Registration Dossier

Administrative data

Description of key information

Based on the weight of evidence of all available data within an analogue approach, the available data on skin sensitisation do not meet the criteria for classification to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and therefore it is expected thattrometamol has no skin sensitisation potential.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Referenceopen allclose all

Endpoint:
skin sensitisation: in vitro
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
an in vitro skin sensitisation study does not need to be conducted because adequate data from an in vivo skin sensitisation study are available
Endpoint:
skin sensitisation: in vitro
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
GLP-guideline study, tested with the source substance 2-amino-2-methyl-1,3-propanediol (CAS 115-69-5). In accordance to the ECHA guidance document "Practical guide 6: How to report read-across and categories (March 2010)", the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance.
Justification for type of information:
The jusitification for read-across has been attached in section 13 of this IUCLID.
Principles of method if other than guideline:
To test direct peptide reactivity which is a key pathway leading to skin sensitisation, the test substance was investigated for peptide depletion by chemical reaction. The assay method established by Natsch and Gfeller (2008) was validated and improved in the testing facility and utilised in this study.
GLP compliance:
yes
Type of study:
other: peptide binding assay
Justification for non-LLNA method:
Use of an in vitro methos to assess senstization potential by assessment of peptide reactivity
Details on study design:
Method developed by Natsch and Gfeller (2008) uses a single peptide and analyzes depletion of the peptide and formation of a the covalent adduct with LC-MS methods.Briefly, a standard hepta-peptide containing one cysteine, two lysines is incubated with a 10-fold excess of test article in neutral pH condition. After a 24 hour incubation, the reaction mixture is subjected to the HPLC-UV-MS analyses to measure remaining parent peptides. The amount of depleted peptide due to reaction with the test article will be calculated and used to determine protein reactivity of the test article which is then used as to evaluate the skin sensitization potential. Based on the results from previous studies, if there is more than 15% peptide depletion by the test article, the chemical is likely to have skin sensitization potential (Gerberick et al., 2004; Natsch and Gfeller 2008). Furthermore, formation of covalent adducts between the peptide and test articles would be considered as an indicator of potential skin sensitization.
Key result
Parameter:
other: Peptide depletion
Remarks:
Negative peptide reactivity
Value:
4.22
Vehicle controls validity:
valid
Remarks:
Negative control; vehicle control
Negative controls validity:
valid
Remarks:
Same as vehicle control
Positive controls validity:
valid
Remarks:
Diethyl malaete
Remarks on result:
other: Other: peptide reactivity
Remarks:
Negative for peptide reactivity

The test substance was completely soluble in acetonitrile and was not precipitated by mixing with peptide solutions. After 24 h incubation, there was no colour change or a precipitate observed from the test substance. The test article did not have any UV absorbance at 220 nm through entire HPLC chromatography and therefore there was no interference with HPLC-UV analyses for peptides. Furthermore, the test substance did not interfere with the MS detections used in the test system that were monitoring higher than 700.0 m/z. Using the established calibration curve, the concentrations of free peptide were calculated for each sample (Table 1). Average peptide depletion by the test substance was 4.22 ± 1.84%. Negative and positive controls resulted in 4.83 ± 1.66% and 96.13 ± 0.21% peptide depletion, respectively. These results confirmed the assay was valid. Because there was no peptide depletion by the test substance, no further analysis was performed to measure dimerized- or oxidized-peptide by the test substance.

 

Table 1: Individual data from free peptide quantitation and average peptide depletion

Group

Replicate#

Analyte Peak Area (counts)

Peptide conc. (mM)

Peptide depletion (%)

Average depletion (%)

