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Description of key information

The skin sensitization potential of test chemical was assessed in various experimental studies conducted on human subjects and rabbits. Based on the available data for the test chemical, it can be concluded that the test chemical is unable to cause skin sensitization and thus can be considered as not sensitizing. Comparing the above annotations with the criteria of CLP regulation, it can be classified under the category “Non-Skin Sensitizer”.

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:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Justification for type of information:
Data is from peer reviewed journal.
Qualifier:
according to guideline
Guideline:
other: as mentioned below
Principles of method if other than guideline:
Human Repeat Insult Patch Test was conducted on an exclusive panel of 200 male and female volunteers to assess the skin sensitization potential of test chemical.
GLP compliance:
not specified
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
Not applicable
Species:
guinea pig
Strain:
Hartley
Remarks:
albino
Sex:
male/female
Details on test animals and environmental conditions:
- Age at study initiation: Young adult Hartley albino guinea pigs
- Weight at study initiation: 306-528 g
Route:
intradermal and epicutaneous
Vehicle:
not specified
Concentration / amount:
Intradermal application:
0.1 ml of 50% (v/v) Freund's Complete Adjuvant (FCA) water emulsion, the test material, and the test material in FCA/water emulsion.

Topical application: 0.3 ml –applied to saturation
Day(s)/duration:
48 hours
Adequacy of induction:
other: The concentration that produced only local necrosis (i.e., no extensive necrosis or ulceration) was used for the intradermal induction. The highest concentration that produced only mild irritation was appropriate for the topical induction.
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
not specified
Concentration / amount:
75%
Day(s)/duration:
48 hours
Adequacy of challenge:
highest non-irritant concentration
No. of animals per dose:
10 guinea pigs/ group
Details on study design:
RANGE FINDING TESTS: Range-finding studies were conducted to select appropriate concentrations of test chemical for the intradermal and topical procedures. Animals were inspected 24 and 48 h after dosing for signs of inflammation, necrosis, and ulceration. The concentration that produced only local necrosis (i.e., no extensive necrosis or ulceration) was used for the intradermal induction. The highest concentration that produced only mild irritation was appropriate for the topical induction, and the highest concentration that did not produce irritation was used for the topical challenge.

MAIN STUDY
A. INDUCTION EXPOSURE: INTRADERMAL
- No. of exposures:1
- Exposure period: 9 days
- Test groups:10 guinea pigs
- Control group:10 guinea pigs
- Site: each guinea pig received 0.1 ml intradermal induction injections into two sites each of the clipped shoulder skin.
- Frequency of applications: not specified
- Duration: 5-9 days
-Concentrations: 0.1 ml of 50% (v/v) Freund's Complete Adjuvant (FCA) water emulsion, the test material, and the test material in FCA/water emulsion.


A.II. INDUCTION EXPOSURE: TOPICAL
- No. of exposures: 1
- Exposure period: 48 hours
- Test groups: 10 guinea pigs
- Control group: 10 guinea pigs
- Site: not specified
- Frequency of applications: not specified
- Duration: 48 hours
- Concentrations:0.3 ml –applied to saturation


B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: 12-16 days later
- Exposure period:24 hours
- Test groups: 10 guinea pigs
- Control group: 10 guinea pigs
- Site: a previously untreated site (right flank)
- Concentrations: 75%
- Evaluation (hr after challenge): 24-48 h after removal of the occlusive dressings

OTHER: If the test article was nonirritating, 10% (w/w) sodium lauryl sulfate in petrolatum might be massaged into the skin to produce a mild inflammatory response.
Challenge controls:
Vehicle control animals were similarly treated with distilled water.
Positive control substance(s):
yes
Remarks:
Positive control animals were similarly treated with 5 % formaldehyde.
Reading:
1st reading
Hours after challenge:
48
Group:
test chemical
Dose level:
75%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
The severity indices in the test group were comparable to those produced in the irritation control groups, suggesting that sensitization had not been induced.
Remarks on result:
no indication of skin sensitisation

Twenty nine of the 30 animals (97%) challenged with 5% formaldehyde (positive control) showed clear skin responses, while all the irritation control animals were free of skin responses, confirming the validity of this skin sensitization test.

