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Description of key information

A Guinea Pig Maximization Test (GPMT) was conducted on MTDID 18990.

The results of the study was: Category 1A sensitizer when tested according to OECD 406.

The dermal sensitization potential of T-7353 was evaluated in the Maximization Test using male albino guinea pigs. This study was performed in compliance with OECD GLP (1997). The study design was based on OECD 406 (1992) and US EPA OPPTS 870.2600 (1998). T-7353 was prepared in mineral oil (vehicle) just prior to each dosing procedure. A pre-test rangefinder determined the appropriate doses for the intradermal and epidermal inductions and for the challenge phase. The test group (20 animals) received intradermal induction injections of 0.1 ml/site of a 1:1 mixture of Freund's Complete Adjuvant (FCA):water, 1% test article in vehicle, and 1% test article in 1:1 FCA/water.  A control group (10 animals) received the same induction treatment with the exclusion of test article.  Approximately 24 hours prior to the epidermal induction, the control group animals were pretreated with a 10% w/w sodium lauryl sulfate suspension in petrolateum. The test group animals did not need to be pretreated. The epidermal induction of sensitization was conducted under occlusion with 100% T-7353 (test group) or vehicle only (control group) one week after the intradermal induction. Two weeks after epidermal induction the control and test animals were challenged by epidermal application of 50% T-7353 and vehicle under occlusive dressing. Skin reactions were evaluated at 24 and 48 hours after removal of the dressing. A positive control (alpha-hexylcinnamaldehyde) is tested by this contract lab approximately every 6 months and the most recent test confirmed the validity of the experimental technique. No erythema or edema was observed at any site in the control group animals. No skin reactions were observed at the control sites in the test groupanimals. Mild to intense dermal reactions were observed at 19/20 test article sites in the test group animals (95% responding). Desquamation was also observed within these sites in 7/20 test group animals.  Based on the results of the study (95% responding, intradermal induction dose of 1%) the test article is a Category 1A 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
Study period:
2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
1996
Deviations:
no
Remarks:
No deviations ocurred that impacted the integrity of the study.
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
This study was conducted in 2000, prior to development of the REACH legislation and prior to the LLNA becoming a widely-used test method for sensitization.
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch number of test material: 3M Company, Lot not reported
- Expiration date of the lot/batch: No data
- Purity test date: No data

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: The test material was stored at room temperature.
- Stability under storage conditions: No data
- Stability under test conditions: No data
- Solubility and stability of the test substance in the solvent/dispersant/vehicle/test medium: No data
- Reactivity of the test substance with the solvent/vehicle /test medium (if applicable): No data

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: The test article was dosed in mineral oil or sterile water/FCA (Freund's Complete Adjuvant)
Species:
guinea pig
Strain:
Hartley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories
- Microbiological status of animals, when known: No data
- Age at study initiation: "Young Adult"
- Weight at study initiation: 390-432 grams
- Housing: After receipt, the animals were acclimated for a period of at least 5 days. During acclimation and throughout the study, the animals were individually housed in suspended, stainless steel cages.
- Diet (e.g. ad libitum): The animals were provided continuous access to certified guinea pig diet (#5026, Purina Mills, Inc.)
- Water (e.g. ad libitum): Tap water ad libitum.
- Acclimation period: At least 5 days
- Indication of any skin lesions: No data

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18-26
- Humidity (%): 30-70
- Air changes (per hr): No data
- Photoperiod (hrs dark / hrs light): 12/12
- IN-LIFE DATES: From: 04 January 2000 To: 11 February 2000
Route:
intradermal
Vehicle:
other: Mineral Oil
Concentration / amount:
0.1 mL of 1% w/v test article in mineral oil and in FCA/Sterile water
Day(s)/duration:
Day 1
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
Route:
epicutaneous, occlusive
Vehicle:
unchanged (no vehicle)
Concentration / amount:
The undiluted test article was applied to saturation to a 2 cm x 4 cm whatman no. 3 filter paper
Day(s)/duration:
Day 8, test substance removed after a 48 hour exposure.
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
other: Mineral Oil
Concentration / amount:
50% w/v mixture of the test material in mineral oil was applied to saturation to 2 cm x 2 cm Whatman No. 3 filter paper and placed on the right side of the shaved skin of the animal.
Day(s)/duration:
Day 22, 24 hour exposure.
Adequacy of challenge:
highest non-irritant concentration
No. of animals per dose:
20 animals were utlized in the test group, 10 in the control group.
Details on study design:
RANGE FINDING TESTS:
An irritation screening study using eight animals was conducted to determine the irritation threshold of the test material. The purpose of the irritation screening study was to find the highest test material concentration that does not produce excessive irritation to use for intradermal injections, a moderately irritating concentration to use for the topical induction application, and the highest nonirritating topical concentration to be used for the challenge application. One irritation screening subgroup of four animals was treated intradermally with the test material at concentrations of 1,5, 10, 15, and 25% w/v in mineral oil with each animal receiving all five concentrations of the test material. Each test material concentration was administered as a 0. l-mL intradermal injection into a single shaved site on each animal. The injection sites were evaluated for erythema and edema reactions at 24 and 48 hours after injection. A second irritation screening subgroup of four animals first received duplicate 0.1 -mL intradermal injections of a 1:l dilution of Freund's Complete Adjuvant (FCA) and sterile water on the shaved shoulder area (one injection on each side of the midline). Eight days after administration of the intradermal injections, the animals received a topical application of T-7353 undiluted and at concentrations of 25, 50, and 75% w/v in mineral oil. Four application sites were selected on the shaved back of each animal (two on the right side and two on the left side). Each animal received all four concentrations of the test material. The test material concentrations were applied to saturation on 2-cm x 2-cm Whatman No. 3 filter papers, placed over the respective application sites, covered with overlapping strips of Blenderm tape, and overwrapped with Elastoplast 'tape. The patches remained in place for 24 hours after which they were removed. Any residual material was then removed from the application sites using liquid Ivory soap mixed with water, rinsed with water, and dried with disposable paper towels. The application sites were observed for dermal reactions at 24 and 48 hours after patch removal. The sites were shaved before the 24-hour observation.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2 (one intradermal, one epicutaneous)
- Exposure period: Intradermal on Day 1, epicutaneous on Day 8.
- Test groups: 20 animals
- Control group: 10 animals
- Site: Midline of the shoulder region.
- Frequency of applications: One intradermal on Day 1, one epicutaneous on Day 8.
- Duration: The epicutaneous exposure was 48 hours.
- Concentrations: Intradermal: 1% test article, Epicutaneous: Undiluted test article

