Pyrasulfotole

Endpoint summary

Description of key information

Skin sensitisation (OECD 406): not sensisiting

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:

06 Apr - 14 Jun 2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

adopted 17 Jul 1992

Deviations:

no

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

The study was conducted prior to the current requirement in Regulation (EC) 1907/2006 to perform an LLNA study (OECD 429) as the preferred in vivo skin sensitisation study.

Species:

guinea pig

Strain:

other: Crl:HA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratory Animal Breeders, Kisslegg, Germany
- Females nulliparous and non-pregnant: yes
- Age at study initiation: 5 - 6 weeks
- Weight at study initiation: 296 - 393 g
- Housing: 5 animals (acclimation period) or 2 - 3 animals (study period) in type IV Makrolon® cages with low-dust wood shavings bedding (Rettenmeier & Söhne GmbH & Co., Rosenberg, Germany)
- Diet: Provimi Kliba 3420 - Maintenance Diet for Guinea Pigs, Provimi Kliba AG, ad libitum
- Water: tap water, ad libitum
- Acclimation period: at least 5 days
- Indication of any skin lesions: no

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 40 - 70%
- Air changes (per hr): ≥ 10
- Photoperiod (hrs dark / hrs light): 12/12

Route:

intradermal

Vehicle:

physiological saline

Concentration / amount:

5% (40 mg/animal)

Day(s)/duration:

single injection

Adequacy of induction:

other: highest concentration used in a dose-range-finding study for intradermal induction leading to wheal after 24 and 48 h in the test animal

Route:

epicutaneous, occlusive

Vehicle:

physiological saline

Concentration / amount:

6% (30 mg/animal)

Day(s)/duration:

48 h

Adequacy of induction:

other: concentration used in a dose-range-finding study and induced slight localized redness after 48 h in 3/4 animals

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

physiological saline

Concentration / amount:

3% (15 mg/animal)

Day(s)/duration:

24 h

Adequacy of challenge:

other: highest concentration used in a dose-range-finding study for challenge which was non-irritant

No. of animals per dose:

Range-finding study: 1 (intradermal induction), 4 (topical induction), 2 (challenge)
Main study: 10 (controls), 20 (test group)

Details on study design:

RANGE FINDING TESTS:
For the dose range-finding for intradermal induction one animal was given intradermal injections with 0.1 mL of 0, 1, 2.5 and 5% test substance in physiological saline. The evaluation of the injection sites 24 and 48 h showed no effect at the 0% site but wheal at all other sites. Thus, 5% of the test substance was selected for the intradermal induction. For topical induction two studies with four animals each and three concentration (0, 12, 25 and 50% in the first study and 0, 1, 3 and 6% in the second study respectively) were conducted. The skin reactions were evaluated 48 and 72 h after start of application and based on the findings 6% of the test substance was selected for epicutaneous induction. Two animals were administered three concentrations of the test substance (0, 0.5, 1 and 3%) under occlusive conditions for 24 h for the dose range-finding for challenge. The skin reactions were evaluated 48 and 72 h after start of application and based on the findings 3% of the test substance was selected for challenge.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2 (intradermal and epicutaneous, respectively)
- Exposure period: single injection (intradermal) and 48 h (epicutaneous)
- Test groups:
Injection 1: a 1:1 mixture FCA/physiological saline solution
Injection 2: 5% test substance in physiological saline solution
Injection 3: equal amounts of 5% test substance in physiological saline solution and FCA
Epicutaneous: 0.5 mL 6% test substance in physiological saline solution
- Control group:
Injection 1: a 1:1 mixture FCA/physiological saline solution
Injection 2: undiluted physiological saline solution
Injection 3: a 1:1 mixture FCA/physiological saline solution
Epicutaneous: 0.5 mL physiological saline solution
- Site: cranial/bilateral (injection 1 and 3), medial/bilateral (injection 2)
- Frequency of applications: single injection (intradermal), single application (epicutaneous induction; one week after intradermal application)
- Duration: 9 days
- Concentrations: intradermal induction 5%, epicutaneous 6%

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: three weeks after intradermal induction (day 21)
- Exposure period: 24 h
- Test groups: 3% test substance in physiological saline solution
- Control group: 3% test substance in physiological saline solution
- Site: right flank (caudal)
- Concentrations: 3%
- Evaluation (hr after challenge): 48 and 72 h after the start of the application to induce the challenge (24 and 48 h after patch removal)

OTHER:
- Clinical signs: The animals were observed for clinical signs at least once daily throughout the entire study period.
- Body weights: The body weights of the animals were recorded before the first induction and at the end of the study.

