Tin bis(2-ethylhexanoate)

Endpoint summary

Description of key information

Guinea pig sensitisation test, OECD 406, sensitising

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Qualifier:

according to guideline

Guideline:

other: Magnusson and Klingman (1970)

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

Study performed prior to the implementation of REACH.

Species:

guinea pig

Strain:

Himalayan

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: BRL Ltd., Basel, Switzerland
- Age at study initiation: approx. 9 weeks
- Weight at study initiation: 344-465 g
- Housing: group housing of 2 animals per cage with wire-mesh floors
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 deg C
- Humidity (%): 55
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12 hours light / 12 hours dark

IN-LIFE DATES: From: 1991-09-17 To: 1991-09-24

Route:

intradermal

Vehicle:

propylene glycol

Concentration / amount:

2 %

Day(s)/duration:

1

Route:

epicutaneous, open

Vehicle:

propylene glycol

Concentration / amount:

50%

Day(s)/duration:

8-10

Route:

other: epicutaneous, semiocclusive and occlusive

Vehicle:

propylene glycol

Concentration / amount:

10%, 5% and 2%

No. of animals per dose:

Preliminary: 5
Experimental: 20
Control: 10

Details on study design:

RANGE FINDING TESTS: primary irritation experiments were conducted to identify irritant test substance concentrations suitable for induction phase of the main study. In addition, a suitable non-irritant concentration was identified.

Intradermal injection
- No. of exposures: four (0.1 mL/site)
- Exposure period: 24 hours
- Test groups: one animal
- Control group: no
- Site: clipped shoulder region
- Frequency of applications: once
- Duration: 24 and 48 hour readings
- Concentrations: 5% w/w

Epidermal application
- No. of exposures: one (0.5 mL) undiluted
- Exposure period: 24 hours
- Test groups: one animal; same animal intradermally injected
- Control group: no
- Site: shaved left flank
- Frequency of applications: once
- Duration: 24 and 48 hour readings

Epidermal application
- No. of exposures: one (0.5 mL)
- Exposure period: 24 hours
- Test groups: four other animals
- Control group: no
- Site: shaved left flank
- Frequency of applications: once
- Duration: 24 and 48 hour readings
- Concentration: 100%, 50%, 25% and 10% w/w

MAIN STUDY
A. INDUCTION EXPOSURE- intradermal injection
- No. of exposures: 3, 0.1 mL
- Exposure period: 9 days
- Test groups: one
- Control group: yes, vehicle only
- Site: clipped dorsal scapular area
- Frequency of applications: once
- Duration: 9 days
- Concentrations: 2% w/w with propylene glycol; Freund's Complete Adjuvant 50:50 with distilled water; test substance at twice the concentration used emulsified in a 50:50 mixture of Freund's Complete Adjuvant

INDUCTION EXPOSURE-epidermal applications- seven days after intradermal injections
- No. of exposures: 3, 0.1 mL
- Exposure period: 48 hours
- Test groups: one
- Control group: yes, vehicle only
- Site: clipped and shaved scapular area, placed between the injection sites
- Frequency of applications: once
- Duration: 48 hours
- Concentrations: 50% w/w in propylene glycol

B. CHALLENGE EXPOSURE
- No. of exposures: 3, 0.05 mL
- Day(s) of challenge: one
- Exposure period: 24 hours
- Test groups: one
- Control group: yes, vehicle only
- Site: clipped and shaved left flank
- Concentrations: 10%, 5%, 2%
- Evaluation (hr after challenge): 24

Challenge controls:

propylene glycol

Positive control substance(s):

no

Positive control results:

Not applicable

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

2% in propylene glycol

No. with + reactions:

13

Total no. in group:

20

Clinical observations:

redness and scaliness

Remarks on result:

positive indication of skin sensitisation

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

5% in propylene glycol

No. with + reactions:

16

Total no. in group:

20

Clinical observations:

redness and scaliness

Remarks on result:

positive indication of skin sensitisation

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

10% in propylene glycol

No. with + reactions:

17

Total no. in group:

20

Clinical observations:

redness, crust, swelling, and scaliness

Remarks on result:

positive indication of skin sensitisation

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

2% in propylene glycol

No. with + reactions:

13

Total no. in group:

20

Clinical observations:

redness and scaliness

Remarks on result:

positive indication of skin sensitisation

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

5% in propylene glycol

No. with + reactions:

16

Total no. in group:

20

Clinical observations:

redness and scaliness

Remarks on result:

positive indication of skin sensitisation

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

10% in propylene glycol

No. with + reactions:

17

Total no. in group:

20

Clinical observations:

redness, crust, swelling, and scaliness

Remarks on result:

positive indication of skin sensitisation

Group:

positive control

Remarks on result:

not measured/tested

Remarks:

no positive control included

Group:

negative control

Remarks on result:

not measured/tested

Remarks:

not specified

Reading:

rechallenge

Group:

test chemical

Remarks on result:

not measured/tested

Remarks:

no rechallenge included

During the primary irritation experiments, no signs of systemic toxicity were observed; however, body weight loss was noted in 3 of the 5 animals tested.

During the main study, no symptoms of systemic toxicity were observed and no mortality occurred. Average body weight gain of test and control animals was comparable. After the 48 hours occluded epidermal induction exposure, test animals showed slight to severe erythema and slight to well-defined edema. In the challenge test, 20, 16 and 13 test animals showed a positive skin reaction in response to the 10%, 5% and 2% test substance concentrations, respectively. Based on these results, a sensitization rate of 85% was determined. The test substance should be considered to have extreme sensitizing properties.

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Conclusions:

The results of this study lead to a sensitization rate of 85%, which indicates that the test substance has extreme sensitizing properties in this test. The substance is classified as a skin sensitizer.

Executive summary:

The purpose of the study was to obtain information on the potential of the test substance to induce delayed contact hypersensitivity (skin sensitization) in the guinea pig after intradermal and epidermal exposures.

This study was carried out in accordance with the OECD Guideline No. 406, the EEC Directive 84/449/EEC, Part B.6, and the method described by Magnusson and Kligman.

After identification of the slightly irritating and the non-irritating test substance concentrations in the primary irritation experiments, a main study was performed with the selected test substance concentrations. The experimental animals were intradermally injected with a 2% concentration and epidermally exposed to a 50% concentration, while control animals were similarly treated, but with the vehicle only. Immediately after the epidermal exposure, the skin irritation was scored. Two weeks after the epidermal application all animals were challenged with test substance concentrations of 10%, 5% and 2%, and the vehicle. The challenge reactions were assessed 24 and 48 hours after bandage removal.

The epidermal exposure of the test substance in the induction phase resulted in slight to severe skin irritation. The epidermal exposure of the test substance in the challenge phase resulted in 17 positive sensitization reactions in response to the 10% test substance concentration.

Under the conditions used in this study, the test substance resulted in a sensitization rate of 85 %.

Applying the rating of allergenicity described by Kligman, A.M. (1966) on the results obtained in this test, the test substance is considered to have extreme sesitizing properties.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

Tin bis(2 -ethylhexanoate) was evaluated in the Guinea Pig Maximization test protocol. This study was assigned a reliability rating of K-1. Female Himalayan albino guinea pigs (SPF-quality, approximately 9 weeks old) were used in the study. Intradermal induction concentrations were 2% w/w tin bis(2 -ethylhexanoate) in propylene glycol and also 4% tin bis(2 -ethylhexanoate) in solution emulsified in 50:50 Freunds Complete Adjuvant. After one week, test animals were treated with 0.5 ml of a 50% solution of the test substance in propylene glycol applied epidermally on a moistened patch secured with tape between the injection sites. Control animals were treated with propylene glycol only. After 48 hours, the dressings and residual test material were removed, and the reaction sites were immediately assessed for erythema and edema. Test and control guinea pigs were challenged two weeks after the epidermal application with 10%, 5%, or 2% solutions of tin bis (2 -ethylhexanoate) in propylene glycol. Challenge applications were performed using Square chambers attached to Micropore tape and held in place with elastic bandages. Dressings and residual test substance were removed after 24 hours. Sites were assessed for redness and swelling 24 and 48 hours after removal of the dressing. In the challenge test, 20, 16 and 13 test animals showed a positive skin reaction in response to the 10%, 5% and 2% test substance concentrations, respectively. A sensitization rate of 85% was determined. [Air Products test]

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the available studies the registered substance is classified as Skin Sens. Cat. 1B ( H317: May cause an allergic skin reaction.) according to Regulation (EC) No 1272/2008.