water (e.g. ad libitum): tap water ad libitum
- Acclimation period: at least five days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 - 22
- Humidity (%): 48 - 56
- Air changes (per hr): approx. 15
- Photoperiod (hrs dark / hrs light): 12 / 12

Other: each animal was selected at random and given a number unique within the study which was written on a small area of clipped rump using a black indelible marker-pen.

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal and epicutaneous

Vehicle:

water

Induction 2

Concentration / amount:

5 % w/v solution in distilled water (Intradermal induction)
undiluted as supplied (Topical induction)
undiluted as supplied and 75 % v/v in water (Topical induction)

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

water

Challenge 2

Concentration / amount:

5 % w/v solution in distilled water (Intradermal induction)
undiluted as supplied (Topical induction)
undiluted as supplied and 75 % v/v in water (Topical induction)

No. of animals per dose:

10 (test group)
5 (control group)

Details on study design:

RANGE FINDING TESTS:
- Single intradermal exposure with 0.1 mL of either 1 %, 5 %, 10 % or 25 % w/v of the test item in distilled water, sighting test, for intradermal induction
- Two guinea pigs, intradermally injected with Freund's Complete Adjuvant fifteen days earlier, were topically (occlusive) exposed to 100 %, 75 %, 50 % and 25 % v/v of the test item in distilled water, for topical induction
- 100 %, 75 %, 50 % and 25 % v/v of the test item in distilled water, 14 d after induction with Freund´s Complete Adjuvant analogue to control animals in the main study, for topical challenge

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 1 intradermal (row of three injections, see additional information), 1 topical 7 days later
- Exposure period: 48 h for topical induction
- Test groups:
Intradermal Induction: row of three injections, (1) Freund´s Complete Adjuvans (FCA) and H2O dest. 1:1, (2) 5% w/v solution of the test material in distilled water, (3) 5 % w/v solution of the test material in distilled water and FCA plus H2O dest. 1:1
Topical induction: undiluted test material
- Control group:
Intradermal Induction: row of three injections, (1) Freund´s Complete Adjuvans (FCA) and H2O dest. 1:1, (2) distilled water, (3) 50% distilled water and FCA plus H2O dest. 1:1
Topical induction: bare filter paper
- Site: shoulder
- Frequency of applications: Day 1 and 7
- Duration: Total 9 d
- Concentrations: 5 % w/v in water (intradermal), undiluted (topical)

B. CHALLENGE EXPOSURE
- No. of exposures:
- Day(s) of challenge: Day 21
- Exposure period: 48h
- Test groups: undiluted as supplied and 75 % v/v of test item in distilled water
- Control group: undiluted as supplied and 75 % v/v of test item in distilled water
- Site: right (100 % test item) and left (75 % v/v) shorn flank
- Concentrations: undiluted and 75 % v/v
- Evaluation (hr after challenge): 24h and 48 h

Challenge controls:

5 animals, undiluted test item and 75 % v/v of test item in distilled water

Positive control substance(s):

yes

Remarks:

historical control data from Neomycin Sulphate, 2-Mercaptobenzothiazole, 2,4-Dinitrochlorobenzene

Results and discussion

Positive control results:

See attached background material "Driscoll_PositiveControlData" which demonstrates clearly that the laboratory has the capability to identify positive dermal sensitizers.
The incidences of sensitization of the test animals were 60% (Neomycin Sulphate), 70 - 90 % (2-Mercaptobenzothiazole) and 100 % (2,4-Dinitrochlorobenzene).

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

100 % of the test item as supplied

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

No skin reactions or differences in body weight gain compared to control were noted.

Remarks on result:

other: see Remark

Remarks:

Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 100 % of the test item as supplied. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: No skin reactions or differences in body weight gain compared to control were noted..

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

100 % of the test item as supplied

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

No skin reactions or differences in body weight gain compared to control were noted.

Remarks on result:

other: see Remark

Remarks:

Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 100 % of the test item as supplied. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: No skin reactions or differences in body weight gain compared to control were noted..

Results 3

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

75 % v/v of the test item in distilled water

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

No skin reactions or differences in body weight gain compared to control were noted.

Remarks on result:

other: see Remark

Remarks:

Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 75 % v/v of the test item in distilled water. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: No skin reactions or differences in body weight gain compared to control were noted..

Results 4

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

75 % v/v of the test item in distilled water

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

No skin reactions or differences in body weight gain compared to control were noted.

Remarks on result:

other: see Remark

Remarks:

Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 75 % v/v of the test item in distilled water. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: No skin reactions or differences in body weight gain compared to control were noted..

Results 5

Reading:

1st reading

Hours after challenge:

24

Group:

other: challenge control

Dose level:

100 % of the test item as supplied

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

No skin reactions were noted.

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: other: challenge control. Dose level: 100 % of the test item as supplied. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: No skin reactions were noted..

Results 6

Reading:

2nd reading

Hours after challenge:

48

Group:

other: challenge control

Dose level:

100 % of the test item as supplied

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

No skin reactions were noted.

