Dibutoxydibutylstannane

Endpoint summary

Description of key information

Skin:
The following study was submitted as the key study:
Sanders, A (2010) ACUTE DERMAL TOXICITY (LIMIT TEST) IN THE RAT. Harlan Laboratories Limited, Shardlow Business Park, Shardlow, Derbyshire, DE72 2GD, UK. Owner company: Chemtura Corporation, 199 Benson Road, Middlebury, CONNECTICUT 06749, USA. Report No.: 41003850.
Two in vitro studies were provided as supporting information:
Warren, N (2010) IN VITRO SKIN CORROSION IN THE EPISKIN(TM) RECONSTITUTED HUMAN EPIDERMIS MODEL. Harlan Laboratories Limited, Shardlow Business Park, Shardlow, Derbyshire, DE72 2GD, UK. Owner company: Chemtura Corporation, 199 Benson Road, Middlebury, CONNECTICUT 06749, USA. Report No.: 3103/0039.
Warren, N (2010) DETERMINATION OF SKIN IRRITATION POTENTIAL USING THE EPISKIN(TM) RECONSTITUTED HUMAN EPIDERMIS MODEL. Harlan Laboratories Limited, Shardlow Business Park, Shardlow, Derbyshire, DE72 2GD, UK. Owner company: Chemtura Corporation, 199 Benson Road, Middlebury, CONNECTICUT 06749, USA. Report No.: 3103/0040.
The 2 in vitro studies, were assigned a reliability score of 1, both were conducted to GLP & to a validated method. The acute dermal toxicity study was assigned a score of 2 as the method was not a standard irritation/corrosion test.
Eye:
The Sanders, 2010 study (in vivo eye irritation) was provided as the key study
A Sanders (2010) ACUTE EYE IRRITATION IN THE RABBIT.  Harlan Laboratories Limited, Shardlow Business Park, Shardlow, Derbyshire, DE72 2GD UK.
Two in vitro studies were also presented; Warren, N (2010) ASSESSMENT OF OCULAR IRRITATION POTENTIAL USING THE SKINETHIC RECONSTITUTED HUMAN CORNEAL EPITHELIUM MODEL, PROJECT No.: 3103/0041 & Warren, N (2010) THE BOVINE CORNEAL OPACITY AND PERMEABILITY ASSAY (BCOP), PROJECT No.: 41003513.
The Sanders, 2010 study and the Warren, 2010, BCOP study were assigned a reliability score of 1 as they were conducted to OECD guidelines & GLP. The other in vitro study was assigned a score of 2 as it is a pre-validated study. 

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

The study was performed between 22 September 2010 and 29 September 2010.

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study was performed to the OECD testing guideline for acute dermal toxicity. The study was performed in compliance with GLP.

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 402 (Acute Dermal Toxicity)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EU Method B.3 (Acute Toxicity (Dermal))

Deviations:

no

Principles of method if other than guideline:

The study was performed to the OECD guideline 402 to determine the acute dermal toxicity of the substance.

GLP compliance:

yes (incl. QA statement)

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories U.K. Ltd., Oxon, UK.
- Age at study initiation: eight to twelve weeks of age
- Weight at study initiation: animals weighed at least 200g
- Housing: The animals were housed in suspended solid floor polypropylene cages furnished with woodflakes.
- Diet/water (e.g. ad libitum): Free access to mains drinking water and food (2014 Teklad Global Rodent diet supplied by Harlan Laboratories U.K. Ltd., Oxon, UK) was allowed throughout the test. The diet, drinking water and bedding were routinely analysed and were considered not to contain any contaminants that could reasonably be expected to affect the purpose or integrity of the study.
- Acclimation period: acclimatisation period of at least five days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 to 25°C
- Humidity (%): 30 to 70%
- Air changes (per hr): at least fifteen changes per hour
- Photoperiod (hrs dark / hrs light): lighting was controlled by a time switch to give twelve hours continuous light (06:00 to 18:00) and twelve hours darkness.

Type of coverage:

semiocclusive

Preparation of test site:

shaved

Vehicle:

unchanged (no vehicle)

Controls:

not specified

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 1.77 ml/kg (dose 2000 mg/kg bw)

Duration of treatment / exposure:

24 hours

Observation period:

7 days

Number of animals:

2

Details on study design:

TEST SITE
- % coverage: The calculated volume of test material, as received, was applied as evenly as possible to an area of shorn skin (approximately 10% of the total body surface area) using a graduated syringe.
- Type of wrap if used: A piece of surgical gauze was placed over the treatment area and semi-occluded with a piece of self adhesive bandage.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): After the 24-Hour contact period the bandage was carefully removed and the treated skin and surrounding hair wiped with cotton wool moistened with arachis oil BP to remove any residual test material.

