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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
9th October to 20th November 1996
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The Protocol, study conduct, and the final report were audited by the Quality Assurance Unit in accordance with applicable Standard Operating Procedures (SOPs). The study was EPA regulated and was listed on the test facility's master list of regulated studies. Not a guideline study but looks similar to OECD 406 and done to GLP. Skin irritation was observed in the animals in the naive control group.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997
Report Date:
1997

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
Buehler Method
Deviations:
no
GLP compliance:
yes
Type of study:
Buehler test
Justification for non-LLNA method:
Existing study

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
122384-85-4/68855-45-8
Phenol, dodecyl-, sulfurized, calcium salts
Purity not provided.

In vivo test system

Test animals

Species:
guinea pig
Strain:
Hartley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Sprague Dawley, Inc. P.O. Box 29176 Indianapolis, Indiana 46229
- Age at study initiation: 6-11 weeks old (±5 days).
- Weight at study initiation: At the start of the pilot phase of testing the pilot animals weighed 114 - 489 grams
- Housing: Animals were individually housed in wire mesh suspension cages.
- Diet/water (e.g. ad libitum): Teklad Guinea Pig Diet and tap water were supplied ad libitum during both acclimation and test periods.
- Acclimation period: Prior to use, all animals were acclimated for at least seven days.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 64-79° F
- Humidity (%): 30-70%.
- Photoperiod (hrs dark / hrs light): 12-hour light/12-hour dark cycle

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
other: mineral oil
Concentration / amount:
Pilot irritation: 0.5, 1, 2.5, 5, 10, 25, 50 and 100%
Induction phase: 25%
Challenge phase: 5%
Naive Control phase: 5%
Challengeopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
other: mineral oil
Concentration / amount:
Pilot irritation: 0.5, 1, 2.5, 5, 10, 25, 50 and 100%
Induction phase: 25%
Challenge phase: 5%
Naive Control phase: 5%
No. of animals per dose:
8 for pilot irritation study; 10 for naive control; 20 for sensitization test animals (equal numbers of males/females)
Details on study design:
RANGE FINDING TESTS:
Irritation Screening (Pilot):
The irritation phase had the purpose of determining the proper level of test material to be used in the induction and challenge phases. The irritation potential of the test material at levels of undiluted, 50%, 25%, 10%, 5%, 2.5%, 1%. and 0.5% was evaluated in two groups of four animals each. Four levels of the test material were evaluated per animal such that each animal al in a given pilot group was exposed to the same levels. Dilutions of the test material were formulated w/v in Mineral Oil. Immediately following formulation, the dilutions were heated in a 60°C water bath to achieve solubility. The test material was allowed to cool prior to application. The position of the different concentrations of the test material on the animals was varied to adjust for possible site-to-site variation in response.
The day prior to test material exposure, the hair was removed from each of the animal's backs using a snail animal clipper. Closed patches were applied to the animals in the following manner: A 0.3 ml quantity of each test preparation was applied into a 25 mm Hill Top Chamber®. The animal was placed into the restrainer, and the chambers were applied to the clipped surface as quickly as possible. The chambers were occluded with rubber dental dam pulled taut and fastened to the bottom of the restrainer with clips. The restrainer was adjusted to minimize movement of the animal during exposure. Approximately six hours later, the dental dam and chambers were removed and the animal was taken from the restrainer and placed in its cage.
The day following the irritation exposure all animals were depilated and scored as described under the "Observations" section.


MAIN STUDY
A. INDUCTION EXPOSURE
The purpose of this phase was to dermally expose the animals so that if the material was a sensitizer, the physiological process required to ultimately allow the generation of an immunological response could be initiated.

The left shoulder (Site 1) of each animal was clipped with a small animal clipper the day before exposure.
The animals were restrained, and a 0.3 ml quantity of the test preparation was applied using a Hill Top Chamber® as previously described under the "Irritation Screening" section. The procedure was repeated at the same site once a week for the next two weeks for a total of three approximate six-hour exposures (the interval between induction exposures varied from six to seven days). After the last induction exposure, the animals were left untreated for approximately two weeks (14 days) before primary challenge.


B. CHALLENGE EXPOSURE
The purpose of this phase was to investigate the elicitation of response. The test animals, which had three previous exposures to the test material at appropriate intervals, were again exposed in the challenge phase approximately two weeks after the last induction exposure. In addition, ten naive animals, which had never been exposed to the test material, were concurrently treated with the same test material concentration.

The same exposure procedure as for the "Induction Phase" was used except the chambers were applied to a skin site that had not been exposed previously. The test animals received a single patch of the test material at Site 2. The naive control animals. common to this study and another study [HTR Project No. 96-8244-21] received one patch of each of the respective test materials at Sites 2 and 5. The patch sites were rotated to reduce site-to-site variations in response.

