N-butylphosphorothioic triamide

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Study conducted from 17 April 1984 to 18 may 1984

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study conducted in accordance with generally accepted scientific principles, possibly with incomplete reporting or methodological deficiencies, which do not affect the quality of relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1984

Report date:

1984

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

In the Guinea Pig Maximization Test the study assess the N-(n-butyl) Thiophosphoric Triamide for its potential to produce dermal sensitization in female Hartley strain guinea pigs. The study follows the procedure based on that which is described by Magnusson and Kligman:

1. Magnusson~ B. and Kligman. A.M. The identification of contact allergens by animal assay. The guinea pig maximization test J. Invest. Dermatol. 52:268-276. 1969.
2.Magnusson. B. and Kligman. A.M. Allergic Contact Dermatitis in the Guinea Pig. Identification of Contact Allergens. Springfield. IL.: Thomas, Ch. 8. 1970.
3.Magnusson. B. The relevance of results obtained with the guinea pig maximization test. In Animal Models in Dermatology. ed. H. Maibach. Edinburgh: Churchill Livingstone, pp. 76-83. 1975.

A judgment concerning the presence or absence of sensitization was made for each animal by comparing its challenge response(s) to the challenge responses of negative control animals. The validity of the test procedure was confirmed by concurrently testing a positive control standard, dinitrochlorobenzene, on animals from the same shipment.

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

Study conducted prior to LLNA being the recommended study.

Test material

Test material information

Constituent 1

Details on test material:

- Name of test material (as cited in study report): N-(N-butyl) Thiophosphoric Triamide
- Substance type: Organic
- Physical state: Not reported
- Analytical purity: Not reported
- Sample No.: 8245-76
- Lot/batch No.: Not reported
- Expiration date of the lot/batch: Not reported
- Stability under test conditions: Assumed stable for study duration
- Shelf-life: Assumed stable for study duration
- Storage condition of test material: Room temperature

In vivo test system

Test animals

Species:

guinea pig

Strain:

Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River, Kingston, NY
- Age at study initiation: 5-6 Weeks
- Weight at study initiation: Not stated
- Housing: maximum 3 animals per cage
- Diet (e.g. ad libitum): Agway Charles River Guinea Pig Formula
- Water (e.g. ad libitum): tap water available ad libitum
- Acclimation period:

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 4·C
- Humidity (%): 50 ± 15 %
- Air changes (per hr): not stated
- Photoperiod 12 hrs dark / 12 hrs light

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal and epicutaneous

Vehicle:

propylene glycol

Induction 2

Concentration / amount:

10 %

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

propylene glycol

Challenge 2

Concentration / amount:

10 %

No. of animals per dose:

Pre-test group: 8
Test material Group: 15
Negative Control Group: 6

Details on study design:

RANGE FINDING TESTS:
Several animals are used to pretest the test material and vehicles to determine the dermal irritation threshold concentration. These animals are shaved on the left flank, to which is applied a 2 x 2 cm filter paper patch which contains 0.2 mL of the test concentration. The trunks of the animals are wrapped for 24 hours with a three inch wide elastic bandage to hold the patch in contact with the skin. Wrappings are removed after the 24 h exposure and, based on skin reactions at 48 h, a concentration of the test material to be used on test is determined.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2
- Exposure period: 48 hours
- Test groups: 15
- Control group: 6
- Site: shoulder region
- Frequency of applications: Three pairs of intradermal injections (Induction stage 1) and once (induction stage 2)
- Duration: 14 days (induction stage 1 and induction stage 2)
- Concentrations: 10 %

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: 1
- Exposure period: 24 hours
- Test groups: 15
- Control group: 3
- Site: shoulder flanks
- Concentrations: 10 %
- Evaluation (hr after challenge): 21 hours

The remaining three animals are reserved for possible rechallenge.

OTHER:

a. If the first challenge is negative, then a second challenge will be performed one week later on the test group and three naive control animals.

b. The concentration (generally, between 1-5%) of test article in vehicle and in FCA that can be injected i.d without eliciting a strong local or systemic toxic reaction will be used. This will be determined by preliminary experimentation.

c. For induction stage 2, a concentration of test article in vehicle will be determined prior to the study start date. The concentration will be the highest level that can be well tolerated locally and generally by the guinea pig, but yet is mildly irritating (if possible).

d. The highest concentration of test article in vehicle found to be nonirritating to the guinea pig skin by preliminary experimentation will be used for challenge application.

e. Pretest performed to determine concentrations for b.c and/or d. if necessary.