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: other: challenge control. Dose level: 100 % of the test item as supplied. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: No skin reactions were noted..

Results 7

Reading:

1st reading

Hours after challenge:

24

Group:

other: challenge control

Dose level:

75 % v/v of the test item in distilled water

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

No skin reactions were noted.

Remarks on result:

other: see Remark

Remarks:

Reading: 1st reading. . Hours after challenge: 24.0. Group: other: challenge control. Dose level: 75 % v/v of the test item in distilled water. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: No skin reactions were noted..

Results 8

Reading:

2nd reading

Hours after challenge:

48

Group:

other: challenge control

Dose level:

75 % v/v of the test item in distilled water

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

No skin reactions were noted.

Remarks on result:

other: see Remark

Remarks:

Reading: 2nd reading. . Hours after challenge: 48.0. Group: other: challenge control. Dose level: 75 % v/v of the test item in distilled water. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: No skin reactions were noted..

Any other information on results incl. tables

 

TABLE 1
Challenge concentrations: Undiluted as supplied and 75 % v/v Vehicle: Distilled water
Animal Number	Skin Reactions (Hours After Removal of Dressing)
	24 Hours						48 Hours
	100 %			75 %			100 %			75 %
	Er	Oe	Other	Er	Oe	Other	Er	Oe	Other	Er	Oe	Other
Individual skin reactions in test animals after challenge
1	0	0	-	0	0	-	0	0	-	0	0	-
2	0	0	-	0	0	-	0	0	-	0	0	-
3	0	0	-	0	0	-	0	0	-	0	0	-
4	0	0	-	0	0	-	0	0	-	0	0	-
5	0	0	-	0	0	-	0	0	-	0	0	-
6	0	0	-	0	0	-	0	0	-	0	0	-
^7	0	0	-	0	0	-	0	0	-	0	0	-
8	0	0	-	0	0	-	0	0	-	0	0	-
^9	0	0	-	0	0	-	0	0	-	0	0	-
10	0	0	-	0	0	-	0	0	-	0	0	-
Individual skin reactions in control animals after challenge
11	0	0	-	0	0	-	0	0	-	0	0	-
12	0	0	-	0	0	-	0	0	-	0	0	-
13	0	0	-	0	0	-	0	0	-	0	0	-
14	0	0	-	0	0	-	0	0	-	0	0	-
15	0	0	-	0	0	-	0	0	-	0	0	-

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The present study is a well-documented GLP study according OECD Guideline 406 (Guinea pig maximisation test) with the restriction, that it was conducted not on Choline bicarbonate but on a formulation with Choline chloride (320 g/L) and Chlorocholine chloride (CCC, 460 g/L), whereas the latter was shown not to be a sensitizer in the study by Suresh. So in general, the study was classified as Klimisch 2 and hence, the results can be safely used to assess the sensitising potential of the read-across substance Choline chloride and hence choline bicarbonate. The test item contains to relevant parts the choline cation, i.e. 41 % of the solid ingredients are Choline chloride, which can be assumed to be the only cause for a possible sensitizing effect, and the solvent (water) is not a known sensitizer. So since neither water nor CCC, which may also serve as a read-across substance, was shown to be a dermal sensitizer, it can be concluded that every possible positive result obtained from the formulation must be attributed to Choline chloride and hence, Choline bicarbonate. Since no animal of the test group at no timepoint of observation showed any skin reaction during the challenge phase, and the dose of the test item was properly determined by preliminary sighting tests as the demanded highest non-irritating dose, it can safely be concluded that the test item did not exhibit any sensitizing properties and consequently, that choline hydrogen carbonate is non-sensitizing, too. Hence, choline carbonate does not need to be classified as skin-sensitizer, neither according Regulation 1272/2008/EC nor Directive 67/548/EEC.

Executive summary:

In a dermal sensitization study according GLP and OECD Guideline 406 with a formulation of the read-across substance Choline chloride (CC) and Chlorocholine chloride (CCC) (320 g/L CC, 460 g/L CCC) in water, 8 - 12 weeks old male albino Dunkin Hartley guinea pigs (10 animals/ test were tested in the Guinea pig maximization test (GPMT according to Magnus and Kligmann)). Induction was performed once intradermal (Day 1) and once topical (Day 7, occlusive), topical challenge was on Day 21 (occlusive). Historical data from Neomycin Sulphate, 2-Mercaptobenzothiazole and 2,4-Dinitrochlorobenzene served as positive controls and induced the anticipated effect.

No skin reactions were observed, neither in the test nor control group, and body weight gain of the test group was similar to control. Since no sensitizing effects were noted in none of the test animals in this study, the formulation of CC and CCC, and consequently also pure Choline chloride or Choline bicarbonate, is not a dermal sensitizer, and does therefore not need to be classified as sensitising to the skin, neither according Regulation 1272/2008/EC nor Directive 67/548/EEC.