Dibutyltin dilaurate

Endpoint summary

Description of key information

Skin Corrosivity: The purpose of the study was to investigate whether the test material was acutely toxic via the dermal route, however the study included irritation and corrosion observations. Signs of dermal irritation noted were very slight erythema, light brown discolouration of the epidermis, blanching of the skin, small superficial scattered scabs, hardened light brown coloured scab, hardened dark brown/black coloured scab, scab cracking, scab lifting at edges to reveal dried blood, scab lifting to reveal glossy skin, scab undulating and glossy skin. The scab/damaged tissue at the test site of one animal has sloughed off revealing a crater (ulcer) over the majority of the test site.
Eye irritancy: The purpose of the study was to assess the potential for occular irritancy (and corrosion) of the test material in vivo in a suitable animal model. The test material was administered to the eyes of two New Zealand White rabbits, and assessed for effects. The test item produced a maximum group mean score of 39.0 and was classified as a severe irritant (Class 6 on a 1 to 8 scale) to the rabbit eye according to a modified Kay and Calandra classification system.

Corrositex (OECD 435): Non-Corrosive

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Reference 1

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

The study was performed between 28 April 2010 and 30 April 2010.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study conducted to GLP.

Qualifier:

according to guideline

Guideline:

other: OECD 431 “In Vitro Skin Corrosion: Human Skin Model Test” (adopted 13 April 2004)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Species:

other: Reconstituted Human Epidermis (RHE)

Strain:

other: Not applicable

Details on test animals or test system and environmental conditions:

The EPISKIN model is a three-dimensional reconstituted human epidermis model consisting of adult human-derived epidermal keratinocytes seeded on a dermal substitute consisting of a collagen type I matrix coated with type IV collagen. A highly differentiated and stratified epidermis model is obtained after a 13 day culture period comprising the main basal, supra basal, spinous and granular layers and a functional stratum corneum.

EPISKIN Model Kit 0.38 cm2
Supplier: SkinEthic Laboratories, Nice, France
Date received: 27 April 2010

Vehicle:

unchanged (no vehicle)

Controls:

other: Duplicate tissues, treated with 50 µl of 0.9% w/v sodium chloride solution served as negative controls. Duplicate tissues, treated with 50 µl of glacial acetic acid served as positive controls.

Amount / concentration applied:

50 µl of the test material was applied topically to the corresponding tissues ensuring uniform coverage of the tissues.

Duration of treatment / exposure:

Duplicate tissues were treated with the test material for exposure periods of 3, 60 and 240 minutes.

Number of animals:

Not applicable.

Irritation / corrosion parameter:

other: other: Relative mean viability (%)

Value:

103.4

Remarks on result:

other:

Remarks:

Basis: other: n/a. Time point: 3 minutes. Reversibility: other: n/a. (migrated information)

Irritation / corrosion parameter:

other: other: Relative mean viability (%)

Value:

94.7

Remarks on result:

other:

Remarks:

Basis: other: n/a. Time point: 60 minutes. Reversibility: other: n/a. (migrated information)

Irritation / corrosion parameter:

other: other: Relative mean viability (%)

Value:

78.7

Remarks on result:

other:

Remarks:

Basis: other: n/a. Time point: 240 minutes. Reversibility: other: n/a. (migrated information)

Irritant / corrosive response data:

Direct MTT Reduction:
An assessment found the test material was able to directly reduce MTT. Therefore, an additional procedure using water-killed tissues was performed during the determination of skin corrosion potential. However, the results obtained showed that no degree of interference due to direct reduction of MTT occurred. It was therefore considered unnecessary to use the results of the water-killed tissues for quantitative correction of results or for reporting purposes.

Test Material, Positive Control Material and Negative Control Material:
Mean OD540 values and viabilities for the negative control, positive control and test material are given in Table 1.
The relative mean viability of the test material treated tissues was as follows:
240 minutes exposure: 78.7%
60 minutes exposure: 94.7%
3 minutes exposure: 103.4%

The qualitative evaluation of tissue viability is given in Table 2.

Following the 3, 60 and 240 Minute exposure periods the test material treated tissues appeared blue which was considered to be indicative of viable tissue.

Quality Criteria:
The relative mean tissue viability for the positive control treated tissues was 4.8% relative to the negative control treated tissues following the 240-minute exposure period. The positive control acceptance criterion was therefore satisfied.

The test material was considered to be Non-Corrosive to the skin and accredited the EU risk phrase of No label and a UN packing group Non-Corrosive.

