Propargite

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12th December 1991 to 18th January 1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

EPA OPP 81-6 (Skin Sensitisation)

Deviations:

no

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

EPA OTS 798.4100 (Skin Sensitisation)

Deviations:

no

Test guideline 3

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes

Type of study:

Buehler test

Justification for non-LLNA method:

The study was conducted prior to the LLNA becoming the preferred method in the EU.

Test material

Test material information

Constituent 1

Reference substance name:

Propargite

EC Number:

219-006-1

EC Name:

Propargite

Cas Number:

2312-35-8

Molecular formula:

C19H26O4S

IUPAC Name:

propargite

Test material form:

liquid

Details on test material:

- Stability under test conditions: stable for at least one year at room temperature
- Storage condition of test material: sealed container at room temperature

In vivo test system

Test animals

Species:

guinea pig

Strain:

Hartley

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Kuiper Rabbit Ranch, Gary, Indiana, USA
- Age at study initiation: young adult
- Weight at study initiation: 361-457 g
- Housing: individual suspended wire-mesh cages
- Diet: Purina® Guinea Pig Chow® #5025 ad libitum
- Water: tap water ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature: 66-73 ºF
- Humidity: 30-74 %
- Photoperiod: 12 hours light/12 hours dark

Study design: in vivo (non-LLNA)

Induction

Route:

epicutaneous, occlusive

Vehicle:

other: ethanol and acetone for primary irritation phase and ethanol for induction phase

Concentration / amount:

0.1 % w/v

Challenge

Challenge 1

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

other: acetone for challenge phase

Concentration / amount:

0.2 % w/v at challenge

Challenge 2

No.:

#2

Route:

epicutaneous, occlusive

Vehicle:

other: acetone for rechallenge

Concentration / amount:

0.1 and 0.2 % w/v at rechallenge

No. of animals per dose:

Fifteen animals of each sex in the main study and eight animals of each sex in the primary irritation phase.

Details on study design:

RANGE FINDING TESTS:
0.4 mL of the test material was applied to animals at concentrations of 0.025, 0.05, 0.1, 02, 0.4, 0.8 and 1.5 % to determine the primary irritation index. Test material was applied for six hours occluded exposure.

MAIN STUDY
A. INDUCTION EXPOSURE
- Exposure period: 6 hours
- Test groups: two (one with ethanol as vehicle and one with acetone as vehicle)
- Frequency of applications: once per week
- Duration: three weeks
- Concentrations: 0.2 % w/v

B. CHALLENGE EXPOSURE
- No. of exposures: two (challenge and rechallenge a week later)
- Exposure period: 6 hours
- Test groups: one
- Control group: two (challenge and rechallenge)
- Concentrations: 0.2 % w/v (challenge); 0.1 and 0.2 % w/v (rechallenge)
- Dose: 0.4 mL/site

Positive control substance(s):

yes

Remarks:

0.25 % w/v dinitrochlorobenzene in 80 % ethanol

Results and discussion

In vivo (non-LLNA)

Results

Results 1

Key result

Reading:

other: challenge

Hours after challenge:

48

Group:

test chemical

Dose level:

0.2 % w/v test material.

Remarks on result:

other: sensitisation incidence index of 8 %

Results 2

Key result

Reading:

rechallenge

Hours after challenge:

48

Group:

test chemical

Dose level:

0.1 and 0.2 % w/v

Remarks on result:

other: sensitisation incidence index of 0 %

Any other information on results incl. tables

None of the animals died and there were no remarkable changes or differences observed in body weights.

Primary irritation phase

In the primary irritation phase, 0.1 and 0.2 % w/v were the highest concentrations tested that caused no or slight irritation. They were therefore selected as the doses to be used in the main study.

Induction phase

The first induction dose caused slight patchy erythema in six animals. The second dose caused slight patchy erythema in five animals and moderate patchy erythema in one animal. The third dose caused slight patchy erythema in ten animals and moderate patchy erythema (with eschar) in one animal. The responses in the induction phase to the positive control substance were significantly more marked.