The day following irritation screening and primary challenge, all animals were depilated with a commercial depilatory. The depilatory was placed on the test sites and surrounding area and left on for no more than fifteen minutes. The depilatory was thoroughly removed with warm, running water.
The animals were dried with a towel and returned to their cages.

Following a minimum of two hours after depilation. the test sites were graded using the following scale:

0 = no reaction
± = slight, patchy erythema
1 = slight but confluent, or moderate patchy erythema
2 = moderate erythema
3 = severe erythema with or without edema

The grading was repeated the following day. For reporting purposes, the first and second gradings were designated as 24 and 48 hour readings, respectively.


OTHER:
Challenge controls:
Naive controls were used.
Positive control substance(s):
yes
Remarks:
Hexyl cinnamic adlehyde and 1-chloro-2,4-dinitrobenzene served as historic positive controls.

Results and discussion

Positive control results:
Group 1 test animals received one induction treatment utilizing 1-CHLORO-2,4-DINITROBENZENE (DNCB) at a concentration of 0.3% formulated w/v in 95% ethanol. Approximately two weeks (14 days) following the induction treatment, a primary challenge treatment was conducted utilizing the ten test animals and five naive control animals. Each animal received 1-CHLORO-2,4-DINITROBENZENE (DNCB) at concentrations of 0.1%, 0.05%, and 0.01% formulated w/v in acetone.

Group 2 test animals received three induction treatments utilizing a - Hexylcinnamaldehyde, tech., 85% at a concentration of 2.5% formulated w/v in 95% ethanol. Approximately two weeks (16 days) following the induction treatments, a primary challenge treatment was conducted utilizing the ten test animals and five naive control animals. Each animal received a - Hexylcinnamaldehyde, tech., 85% at concentrations of 5%, 2.5%, and 1.0% formulated w/v in acetone.

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
5% w/v in mineral oil
No. with + reactions:
6
Total no. in group:
20
Clinical observations:
6 animals with slight but confluent, or moderate patchy erythema (1) and 14 animals with slight, patchy erythema (±)
Remarks on result:
other: see Remark
Remarks:
Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 5% w/v in mineral oil. No with. + reactions: 6.0. Total no. in groups: 20.0. Clinical observations: 6 animals with slight but confluent, or moderate patchy erythema (1) and 14 animals with slight, patchy erythema (±).
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
5% w/v in mineral oil
No. with + reactions:
3
Total no. in group:
10
Clinical observations:
3 animals with slight but confluent, or moderate patchy erythema (1) and 7 animals with slight, patchy erythema (±)
Remarks on result:
other: see Remark
Remarks:
Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 5% w/v in mineral oil. No with. + reactions: 3.0. Total no. in groups: 10.0. Clinical observations: 3 animals with slight but confluent, or moderate patchy erythema (1) and 7 animals with slight, patchy erythema (±).
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
5% w/v in mineral oil
No. with + reactions:
2
Total no. in group:
20
Clinical observations:
2 animals with slight but confluent, or moderate patchy erythema (1) and 18 animals with slight, patchy erythema (±)
Remarks on result:
other: see Remark
Remarks:
Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 5% w/v in mineral oil. No with. + reactions: 2.0. Total no. in groups: 20.0. Clinical observations: 2 animals with slight but confluent, or moderate patchy erythema (1) and 18 animals with slight, patchy erythema (±).
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
5% w/v in mineral oil
No. with + reactions:
2
Total no. in group:
10
Clinical observations:
2 animals with slight but confluent, or moderate patchy erythema (1) and 8 animals with slight, patchy erythema (±)
Remarks on result:
other: see Remark
Remarks:
Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 5% w/v in mineral oil. No with. + reactions: 2.0. Total no. in groups: 10.0. Clinical observations: 2 animals with slight but confluent, or moderate patchy erythema (1) and 8 animals with slight, patchy erythema (±).

Any other information on results incl. tables

Following challenge using a 5% w/v formulation of the test material in mineral oil, the incidence of grade 1 responses in the test group (6/20) was comparable to that of the naive control group (3/10). The incidence and severity data suggest that the test material was not a dermal sensitizer.

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information
Conclusions:
The test material was not considered a sensitizer in the Hartley guinea pig.
Executive summary:

The potential of the test material, as a 25% w/v formulation in Mineral Oil, to produce delayed contact hypersensitivity in guinea pigs was evaluated using an adaptation of the method of Ritz and Buehler.

Following primary challenge using the test material, as a 5% w/v formulation in Mineral Oil, the incidence of grade I responses in the test group (6 of 20) was compared to that of the naive control group (3 of 10). The incidence and severity of these responses in the test group were essentially comparable to those produced by the naive control group indicating that sensitization had not been induced.