Table 1.              Mean OD₅₄₀ Values and Viabilities for the Negative Control Material, Positive Control Material and Test Material

Material	Exposure Period	Mean OD540of duplicate tissues	Relative mean viability (%)
Negative Control Material	240 Minutes	0.207	100*
Positive Control Material	240 Minutes	0.010	4.8
Test Material	240 Minutes	0.163	78.7
	60 Minutes	0.196	94.7
	3 Minutes	0.214	103.4

* =     The mean viability of the negative control tissues is set at 100%

Table 2.             Qualitative Evaluation of Tissue Viability (MTT uptake visual evaluation)

Material	Exposure Period	Tissue 1	Tissue 2
Negative Control Material	240 Minutes	-	-
Positive Control Material	240 Minutes	++	++
Test Material	240 Minutes	-	-
	60 Minutes	-	-
	3 Minutes	-	-

MTT Visual Scoring Scheme of EpiSkin Tissues

- = Blue tissue (viable)

+ = Blue/white tissue (semi-viable)

++ = Tissue completely white (dead)

Interpretation of results:

other: Non-Corrosive to the skin

Conclusions:

The test material was considered to be Non-Corrosive to the skin and accredited the EU risk phrase of No label and a UN packing group Non-Corrosive.

Executive summary:

The purpose of this test is to evaluate the corrosivity potential of the test material using the EPISKIN^TM in vitro Reconstituted Human Epidermis (RHE) Model after treatment periods of 3, 60 and 240 minutes. This method was designed to meet the requirements of the OECD Guideline for the Testing of Chemicals No. 431 “In Vitro Skin Corrosion: Human Skin Model Test” (adopted 13 April 2004).

The EPISKIN model is able to distinguish between corrosive and non-corrosive chemicals for all of the chemical types studied, and is also able to distinguish between known R35 (UN packing group I) and R34 (UN packing group II & III) chemicals.

Duplicate tissues were treated with the test material for exposure periods of 3, 60 and 240 minutes. At the end of the exposure period the test material was rinsed from each tissue before each tissue was taken for MTT-loading. After MTT loading a total biopsy of each epidermis was made and placed into micro tubes containing acidified isopropanol for extraction of formazan crystals out of the MTT-loaded tissues.

At the end of the formazan extraction period each tube was mixed thoroughly and duplicate 200 µl samples were transferred to the appropriate wells of a pre-labelled 96 well plate. The optical density was measured at 540 nm.

Data are presented in the form of percentage viability (MTT reduction in the test material treated tissues relative to negative control tissues).

The relative mean viability of the test material treated tissues was:

240 minutes exposure: 78.7%

60 minutes exposure: 94.7%

3 minutes exposure: 103.4%

The quality criteria required for acceptance of results in the test were satisfied.

The test material was considered to be Non-Corrosive to the skin and accredited the EU risk phrase of No label and a UN packing group Non-Corrosive.

Reference 2

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

The study was performed between 26 May 2010 and 01 June 2010.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Validated in vitro skin irritation study conducted to GLP.

Qualifier:

according to guideline

Guideline:

other: Validated in vitro method following the EPISKIN reconstituted human epidermis model

Deviations:

not applicable

GLP compliance:

yes (incl. QA statement)

Species:

other: Reconstituted Human Epidermis (RHE)

Strain:

other: Not applicable

Details on test animals or test system and environmental conditions:

The EPISKIN model is a three-dimensional reconstituted human epidermis model consisting of adult human-derived epidermal keratinocytes seeded on a dermal substitute consisting of a collagen type I matrix coated with type IV collagen. A highly differentiated and stratified epidermis model is obtained after a 13 Day culture period comprising of the main basal, supra basal, spinous and granular layers and a functional stratum corneum.

EPISKIN(TM) MODEL KIT
Date received: 26 May 2010

Vehicle:

unchanged (no vehicle)

Controls:

other: Triplicate tissues treated with 10 µl of PBS served as the negative controls and triplicate tissues treated with 10 µl of SDS 5% w/v served as the positive controls.

Amount / concentration applied:

10 µl of the test material was applied to the epidermis surface.

Duration of treatment / exposure:

Triplicate tissues were treated with the test material for an exposure period of 15 minutes followed by a post exposure incubation period of 42 hours.

Number of animals:

Not applicable

Irritation / corrosion parameter:

other: other: Relative mean viability (%)

Value:

94.2

Remarks on result:

other:

Remarks:

Basis: mean. Time point: 15 minutes. Reversibility: other: n/a. (migrated information)

The test material was considered to be Non-Irritant (NI).

Quality Criteria:

The relative mean tissue viability for the positive control treated tissues was ≤40% relative to the negative control treated tissues and the standard deviation value of the percentage viability was ≤20%. The positive control acceptance criterion was therefore satisfied.

The mean OD₅₄₀ for the negative control treated tissues was ≥0.6 and the SD value of the percentage viability was ≤20%. The negative control acceptance criterion was therefore satisfied.