OBSERVATIONS
- Time after start of exposure: 24 hours
- Duration of observation period following administration: 7 days
- Frequency of observations and weighing: The animals were observed for deaths or overt signs of toxicity ½, 1, 2 and 4 hours after dosing and subsequently once daily for seven days. Individual bodyweights were recorded prior to application of the test material on Day 0 and death (Day 7).
- Necropsy of survivors performed: yes
- Other examinations performed: All animals were subjected to gross necropsy. This consisted of an external examination and opening of the abdominal and thoracic cavities. The appearance of any macroscopic abnormalities was recorded. No tissues were retained.

Irritant / corrosive response data:

Dermal Reactions
Individual dermal reactions are given in Table 2.
Signs of dermal irritation noted were very slight or well-defined erythema and hardened dark brown black coloured scab were noted at both test sites. Additional signs of dermal irritation noted at the test site of the male were hardened light brown coloured scab and scab cracking. Additional signs of dermal irritation noted in the female were haemorrhage of dermal capillaries, hardened light brown coloured scab, small areas of pale green coloured dermal necrosis scattered around the edges of the test site, blanching of the skin and hardened dark brown coloured scab, approximately 10 mm x 20 mm in size, surrounded by loss of skin elasticity and light brown discolouration of the epidermis. Adverse dermal reactions prevented accurate evaluation of erythema and oedema at both test sites six and seven days after dosing. The reactions noted in the male were considered to be indicative of dermal corrosion.

Other effects:

Mortality Data: Both animals were killed for humane reasons seven days after dosing, due to the approach of the moderate severity limit set by the UK Home Office.

Clinical Observations: Signs of systemic toxicity noted were hunched posture, pilo-erection, lethargy, dehydration and pallor of the extremities.

Bodyweight: Bodyweight loss was noted over the study period.

Necropsy: Raised limiting ridge of the stomach and scattered dermal haemorrhage at the sub cutaneous site of application were noted at necropsy.

Due to severe/corrosive dermal reactions no further animals were treated with the test item.

Table 1              Individual Clinical Observations and Mortality Data

Dose Level mg/kg	Animal Number and Sex	Effects Noted After Initiation of Exposure (Hours)				Effects Noted After Initiation of Exposure (Days)
		½	1	2	4	1	2	3	4	5	6	7
2000	1-0 Male	0	0	0	0	0	0	0	0	H	HPDh	HPDhEX*
	2-0 Female	0	0	0	0	0	0	0	0	H	HPLDh	HPLDhEX*

0 = No signs of systemic toxicity

H = Hunched posture

P = Pilo-erection

L = Lethargy

Dh = Dehydration

E = Pallor of the extremities

X* = Animal killed for humane reasons due to the approach of the moderate severity limit set by the UK Home Office

Table 2              Individual Dermal Reactions

Dose Level mg/kg		Animal Number and Sex		Observation		Effects Noted After Initiation of Exposure (Days)
			1			2		3		4		5		6		7
2000		1-0 Male		Erythema		0		1		1		1		1		?e		?e
			Oedema		0		0		0		0		0		?od		?od
			Other		0		0		0		0		0		St		SpSk
		2-0 Female		Erythema		1		1		0		0		0		?e		?e
			Oedema		0		0		0		0		0		?od		?od
			Other		0		0		0		Hd		Hd		St		NBlSt*LeBr

0 = No reactions

Hd = Haemorrhage of dermal capillaries

St = Hardened dark brown black coloured scab

Sp = Hardened light brown coloured scab

Sk = Scab cracking

N = Small areas of pale green coloured dermal necrosis scattered around the edges of the test site

Bl = Blanching of the skin

St* = Hardened dark brown coloured scab, approximately 10 mm x 20 mm in size

Le = Loss of skin elasticity

Br = Light brown discolouration of the epidermis

?e = Adverse dermal reactions prevent accurate evaluation of erythema

?od = Adverse dermal reactions prevent accurate evaluation of oedema

Table 3              Individual Bodyweights and Weekly Bodyweight Changes

Dose Level mg/kg	Animal Number and Sex	Bodyweight (g) at Day			At Death	Bodyweight Change (g) During Week
		0	7	14		1	2
2000	1-0 Male	223	-	-	166	-	-
	2-0 Female	211	-	-	160	-	-

