N-butylphosphorothioic triamide

Acute Toxicity: dermal

Administrative data

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Between 12 August and 11 November 1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Report date:

1994

Materials and methods

Test guideline

Test guideline 1

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Deviations:

yes

Remarks:

(occlusive conditions)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OTS 798.1100 (Acute Dermal Toxicity)

Deviations:

yes

Remarks:

(occlusive conditions)

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

435-740-7

EC Name:

-

Cas Number:

94317-64-3

Molecular formula:

C4H14N3PS

IUPAC Name:

Phosphorothioic triamide, N-butyl-

Constituent 2

Reference substance name:

N-(n-butyl) thiophosphoric triamide (NBPT)

IUPAC Name:

N-(n-butyl) thiophosphoric triamide (NBPT)

Details on test material:

Sponsor's identification: N-(n-butyl) thiophosphoric triamide (NBPT)
Substance type: Organic
Physical state: Light-tan, waxy solid
Analytical purity: 87 %
Batch number: Not reported
Date received: Not reported
Storage conditions: The test material was stored refrigerated before the range-finding study, then was moved to room temperature storage

Test animals

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

Test Animals:
Animals: Hra:(NZW)SPF strain

Rationale: Historically, the New Zealand White albino rabbit has been the animal of choice because of the large amount of background information on this species.

- Source: from HRP, Inc., Kalamazoo, Michigan

- Age at study initiation: Adult albino rabbits
- Weight at study initiation: 2.4 to 2.8 kg
- Fasting period before study: Not stated
- Housing: animals were individually housed in screen-bottom stainless steel cage
- Diet: a measured amount of Laboratory Rabbit Diet HF #5326, PMI Feeds
- Water: ad libitum
- Acclimation period: at least 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19° to 23°C
- Humidity (%): relative humidity of 50% ±20%
- Air changes (per hr): Not stated
- Photoperiod (hrs dark / hrs light): 12-hour light/12-hour dark lighting cycle

IN-LIFE DATES: From: To:
In-life Start Date: 17 August 1994
In-life Termination Date: 31 August 1994

Administration / exposure

Type of coverage:

occlusive

Vehicle:

other: Each dose was thoroughly moistened with distilled water before application

Details on dermal exposure:

TEST SITE
- Area of exposure:
- % coverage: not less than 10% of the total body surface

- Type of wrap if used: The area of application was covered with a 10-cm x 10-cm gauze patch secured with paper tape and overwrapped with Saran Wrap® and Elastoplast® tape to provide an occlusive dressing.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): the test sites were washed using tap water and disposable paper towels.

- Time after start of exposure: 24 hours

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.05 g/cm²

- Concentration (if solution): Not applicable
- Constant volume or concentration used: yes
- For solids, paste formed: yes

VEHICLE
- Amount(s) applied (volume or weight with unit): Not applicable
- Concentration (if solution): Not applicable
- Lot/batch no. (if required): not applicable

Duration of exposure:

24 hours

Doses:

2000 mg/kg body weight

No. of animals per sex per dose:

5 per sex per dose

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days

- Frequency of observations and weighing: Clinical observations and mortality checks were conducted at approximately 1, 2.5, and 4 hours after test material administration. Additional clinical observations and twice a day mortality checks (morning and afternoon) were conducted daily thereafter for 14 days.

Body weights were determined before test material application (Day 0), at Day 7, and at termination of the experimental phase (Day 14).

The initial dermal irritation reading was made approximately 30 minutes after removal’of the test material according to the Draize technique (recorded as the Day 1 score). Subsequent readings of dermal irritation were made on Days 3, 7, 10, and 14.

- Necropsy of survivors performed: yes

- Other examinations performed: clinical signs, body weight,organ weights, histopathology, other:

Statistics:

No statistical analysis was performed.

Results and discussion

Preliminary study:

Not applicable

Effect levels

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Remarks on result:

other: 95% confidence limits not reported.

Mortality:

No mortality was observed during the study.

Clinical signs:

All animals appeared normal with the exception of 4 animals which exhibited soft stool on Days 1 and/or 2. All animals returned to a normal appearance by Day 3 after treatment.

Body weight:

All animals showed expected gains in bodyweight over the study period.

Gross pathology:

There were 10 rabbits (five males, and five females) euthanized and necropsied at the termination of the study. There were no visible lesions in any of the animals.

Other findings:

None.

Applicant's summary and conclusion

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The test material, N-(n-butyl) thiophosphoric triamide (NBPT), was evaluated for its acute dermal toxicity potential in male and female rabbits when administered as a single topical application at a level of 2000 mg/kg of body weight. The estimated dermal LD50 for male and female rabbits was determined to be greater than 2000 mg/kg.

Executive summary:

The study was conducted in accordance with the EPA Guidelines, EPA OTS 798.1100 (Acute Dermal Toxicity)

The objective of this study was to assess the systemic toxicity and relative skin irritancy of a test material when applied to the skin of adult albino rabbits of the Hra:(NZW)SPF strain procured from HRP, Inc., Kalamazoo, Michigan. The test material, N-(n-butyl) thiophosphoric triamide (NBPT), was evaluated for its acute dermal toxicity potential in male and female rabbits when administered as a single topical application at a level of 2000 mg/kg of body weight. The estimated dermal LD₅₀ for male and female rabbits was determined to be greater than 2000 mg/kg. All animals appeared normal with the exception of 4 animals which exhibited soft stool on Days 1 and/or 2. All animals returned to a normal appearance by Day 3 after treatment.

Mortality. There were no deaths.

Clinical Observations. There were no signs of systemic toxicity.

Dermal Irritation.  The test material produced slight to severe dermal irritation.

Bodyweight. All animals exhibited body weight gain throughout the study.

Necropsy.  The gross necropsy at termination revealed no visible lesions.

Conclusion.  The test material, N-(n-butyl) thiophosphoric triamide (NBPT), was evaluated for its acute dermal toxicity potential in male and female rabbits when administered as a single topical application at a level of 2000 mg/kg of body weight. The estimated dermal LD50 for male and female rabbits was determined to be greater than 2000 mg/kg.