Table 1              

Mean OD₅₄₀ Values and Percentage Viabilities for the Negative Control Material, Positive Control Material and Test Material

Material	OD540 of tissues	Mean OD540 of triplicate tissues	±SDof OD540	Relative individual tissue viability (%)	Relative mean viability (%)	± SD of Relative mean viability (%)
Negative Control Material	0.732	0.772	0.082	94.8	100*	10.6
	0.718			93.0
	0.866			112.2
Positive Control Material	0.049	0.050	0.009	6.3	6.5	1.2
	0.042			5.4
	0.060			7.8
Test Material	0.632	0.727	0.087	81.9	94.2	11.2
	0.746			96.6
	0.803			104.0

SD = Standard deviation

* = The mean viability of the negative control tissues is set at 100%

Table 2              Qualitative Evaluation of Tissue Viability (MTT uptake visual evaluation)

Material	Tissue 1	Tissue 2	Tissue 3
Negative Control Material	-	-	-
Positive Control Material	++	++	++
Test Material	-	-	-

MTT visual scoring scheme

- = blue tissue (viable)

+ = blue/white tissue (semi-viable)

++ = tissue is completely white (dead)

Interpretation of results:

not irritating

Remarks:

Migrated information

Conclusions:

The test material was considered to be Non-Irritant (NI).

Executive summary:

The purpose of this test was to evaluate the skin irritation potential of the test material using the EPISKIN^TM reconstituted human epidermis model after a treatment period of 15 minutes followed by a post exposure incubation period of 42 hours. The principle of the assay was based on the measurement of cytotoxicity in reconstituted human epidermal cultures following topical exposure to the test material by means of the colourimetric MTT reduction assay. Cell viability is measured by enzymatic reduction of the yellow MTT tetrazolium salt (3 [4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) to a blue formazan salt (within the mitochondria of viable cells) in the test material treated tissues relative to the negative controls. The concentration of the inflammatory mediator IL-1α in the culture medium retained following the 42 Hour post-exposure incubation period is also determined for test materials which are found to be borderline non-irritant based upon the MTT reduction endpoint. This complimentary end point will be used to either confirm a non-irritant result or will be used to override the non irritant result.

Triplicate tissues were treated with the test material for an exposure period of 15 minutes. At the end of the exposure period each tissue was rinsed before incubating for approximately 42 hours. At the end of the post exposure incubation period each tissue was taken for MTT-loading. The maintenance medium from beneath each tissue was transferred to pre labelled micro tubes and stored in a freezer for possible inflammatory mediator determination. After MTT loading a total biopsy of each epidermis was made and placed into micro tubes containing acidified isopropanol for extraction of formazan crystals out of the MTT loaded tissues.

At the end of the formazan extraction period each tube was mixed thoroughly and duplicate 200 µl samples were transferred to the appropriate wells of a pre labelled 96 well plate. The optical density was measured at 540 nm.

Data are presented in the form of percentage viability (MTT reduction in the test material treated tissues relative to negative control tissues).

The relative mean viability of the test material treated tissues was 94.2% after the 15 Minute exposure period.

The quality criteria required for acceptance of results in the test were satisfied.

The test material was considered to be Non-Irritant (NI).

Reference 3

Endpoint:

skin irritation / corrosion, other

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 435 (In Vitro Membrane Barrier Test Method for Skin Corrosion)

Version / remarks:

Corrositex®: An In Vitro Method for Assessing Dermal Corrosivity Potential of Chemicals, NIH Publication No. 99-4495, June 1999

GLP compliance:

yes

Specific details on test material used for the study:

Batch TF5E10T471

Test system:

artificial membrane barrier model

Details on test system:

The Corrositex® (InVitro International, Placentia, CA) test is a standardized and reproducible method that can be employed to determine the potential corrosivity and the Packing Group classification of specified categories of chemical compounds under the hazardous materials transportation regulations administered by the U.S. Department of Transportation (DOT) and international dangerous goods codes. The Corrositex® test predicts1,2 the in vivo corrosive potential of a chemical compound or mixture by using as an endpoint the amount of time it takes for a chemical to permeate or destroy a synthetic biobarrier. A color change in a proprietary liquid Chemical Detection System (CDS) is used to indicate that the chemical has passed through the biobarrier.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Irritation / corrosion parameter:

penetration time (in minutes)

Value:

> 70.34

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: Non-Corrosive

Remarks:

Neutral Red Method

Conclusions:

Fomrez SUL-4 (DBTL, CAS 77-58-7) is not skin corrosive

Executive summary:

Test article Fomrez SUL-4, Lot/Batch# TF5E10T471 was analyzed using the Corrositex® test method to determine its dermal corrosivity potential and U.N. Packing Group classification. The 1.0 N Sodium Hydroxide plus Neutral Red Positive Control had a breakthrough time of 16.50 minutes, which fell within the range allowed (>14.7 and <20.7 minutes). The 1% Acetic Acid plus Neutral Red Negative Control had a breakthrough time of >70.00 minutes, which met the acceptance criterion of >60 minutes.

The results of this study indicated that the test article plus Neutral Red was compatible with the Corrositex® system. Based on the pH of the test article, it was assigned as a Category 2 test article. The results obtained from the evaluation of four replicate tests demonstrated that a mean time of >70.34 minutes was required to penetrate the synthetic biobarriers. These findings lead to the classification of this test article as a Non-Corrosive material

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available