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Description of key information

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
Study period:
10 June 2002 and 22 July 2002
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficincies, which do not affect the quality of relevant results.
Qualifier:
according to guideline
Guideline:
EU Method B.6 (Skin Sensitisation)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 870.2600 (Skin Sensitisation)
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: Japanese Ministry of Agriculture, Forestry and Fisheries, Test Data for Registration of Agricultural Chemicals, Skin sensitization (2-1-6), 12 NohSan No. 8147, Agricultural Production Bureau, November 24, 2000.
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of study:
Buehler test
Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
male
Details on test animals and environmental conditions:
Thirty healthy male albino guinea-pigs of the Dunkin/Hartley strain were obtained from D. Hall, Newchurch, Staffordshire, England.
The animals were approximately four to five weeks of age on arrival and were acclimatised to the experimental environment for eight days prior to the start of the main study. The main study guinea-pigs were within the weight range 307 - 439 g at the start of the study (Day 1).
An additional four animals from the same supplier were used for the preliminary investigations.
The animals on the main study were allocated without conscious bias to two groups as follows:

Group Number of Animals Animal Numbers
Control animals 10 330 - 339
Test animals 20 340 - 359

The guinea-pigs were housed in groups of five in suspended metal cages with wire mesh floors.
A vitamin C enriched guinea-pig diet (SDS FDI MOD SQC) and drinking water were provided ad libitum.
For environmental enrichment, autoclaved hay was given to the guinea-pigs three times weekly at irregular intervals and plastic tubular pipes were included in the cage. These procedures, which alleviate boredom and stereotype behaviours are standard practice at this laboratory and are not considered to have any influence on test results interpretation.
The batch(es) of diet used for the study was analysed by the supplier for nutrients, possible contaminants or micro-organisms, likely to be present in the diet, and which, if in excess, may have had an undesirable effect on the test system. The certificates of analyses are lodged in Huntingdon Life Sciences Ltd.
Archives. There were no known contaminants present in the diet which were expected to be capable of interfering with the study outcome.
Results of routine physical and chemical examination of drinking water, as conducted by the supplier are made available to Huntingdon Life Sciences Limited.
Animal room environmental controls were set to maintain temperature within the range 20 ± 3°C and relative humidity within 40 to 70%. These environmental parameters were recorded daily and the permanent record archived with other departmental raw data. Lighting was controlled by means of a time switch to give 12 hours of artificial light (0600 - 1800 hours GMT) in each 24 hour period.
Each animal was identified by ear tattoo number. This number was unique within the Huntingdon Life Sciences Short Term Studies Group throughout the duration of the study. Each cage was identified by a coloured label displaying the study number, animal numbers and the initials of the Study Director and Home Office licensee.
Route:
epicutaneous, occlusive
Vehicle:
other: Alembicol D (A product of coconut oil, supplied by Alembic Products, Saltney, Chester, England)
Concentration / amount:
Preliminary study
Approximately 0.5 mL of a range of concentrations (25% w/v, 50%, 75% and 100% w/v).

Main Study
Three Inductions each at 100% w/v in Alembicol D.
Topical challenge: 100% w/v in Alembicol D.
Route:
epicutaneous, occlusive
Vehicle:
other: Alembicol D (A product of coconut oil, supplied by Alembic Products, Saltney, Chester, England)
Concentration / amount:
Preliminary study
Approximately 0.5 mL of a range of concentrations (25% w/v, 50%, 75% and 100% w/v).

Main Study
Three Inductions each at 100% w/v in Alembicol D.
Topical challenge: 100% w/v in Alembicol D.
No. of animals per dose:
20 animals
Details on study design:
TEST SUBSTANCE PREPARATION
A vehicle trial conducted with ST888YK showed that it formed a pale pink suspension in Alembicol Dl. The maximum practical concentration for topical application was approximately 100% w/v.
ST888YK was prepared prior to application on the day of dosing in Alembicol D. The concentrations used are described in the treatment procedure.
The absorption of ST888YK was not determined.
The homogeneity, stability and purity ofST888YK were the responsibility of the Sponsor.

