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Diss Factsheets

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:
March - April 1984
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1984
Report date:
1984

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
other: EPA Pesticide Assessment Guidelines
Deviations:
yes
Remarks:
no weighing at termination (purpose or integrity of the study not affected)
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
The study was conducted in 1984 when the LLNA was not yet an established method with regulatory acceptance.

Test material

Constituent 1
Chemical structure
Reference substance name:
Ethoprophos
EC Number:
236-152-1
EC Name:
Ethoprophos
Cas Number:
13194-48-4
Molecular formula:
C8H19O2PS2
IUPAC Name:
ethyl bis(propylsulfanyl)phosphinate
Test material form:
liquid

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Redfern Animal Breeders, Ely Grange, Frant, Tunbridge-Wells,TN3 9DZ.
- Females nulliparous and non-pregnant: not specified
- Age at study initiation: young, no further specification
- Weight at study initiation: 484 to 531 g
- Housing: caged in groups of 2 by dose group in grid floor polypropylene cages
- Diet (ad libitum): (Guinea Pig diet, Standard with Vitamin C, Special Diets Services Ltd., Stepfield, Witham, Essex
- Water (ad libitum): yes, quality was issued by the Yorkshire Water Authority
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17 - 23
- Humidity (%): 40 - 69
- Air changes (per hr):- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal
Vehicle:
polyethylene glycol
Remarks:
200
Concentration / amount:
1 mL; 1% v/v
Day(s)/duration:
Day 1
Adequacy of induction:
other: well tolerated systemically
Route:
epicutaneous, occlusive
Vehicle:
polyethylene glycol
Remarks:
200
Concentration / amount:
0.5 mL; 10% v/v
Day(s)/duration:
Day 7; 48 h
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
Challenge
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
polyethylene glycol
Remarks:
200
Concentration / amount:
0.5 mL; 10% v/v
Day(s)/duration:
Day 21; 24 h
Adequacy of challenge:
other: highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
No. of animals per dose:
20 animals
Details on study design:
RANGE FINDING TESTS:
Toxicity data indicated the test article was toxic by dermal application. To confirm this toxicity and to establish the threshold irritant concentrations a screening study was performed. The test article in corn oil was applied at doses of 10, 50 and 100 mg/kg bw to the shaved back of each animal once only under occlusive patches for a period of 6 hours. The animals were observed for mortality during the day of dosing and subsequently once daily for 7 days. In addition the treatment sites were assessed for irritation the day following treatment.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: intradermal: 3; topical: 1
- Exposure period: intradermal: not applicable; topical: 48 h
- Test groups: 1
intradermal induction:
1. 0.1 ml 1.0% v/v Ethoprop in polyethylene glycol 200
2. 0.1 ml Complete Adjuvant (50% v/v in water)
3. 0.1 ml 1.0% v/v Ethoprop emulsified in 50% v/v
- Control group: 1
intradermal induction:
1. 0.1 ml Polyethylene glycol
2. 0.1 ml Complete Adjuvant (50% v/v in water)
3. 0.1 ml Complete Adjuvant (50% v/v in water)
- Site: shoulder region
- Concentrations: intradermal: 1%; topical: 10%

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day of challenge: Day 21
- Exposure period: 24 h
- Test groups: 1
- Control group: 1
- Site: flank
- Concentrations: 10%
- Evaluation (hr after challenge): 24 and 48
Challenge controls:
Polyethylene glycol 200 (PEG 200)
Positive control substance(s):
no

Results and discussion

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
other: negative challenge control
Dose level:
0
No. with + reactions:
0
Total no. in group:
19
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
other: negative challenge control
Dose level:
0
No. with + reactions:
0
Total no. in group:
19
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
0
No. with + reactions:
0
Total no. in group:
0
Remarks on result:
not measured/tested
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
0
No. with + reactions:
0
Total no. in group:
0
Remarks on result:
not measured/tested
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
10%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
10%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
10%
No. with + reactions:
9
Total no. in group:
19
Remarks on result:
positive indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
10%
No. with + reactions:
11
Total no. in group:
19
Remarks on result:
positive indication of skin sensitisation

Any other information on results incl. tables

RANGE FINDING TESTS:


No deaths were noted during the study period. Slight redness was noted on the treatment sites of both animals exposed to the test item at a concentration of 5.0% v/v. No irritation was noted on exposure to concentrations of 2.5% v/v or 0.5% v/v.
A concentration of 10% v/v test subtance was considered to be the maximum irritant concentration and was used for both topical induction and challenge.


 


MAIN STUDY


One test animal was found dead on day 9. Nine of the 19 surviving animals showed scattered mild redness at the 24 hour observation. These reactions were also seen in 11 of the 19 animals at the 48 hour observation. No adverse skin reactions were noted on the test animals using vehicle only. No adverse skin reactions were noted in control animals exposed to test and control articles at either the 24 or 48 hour observation.

Applicant's summary and conclusion

Interpretation of results:
Category 1 (skin sensitising) based on GHS criteria
Conclusions:
The test item was shown to be a potential skin sensitiser under the conditions of this study.
Executive summary:

Intradermal induction was performed on 20 test animals using 0.1 mL injections of the test item (1.0% v/v in PEG 200) and Freund’s Complete Adjuvant (50% v/v in water). Ten control animals were similarly treated, with vehicle replacing the test material. One week following intradermal induction, topical induction was performed on test animals using a 48 hour occlusive application of ethoprophos (10% v/v in PEG 200). Control animals were similarly treated with vehicle alone. Two weeks after topical induction, all animals were challenged using a 24 hour occlusive application of ethoprophos (10% v/v in PEG 200). Vehicle was applied to the opposite flank to serve as control. The test item caused scattered mild erythema in test animals at the ethoprophos-treated skin site as detailed below. Control animals and vehicle-treated flanks showed no skin reaction.


The test item was shown to be a potential skin sensitiser under the conditions of this study.