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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:
2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2006
Report Date:
2006

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Qualifier:
according to
Guideline:
EU Method B.6 (Skin Sensitisation)
GLP compliance:
yes (incl. certificate)
Type of study:
Buehler test
Justification for non-LLNA method:
The study was already available and it is considered relevant and conclusive.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Type:
Constituent
Type:
Constituent
Test material form:
solid: crystalline
Details on test material:
the racemate is characterized by CAS-number 7696-12-0
Specific details on test material used for the study:
- Batch No.of test material: TM1027



In vivo test system

Test animals

Species:
guinea pig
Strain:
other: Albino, NIH (Dunkin Hartley)
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Toxicology Department Advinus Therapeutics Private Limited Bangalore 560 058, INDIA
- Age at study initiation: 6 – 8 weeks
- Weight at study initiation: Males: 330 - 488 g; Females : 332 - 440 g
- Housing: Animals were housed individually in suspended polypropylene bottom mesh cages (size: approx: L 410 x B 280 x H 140 mm) with stainless steel top grill having facilities for pelletted food and drinking water in a glass bottle. Cages were changed twice a week, litter trays were changed once and litter sheets were changed thrice a week.
- Diet: ad libitum
- Water: ad libitum


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 - 23 °C
- Humidity (%): 30 - 70 %
- Photoperiod (hrs dark / hrs light): 12 h light, 12 h darkness

Study design: in vivo (non-LLNA)

Induction
Route:
epicutaneous, occlusive
Vehicle:
water
Concentration / amount:
0.5 g as a paste in de-ionised water
Day(s)/duration:
Days 1, 8 and 15/ 6 hours
Adequacy of induction:
other: No skin reactions have been observed during the pre-test study, hence, 0.5 g of the test item as a paste (equivalent to 100% concentration) was selected for the induction and challenge applications of the main study as the maximum dose possible..
Challenge
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
water
Concentration / amount:
100% (0.5 g of test item finely ground and prepared as a paste)
Day(s)/duration:
6 hours contact
Adequacy of challenge:
other: maximum dose possible
No. of animals per dose:
10 animals (5 males + 5 females) for vehicle control group
10 animals (5 males + 5 females) for positive control group
10 animals (5 males + 5 females) for treatment induction group
10 animals (5 males + 5 females) for treatment challenge group
Details on study design:
RANGE FINDING TESTS: A pre-study was conducted with four guinea pigs (2 males and 2 females) to determine the maximum concentration of the test item which caused slight irritation for induction application and the maximum non-irritant concentration for the challenge application, at the doses of 5, 25 and 50% w/v of the test item in acetone, 0.5 ml of these concentrations were applied in between the prepared area of skin and cotton gauze [(size 2 x 3 cm – 6 ply)]. Similarly 0.5 g of the finely ground test item was weighed and made into a paste by adding de-ionised water and the paste (which was equivalent to 100% concentration) was completely transferred to the cotton gauze and applied to the prepared area of skin (closely-clipped flanks of Guinea pig - two patches per animal). The patches were held in place with non-irritating adhesive tape and crepe bandage over which a clean cotton cloth (many tailed bandage) was tied to anchor the crepe bandage.
The test item contact period was 6 hours after which the test patches were removed and the area was cleaned with normal saline swabs and wiped dry with cotton. There were no skin reactions (at 1, 24, 48 and 72 hours post removal observations) at the tested doses.
Hence, 0.5 g of the test item as a paste (which is equivalent to 100% concentration) in de-ionised water was selected for the topical induction and challenge applications of the main study as the maximum dose possible.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 3
- Exposure period: days 1, 8, 15
- Duration: 6 h
- Concentrations: 100%

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: 1
- Exposure period: day 28
- Concentrations: 100%
- Evaluation (hr after challenge):
skin reactions at 1 and 24 h post removal of the test patch
toxic signs and pre-terminal deaths at 2, 4 and 6 hours post application on treatment days, twice daily on evaluation days and once a day on other days.
Challenge controls:
positive control with 2-MBT: 2-Mercaptobenzothiazole
Positive control substance(s):
yes
Remarks:
2-MBT: 2-Mercaptobenzothiazole

