Bis(ethyl acetoacetato-O1',O3)bis(propan-2-olato)titanium

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:

weight of evidence

Study period:

January 11, 1978 - April 14, 1978

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Method is not validated and the documentation is insufficient for assessment

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline followed

Principles of method if other than guideline:

Two days after the primary irritation test (see chapter 7.3.1 Skin irritation/corrosion.weight_of_evidence.001), induction phase for sensitisation test was started. A series of four intradermal injections of 0.1ml of a 1% test substance solution in dimethyl phthalate (DMP) was given to ten guinea pigs, one each week over three-week period. Following two-week rest period, the test animals were challenged for sensitization by applying 0.05ml of a 50% and 5% suspension of test material in DMP on shaved shoulder skin. At the same time a control group of 10 previously unexposed guinea pigs received similair applications to provide a direct comparison of the challenge reactions.
The skin at the challenge site was evaluated for irritation at 24 and 48 hours after application. Sensitization was defined as a significant score increase at challenge over the response expected from the same amount applied initially or on the concurrent controls.

GLP compliance:

no

Type of study:

not specified

Justification for non-LLNA method:

The study predates current guidelines and requirements.

Species:

guinea pig

Strain:

other: albino

Sex:

not specified

Details on test animals and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 541g
- Weigh at study conclusion: 724g
CONTROL ANIMALS
- Weigh at study conclusion: 718g

Route:

intradermal

Vehicle:

other: dimethyl phthalate

Concentration / amount:

0.1ml of a 1% solution (vol/vol)

Day(s)/duration:

Day 0, 7, 14, 21

Route:

epicutaneous, open

Vehicle:

other: dimethyl phthalate

Concentration / amount:

5% and 50% solution (0.05ml)

Day(s)/duration:

Challenge after two-week rest period

No. of animals per dose:

10 animals in test group
9 animals in control group (one animal died prior the challenge)

Details on study design:

RANGE FINDING TEST:
A range finding test was conducted with the test material to determine a no to minimally irritating concentration. Range finding test with three guinea pigs showed that 100% concentration of the test material is mildly irritating.

MAIN STUDY:
A. INDUCTION EXPOSURE
- No. of exposures: 4
- Exposure period: 3 weeks
- Test groups: Test substance in dimethyl phthalate
- Control group: no exposure
- Site: sacral intradermal injections
- Frequency of applications: every 7th day
- Duration: 0-21 d
- Concentrations: 1% test material (vol/vol) in dimethyl phthalate

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: 35
- Exposure period: 24 and 48 hours
- Test groups: Test substance in 5% and 50% solution in DMP
- Control group: Test substance in 5% and 50% solution in DMP
- Site: shoulder skin
- Concentrations: two different
- Evaluation (hr after challenge): 24, 48

Challenge controls:

A control group of 9 previously unexposed guinea pigs received similair applications than the test group at the time of challenge to provide a direct comparison of the challenge reactions.

Positive control substance(s):

no

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Remarks on result:

not measured/tested

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Remarks on result:

not measured/tested

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

50% solution in dimethyl phthalate

No. with + reactions:

6

Total no. in group:

10

Clinical observations:

not recorded

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 50% solution in dimethyl phthalate. No with. + reactions: 6.0. Total no. in groups: 10.0. Clinical observations: not recorded.

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

50% solution in dimethyl phthalate

No. with + reactions:

3

Total no. in group:

9

Clinical observations:

not recorded

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 50% solution in dimethyl phthalate. No with. + reactions: 3.0. Total no. in groups: 9.0. Clinical observations: not recorded.

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

50% solution in dimethyl phthalate

No. with + reactions:

2

Total no. in group:

10

Clinical observations:

not recorded

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 50% solution in dimethyl phthalate. No with. + reactions: 2.0. Total no. in groups: 10.0. Clinical observations: not recorded.

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

50% solution in dimethyl phthalate

No. with + reactions:

3

Total no. in group:

9

Clinical observations:

not recorded

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 50% solution in dimethyl phthalate. No with. + reactions: 3.0. Total no. in groups: 9.0. Clinical observations: not recorded.