Test substance

1

15300000

98.03

1.97

4.22 ± 1.84

2

15200000

97.37

2.63

3

14700000

94.07

5.93

4

14700000

94.07

5.93

5

14900000

95.39

4.61

Negative control

1

14600000

93.40

6.60

4.83 ± 1.66

2

14900000

95.39

4.61

3

15100000

96.71

3.29

Positive control

1

1030000

3.78

96.22

96.13 ± 0.21

2

1080000

4.11

95.89

3

1020000

3.71

96.29

Interpretation of results:
other: Under the test conditions, there is no evidence that the test substance contains direct protein reactivity which would cause skin sensitisation.
Remarks:
Criteria used for interpretation of results: EU
Endpoint:
skin sensitisation: in vivo (non-LLNA)
Remarks:
Study conducted prior to use of LLNA; test results are valid
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Study period:
30 Mar - 10 Sep 1981
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Justification for type of information:
The jusitification for read-across has been attached in section 13 of this IUCLID.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
yes
Remarks:
-limited documentation
GLP compliance:
no
Type of study:
Buehler test
Justification for non-LLNA method:
Tested conducted prior to standard use of LLNA testing; test results from Buehler are considered to be acceptable for this end point
Species:
guinea pig
Strain:
Hartley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS- Source: Murphy Breeding Laboratories, Inc., Plainfield, Illinois, USA- Age at study initiation: at least 4 weeks- Weight at study initiation: at least 200 g- Housing: 5 per cage- Diet (e.g. ad libitum): Purina Guinea Pig Chow #5026, ad libitum- Water (e.g. ad libitum): tap water, ad libitum- Acclimation period: at least one week
Route:
epicutaneous, occlusive
Vehicle:
other: water and saline
Concentration / amount:
induction:group I (treatment group): 0.5 mL of a 0.5% aqueous solution of AEPD (first 5 applications); 0.5 mL of a 0.05% aqueous solution of AEPD (last 5 applications)group IV (positive control group): 0.5 mL of 0.3% dinitrochlorobenzene solution (DNCB, solubilised in a minimum volume of alcohol and made to volume with saline)group V, VII, VIII (negative control groups): 0.5 mL of saline challenge:group I (treatment group): 0.5 mL of a 0.05% and a 1% aqueous solution of AEPD group V (negative control group for AEPD): 0.5 mL of a 0.05% and a 1% aqueous solution of AEPD group IV (positive control): 0.5 mL of 0.3% dinitrochlorobenzene solution (DNCB, solubilised in acetone instead of alcohol)group VIII (negative control group for DNCB): 0.5 mL of 0.3% dinitrochlorobenzene solution (DNCB, solubilised in acetone instead of alcohol)group VII (negative control): 0.5 mL of saline
Route:
epicutaneous, occlusive
Vehicle:
other: water and saline
Concentration / amount:
induction:group I (treatment group): 0.5 mL of a 0.5% aqueous solution of AEPD (first 5 applications); 0.5 mL of a 0.05% aqueous solution of AEPD (last 5 applications)group IV (positive control group): 0.5 mL of 0.3% dinitrochlorobenzene solution (DNCB, solubilised in a minimum volume of alcohol and made to volume with saline)group V, VII, VIII (negative control groups): 0.5 mL of saline challenge:group I (treatment group): 0.5 mL of a 0.05% and a 1% aqueous solution of AEPD group V (negative control group for AEPD): 0.5 mL of a 0.05% and a 1% aqueous solution of AEPD group IV (positive control): 0.5 mL of 0.3% dinitrochlorobenzene solution (DNCB, solubilised in acetone instead of alcohol)group VIII (negative control group for DNCB): 0.5 mL of 0.3% dinitrochlorobenzene solution (DNCB, solubilised in acetone instead of alcohol)group VII (negative control): 0.5 mL of saline
No. of animals per dose:
50 (10 per group)
Details on study design:
RANGE FINDING TESTS: The test material was topically applied, at different concentrations on the skin of a guinea pig according to the occlusive patch technique for 24 h. After 24 h, the patches were removed and the skine sites were examined for irritation. The concentration of the test material which produces minimal irritation will be used for the test.In the initial test, all animals in the test and the negative controls developed skin rashes and the skin sensitisation reactions could not to be evaluated. Therefore the test was repeated with a new batch of animals.MAIN STUDYA. INDUCTION EXPOSURE- No. of exposures: 10- Exposure period: ca. 3 weeks- Test groups: epicutaneous; 0.5 mL aqueous solution of AEPD - Control group: 0.5 mL saline- Site: the animals´ backs and