- = Animal dead

Table 4              Individual Necropsy Findings

Dose Level mg/kg	Animal Number and Sex	Time of Death	Macroscopic Observations
2000	1-0 Male	Humanely killed Day 7	Stomach: raised limiting ridge Sub-cutaneous at the site of application: scattered dermal haemorrhage
	2-0 Female	Humanely killed Day 7	Stomach: raised limiting ridge Sub-cutaneous at the site of application: scattered dermal haemorrhage

 

Interpretation of results:

corrosive

Remarks:

Migrated information Criteria used for interpretation of results: expert judgment

Conclusions:

Signs of dermal irritation noted were Very slight or well-defined erythema and hardened dark brown black coloured scab were noted at both test sites. Additional signs of dermal irritation noted at the test site of the male were hardened light brown coloured scab and scab cracking. Additional signs of dermal irritation noted in the female were haemorrhage of dermal capillaries, hardened light brown coloured scab, small areas of pale green coloured dermal necrosis scattered around the edges of the test site, blanching of the skin and hardened dark brown coloured scab, approximately 10 mm x 20 mm in size, surrounded by loss of skin elasticity and light brown discolouration of the epidermis. Adverse dermal reactions prevented accurate evaluation of erythema and oedema at both test sites six and seven days after dosing. The reactions noted in the male were considered to be indicative of dermal corrosion.

Executive summary:

The study was performed to assess the acute dermal toxicity of the test item in the Wistar strain rat. The method was designed to meet the requirements of the following:

 OECD Guidelines for the Testing of Chemicals No. 402 “Acute Dermal Toxicity” (adopted 24 February 1987)

 Method B3 Acute Toxicity (Dermal) of Commission Regulation (EC) No. 440/2008

Initially, two animals (one male and one female) were given a single, 24-hour, semi-occluded dermal application of the undiluted test item to intact skin at a dose level of 2000 mg/kg bodyweight. Based on the results of the initial test, no further animals were treated.

Signs of dermal irritation noted were well-defined erythema, haemorrhage of dermal capillaries, hardened light brown, dark brown or dark brown black coloured scab, scab cracking, blanching of the skin, loss of skin elasticity, light brown discolouration of the epidermis and small areas of pale green coloured dermal necrosis.

The reactions noted in the male were considered to be indicative of dermal corrosion.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (corrosive)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

The study was performed between 22 September 2010 and 23 September 2010.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study conducted to GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.5 (Acute Toxicity: Eye Irritation / Corrosion)

Deviations:

no

Principles of method if other than guideline:

An assessment of the initial pain reaction was not performed. This deviation from the General Study Plan was considered not to affect the purpose or integrity of the study.

GLP compliance:

yes (incl. QA statement)

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories U.K. Ltd., Loughborough, UK.
- Age at study initiation: twelve to twenty weeks old
- Weight at study initiation: 2.52 kg
- Housing: The animal was housed in a suspended cage.
- Diet/water (e.g. ad libitum): Free access to mains drinking water and food (2030 Teklad Global Rabbit diet supplied by Harlan Laboratories U.K. Ltd., Oxon, UK) was allowed throughout the study. The diet and drinking water were considered not to contain any contaminant of a level that might have affected the purpose or integrity of the study.
- Acclimation period: at least five days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17 to 23°C
- Humidity (%): 30 to 70%
- Air changes (per hr): The rate of air exchange was at least fifteen changes per hour
- Photoperiod (hrs dark / hrs light): lighting was controlled by a time switch to give twelve hours continuous light (06:00 to 18:00) and twelve hours darkness.

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent no treatment

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): A volume of 0.1 ml of the test material was placed into the conjunctival sac of the right eye, formed by gently pulling the lower lid away from the eyeball.

Duration of treatment / exposure:

The upper and lower eyelids were held together for about one second immediately after treatment, to prevent loss of the test material, and then released.

Observation period (in vivo):

Assessment of ocular damage/irritation was made approximately 1 hour and 24 hours.