Challenge controls:

The control group is actually a challenge control.

Positive control substance(s):

yes

Remarks:

(alpha hexyl cinnamic aldehyde formulated in polyethylene glycol 400; intradermal induction: 5%, epicutaneous induction: 25%, challenge: 12%)

Positive control results:

100% of the test animals exhibited dermal reactions in the challenge treatment with the positive control substance. There was no reddening of the skin to be observed on control group animals.

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

Induction: 0%; challenge: 3%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

strong effects up to encrustation at the injection sites after intradermal induction

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

Induction: 5% (intradermal) and 6% (epicutaneous); challenge: 3%

No. with + reactions:

0

Total no. in group:

19

Clinical observations:

strong effects up to encrustation at the injection sites after intradermal induction; clinical signs (poor general condition, piloerection, laboured breathing, pale) and subsequent death (day 15) in 1/20 animal

Remarks on result:

no indication of skin sensitisation

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

Induction: 0%, challenge: 3%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

strong effects up to encrustation at the injection sites after intradermal induction

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

Induction: 5% (intradermal) and 6% (epicutaneous), challenge: 3%

No. with + reactions:

0

Total no. in group:

19

Clinical observations:

strong effects up to encrustation at the injection sites after intradermal induction; clinical signs (poor general condition, piloerection, laboured breathing, pale) and subsequent death (day 15) in 1/20 animal

Remarks on result:

no indication of skin sensitisation

Reading:

1st reading

Group:

positive control

Dose level:

Induction: 5% (intradermal) and 25% (epicutaneous), challenge: 12%

Remarks on result:

positive indication of skin sensitisation

Remarks:

100% of the test animals exhibited dermal reactions in the challenge treatment.

- Body weights:

At the end of the study, the mean body weight of the treatment group animals was in the same range than that of the control group animals.

Interpretation of results:

other: CLP/GHS criteria not met; no classification required according to Regulation (EC) No. 1272/208

Conclusions:

The study was performed in accordance to OECD TG 406 under GLP conditions and is considered reliable. The test substance was non-sensitizing.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Regarding skin sensitisation a reliable study is available. A study for respiratory sensitisation potential is not available.

The skin sensitising potential of the test substance was investigated in a guinea pig maximisation test (GPMT test) performed according to OECD Guideline 406 and in compliance with GLP (M-072614-01-2). 30 female Crl:HA guinea pigs were used (20 animals as test group, 10 animals as control group) to evaluate skin sensitising effects. The test material was formulated in physiological saline. The induction and challenge concentrations were determined in a range-finding study. The intradermal induction was conducted by administration of three pairs of injections. The first pair of injections was of Freund's complete adjuvant (FCA) diluted 1:1 in physiological saline, the second pair was of 5% of the test substance, and the third pair of injections was of 5% of the test substance with FCA. The control group received three pairs of injections that were the same as the test group except for the absence of the test material. One week following intradermal induction the hair of the test area was shorn and another one day later an epicutaneous induction under occlusive conditions for 48 h was performed. For the test group, the patches contained 0.5 mL of a 6% test substance solution in physiological saline, while for the control group the patches contained only physiological saline. Three weeks after the intradermal induction the dorsal area and right flank of all animals was shorn and another one day later the animals were challenged with 3% of the test substance under occlusive conditions for 24 h. Patches placed on the flank contained physiological saline as control. Skin reactions were evaluated at 48 and 72 h after the beginning of the challenge period. In addition, clinical signs were noted at least once daily throughout the duration of the experiment and body weights were measured prior to the first induction, and at the end of the study.

Positive control studies were conducted on a regular basis using alpha hexyl cinnamic aldehyde in PEG400, at concentrations of 5% for intradermal induction, 25% for topical induction, and 12% for challenge. In the iteration applicable to the current study, 100% of the animals challenged exhibited dermal reactions, while there were no reactions observed in the negative control group animals.

One animal in the test item group showed clinical signs during day 10 to day 14 (poor general condition, piloerection, labored breathing, and pallor), and died on day 15. There were no other clinical signs or body weight differences between the treated and control animals observed. In both the control and the test group, wheals and encrustations were noted after the intradermal induction. There were no reactions after topical administration and no reactions to dermal challenge administration of the test substance noted in either control or test animals.

The test material was evaluated as not skin sensitising under the conditions of this test.

Justification for classification or non-classification

The available data on skin sensitisation do not meet the criteria for classification according to Regulation (EC) 1272/2008, and are therefore conclusive but not sufficient for classification.