spirodiclofen (ISO);3-(2,4-dichlorophenyl)-2-oxo-1-oxaspiro[4.5]dec-3-en-4-yl 2,2-dimethylbutyrate

Endpoint summary

Description of key information

In vitro/in chemico data are not available; the available in vivo study predates the adoption of validated test in vitro test methods for skin sensitisation.

A guinea pig Maximisation tes (GLP, OECD 406) is available for spirodiclofen.

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:

In-life initiated/completed: 25-June-1996 to 26-July-1996

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Version / remarks:

not specified

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Version / remarks:

Previously known as EEC B.6.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

The study was performed to the OECD test guideline (OECD 406) in place at the time (1996), and therefore predates the adoption of the LLNA (OECD 429) in 2002. The study is scientifically valid and adequate for hazard assessment and classification purposes.

Species:

guinea pig

Strain:

Dunkin-Hartley

Remarks:

Hsd PoC:DH

Sex:

female

Details on test animals and environmental conditions:

A total of 25 female animals were used in the study, including those employed in the range-finding tests to determine the induction and challenge concentrations.

Acclimatisation: Following receipt, the animals scheduled for this study were adapted to the maintenance conditions for a period of at least seven days before treatment, and their state of health was monitored.

State of health: Only healthy animals exhibiting no clinical signs were used for the study. The animals were not vaccinated or treated against infections either before receipt, or during the adaptation or study periods. The females were nulliparous and non-pregnant.

Age and body weight: The guinea pigs exhibited a mean weight of 288-295 grams at the beginning of the study. This weight corresponds to an age of 5 - 7 weeks.

During the adaptation and study period the animals were conventionally kept in type IV Makrolon® cages [4], in groups of five during the adaptation period and in groups of two or three per cage throughout the study period. The cages were exchanged for ones with clean bedding two times per week. Low-dust wood shavings were used as bedding. The wood shavings were spotchecked for contaminant levels. Records of these test results are filed at BAYER AG. The analytical results provided no evidence for an effect on the study objective. All animals used in this study were kept in the same animal room, one in which guinea pigs from other sensitization studies were also housed. Adequate separation, unambiguous cage markings and suitable organization of the work ensured that animals were not mixed up.

The animal room was swept out with a broom each day, and thoroughly cleaned with water once weekly. The room was disinfected at least once each month with Zephirol® 10% (10 grams benzalkonium chloride per 100 grams disinfectant; working dilution 2%, corresponding to 20 ml per liter of water). Contamination of the diet and contact with the experimental animals were avoided during this work. No pest control measures were carried out in the animal rooms. KILLIGERM Roach Traps ®, a cockroach trap which uses no pesticides, was placed in the animal room from July 10, 1996.

Diet: The diet consisted of "Altromin®3020 - Maintenance Diet for Guinea Pigs" and of tap water. Food and water were provided ad libitum.

Climatic Conditions:
Room temperature: 22 +/- 3°C (possibly drifting higher at outdoor temperatures above 24°C)
Relative humidity: 40 - 60 %
Light/dark cycle: Twelve hours; artificial lighting from 6 AM to 6 PM CET
Air exchange rate: >= 10 times per hour

Occasional deviations from these standards occurred at times including the period following the cleaning of the animal room. They had no apparent effect in the course of the study.

Route:

epicutaneous, occlusive

Vehicle:

physiological saline

Concentration / amount:

0.5 ml Spirodiclofen 50% in physiological saline solution containing 2% Cremophor EL®

Day(s)/duration:

48 hours

Adequacy of induction:

other: Performed one week after intradermal induction.

Route:

intradermal

Vehicle:

physiological saline

Concentration / amount:

No test substance used - complete Freund's adjuvant only

Adequacy of induction:

not specified

Route:

intradermal

Vehicle:

physiological saline

Concentration / amount:

5% Spirodiclofen formulated in physiological saline solution containing 2% Cremophor EL®

Adequacy of induction:

not specified

Route:

intradermal

Vehicle:

physiological saline

Remarks:

and complete Freund's adjuvant.

Concentration / amount:

5% Spirodiclofen formulated at equal parts in sterile physiological saline solution and
complete Freund's adjuvant.

Adequacy of induction:

not specified

No.:

#2

Route:

epicutaneous, occlusive

Vehicle:

not specified

Concentration / amount:

50% test substance formulation - The volume applied in each case was 0.5 ml. shaved right flank of the animals is where the test substance was applied.

Day(s)/duration:

24 hours

Adequacy of challenge:

not specified

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

not specified

Concentration / amount:

50% test substance formulation - The volume applied in each case was 0.5 ml. shaved left flank of the animals is where the test substance was applied.

Day(s)/duration:

24 hours

Adequacy of challenge:

not specified

No. of animals per dose:

10 animals in main study group, 5 in the control group and 5 in the dose range-finding group.

Details on study design:

The test substance was formulated in sterile physiological saline solution containing 2% Cremophor EL to yield a suspension. A 5% concentration was used for intradermal, and a 50% concentration for topical induction. A 50% concentration was used for the first and second challenge.

Challenge controls:

Yes - a 50% formulated substance of the test material was used for both Challenges.

Positive control substance(s):

no

Positive control results:

N/A

Reading:

1st reading

Hours after challenge:

72

Group:

positive control

Dose level:

NA

Clinical observations:

NA

Remarks on result:

not measured/tested

Reading:

1st reading

Hours after challenge:

48

Group:

positive control

Dose level:

NA

Clinical observations:

NA

Remarks on result:

not measured/tested

Key result

Reading:

1st reading

Hours after challenge:

72

Group:

test chemical

Dose level:

50% test substance formulation

No. with + reactions:

1

Total no. in group:

10

Clinical observations:

None

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

test chemical

Dose level:

50% test substance formulation

No. with + reactions:

4

Total no. in group:

10

Clinical observations:

None

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

72

Group:

negative control

Dose level:

Vehicle only

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

None

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

negative control

Dose level:

Vehicle only

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

None

Remarks on result:

no indication of skin sensitisation

Interpretation of results:

Category 1B (indication of skin sensitising potential) based on GHS criteria

Conclusions:

Spirodiclofen showed evidence of skin sensitisation potential under the conditions of this study.

Executive summary:

The skin sensitisation potential of spirodiclofen was investigated in a Guinea Pig Maximization Test (GPMT) using female Dunkin-Hartley guinea pigs.  The study was conducted using concentrations of 5% for intradermal induction and 50% for topical induction.  Two challenge applications were made, using 50% test material.  The test material was formulated in physiological saline solution containing 2% Cremophor EL to yield a suspension.  The first and the second challenge resulted in skin reactions in 4 of 10 (40%) animals in the test group and 0 of 10 animals in the control group. However, only one animal showed a positive reaction in both challenge treatments.  Spirodiclofen showed evidence of skin sensitisation potential under the conditions of this study, and requires classification as a skin sensitiser (Cat 1B) according to the CLP criteria.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

No data are available; there is no evidence or structural alerts raising concerns  that spirodiclofen is a respiratory sensitiser.

Justification for classification or non-classification

The results of the Maximisation assay with spirodiclofen demonstrate skin sensitisation potential.  According to the CLP criteria, classification as a skin sensitiser in Category 1B is appropriate.  This is consistent with the harmonised classification and the RAC opinion.  RAC noted that the positive response in the Guinea Pig Maximization Test was 40% with an intradermal induction dose of >1%. The data were therefore considered sufficient for sub-classification.  The response of 40% animals with positive skin reactions is comparably low at such a high intradermal induction dose of 5%. RAC concluded that classification of spirodiclofen for skin sensitisation in Cat 1B was appropriate.