Registration Dossier

Toxicological information

Acute Toxicity: dermal

Currently viewing:

Administrative data

Endpoint:
acute toxicity: dermal
Type of information:
experimental study
Adequacy of study:
key study
Study period:
15 August 1984 to 25 September 1984
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Study conducted in accordance with recognised guideline. Although no data is available on the study's GLP compliance equivalent quality assurance methods were in place at the testing laboratory. The substance is present in an oil formulation at ca.30% and a purity correction performed to give the LD50 of the substance itself.

Data source

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

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 402 (Acute Dermal Toxicity)
Deviations:
no
GLP compliance:
not specified
Remarks:
QA and study director statements included in the report
Test type:
standard acute method
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): DNBP formulation.
- Commercial name; Dinoseb (DNBP) in oil 300 g/l
- Substance type: solution
- Physical state: liquid
- Analytical purity: 30 – 31.2% in oil
- Storage condition of test material: Ambient conditions

Test animals

Species:
rat
Strain:
other: HC/CFY (Remote Sprague-Dawley)
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Hacking and Churchill Limited, Huntingdon, Cambridgeshire, England
- Age at study initiation: approximately six to eight weeks of age
- Weight at study initiation: weight range of 194 to 253 g
- Housing: Individually housed in metal cages with wire mesh floors
- Diet (e.g. ad libitum): ad libitum - Scientific Feeds LAD 1 obtained from Special Diet Services Ltd., Witham, Essex, England
- Water (e.g. ad libitum): ad libitum
- Acclimation period: minimum period of 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23°C to 24°C
- Humidity (%): 65%
- Air changes (per hr): at least 15
- Photoperiod (hrs dark / hrs light): 12 h light/12 h dark

IN-LIFE DATES: From: To: The study was undertaken between 15 August and 25 September 1984

Administration / exposure

Type of coverage:
occlusive
Vehicle:
unchanged (no vehicle)
Details on dermal exposure:
TEST SITE
- Area of exposure: dorsal lumbar region
- % coverage: 10% of the total body surface
- Type of wrap if used: covered with gauze which was held in place with an impermeable dressing encircled firmly around the trunk.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): decontaminated by washing in warm (30-40°C) water and blotting dry with absorbent paper.
- Time after start of exposure: 24 hours

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): used as received; volumes applied between 0.51 to 2 ml/kg bw
- Concentration (if solution): 30-31.2% w/v DNBP in oil
Duration of exposure:
24 hours
Doses:
500, 640, 800, 1260 & 2000 mg/kg (0.51, 0.65, 0.82, 1.29 and 2 ml/kg, respectively)
No. of animals per sex per dose:
5 males and 5 females
Control animals:
not specified
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Animals were observed soon after dosing; then at frequent intervals for the remainder of Day 1. On subsequent days the animals were observed at least twice per day. Clinical signs were recorded at each observation.
- Necropsy of survivors performed: yes
- Other examinations performed: Surviving animals in the main study were killed on Day 15 by carbon dioxide asphyxiation. All animals that died during the study and those killed on Day 15 were subjected to a macroscopic post mortem examination which consisted of opening the abdominal, thoracic and cranial cavities. The macroscopic appearance of abnormal organs when present was recorded.
Statistics:
The acute median lethal dermal dose (LD50) to rats was calculated using the method of:
Finney (1971) Probit Analysis (3rd Edition) Cambridge University Press.

Separate LD50 values for males and females were estimated by undertaking probit analysis on the mortality data by fitting two parallel lines on the data (males only and females only) using the technique described by Finney (1978, Statistical Method in Biological Assay, 3rd Edition, Charles Griffin, London). A chi-squared test was carried out to check that the data did not contain any evidence for non-parallelism.