flanks- Frequency of applications: 2 to 3 times a week- Duration: 24 h- Concentrations: 0.5% (the first 5 applications) and 0.05% (the last 5 applications) solution of AEPDB. CHALLENGE EXPOSURE- No. of exposures: 1- Day(s) of challenge: 1 day (24 h)- Exposure period: 1 day- Test groups: 0.5 mL of aqueous solution of AEPD- Control group: 0.5 mL of aqueous solution of AEPD- Site: the animals´ backs and flanks- Concentrations: 0.05 and 1% solution of AEPD- Evaluation (hr after challenge): 24 and 48 hOTHER:Induction period:After 24 h exposure the patches were removed, the treated skin sites cleaned and scored at 24 and 48 h for erythema and edema according to Draize.At 48 h the topical application procedure was repeated with each group of animals two to three times a week until a total of 10 applications have been made. After the last application, the animals were allowed to rest for two weeks. Challenge:After 24 h exposure, the patches were removed and the skin sites cleaned. The challenge sites were depilated with Nair (a hair removal product with the active ingredients: calcium hydroxide and sodium hydroxide). 3 h after removal of the hair, the challenge sites were scored for inflammatory skin reactions (erythema and edema) according to Draize. Theses sites were scored again at 48 h.
Challenge controls:
Negative controls:group VII: true negative control groupgroup V: negative control group for AEPD group VIII: negative control group for DNCB
Positive control substance(s):
yes
Remarks:
induction: 0.3% solution of dinitrochlorobenzene (DNCB) in alcohol:saline (20:80); challenge: 0.3% solution of dinitrochlorobenzene (DNCB) in acetone instead of alcohol
Positive control results:
Positive control responded as expected with a clear sensitising response at 24 h (8 of 10 animals) and 48 hours (8 of 10 animals).
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
0.05%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 0.05%. No with. + reactions: 0.0. Total no. in groups: 10.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
0.05%
No. with + reactions:
1
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 0.05%. No with. + reactions: 1.0. Total no. in groups: 10.0.
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
1%
No. with + reactions:
4
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 1%. No with. + reactions: 4.0. Total no. in groups: 10.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
1%
No. with + reactions:
1
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 1%. No with. + reactions: 1.0. Total no. in groups: 10.0.
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
0.3%
No. with + reactions:
8
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: positive control. Dose level: 0.3%. No with. + reactions: 8.0. Total no. in groups: 10.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
0.3%
No. with + reactions:
8
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: positive control. Dose level: 0.3%. No with. + reactions: 8.0. Total no. in groups: 10.0.
Reading:
1st reading
Hours after challenge:
24
Group:
other: negative control for AEPD
Dose level:
0.05%
No. with + reactions:
6
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group:
Reading:
2nd reading
Hours after challenge:
48
Group:
other: negative control for AEPD
Dose level:
0.05%
No. with + reactions:
6
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group:
Reading:
1st reading
Hours after challenge:
24
Group:
other: negative control for AEPD
Dose level:
1%
No. with + reactions:
8
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group:
Reading:
2nd reading
Hours after challenge:
48
Group:
other: negative control for AEPD
Dose level:
1%
No. with + reactions:
6
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group:
Reading:
1st reading
Hours after challenge:
24
Group:
other: negative control for DNCB
Dose level:
0.3%
No. with + reactions:
2
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group:
Reading:
2nd reading
Hours after challenge:
48
Group:
other: negative control for DNCB
Dose level:
0.3%
No. with + reactions:
5
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group:
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
saline
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: saline. No with. + reactions: 0.0. Total no. in groups: 10.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
saline
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: saline. No with. + reactions: 0.0. Total no. in groups: 10.0.