Number of animals or in vitro replicates:

1

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): none
- Time after start of exposure: n/a

SCORING SYSTEM: Assessment of ocular damage/irritation was made approximately 1 and 24 hours following treatment, according to the numerical evaluation given in Appendix 1, (from Draize J H (1977) "Dermal and Eye Toxicity Tests" In: Principles and Procedures for Evaluating the Toxicity of Household Substances, National Academy of Sciences, Washington DC p.48 to 49).

TOOL USED TO ASSESS SCORE: Examination of the eye was facilitated by the use of the light source from a standard ophthalmoscope.

Irritation parameter:

cornea opacity score

Remarks:

degree of opacity

Basis:

animal #1

Time point:

other: 24 hours

Score:

1

Max. score:

4

Reversibility:

not reversible

Irritation parameter:

cornea opacity score

Remarks:

area of cornea involved

Basis:

animal #1

Time point:

other: 24 hours

Score:

4

Max. score:

4

Reversibility:

not reversible

Irritation parameter:

iris score

Basis:

animal #1

Time point:

other: 24 hours

Score:

1

Max. score:

2

Reversibility:

not reversible

Irritation parameter:

conjunctivae score

Basis:

animal #1

Time point:

other: 24 hours

Score:

3

Max. score:

3

Reversibility:

not reversible

Irritation parameter:

chemosis score

Basis:

animal #1

Time point:

other: 24 hours

Score:

3

Max. score:

4

Reversibility:

not reversible

Irritant / corrosive response data:

Severe conjunctival irritation was noted in the treated eye one hour after treatment. Scattered or diffuse corneal opacity, iridial inflammation and severe conjunctival irritation were noted in the treated eye at the 24-Hour observation.

Other effects:

Other ocular effects noted at the 24-Hour observation were haemorrhage of the upper and lower conjunctival membranes and blood stained discharge from the conjunctival and nictitating membranes.

Due to the severity of the reactions the animal was killed for humane reasons immediately after the 24 hour observation in accordance with current UK Home Office guidelines.

Table 1              Individual Scores for Ocular Irritation

Rabbit Number and Sex	69630 Male
Time After Treatment	1 Hour	24 Hours
CORNEA
Degree of Opacity	0	1
Area of Cornea Involved	0	4
IRIS	0	1
CONJUNCTIVA
Redness	2	3HBs
Chemosis	3	3
Discharge	3	3

H = Haemorrhage of the upper and lower conjunctival membranes

Bs = Blood stained discharge from the conjunctival and nictitating membranes

Table 2              Individual Bodyweights and Bodyweight Changes

Rabbit Number and Sex	Individual Bodyweight (kg)		Bodyweight Change (kg)
	Day 0	Day 1
69630Male	2.52	2.46	-0.06

Interpretation of results:

Category 1 (irreversible effects on the eye) based on GHS criteria

Remarks:

Migrated information

Conclusions:

The test item was considered to be corrosive to the rabbit eye.

Executive summary:

The study was performed to assess the irritancy potential of the test item to the eye of the New Zealand White rabbit. The method was designed to meet the requirements of the following:

- OECD Guidelines for the Testing of Chemicals No. 405 “Acute Eye Irritation/Corrosion” (adopted)

-  Method B5 Acute Toxicity (Eye Irritation) of CommissionRegulation (EC) No. 440/2008

A single application of the test item to the non-irrigated eye of one rabbit produced scattered or diffuse corneal opacity, iridial inflammation, severe conjunctival irritation, haemorrhage of the conjunctival and nictitating membranes and blood stained discharge. Due to the severity of the reactions the animal was killed for humane reasons immediately after the 24-hour observation in accordance with current UK Home Office guidelines.

Based on the results of the study the test item was considered to be corrosive to the rabbit eye, in addition, the test item was considered to be an irritant according to EU labelling regulations Commission Directive 2001/59/EC. It is reasonable to assume that the symbol “Xi”, the indication of danger “Irritant” and the highest risk phrase R 41 “RISK OF SERIOUS DAMAGE TO EYES” are therefore required.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Additional information

Skin:

This endpoint was addressed with the submission of an acute dermal toxicity study which included observations of local effects suitable for assessment under this endpoint. This was the only available in vivo study which included demonstrable effects. Two further in vitro studies were provided as supporting information.