Interpretation of results:
other: not sensitizing
Conclusions:
The test material was considered to be not sensitizing on skin of guinea pigs in a Guinea pig maximisation test described by Magnusson and Kligman.
Executive summary:

A Guinea pig maximisation test was conducted to evaluate the allergic contact sensitization potential of test chemical.

 

Range-finding studies were conducted to select appropriate concentrations of test chemical for the intradermal and topical procedures. Animals were inspected 24 and 48 h after dosing for signs of inflammation, necrosis, and ulceration. The concentration that produced only local necrosis (i.e., no extensive necrosis or ulceration) was used for the intradermal induction. The highest concentration that produced only mild irritation was appropriate for the topical induction, and the highest concentration that did not produce irritation was used for the topical challenge.

 

In the definitive sensitization test, groups of 10 male and 10 female guinea pigs each received 0.1 ml intradermal induction injections into two sites each of the clipped shoulder skin as follows: 50% (v/v) Freund's Complete Adjuvant (FCA) water emulsion, the test material, and the test material in FCA/water emulsion. Topical inductions were conducted 5-9 days later. If the test article was nonirritating, 10% (w/w) sodium lauryl sulfate in petrolatum might be massaged into the skin to produce a mild inflammatory response. The test material was applied to saturation (0.3 ml) to a 2 x 4 cm filter paper that was then placed on the test site and secured with tape. The patches were left in place for about 48 h, after which they were removed and the skin wiped free of any excess test material.

 

Topical challenge was undertaken 12-16 days later by applying 2 x 2 cm filter paper squares soaked in the appropriate concentration of the test material to a previously untreated site (right flank). Patches were left in place for 24 h, and the sites inspected for signs of irritation 24-48 h after removal of the occlusive dressings.

 

Positive control and vehicle control animals were similarly treated with 5 % formaldehyde and distilled water, respectively. Irritation control animals received the same challenge procedures as in the definitive sensitization study, but did not undergo the preceding intradermal and topical induction procedures.

 

These naive animals allowed differentiation between primary skin irritation due to the test material and those produced by a hypersensitivity reaction.

 

In general, scores of 1 or greater were considered clearly indicative of sensitization. Scores of 0.5 were considered equivocal, although a high percentage of 0.5 scores with no response in irritation control animals would be considered suggestive of sensitization. The percentage of animals reacting, rather than the intensity of reactions, was the criterion for assessing sensitization potency.

 

The Twenty nine of the 30 animals (97%) challenged with 5% formaldehyde (positive control) showed clear skin responses, while all the irritation control animals were free of skin responses, confirming the validity of this skin sensitization test.

 

The severity indices in the test group were comparable to those produced in the irritation control groups, suggesting that sensitization had not been induced. 

 

Since the test chemical did not cause skin sensitization in treated group, the chemical was considered to be not sensitizing to the skin of guinea pigs in a Guinea pig maximisation test described by Magnusson and Kligman.

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

Various studies has been investigated for the test chemical to observe the potential for skin sensitization to a greater or lesser extent. The studies are based on in vivo experiments in human and rabbits for test chemical which have been summarized as below:

A Guinea pig maximisation test was conducted to evaluate the allergic contact sensitization potential of test chemical. Range-finding studies were conducted to select appropriate concentrations of test chemical for the intradermal and topical procedures. Animals were inspected 24 and 48 h after dosing for signs of inflammation, necrosis, and ulceration. The concentration that produced only local necrosis (i.e., no extensive necrosis or ulceration) was used for the intradermal induction. The highest concentration that produced only mild irritation was appropriate for the topical induction, and the highest concentration that did not produce irritation was used for the topical challenge. In the definitive sensitization test, groups of 10 male and 10 female guinea pigs each received 0.1 ml intradermal induction injections into two sites each of the clipped shoulder skin as follows: 50% (v/v) Freund's Complete Adjuvant (FCA) water emulsion, the test material, and the test material in FCA/water emulsion. Topical inductions were conducted 5-9 days later. If the test article was nonirritating, 10% (w/w) sodium lauryl sulfate in petrolatum might be massaged into the skin to produce a mild inflammatory response. The test material was applied to saturation (0.3 ml) to a 2 x 4 cm filter paper that was then placed on the test site and secured with tape. The patches were left in place for about 48 h, after which they were removed and the skin wiped free of any excess test material. Topical challenge was undertaken 12-16 days later by applying 2 x 2 cm filter paper squares soaked in the appropriate concentration of the test material to a previously untreated site (right flank). Patches were left in place for 24 h, and the sites inspected for signs of irritation 24-48 h after removal of the occlusive dressings. Positive control and vehicle control animals were similarly treated with 5 % formaldehyde and distilled water, respectively. Irritation control animals received the same challenge procedures as in the definitive sensitization study, but did not undergo the preceding intradermal and topical induction procedures. These naive animals allowed differentiation between primary skin irritation due to the test material and those produced by a hypersensitivity reaction. In general, scores of 1 or greater were considered clearly indicative of sensitization. Scores of 0.5 were considered equivocal, although a high percentage of 0.5 scores with no response in irritation control animals would be considered suggestive of sensitization. The percentage of animals reacting, rather than the intensity of reactions, was the criterion for assessing sensitization potency. The Twenty nine of the 30 animals (97%) challenged with 5% formaldehyde (positive control) showed clear skin responses, while all the irritation control animals were free of skin responses, confirming the validity of this skin sensitization test. The severity indices in the test group were comparable to those produced in the irritation control groups, suggesting that sensitization had not been induced.  Since the test chemical did not cause skin sensitization in treated group, the chemical was considered to be not sensitizing to the skin of guinea pigs in a Guinea pig maximisation test described by Magnusson and Kligman.