Results and discussion

Preliminary study:
A trial test was carried out by dosing two male and two female rats at 1000 mg/kg bodyweight. None of the treated animals died.
Effect levelsopen allclose all
Sex:
male/female
Dose descriptor:
LD50
Effect level:
217.5 mg/kg bw
Based on:
act. ingr.
95% CL:
192.6 - 257.4
Remarks on result:
other: Corrected for purity
Sex:
male
Dose descriptor:
LD50
Effect level:
242.7 mg/kg bw
Based on:
act. ingr.
95% CL:
203.7 - 313.2
Remarks on result:
other: Corrected for purity
Sex:
female
Dose descriptor:
LD50
Effect level:
198.3 mg/kg bw
Based on:
act. ingr.
95% CL:
165 - 234
Remarks on result:
other: Corrected for purity
Sex:
male/female
Dose descriptor:
LD50
Effect level:
725 mg/kg bw
Based on:
test mat.
95% CL:
642 - 858
Mortality:
Mortalities occurred among rats treated at dose levels of 640 mg/kg and above from within four and 25 hours of dosing.
Clinical signs:
Clinical signs observed among animals treated with DNBP formulation were lethargy, ptosis, pallor of the extremities, diuresis, increased salivation and increased respiratory rate.
Other than animals treated at 1260 mg/kg these signs were not generally observed during the six hours post dose and as all mortalities had occurred by the first observation on Day 2 an unusual pattern of clinical signs was observed.
Recovery as judged by external appearance and behaviour was apparently complete on Day 3.
Body weight:
Bodyweight losses were recorded for the rats that died. Bodyweight gains were recorded for all rats on Days 8 and 15.
Gross pathology:
Autopsy of animals which died during the test revealed congestion of the lungs and pallor of the liver, kidneys and spleen. Slight congestion of the subcutaneous blood vessels at the treatment site was seen among these animals.
Terminal autopsy findings were normal.
Other findings:
No dermal reactions were observed in any animal although yellow staining of the skin precluded an accurate assessment of erythema.

Any other information on results incl. tables

The acute median lethal dermal dose and its 95% confidence limits were estimated to be:

Males and females combined: 725 (642 to 858) mg/kg

The slope of the probit line was 11.0 with a standard error of 3.4 using log transformation of dose.

When probit analysis was carried out on the mortality data by fitting two parallel lines the values were:

Males only: 809 (679 to 1044) mg/kg bodyweight

Females only: 661 (550 to 780) mg/kg bodyweight

The slope of the parallel probit lines was 12.3 with a standard error of 3.8 using log transformation of dose. The heterogeneity factor was not significant.

The chi-squared test for parallelism gave no evidence of non-parallelism.

Table 1. Mortality data for groups of rats dosed dermally with DNBP formulation - Preliminary study.

Dose
(g/kg)
Mortality ratio (No. of deaths / No. dosed)     Time of death after dosing (hours)
Male Female Combined
1 0/2 0/2 0/4 -

Table 2. Time and number of deaths of rats dosed dermally with DNBP formulation - Main study.

Sex Dose
(mg/kg)
Number of deaths in a group of 5 Day
1 2 3 15
Hours after dosing
½ 1 2 3 4 5 6 a b a b a b
Male 500 0                          
640 0                          
800 3               3          
1260 5         2 2   1          
2000 5               5          
Female 500 0                          
640 4               4          
800 3               3          
1260 5               5          
200 5               5          

Applicant's summary and conclusion

Interpretation of results:
toxic
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
The LD50 of the substance as tested was determined to be 725 mg/kg bw to both male and female rats which is equivalent to approximately 217.5 mg/kg bw for the active ingredient. The substance is therefore classified as toxic.
Executive summary:

In an acute dermal toxicity study conducted in accordance with OECD method 402 and under an appropriate quality assurance system, groups of 5 male and 5 female rats, the animals were dosed dermally with a 30-31.2% w/v preparation of the substance in oil. The animals were dosed at 500, 640, 800, 1260 & 2000 mg/kg bodyweight and were observed for 14 days after an exposure period of 24 hours.

The LD50 of the substance as tested was determined to be 725 mg/kg bw to both male and female rats which is equivalent to approximately 217.5 mg/kg bw for the active ingredient. The substance is therefore classified as toxic.