RANGE FINDING TESTS:
The topical irritancy of a range of dilutions of ST888YK was investigated to identify where possible (a) the minimum irritant test substance concentrations suitable for the induction phase of the main study and (b) a maximum non-irritant concentration for the challenge phase.
Approximately 0.5 mL of a range of concentrations (25% w/v to 100% w/v) of ST888YK in Alembicol D was applied to patches of surgical gauze (2 x 2 cm). These were placed on the clipped and shaved flanks of each of four guinea-pigs. The patches were covered by a strip of "Blenderm" and firmly secured by "Elastoplast" wound round the trunk and fixed with an impervious plastic adhesive tape. After an exposure period of approximately six hours the dressings were removed and the sites were assessed for erythema and oedema. Further examination of the sites was carried out approximately 24 and 48 hours after removal of the
dressings.

Selection of concentrations of test substance for the main study
Based on the results of the preliminary investigations, the following concentrations of ST888YK were selected:
Induction topical application - 100% w/v in Alembicol D.
Topical challenge - 100% w/v in Alembicol D.
From preliminary investigations 100% w/v in Alembicol D was the maximum practical concentration that could be prepared and dosed topically which did not give rise to irritating effects.

MAIN STUDY
A. INDUCTION EXPOSURE
Induction application - test animals
Prior to each induction application, the skin on the left shoulder region of the guinea-pig was clipped free of hair using electric clippers and shaved/reshaved prior to dosing.
A 2 x 2 cm patch of surgical gauze was saturated with approximately 0.5 mL of ST888YK, 100% w/v in Alembicol D.
The patch was placed on the skin and covered by a length of impermeable plastic adhesive tape "Blenderm". This in turn was firmly secured by elastic adhesive bandage "Elastoplast" wound round the torso of the animals and fixed with an impervious plastic adhesive tape. Contact with the skin was maintained for approximately 6 hours for each induction exposure, following which the dressings were removed.
One induction application was made in this manner on Days 1, 8 and 15 so a total of three induction applications were made.

Induction - control animals
During the induction phase, the control animals were treated similarly to the test animals with the exception that the test substance was omitted from the induction applications.

B. CHALLENGE EXPOSURE
Challenge - control and test animals
The control and test animals were challenged topically two weeks after the final induction application using ST888YK, 100% w/v in Alembicol D.
One day prior to dosing hair was removed by clipping then shaving an area on the right flank of each guinea-pig to expose a naive area of skin. A 2 x 2 cm surgical gauze patch was saturated with approximately 0.5 mL of ST888YK, 100% w/v in Alembicol D and applied to the flank in a similar manner to the induction applications.
The patches were sealed to the flank under strips of "Blenderm" secured with "Elastoplast" wound round the trunk and fixed with impervious plastic adhesive tape. Dressings were left in place for approximately 6 hours after which time they were removed.

OBSERVATIONS
Clinical signs
All animals were observed daily for signs of ill health or toxicity.
Bodyweight
The bodyweight of each guinea-pig on the main study was recorded on Day 1 (day of first topical application) and following completion of the study prior to termination.
Dermal responses
Dermal reactions were assessed using the numerical system detailed in "any other information on materials and methods" below.
Challenge controls:
Please see details above.
Positive control substance(s):
yes
Remarks:
The sensitivity of the guinea-pig strain used is checked periodically at Huntipgdon Life Sciences with hexyl cinnamic aldehyde (HCA) - a known moderate sensitizer.
Positive control results:
The study was conducted using the guinea-pig and a known moderate sensitizer - hexyl cinnamic aldehyde (HCA) The method followed was that described in:
BUEHLER, E.V. (1965) Delayed contact hypersensitivity in the guinea-pig. Arch. Dermato/., 91, 171-177.
This positive control study was conducted between 18 June 2002 and 18 July 2002 using twenty female (nulliparous and non-pregnant) albino guinea-pigs of the Dunkin Hartley strain supplied by D Hall, Staffordshire, UK. The HCA used for the study was a clear yellow liquid, batch number 01016AQ, expiry date 14 December 2002, supplied by Aldrich Chemicals.
Based on historical data the following concentrations of HCA were administered:
Induction topical applications: HCA, as supplied
Challenge application: HCA, as supplied

INDUCTION
Slight dermal reactions were observed for nine out of ten test animals during the induction period and no dermal reactions were observed for the control animals.
CHALLENGE
Dermal reactions were seen in nine out of the ten test animals compared to none for controls, therefore the reactions seen in these nine test animals were considered to represent evidence of hypersensitivity (skin sensitization).