Challenge phase

In the test group, slight patchy erythema and moderate patchy erythema was noted in five animals and one animal, respectively, 24 hours after the challenge dose with 0.2 % w/v test material. At 48 hours, slight patchy erythema was seen in five animals. Slight patchy erythema was seen in three of the naive control animals at 24 and 48 hours post-dose. The responses in the challenge phase to the positive control material were significantly more marked. In this phase, only 1/12 animals in the test group (previously exposed) exhibited a grade 1 (moderate patchy erythema) response. Since all responses in the naive control group (previously unexposed) were less than grade 1, a sensitisation incidence index of 8 % was apparent for the test group. The sensitisation incidence index for the positive control group was 100 % in this phase.

Rechallenge phase

Following rechallenge with 0.1 % w/v test material, slight patchy erythema was noted in four animals and three animals, 24 and 48 hours post-dose, respectively. There were no irritation responses in the naive control animals following rechallenge with 0.1 % w/v test material. Following rechallenge with 0.2 % w/v test material, slight patchy erythema was noted in eight animals at 24 hours, with one animal exhibiting moderate patchy erythema (a Grade 1 response). This Grade 1 response was not considered indicative of sensitisation, however, as a grade 1 response was also observed in the naive group at this dose and time point. At 48 hours, slight patchy erythema was seen in five and one animals in the 0.2 % w/v and naive groups, respectively. In this phase, no animals in the 0.1 and 0.2 % w/v test groups (previously exposed) exhibited equal to/greater than grade 1 responses, the only exception being in one animal as discussed, but this was matched by a concurrent Grade 1 response in the naive control group. There were no other grade 1 responses in the naive control group. Therefore, a sensitisation incidence index of 0 % was apparent for the test group at rechallenge.

Applicant's summary and conclusion

Interpretation of results:

other: Not classified in accordance with EU criteria

Conclusions:

Based solely on the sensitisation index of 8 % at challenge dosing, the test material could be considered to be a weak sensitiser. However, there was no evidence of sensitisation at re-challenge. Moreover, the single grade 1 response seen in the test group at the first challenge could have been due to primary irritation rather than sensitisation. This hypothesis is supported by the fact that the 0.2 % w/v dose employed at first challenge was clearly minimally irritating to both test and nalive control animals. Therefore, taken together, the results indicate that the test material is non-sensitising to guinea pigs under the conditions of this study.

Executive summary:

Six male and female guinea pigs were dosed topically with the test material once per week for three weeks for a total of three induction exposures. Two weeks after the last induction exposure, animals were challenge dosed for detection of sensitisation by topical application of known non-irritating concentration of the test material to previously unexposed areas of the skin. One week after challenge dosing, animals were rechallenged to confirm the initial challenge results.

Two naive groups of three male and three female guinea pigs each were dosed only at challenge and rechallenge respectively, in the same manner as the test group and served as irritation controls.

Reactions to challenge and rechallenge were evaluated at approximately 24 and 48 hours after completion of exposure. Body weights and clinical observations were recorded just prior to study initiation and at termination.

There were no deaths, test material related clinical findings or remarkable body weight changes during the study.

Following the initial challenge with a 0.2 % concentration of test material, there was a single grade 1 reaction in the test group at 24 hours that exceeded the highest reaction in the naive control I group. There were five and three grade ± (slight patchy erythema) reactions at 24 and 48 hours in the test and naive control groups respectively.

Following the rechallenge with both a 0.1 and 0.2 % concentration of test material, there were no reactions in the test group that could be attributed to sensitisation. The 0.1 % concentration induced four and three grade ± reactions in the test group at 24 and 48 hours, respectively, and no reactions in the naive control II group. The 0.2 % concentration induced a single grade 1 reaction in both the test and naive control II groups at 24 hours. There were eight and five grade ± reactions in the test group at 24 and 48 hours, respectively, and a single grade ± reaction at 24 and 48 hours in the naive control II group.

The incidence of grade ± reactions in both naive control groups and the grade 1 reaction in the naive control II group indicate that the 0.2 % concentration of the test material was minimally irritating. The single grade 1 reaction in the test group following challenge dosing could not clearly be ascribed to sensitisation due to the low levels of irritation caused by the test material. The substance was therefore found to be non-sensitising.