During the induction period (initial ten applications) some of the animals in the test group showed mild erythema when treated with 0.5% solution of P-1050, so the last 5 applications were made with 0.05% solution. The animals in the positive control group showed mild skin reactions during the entire induction period.

Interpretation of results:
ambiguous
Endpoint:
skin sensitisation: in vivo (non-LLNA)
Remarks:
Test conducted prior to use of LLNA; test results are valid
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Study period:
10 Mar - 16 Apr 1980
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Justification for type of information:
The jusitification for read-across has been attached in section 13 of this IUCLID.
Principles of method if other than guideline:
Guinea pigs were injected into dermis with test substance or positive/negative control substance every 48 h for totally 10 applications. The animals were challenged at 2 weeks after final injection with injection of test material at a virgin site. Scores for erythema and edema were evaluated at 24 and 48 h post challenge to assess sensitising response.
GLP compliance:
no
Type of study:
intracutaneous test
Justification for non-LLNA method:
Test conducted prior to standard use of LLNA. Intradermal method per Landsteiner and Jacobs method is valid.
Species:
guinea pig
Strain:
Hartley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS- Weight at study initiation: 250 - 300 g
Route:
intradermal
Vehicle:
physiological saline
Concentration / amount:
induction:group XIV (treatment group): 0.05 mL of a 1% solution of AEPD in saline (first 5 injections); 0.05 mL of a 0.05% solution of AEPD in saline (last 5 injections)group V (positive control group): 0.05 mL of 0.3% dinitrochlorobenzene solution (DNCB, solubilised in a minimum volume of alcohol and made to volume with saline)group XVI, XVII (negative control groups): 0.05 mL of saline challenge:group XIV (treatment group): 0.1 mL of a 0.05% and 0.01% solution of AEPD in saline group XVII (negative control for AEPD): 0.1 mL of a 0.05% and 0.01% solution of AEPD in saline group V (positive control): 0.1 mL of a 0.03% dinitrochlorobenzene solution (DNCB, solubilised in a minimum volume of acetone instead of alcohol and made to volume with saline)group XVI: (negative control DNBC): 0.1 mL of a 0.03% dinitrochlorobenzene solution (DNCB, solubilised in a minimum volume of acetone instead of alcohol and made to volume with saline)
Route:
intradermal
Vehicle:
physiological saline
Concentration / amount:
induction:group XIV (treatment group): 0.05 mL of a 1% solution of AEPD in saline (first 5 injections); 0.05 mL of a 0.05% solution of AEPD in saline (last 5 injections)group V (positive control group): 0.05 mL of 0.3% dinitrochlorobenzene solution (DNCB, solubilised in a minimum volume of alcohol and made to volume with saline)group XVI, XVII (negative control groups): 0.05 mL of saline challenge:group XIV (treatment group): 0.1 mL of a 0.05% and 0.01% solution of AEPD in saline group XVII (negative control for AEPD): 0.1 mL of a 0.05% and 0.01% solution of AEPD in saline group V (positive control): 0.1 mL of a 0.03% dinitrochlorobenzene solution (DNCB, solubilised in a minimum volume of acetone instead of alcohol and made to volume with saline)group XVI: (negative control DNBC): 0.1 mL of a 0.03% dinitrochlorobenzene solution (DNCB, solubilised in a minimum volume of acetone instead of alcohol and made to volume with saline)
No. of animals per dose:
40 (10 per group)
Details on study design:
MAIN STUDYA. INDUCTION EXPOSURE- No. of exposures: 10- Exposure period: ca. 3 weeks- Test groups: 10 injections with AEPD- Control group: 10 injections with saline- Site: the animals´ backs and flanks- Frequency of applications: 2 to 3 times a week- Concentrations: 1% (the first 5 injections) and 0.05% (the last 5 injections) solution of AEPDB. CHALLENGE EXPOSURE- No. of exposures: 1- Day(s) of challenge: 1 day (24 h)- Exposure period: 1 day- Test groups: injection with AEPD- Control group: injection with AEPD- Site: the animals´ backs and flanks- Concentrations: 0.05 and 0.01% solution of AEPD- Evaluation (hr after challenge): 24 and 48 hOTHER:Induction period:After 24 and 48 h, the injected sites were scored for erythema and edema according to Draize. At 48 h, the intradermal injection procedure was repeated for each group with 0.1 mL of each solution 2 or 3 times a week until a total of 10 injections have been made. Thereafter the animals were allowed to rest for two weeks. Challenge:24 h after the challenge injection, the injected sites were depilated with Nair (a hair removal product with the active ingredients: calcium hydroxide and sodium hydroxide). 3 h after removal of the hair, the injected sites were scored for inflammatory skin reactions (erythema and edema) according to Draize. Theses sites were scored again at 48 h.
Challenge controls:
Negative controls: group XVI: negative control group for DNCB group XVII: negative control group for APED
Positive control substance(s):
yes
Remarks:
induction: dinitrochlorobenzene (DNCB) 0.3% solution (solubilised in minium volume of alcohol and made to volume with saline); challenge: 0.03% DNCB (solubilised in minimum volume of acetone instead of alcohol and made to volume with saline)
Positive control results:
DNCB gave an expected positive response scored at 24 h (10 of 10 animals) and at 48 h (9 of 10 animals).
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
0.01%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
0.01%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
0.05%
No. with + reactions:
10
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 0.05%. No with. + skin reactions: 10.0. Total no. in groups: 10.0.
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
0.05%
No. with + reactions:
10
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 0.05%. No with. + skin reactions: 10.0. Total no. in groups: 10.0.
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
0.3%
No. with + reactions:
10
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: positive control. Dose level: 0.3%. No with. + skin reactions: 10.0. Total no. in groups: 10.0.
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
0.3%
No. with + reactions:
9
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: positive control. Dose level: 0.3%. No with. + skin reactions: 9.0. Total no. in groups: 10.0.
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
0.05%
No. with + reactions:
10
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group:
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
0.05%
No. with + reactions:
10
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group:
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
0.01%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group:
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
0.01%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group:
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
other: negative control for DNCB
Dose level:
0.03%
No. with + reactions:
2
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group:
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
other: negative control for DNCB
Dose level:
0.03%
No. with + reactions:
2
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group:

During the induction phase the guinea pigs in the test group showed some skin reactions with AEPD (P-1050). The first five injections were made with 1% solution and the last five injections were made with 0.05% solution. None of the negative control animals showed any skin reactions. The positive control animals showed mild to necrotic skin reactions during the entire induction period.

