Dinoseb

Acute Toxicity: dermal

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

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

Test material information

Constituent 1

Reference substance name:

Dinoseb

EC Number:

201-861-7

EC Name:

Dinoseb

Cas Number:

88-85-7

Molecular formula:

C10H12N2O5

IUPAC Name:

dinoseb

Constituent 2

Reference substance name:

2-secbutyl-4,6-dinitrophenol

IUPAC Name:

2-secbutyl-4,6-dinitrophenol

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 or test system 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 levels

Effect levels 1

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

Effect levels 2

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

Effect levels 3

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

Effect levels 4

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:

other: 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 ob

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:

other: toxic

Remarks:

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.