Results and discussion

Positive control results:
Induction applications :
At first induction erythema of score 1 was observed in 7 out of 10 and edema of score 1 was observed in 5 out of 10 animals at 1 hour post removal of the test patch. At 24 hours, erythema was observed in 3 out of 10 animals.
At second induction erythema of score 1 was observed in 7 out of 10 and edema of score 1 was observed in 4 out of 10 animals at 1 hour post removal of the test patch. At 24 hours, erythema was observed in 3 out of 10 animals.
At third induction erythema of score 1 was observed in 8 out of 10 and edema of score 1 was observed in 4 out of 10 animals at 1 hour post removal of the test patch. At 24 hours, erythema was observed in 2 out of 10 animals
Challenge application :
At the dose of 10 % w/v 8 out of 10 guinea pigs had a score of 1 (discrete or patchy erythema) at 24 hours and 6 out of 10 guinea pigs had erythema at 48 hours post removal of the test patch.
The skin sensitisation rate was 80% (8/10) in the positive control group. The above findings are consistent with the historical results for the positive control in previous studies conducted at this laboratory.

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
100%
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
no
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
100%
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
no
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
0%
No. with + reactions:
0
Total no. in group:
7
Clinical observations:
no
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
0%
No. with + reactions:
0
Total no. in group:
7
Clinical observations:
no
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
2-Mercaptobenzothiazole (2-MBT) at 12% w/v in acetone
No. with + reactions:
8
Total no. in group:
10
Clinical observations:
no
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
2-Mercaptobenzothiazole (2-MBT) at 12% w/v in acetone
No. with + reactions:
6
Total no. in group:
10
Clinical observations:
no

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
The study showed that the test item tetramethrin did not have any skin sensitisation potential when tested in Guinea pigs using the Buehler test method under the stated experimental conditions.

Executive summary:

The test item tetramethrin was tested for its skin sensitisation potential in Guinea pigs using the Buehler test method (OECD Guideline No.406, EEC Method B.6). The animals were given three topical applications (induction) weekly for three weeks (viz., on days 1, 8 and 15 of the test) and one challenge application (viz., on day 29 of the test).

A quantity of 0.5 g of test item as a paste (which is equivalent to 100% concentration) in de-ionised water was transferred completely onto the cotton gauze (2 x 3 cm, 6 ply) and applied on to the prepared area of the left flank as a patch. The test patch was held in close contact with the clipped skin of the animals for 6 hours after each application. The vehicle control group animals were treated similarly with 0.5 ml of de-ionised water but without the test item. Positive control group animals were treated similarly with 0.5 ml of 2-Mercaptobenzothiazole (2-MBT) at a concentration of 12% w/v in acetone. After the three induction applications, on day 29, the animals of both the vehicle control as well as the treatment group (except 3 naive animals from the control group) were challenged by topical application of 0.5 g of the finely ground test item as a paste in de-ionised water, similar to the induction application but applied to the posterior part of the untreated right flank. Similarly, 0.5 ml of de-ionised water was applied at the anterior part of the untreated right flank. For animals in the positive control group 0.5 ml of 2-MBT at a concentration of 10% w/v in acetone was applied to the posterior part and 0.5 ml of acetone to the anterior part of the untreated right flank.

The skin reaction was evaluated in the vehicle control and treatment group animals using the grading scale of Draize, 1959 for induction and the grading scale of Magnusson and Kligman for challenge application. There were no skin animals at induction applications evaluated at 1 and 24 hours post removal of test patch.

The challenge application site was evaluated at 24 and 48 hours post removal of the test patch. There was no skin reaction (erythema) observed in the test item treated animals. In the positive control group animals the skin sensitisation rate was 80% (8/10). The comparison of the skin reaction of the test item treated animals with those of the positive control animals showed that the test item did not cause skin sensitisation in the tested animals.

It is concluded that tetramethrin did not cause skin sensitisation in Guinea pigs using the Buehler Test method under the stated experimental conditions.