Interpretation of Results:
Dermal reactions are scored on a 4-point scale 24 and 48 hours after removal of the patches:
0 - no reaction
1 - scattered mild redness
2 - moderate and diffuse redness
3 - intense redness and swelling

Both the intensity and duration of the test responses to the test article and the vehicle are evaluated. The test agent is a sensitizer if the challenge reactions in the test group clearly outweigh those in the control group. The important statistic in the GPMT is the frequency of sensitization and not the intensity of challenge responses. Under the classification scheme of Kligman the test article is assigned according to the percentage of animals sensitized to 1 of 5 classes, ranging from a weak grade I to an extreme grade V:

MAXIMIZATION GRADING

Sensltlzatlon Rate % Grade Classification
> 0 - 8 I Weak
9 - 28 II Mild
29 - 64 III Moderate
65 - 80 IV Strong
81 - 100 V Extreme

Challenge controls:

3 animals

Positive control substance(s):

yes

Remarks:

Dinitrochlorobenzene

Results and discussion

Positive control results:

100 %

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

10 %

No. with + reactions:

2

Total no. in group:

15

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 10 %. No with. + reactions: 2.0. Total no. in groups: 15.0.

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

10 %

No. with + reactions:

2

Total no. in group:

15

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 10 %. No with. + reactions: 2.0. Total no. in groups: 15.0.

Results 3

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

10 %

No. with + reactions:

0

Total no. in group:

6

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 10 %. No with. + reactions: 0.0. Total no. in groups: 6.0.

Results 4

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

10 %

No. with + reactions:

0

Total no. in group:

6

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 10 %. No with. + reactions: 0.0. Total no. in groups: 6.0.

Any other information on results incl. tables

Maximum concentration not causing irritating effects in preliminary test: 10 %

Evidence of sensitisation of each challenge concentration: 2/15 animals sensitised.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The criteria for classification as a dermal sensitizer according to CLP are not met.

Executive summary:

Introduction:

In the Guinea Pig Maximization Test the study assess the N-(n-butyl) Thiophosphoric Triamide for its potential to produce dermal sensitization in female Hartley strain guinea pigs. The study follows the procedure based on that which is described by Magnusson and Kligman:

1. Magnusson~ B. and Kligman. A.M. The identification of contact allergens by animal assay. The guinea pig maximization test J. Invest. Dermatol. 52:268-276. 1969.

2. Magnusson. B. and Kligman. A.M. Allergic Contact Dermatitis in the Guinea Pig. Identification of Contact Allergens. Springfield. IL.: Thomas, Ch. 8. 1970.

3. Magnusson. B. The relevance of results obtained with the guinea pig maximization test. In Animal Models in Dermatology. ed. H. Maibach. Edinburgh: Churchill Livingstone, pp. 76-83. 1975.

Results:

Under the classification scheme of Kligman the test article is assigned according to the percentage of animals sensitized to 1 of 5 classes, ranging from a weak grade I to an extreme grade V as shown in the following table:

Maximization Grading
Sensitization Rate %	Grade	Classification
> 0 – 8	I	Weak
9 – 28	II	Mild
29 – 64	III	Moderate
65 – 80	IV	Strong
81 – 100	V	Extreme

A judgment concerning the presence or absence of sensitization was made for each animal by comparing its challenge response(s) to the challenge responses of negative control animals. The validity of the test procedure was confirmed by concurrently testing a positive control standard, dinitrochlorobenzene, on animals from the same shipment.

Test Substance: Positive - 13%

Negative Control: Negative - 0%

Positive Control: Positive - 100%

Conclusion:

NBPT produced evidence of skin sensitization in 13% of the animals (2 of 15) at the challenge reading.  While the number of animals studied is lower than the 20 recommended by OECD Guideline 406, the study is well documented and reliable. It is highly unlikely that additional animals would increase the number of animals with positive responses to 30% or greater.  Based upon this information, the criteria for classification as a dermal sensitizer according to CLP are not met.