Interpretation of results:
ambiguous
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

There are no animal data available on skin sensitisation of 2 -amin-2 -(hydroxymethyl)-1,3 -propanediol (trometamol). However, there are reliable data for other substances considered suitable for read-across using the analogue approach. Potential analogues for trometamol are other 2-amino-1,3-propanediols, i.e. substances that share with the target substance a common propane backbone with amine group at 2-carbon position and primary alcohols at 1 and 3 positions: 2-amino-2-ethyl-1,3-propanediol (AEPD), 2-amino-2-methyl-1,3-propanediol (AMPD) and 2-amino-1,3-propanediol (APD). The only structural difference between trometamol and AEPD is a replacement of a hydroxyl group with a methyl group and two further analogues differ in the length of the alkyl side-chain at position 2: from 0 carbon atoms (APD) through 1 (AMPD) to 2 (AEPD). The target substance and the source substances share similar physico-chemical properties.

Trometamol

and the 2-amino-1,3-propanediols are expected to show comparable toxicokinetic characteristics, and it is anticipated that the absorbed amounts of all the aminopropanediols have limited systemic bioavailability and are rapidly eliminated by the kidneys. No relevant metabolism is expected, based on experimental data and on QSAR predictions. The modelling of potential metabolites using the OECD QSAR toolbox v.2.0 (2010) did not predict relevant metabolites of trometamol or of any of the 2-amino-1,3-propanediols. Therefore, no metabolism by cytochrome P450 enzymes in-vivo is expected.

A combined oral repeated dose toxicity study and reproduction/developmental screening test was performed with AEPD according to OECD 422 (Ishida, 2004). No effects on reproduction or fertility and no systemic toxicity were observed up to and including the highest dose level of 1000 mg/kg bw/day. In a non-guideline developmental toxicity screening study performed in rats, AMPD did not shown any potential for causing developmental toxicity at doses of 1000 mg/kg bw/day (Rasoulpour and Andrus, 2011). Furthermore, in an in-vitro developmental screen (limb bud assay) using AMPD, a lack of developmental toxicity (within the scope of the assay) was indicated (Ellis-Hutchings and Marshall, 2011). Available studies via the oral, dermal or intraperitoneal route on these substances also caused no systemic toxicity. The results of the acute studies, as well as the repeated dose studies, demonstrate that the main cause of toxicity was the intrinsic alkalinity of the respective test substances at the site of contact. Inhalation is of no concern, because the low vapour pressure of the pure substances means that exposure is unlikely to occur. In case of spray applications of technical products containing the neat substance, the concentration is very low (< 1%). The Cramer classification (related mainly to the oral route) also indicates a low toxicological concern for trometamol and the 2-amino-1,3-propanediols. Thus, both trometamol and 2-amino-1,3-propanediols are of low concern with regard to systemic toxicity.

By modelling interactions of trometamol and of 2-amino-1,3-propanediols with skin proteins, no structural alerts were found. Therefore, no interactions of trometamol with skin proteins are expected and the read-across between the analogue substances based on molecular similarity and absence of substructures indicating a sensitising potential is justified for the endpoint skin sensitisation. The available data support read-across between trometamol

and 2-amino-1,3-propanediols based on an analogue approach to cover data gaps and to minimise additional animal testing, where possible.

 

There are two skin sensitisation studies available using the analogue substance AEPD.