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: Day 22
- Exposure period: 24 hours
- Test groups: 1 (20 animals)
- Control group: 1 (10 animals)
- Site: The hair was removed from an approximate 5-cm x 5-cm area on the right and left sides of each animal by shaving as before.
- Concentrations: 50% w/v test article in mineral oil
- Evaluation (hr after challenge): 24 and 48 hours following challenge patch removal.
Challenge controls:
Mineral Oil
Positive control substance(s):
yes
Remarks:
A positive control (alpha-hexylcinnamaldehyde) is tested by this contract lab approximately every 6 months and the most recent test confirmed the validity of the experimental technique.
Positive control results:
A positive control (alpha-hexylcinnamaldehyde) is tested by this contract lab approximately every 6 months and the most recent test confirmed the validity of the experimental technique. The results of the most recent test indicate that the test system is valid.
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
50% w/v in mineral oil at challenge
No. with + reactions:
18
Total no. in group:
20
Clinical observations:
Desquamation was observed at the challenge sites in 7/20 test group animals.
Remarks on result:
positive indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
50% w/v test article in mineral oil at challenge.
No. with + reactions:
19
Total no. in group:
20
Clinical observations:
Desquamation was observed within these sites in 7/20 test group animals.
Remarks on result:
positive indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
0% (Mineral Oil only)
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
0% (Mineral Oil only)
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
50% HCA in mineral oil
No. with + reactions:
10
Total no. in group:
10
Remarks on result:
positive indication of skin sensitisation
Interpretation of results:
Category 1 (skin sensitising) based on GHS criteria
Conclusions:
Based on the results of the study (95% responding, intradermal induction dose of 1%) the test article is a Category 1A skin sensitizer.
Executive summary:

The dermal sensitization potential of T-7353 was evaluated in the Maximization Test using male albino guinea pigs. This study was performed in compliance with OECD GLP (1997). The study design was based on OECD 406 (1992) and US EPA OPPTS 870.2600 (1998). T-7353 was prepared in mineral oil (vehicle) just prior to each dosing procedure. A pre-test rangefinder determined the appropriate doses for the intradermal and epidermal inductions and for the challenge phase. The test group (20 animals) received intradermal induction injections of 0.1 ml/site of a 1:1 mixture of Freund's Complete Adjuvant (FCA):water, 1% test article in vehicle, and 1% test article in 1:1 FCA/water.  A control group (10 animals) received the same induction treatment with the exclusion of test article.  Approximately 24 hours prior to the epidermal induction, the control group animals were pretreated with a 10% w/w sodium lauryl sulfate suspension in petrolateum. The test group animals did not need to be pretreated. The epidermal induction of sensitization was conducted under occlusion with 100% T-7353 (test group) or vehicle only (control group) one week after the intradermal induction. Two weeks after epidermal induction the control and test animals were challenged by epidermal application of 50% T-7353 and vehicle under occlusive dressing. Skin reactions were evaluated at 24 and 48 hours after removal of the dressing. A positive control (alpha-hexylcinnamaldehyde) is tested by this contract lab approximately every 6 months and the most recent test confirmed the validity of the experimental technique. No erythema or edema was observed at any site in the control group animals. No skin reactions were observed at the control sites in the test groupanimals. Mild to intense dermal reactions were observed at 19/20 test article sites in the test group animals (95% responding). Desquamation was also observed within these sites in 7/20 test group animals.  Based on the results of the study (95% responding, intradermal induction dose of 1%) the test article is a Category 1A skin sensitizer.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:

The GPMT that was conducted on MTDID 18990 was conducted with a crude formulation with approximately 85 -87% CASRN 68911 -25 -1 and 13 -15% residual CASRN 4246 -51 -9. The purified mixture of MTDID 18990 contains 97.5% CASRN 68911 -25 -1 and 2.5% residual CASRN 4246 -51 -9. No experimental sensitization data exists for CASRN 4246 -51 -9 although it has been REACH registered as a Category 1 sensitizer based on structural alerts for terminal amino groups. In an abundance of caution, the data from the crude MTDID 18990 with higher residuals are applied to the purified MTDID 18990 to assign a Category 1A classification based on the GPMT results.

Justification for classification or non-classification

Based on the results of the study, MTDID 18990 is a Category 1A sensitizer.