Registration Dossier

Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
1992
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The number of animals in the test group was 10 (20 required according to the guideline) and therefore the conclusions of the study are considered less reliable.
Cross-reference
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1992
Report Date:
1992

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EPA OTS 798.4100 (Skin Sensitisation)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of study:
Buehler test
Justification for non-LLNA method:
Read across of existing non-LLNA study on analogue

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: as 50% solution in Solvent Extracted Mineral oil

In vivo test system

Test animals

Species:
guinea pig
Strain:
Hartley
Sex:
male/female
Details on test animals and environmental conditions:
Animals were gang-caged in suspended stainless steel cages with mesh floors. Room temperature - 68-74°F. Each guinea pig was marked with a color code. This mark, together with the sequential animal/cage number assigned to study T-1592 constituted unique identification.
Prior to the period of induction, the highest non-irritating concentration (ENIC) and the minLmally irritating concentration (HIC) of test substance
was determined. The dorsal thoracolumbar region of five guinea pigs was rid of hair by clipping. This area was divided into test sites (2-4 sites
on each side of the midline) on each animal. The test substance was applied neat (100%) and was also diluted with corn oil to yield
concentrations of 75%, 50%, 25%, 12% and 6% w/w. A dose of 0.4 ml of each respective concentration was applied to the pre-assigned, delineated
test sites on each animal (See Table 1). Each site was covered with a Hilltop chamber which was secured in place with hypoallergenic adhesive
tape. After 6 hours of exposure the chambers were removed. Twenty-four hours after application, each site was evaluated for local reactions
(erythema) according to the scoring system. From these results the HNIC and the MIC were established. These were respectively defined as the
highest concentration that produced responses in 4 guinea pigs no more severe than 2 scores of 0.5 and 2 scores of zero and the lowest concentrations that produced mild to moderate irritation. The HIC was used for Induction and the HNIC was used for the challenge.

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
corn oil
Concentration / amount:
The sample was used as a 12% w/w solution in corn oil for the HNIC (highest non-irritating concentration) and a 75% w/w solution in corn oil
for the MIC (minimally irritating concentration).
Challengeopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
corn oil
Concentration / amount:
The sample was used as a 12% w/w solution in corn oil for the HNIC (highest non-irritating concentration) and a 75% w/w solution in corn oil
for the MIC (minimally irritating concentration).
No. of animals per dose:
10 Guinea Pigs Test Group
5 Guinea Pigs Naive Control Group
10 Guinea Pigs Positive Control Group


Details on study design:
Induction and Challenge:
Twenty guinea pigs were divided into subgroups and placed in stainless steel gang cages, 2 to 4 animals per cage. Ten animals were assigned to
the test group and ten were assigned to the positive control group. Prior to each application, the hair was removed from the dorsal thoracolumbar
region of each guinea pig by clipping. The test and positive control substances at their respective MIC's were placed onto a 25 mm Hilltop
Chamber. One dosing chamber was placed over the left scapular/thoracic region of each guinea pig. The chambers were secured in place with
hypoallergenic adhesive tape. They were removed after six hours of exposure and each site was wiped clean of residual material. Twenty-four
and 48 hours after each induction application, readings were made of local reactions (erythema). This process was repeated on the same day each
week until a total of three dose applications had been made. Fourteen days after the third induction dose the HNIC was used for the challenge phase.
These sites were evaluated for a sensitization response (erythema) at 24 and 48 hours after the challenge application.
In addition to the test and positive control animals, ten guinea pigs from the same shipment were maintained under identical environmental
conditions and were treated with the test or positive substance at the HNIC at the time of challenge only. These constituted the "naive" groups.
Challenge controls:
A challenge dose was applied to a naive site on the right side of each guinea pig and to the ten naive control animals using the procedures mentioned above.
Positive control substance(s):
yes
Remarks:
DNCS

Results and discussion

Positive control results:

The positive response to DNCB in Acetone validates the test system used in this study.

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
0.4 ml - 75% w/w solution in corn oil
No. with + reactions:
4
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 0.4 ml - 75% w/w solution in corn oil. No with. + reactions: 4.0. Total no. in groups: 10.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
0.4 ml - 75% w/w solution in corn oil
No. with + reactions:
4
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 0.4 ml - 75% w/w solution in corn oil. No with. + reactions: 4.0. Total no. in groups: 10.0.
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
0.4 ml - 0.15% DNCB in Acetone
No. with + reactions:
9
Total no. in group:
9
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: positive control. Dose level: 0.4 ml - 0.15% DNCB in Acetone. No with. + reactions: 9.0. Total no. in groups: 9.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
0.4 ml - 0.15% DNCB in Acetone
No. with + reactions:
9
Total no. in group:
9
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: positive control. Dose level: 0.4 ml - 0.15% DNCB in Acetone. No with. + reactions: 9.0. Total no. in groups: 9.0.

Applicant's summary and conclusion

Interpretation of results:
sensitising
Remarks:
Migrated information Criteria used for interpretation of results: US EPA pesticides
Conclusions:
Following challenge, 4 of 10 test animals exhibited a positive response in the absence of a similar reaction in the naive group. Based on these
findings and on the evaluation system used (Section 8), the test substance is considered to be a contact sensitizer when applied as a 75% w/w
solution in corn oil, once a week for 3 weeks.
The positive response to ONCB in Acetone validates the test system used in this study.
Executive summary:

The test substance was received from the sponsor on May 5, 1992. After establishing the minimum irritating concentration (HIC) and the highest non-irritating concentration (HNIC) to be 75% and 12% w/w in corn oil respectively, a 3 week induction period was initiated during which 10 young adult male guinea pigs were treated with the test substance at its MIC and 10 were treated with Dinitrochlorobenzene (DNCB) at its MIC (0.08% in 80% aqueous ethanol) (positive controls). Durin'g the induction period the animals were dosed on the same day each week until a total of 3 dose applications was achieved. Fourteen days after the third induction a challenge dose was applied at the respective test and positive control HNIC to a naive site on each group of guinea pigs and approximately 24 and 48 hours later the animals were scored for a sensitization response (erythema).

Two naive control groups of 5 animals each (5 for test and 5 for positive control) were maintained under the Bame environmental conditions and treated with the test or control substances at challenge only. Following challenge, 4 of 10 test animals exhibited a positive response in the absence of a similar reaction in the naive group. Based on these findings and on the evaluation system used, the test substance is considered to be a contact sensitizer when applied as a 75% w/w solution in corn oil, once a week for 3 weeks.

The positive response to DNCB in Acetone validates the test system used in this study.