The above result was supported by Human Repeat Insult Patch Test which was conducted on an exclusive panel of 200 male and female volunteers to assess the skin sensitization potential of test chemical. Each enrolled subject was provided with a schedule of the study activities. They were instructed to avoid wetting the test sites and were asked not to engage in activities that caused excessive perspiration. They were further advised to notify the staff if they experienced any discomfort beyond mild itching and/or observed any adverse changes at the test sites during the study or within 2 weeks of completing the study. The induction phase consisted of nine consecutive applications of the test material in skin patches. The subjects were required to remove the patches about 24 h after application. They returned to the test facility at 48 h intervals to have the sites evaluated and identical patches reapplied. Following the ninth evaluation, the subjects had a 14 day rest period. The challenge phase was initiated during the sixth week, with similar patches applied to sites previously unexposed to the test material. These patches were removed by the subjects after 24 h, and the sites were evaluated twice: at 24 and 48 h later.In the human repeat insult patch test, 200 subsequently completed the study. Ten subjects discontinued for personal reasons, five subjects were dismissed due to noncompliance, and one subject was disqualified when she disclosed that she had become pregnant during the course of the study. No definite skin responses were observed in induction phase. During the challenge phase, definite skin responses were observed at 24 h following application in only one subject (a 69-year-old white woman). However, this subject was free of skin response at the second evaluation 24 h later. Thus on the basis of above findings, the test chemical was considered to be not sensitizing to the skin of treated subjects.

Both the above studies were supported by the intracutaneous guinea pig sensitization tests were performed, following the technique described by Draize.13 to 16 guinea pigs were used and 8 injections were given.Three weeks were allowed for development of sensitivity. Since,no sensitization reactions were observed,the test chemical can be considered as non sensitizing to the guinea pig skin.

Further, The intracutaneous guinea pig sensitization tests were performed, following the technique described by Draize.13 to 16 guinea pigs were used and 8 injections were given.Three weeks were allowed for development of sensitivity. Since,no sensitization reactions were observed,the test chemical can be considered as non sensitizing to the guinea pig skin.

The overall results were further supported by a modified Landsteiner intradermal sensitization test was conducted in groups of 20 male albino guinea pigs. Saline was used as control.During induction, 0.05 ml intradermal dose was given in a series of 8 doses of 0.1 ml of a 0.1 %, aqueous solution of test chemical in 0.85% NaCl was given on alternate days, 3 per week. Following a 3-wk incubation period a challenge dose of 0.05 ml was given intradermally. The test chemical did not induced skin sensitization in any animal at tested concentration. Hence the test material was considered as not sensitizing to the skin.

Thus based on the above key and supporting studies for test chemical, it can be concluded that the test chemical is unable to cause skin sensitization. Comparing the above annotations with the criteria of CLP regulation, it can be classified under the category “Non-Skin Sensitizer”.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

The skin sensitization potential of test substance was observed in various studies. The results obtained from these studies concluded that the chemical is not likely to cause skin sensitization and hence can be classified as non-skin sensitizer.