CONCLUSION
In this study HCA produced evidence of skin sensitization (delayed contact hypersensitivity) in nine of the ten test animals, thus confirming the sensitivity and reliability of the experimental technique to detect hypersensitivity.

Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
0.5 mL 100% w/v in Alembicol D
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 0.5 mL 100% w/v in Alembicol D. No with. + reactions: 0.0. Total no. in groups: 20.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
0.5 mL 100% w/v in Alembicol D
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 0.5 mL 100% w/v in Alembicol D. No with. + reactions: 0.0. Total no. in groups: 20.0.
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
0.5 mL Alembicol D
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: 0.5 mL Alembicol D. No with. + reactions: 0.0. Total no. in groups: 10.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
0.5 mL Alembicol D
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: 0.5 mL Alembicol D. No with. + reactions: 0.0. Total no. in groups: 10.0.

MORTALITY AND CLINICAL SIGNS

There was no death and no sign of ill health or toxicity was observed on this study.

BODYWEIGHT

An increase in bodyweight was recorded for all main study guinea-pigs over the period of the study.

INDUCTION

There was no dermal reaction seen in any of the test or control animals.

CHALLENGE

There was no dermal reaction seen in any of the test or control animals, therefore all twenty test animals gave negative responses.

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
In this study ST888YK did not produce evidence of skin sensitization (delayed contact hypersensitivity) in any of the twenty test animals. ST888YK is not considered to have the potential to cause skin sensitization.
Executive summary:

This study was performed to assess the skin sensitization potential of ST888YK using the guinea-pig. The method followed was that described in:

EEC Methods for the determination of toxicity, Annex to Directive 96/54/EC (Official Journal No. L248, 30.9.96), Part B, Method B.6. Skin sensitization.

OECD Guideline for Testing of Chemicals No. 406 "Skin Sensitization". Adopted 17 July 1992.

EPA Health Effects Test Guidelines OPPTS 870.2600 Skin Sensitization EPA 712-C-98-197. August 1998.

Japanese Ministry of Agriculture, Forestry and Fisheries, Test Data for Registration of Agricultural Chemicals, Skin sensitization (2-1-6), 12 NohSan No. 8147, Agricultural Production Bureau, November 24, 2000.

Based on the results of a preliminary study and in compliance with the guidelines, the following dose levels were selected:

Induction applications (3): ST888YK, 100% w/v in A1embicol D.

Challenge application: ST888YK, 100% w/v in Alembicol D.

Twenty test and ten control guinea-pigs were used in the main study.

In this study ST888YK did not produce evidence of skin sensitization (delayed contact hypersensitivity) in any of the twenty test animals. ST888YK is not considered to have the potential to cause skin sensitization.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

This study was performed to assess the skin sensitization potential of ST888YK using the guinea-pig. The method followed was that described in:

EEC Methods for the determination of toxicity, Annex to Directive 96/54/EC (Official Journal No. L248, 30.9.96), Part B, Method B.6. Skin sensitization.

OECD Guideline for Testing of Chemicals No. 406 "Skin Sensitization". Adopted 17 July 1992.

EPA Health Effects Test Guidelines OPPTS 870.2600 Skin Sensitization EPA 712-C-98-197. August 1998.

Japanese Ministry of Agriculture, Forestry and Fisheries, Test Data for Registration of Agricultural Chemicals, Skin sensitization (2-1-6), 12 NohSan No. 8147, Agricultural Production Bureau, November 24, 2000.

Based on the results of a preliminary study and in compliance with the guidelines, the following dose levels were selected:

Induction applications (3): ST888YK, 100% w/v in A1embicol D.

Challenge application: ST888YK, 100% w/v in Alembicol D.

Twenty test and ten control guinea-pigs were used in the main study.

In this study ST888YK did not produce evidence of skin sensitization (delayed contact hypersensitivity) in any of the twenty test animals. ST888YK is not considered to have the potential to cause skin sensitization.


Migrated from Short description of key information:
In this study ST888YK did not produce evidence of skin sensItIzation (delayed contact hypersensitivity) in any of the twenty test animals. ST888YK is not considered to have the potential to cause skin sensitization.

Justification for selection of skin sensitisation endpoint:
In this study ST888YK did not produce evidence of skin sensitization (delayed contact hypersensitivity) in any of the twenty test animals. ST888YK is not considered to have the potential to cause skin sensitization.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Based on the above information, the test material can be considered to be non-sensitising.

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