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

5% solution in dimethyl phthalate

No. with + reactions:

1

Total no. in group:

10

Clinical observations:

no recorded

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 5% solution in dimethyl phthalate. No with. + reactions: 1.0. Total no. in groups: 10.0. Clinical observations: no recorded.

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

5% solution in dimethyl phthalate

No. with + reactions:

0

Total no. in group:

9

Clinical observations:

not recorded

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 5% solution in dimethyl phthalate. No with. + reactions: 0.0. Total no. in groups: 9.0. Clinical observations: not recorded.

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

5% solution in dimethyl phthalate

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

not recorded

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 5% solution in dimethyl phthalate. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: not recorded.

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

5% solution in dimethyl phthalate

No. with + reactions:

1

Total no. in group:

9

Clinical observations:

not recorded

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 5% solution in dimethyl phthalate. No with. + reactions: 1.0. Total no. in groups: 9.0. Clinical observations: not recorded.

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: expert judgment

Conclusions:

The potential sensitisation properties of Bis(ethyl acetoacetato-O1',O3)bis(propan-2-olato)titanium were tested using primary sensitization test on guinea pigs. Based on the study results test substance is considered as not skin sensitizer. No guideline was followed in this study

.

Executive summary:

Bis(ethyl acetoacetato-O1',O3)bis(propan-2 -olato)titanium was administrated in 1% solution (vol/vol) in dimethyl phthalate in a series of four sacral intradermal injections (10 animals). At the time of challenge 0.05ml 5% and 50% test substance (vol/vol) in dimethyl phthalate was applied and lightly rubbed to the shaved intact shoulder skin. A control group of 9 previously unexposed guinea pigs (one animal died before challenge) received similair applications at the time of challenge to provide a direct comparison of the challenge reactions. At challenge no sensitization response was observed.

This study was regarded not reliable since the method is not validated and the documentation is insufficient for assessment alone. However, the result of this study is used as a weight of evidence in the hazard assessment.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Weight of evidence approach is used to address the sensitization potential of bis(ethylacetoacetato-O1’,O3”) bis(propan-2-olato)titanium. In addition to the sensitization data from substance itself, also relevant read-across data from the analogue category member and from the degradation products is used for hazard assessment. The target substance is hydrolytically unstable having the half-life less than 10 minutes (Brekelmans, M. J. C., 2013). Thus, it is justified to use sensitization test data from the decomposition product, titanium dioxide (TiO2), isopropyl alcohol (IPA) and ethyl acetoacetate (EAA).

The sensitisation potential of bis(ethylacetoacetato-O1’,O3”) bis(propan-2-olato)titanium was investigated in primary sensitisation tests on guinea pigs (Krivanek, 1978). The test substance was administrated in 1 % solution (vol/vol) in dimethyl phthalate in a series of four sacral intradermal injections (10 animals). At the time of challenge 0.05 ml 5 % and 50 % test substance (vol/vol) in dimethyl phthalate was applied and lightly rubbed to the shaved intact shoulder skin. A control group of previously unexposed guinea pigs received similair applications at the time of challenge to provide a direct comparison of the challenge reactions. At challenge no sensitization response was observed. Thus, the target substance is considered as not skin sensitizer.

Further evidence on the skin sensitization comes from the analogue category member of the target substance, titanium tetraisopropanolate. All titanates in this category behave similar way when in contact with water. IPA is released from both target substance and titanium tetraisopropanolate when the substances are in contact with water. The category justification and the read-across justifications are presented in the Annexes of the CSR.

The study by Dreher (2010) was performed under GLP conditions and according to EU method B.42. Titanium tetraisopropanolate hydrolyses rapidly (half-life < 10 minutes) to isopropyl alcohol (IPA) and hydrated titanium dioxide (TiO2) in aqueous media. The vehicle, methyl ethyl ketone (MEK), was chosen since it has the lowest moisture content in comparison with the alternative vehicles, dimethyl sulphoxide (DMSO) and acetone: olive oil 4:1 (AOO). The study appeared to be well conducted with one minor protocol deviation where the scintillation counting was conducted for 5 minutes instead of the 10 minute period directed by the study protocol.