The first skin sensitisation study was conducted similar to OECD 406 (Parekh, 1982). The Buehler´s procedure was used to test the sensitisation potential of AEPD via the topical route. During the induction period some of the guinea pigs in the test group showed mild erythema when treated with 0.5% solution of AEPD (first 5 applications), so the last 5 applications were made with 0.05% solution. The animals in the positive control group showed mild skin reactions during the entire induction period. When challenged with 0.05% AEPD, one animal in the test group showed skin reactions after 48 h and 6 animals in the negative control group at 24 h as well as at 48 h after challenge. A challenge concentration of 1% APED led to skin reactions in more animals of the negative control group (8 of 10) than of the test group (4 of 10) at the 24 h scoring. Also at the second reading, more animals of the negative control group (6/10) than of the test group (1/10) showed skin reactions. At challenge with 0.3% dinitrochlorobenzene (DNCB) solution, the positive control gave a valid response (8/10). Because more animals in the negative control group than in the test group showed skin reactions at challenge, it is not possible to judge the skin sensitisation potential of AEPD based on this study alone. In the skin sensitisation study of Parekh (1982) no data on the pH value of the test substance is given but from other studies it is known that the pH value in a 1% solution of AEPD was 11.18 and that undiluted AEPD had pH 11.78. Therefore, due to the alkaline pH value, it is likely that the skin reactions observed in the present study were caused by irritation rather than by sensitisation.

 

In the second study, the skin sensitisation potential of AEPD was tested via the intradermal route (Parekh, 1982). During the induction phase the guinea pigs in the test group showed slight skin reactions caused by AEPD. The first 5 injections were made with a 1% solution and the last 5 injections were made with a 0.05% solution. None of the negative control animals showed any skin reactions. The positive control animals showed mild to necrotic skin reactions during the entire induction period. Following the challenge with 0.05% AEPD, all animals in the test group (10/10) and in the negative control group (10/10) showed skin reactions, but none of the animals in either group showed skin reactions with a 0.01% solution. The DNCB (0.03%) caused positive skin reactions in the positive control group (10/10) and in some animals in the negative control group (2/10).

In conclusion, it is not possible to distinguish between a skin reaction caused by irritation and a skin reaction due to sensitisation. Therefore, the skin sensitisation potential of AEPD cannot be judged based on this study alone.

 

To assess the skin sensitisation potential of AMPD, an in-vitro assay method established by Natsch and Gfeller (2008) and modified by Jeong (2011) was used to determine the direct peptide reactivity, which is a key pathway leading to skin sensitisation. In this assay, a standard peptide consisting of one cysteine, two lysines and 4 other amino acids was incubated with the test substance in neutral pH condition to test for peptide depletion by chemical reactions (Jeong, 2011). After 24 h incubation, the test substance showed no peptide depletion comparable to the value of the negative control. In contrast to the positive control which depleted most of free peptides and showed a positive result. Under the in-vitro test conditions, there was no evidence that the test substance exhibits direct protein reactivity which would cause skin sensitisation.

 

Human data

Human data on skin sensitisation are available for AEPD. In a human skin sensitisation study, dermatitis patients with present or past occupational exposure to water-based metalworking fluids (MWF) were patch tested with 13 – so far untested – MWF components including AEPD. Only 1 of 160 patients reacted positively to AEPD. This patient did not react to other MWF components, in particular not to monoethanolamine and diethanolamine. Hence, no clinical relevance of a positive test reaction to AEPD could be found. However, not all the MWFs previously used by this patient could be identified. Therefore, previous occupational exposure and relevance could be regarded as possible. The lack of positive test reactions to AEPD may be due to its low sensitising potential or to a relatively low patch test concentration (1% aq.).

 

In order to assess skin sensitisation a weight of evidence approach using all available data is applied. Two skin sensitisation studies are available in guinea pigs using the analogue substance AEPD. However, due to the outcome of both studies, it was not possible to distinguish between a skin reaction caused by irritation and a skin reaction based on skin sensitisation. Also human data on skin sensitisation are available for AEPD. But also the human data showed no clinical relevance of a positive test reaction to AEPD. In addition, the skin sensitisation potential of AMPD was investigated in an in-vitro assay, determining the direct peptide reactivity, which is a key pathway leading to skin sensitisation. This assay performed with AMPD resulted in a negative result and was found to be valid. By modelling interactions of trometamol and of2-amino-1,3-propanediolswith skin proteins, no structural alerts were detected. Taking into account all available data on skin sensitisation, the analogue substances as well as trometamol are considered to have no skin sensitisation potential.

Based on the weight of evidence of all available data within an analogue approach, it can be assumed that TRIS AMINO possesses no skin sensitisation potential.

Justification for classification or non-classification

Based on the weight of evidence of all available data within an analogue approach, the available data on skin sensitisation do not meet the criteria for classification to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and therefore it is expected that trometamol has no skin sensitisation potential.