Sanders A (2010) was provided as the key study. The study was performed to GLP and as it was performed to the standard guidelines for acute dermal toxicity, the observations of local dermal effects were considered to have been performed in line with good scientific principles and therefore assigned a reliability score of 2 according to the criteria outlined in Klimisch (1997). As the only available in vivo study, with clear demonstrable effects, the study was selected as the key study. The study was performed to assess the acute dermal toxicity of the test material in the Wistar strain rat (Performed to OECD Guidelines for the Testing of Chemicals No. 402 "Acute Dermal Toxicity" (adopted 24 February 1987) and Method B3 Acute Toxicity (Dermal) of Commission Regulation (EC) No. 440/2008). Two animals (one male and one female) were given a single, 24-Hour, semi-occluded dermal application of the undiluted test material to intact skin at a dose level of 2000 mg/kg bodyweight. Signs of dermal irritation noted loss of skin elasticity, hardened dark brown/black coloured scab, small areas of pale green coloured dermal necrosis scattered around the edges of the test site, scab cracking. Adverse skin reactions prevented accurate evaluation of erythema and oedema at both test sites during the study. The reactions were considered to be indicative of dermal corrosion.

- The Warren (2010), study investigating skin corrosivity (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).) was assigned a reliability rating of 1 was assigned according to the criteria of Klimisch, 1997 as this was conducted to a guideline study and GLP. The purpose of this test was 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 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.

- The Warren (2010) study investigating skin irritancy (according to a validated in vitro method following the EPISKIN^TM reconstituted human epidermis model.) was assigned a reliability rating of 1 was assigned according to the criteria of Klimisch, 1997 as this was conducted to a validated in vitro method and GLP. 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 test material was considered to be Irritant (I).

Eye:

In two in vitro eye irritation studies (Warren, 2010) the test material was assessed using the SkinEthic Reconstituted Human Corneal model and the Bovine Corneal Opacity and Permeability assay. According to the protocols followed the test material was considered to be Non-Irritant and so an in vivo test was carried out.

In the in vivo study (Sanders, 2010) the study was performed to assess the irritancy potential of the test material to the eye of the New Zealand White rabbit.

A single application of the test item to the non-irrigated eye of one rabbit produced scattered or diffuse corneal opacity, iridial inflammation, severe conjunctival irritation, haemorrhage of the conjunctival and nictitating membranes and blood stained discharge. Due to the severity of the reactions the animal was killed for humane reasons immediately after the 24-hour observation in accordance with current UK Home Office guidelines.

Based on the results of the study the test item was considered to be corrosive to the rabbit eye

The results from the in vitro studies do not correlate with the key study.

Effects on skin irritation/corrosion: corrosive

Effects on eye irritation: highly irritating

Justification for classification or non-classification

Skin corrosivity:

As a precautionary measure the substance has been classified as corrosive to the skin based on a dermal study, although it should be noted that the test material was left on for 24 hours which is longer than the 4-hours given in recognised guidelines for this endpoint, also the corrosion is not seen straight away after exposure, signs of corrosion are not noted until after day 5.

The study does not technically fit the criteria for "corrosive" with regards to Directive 67/548/EEC and also Regulation (EC) no 1272/2008, however corrosive effects are seen in this study around 5 day. Expert judgement has been applied to classify this substance as corrosive.

The test material was considered to be corrosive to the skin. The substance was assigned a classification of Category 1C Corrosive with the risk phrase H314 and the signal "Danger" under the regulation (EC) No.: 1272/2008 and accordingly under the directive 67/548/EEC as C (corrosive) R34 (Causes burns).

Eye:

Following assessment of the in vivo data, the test material was considered to cause severe ocular irritancy in vivo.

Based on the results of the study the test item was considered to be corrosive to the rabbit eye, in addition, the test item was considered to be an irritant according to EU labelling regulations Commission Directive 2001/59/EC. It is reasonable to assume that the symbol “Xi”, the indication of danger “Irritant” and the highest risk phrase R 41 “RISK OF SERIOUS DAMAGE TO EYES” are therefore required. According to the regulation (EC) No.: 1272/2008, the test material is a Category 1 irritant and so will have the hazard statement H318: causes serious eye damage and the 'Danger' symbol.

However, according to Section 3.2.6.2 of Directive 67/548/EEC when a substance is classified as R34, the risk of severe damage to eyes is considered implicit and R41 is not included in the label. Likewise under the regulation (EC) No.: 1272/2008, Section 3.3.2.3 skin corrosive substances shall be considered as leading to serious damage to the eyes as well (Category 1) and hence H318 is not included in the label.