The disintegrations per minute (DPM) /lymph node values that were recorded in this study for the MEK control group were unusually low and the values for the 25 % and 50 % v/v titanium tetraisopropanolate in MEK were also very low with no dose response. The value for the 100 % v/v titanium tetraisopropanolate group was far greater than the control and lower concentration values. As a result of the low control DPM value the stimulation index (SI) for titanium tetraisopropanolate (100 % v/v) was calculated to be > 3. In normal circumstances a value ≥ 3 is classified as a positive response; however, the study director concluded ‘taking into account the above factors, it is considered that the test article is not demonstrating evidence of skin sensitisation. It appears that the abnormally low vehicle control value has produced an artificially high SI value in the high dose group.

As a result of the unexpectedly high SI index reported in this study an expert review of the report was conducted by Basketter (2010). According to Basketter, the choice of MEK as a vehicle was unusual but appropriately justified. The DPM value achieved for the vehicle MEK group (32 DPM/lymph node) was very much lower than expected and referenced published data to confirm that typical values were normally in the range 216-360 DPM/lymph node. Basketter’s review (2010) also noted that the DPM/lymph node counts generated by the vehicle AOO in the positive control studies with hexyl cinnamic aldehyde were between 222 and 1160 DPM/lymph node which are in agreement with AOO values generated by other laboratories, and the values the laboratory obtained with their positive control hexyl cinnamic aldehyde were also in agreement with published data.

Therefore, there is no reason to consider that the test had not been conducted correctly at this laboratory; however the very low MEK control values resulted numerically in a SI of > 3 for titanium tetraisopropanolate which would not be the case if MEK values similar to published data had been generated in this study. According to the expert judgment, whilst sub-threshold SI values (2.5 for both 25 % and 50 % v/v titanium tetraisopropanolate) were generated for the lower concentrations there was no dose response across the increasing concentrations of the substance.

Ethyl acetoacetate (EAA), the decomposition product of the target substance, is not supposed to exhibit skin sensitizing properties since there are no reports on contact allergy taking into account the long experience with human exposure to the substance as an ingredient in cosmetics (European Chemicals Bureau, 2002).

Published information on titanium and TiO2 confirmed that there was no human evidence of skin sensitization, contact dermatitis or appreciable dermal absorption (Clayton & Clayton (eds.), 1981). There is also evidence of a lack of titanium and titanium salt toxicity to the skin demonstrated by its use in the therapy of skin disorders and as a biocompatible implant material (West & Wyzan, 1963 cited in WHO, 1982).

As a conclusion on skin sensitisation, there is available enough information to support the conclusion that Bis(ethylacetoacetato-O1’,O3”) bis(propan-2-olato)titanium is not skin sensitizer. Decomposition products of Bis(ethylacetoacetato-O1’,O3”) bis(propan-2-olato)titanium are not classified as skin sensitizers according to EU regulation No. 1272/2008 (CLP) Annex VI. Furthermore, there is available read-across data from analogue category members to support this conclusion.

Migrated from Short description of key information:
Sensitization tests with guinea pigs: negative

Data from the analogue category member of bis(ethylacetoacetato-O1’,O3”) bis(propan-2-olato)titanium:
Local Lymph Node Assay (LLNA): negative

Bis(ethylacetoacetato-O1’,O3”) bis(propan-2-olato)titanium is not a skin sensitiser based on the studies conducted for the substance and for the analogue category member, titanium tetraisopropanolate.

Justification for selection of skin sensitisation endpoint:
This study predates current guideline. The study is conducted for the target substance.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Bis(ethylacetoacetato-O1’,O3”) bis(propan-2-olato)titanium is not classified for skin sensitisation in accordance to the CLP Regulation No. 1272/2008 and EU Directive 67/548/EEC.