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Acute Toxicity: dermal

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Administrative data

Endpoint:
acute toxicity: dermal
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 2011, March 1st to 2011, April 5
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2011
Report Date:
2011

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 402 (Acute Dermal Toxicity)
Deviations:
no
GLP compliance:
yes
Test type:
standard acute method
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Elevage JANVIER (53940 Le Genest St Isle– France)
- Age at study initiation: males = 7 week-old, females = 8 week-old
- Weight at study initiation: males 225-245 g, females 204-228 g
- Fasting period before study:
- Housing: individually, in solid-bottomed clear polycarbonate cages
- Diet (e.g. ad libitum): M20-SDS, ad libitum
- Water (e.g. ad libitum): tap-water from public distribution system, ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C):19 to 25°C
- Humidity (%):30 to 70%
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): twelve hours continuous light (07.00 to 19.00) and twelve hours darkness

Administration / exposure

Type of coverage:
semiocclusive
Vehicle:
DMSO
Details on dermal exposure:
Approximately 24 hours before the treatment, fur was removed from the dorsal area of the trunk of the test animals by clipping. At least 10 per cent of the body surface area was clear for the application of the test item.

Animals from treated group 1 received by topical application, under porous gauze dressing, an effective dose of 2000 mg/kg body weight of 1,3-Diethyl-2-thiourea (DETU). 4.0 g of the test item was weighed and dimethyl sulfoxide was added to a 20 mL volumetric flask. The preparation was
magnetically stirred to obtain a colorless solution just before the administration. The preparation was administered under a volume of 10 mL/kg body weight, during 24 hours. After 24-hours exposure period, the gauze dressings were removed.

Animals from treated group 2 received by topical application, under porous gauze dressing, an effective dose of 1000 mg/kg body weight of 1,3-Diethyl-2-thiourea (DETU). 1.0 g of the test item was weighed and dimethyl sulfoxide was added to a 10 mL volumetric flask. The preparation was
magnetically stirred to obtain a colorless solution just before the administration. The preparation was administered under a volume of 10 mL/kg body weight, during 24 hours. After 24-hours exposure period, the gauze dressings were removed.
Duration of exposure:
24 hours
Doses:
2000 mg/kg bw for males and females + 1000 mg/kg bw for females
No. of animals per sex per dose:
at 2000 mg/kg bw : 5 males and 5 females
at 1000 mg/kg bw: 5 females
Control animals:
not required
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations: daily
- Frequency of weighing: at D0 (just before administering the test item) then on D2, D7, and D14.
- Necropsy of survivors performed: yes
Statistics:
no

Results and discussion

Effect levelsopen allclose all
Key result
Sex:
male/female
Dose descriptor:
LD50
Effect level:
2 000 mg/kg bw
Sex:
male
Dose descriptor:
LD50
Effect level:
> 2 000 mg/kg bw
Remarks on result:
other: No mortality was observed in males treated with 2000 mg/kg bw
Sex:
female
Dose descriptor:
LD50
Effect level:
> 1 000 - < 2 000 mg/kg bw
Remarks on result:
other: All females died with 2000 mg/kg bw but all females survived when they were treated with 1000 mg/kg bw.
Mortality:
It was noted the death of 5 female rats treated at 2000 mg/kg b.w. (5/5): 3 rats at 47 hours 50 minutes post-dose and 2 rats at 55 hours 25 minutes post-dose. No mortality occurred during the study in the male treated at the dose of 2000 mg/kg b.w. (0/5) or in the female treated at the dose of 1000 mg/kg b.w. (0/5).
Clinical signs:
In females treated with 2000 mg/kg bw, the mortalities were preceded 24 hours post dose, by absence or decrease in spontaneous activity (5/5), in Preyer’s reflex (5/5), in body temperature (5/5), in muscle tone (3/5) and in righting reflex (2/3), bradypnea (5/5), tremors (1/5) and increase of the salivation (3/5). 48 hours post-dose, it was also noted partial or completed ptosis (2/2).
In the male treated at the dose of 2000 mg/kg b.w. it was observed a decrease in the spontaneous activity (5/5) at 24 hours post dose. The animals recovered a normal activity at 48 hours post dose.
In the female treated at the dose of 1000 mg/kg b.w., it was observed a decrease in the spontaneous activity (4/5), in body temperature (1/5) in the muscle tone (1/5) and in righting reflex (1/5) since 3 hours or 24 hours post dose. The animals recovered a normal activity at 48 or 72 hours post dose.
No cutaneous reactions related to the administration of the test item were observed in all groups.
Body weight:
A decrease in the body weight was noted on day 2 in the male treated at 2000 mg/kg b.w.: -8% compared to day 0 (versus +1% for historical control). The animals recovered a normal body weight from day 7.
The body weight evolution of the female treated at the dose of 1000 mg/kg b.w remained normal throughout the study.
Gross pathology:
Females (2000 mg/kg bw) : The macroscopical examination of the dead animals revealed a dark red or bright red coloration of the
lungs (3/5) and an important vascularisation under the treatment area (2/5).
Males (2000 mg/kg bw) and females (1000 mg/kg bw) : The macroscopical examination of the animals at the end of the study did not reveal treatment-related changes.
Other findings:
no

Any other information on results incl. tables

Table 1 / Body weight and weight gain (dose = 2000 mg/kg)

 

Males

D0

D2

D2-D0

D7

D7-D0

D14

D14-D0

Rm 5838

245

240

-5

287

42

347

102

Rm 5839

232

204

-28

255

23

319

87

Rm 5840

239

213

-26

269

30

345

106

Rm 5841

248

228

-20

282

374

359

111

Rm 8542

225

211

-14

261

36

322

97

Mean

237.8

219.2

-18.6

270.8

33.0

338.4

100.6

SD

9.4

14.5

9.4

13.6

7.1

17.2

9.2

 

Females

D0

D2

D2-D0

D7

D7-D0

D14

D14-D0

Rf 5843

209

Died

/

/

/

/

/

Rf 5844

216

190

-26

Died

/

/

/

Rf 5902

207

189

-18

Died

/

/

/

Rf 5903

204

Died

/

/

/

/

/

Rf 5904

213

Died

/

/

/

/

/

Mean

209.8

189.5

-22.0

/

/

/

/

SD

4.8

0.7

5.7

/

/

/

/

 

 

Table 2 / Body weight and weight gain (dose = 1000 mg/kg)

 

Females

D0

D2

D2-D0

D7

D7-D0

D14

D14-D0

Rf 6013

213

209

-4

216

3

229

16

Rf 6014

207

188

-19

210

3

235

28

Rf 6159

228

223

-5

250

22

259

31

Rf 6160

216

210

-6

250

34

272

56

Rf 6161

227

218

-9

249

22

265

38

Mean

218.2

209.6

-8.6

235.0

16.8

252.0

33.8

SD

9.1

13.4

6.1

20.2

13.5

18.9

14.7

 

Applicant's summary and conclusion

Interpretation of results:
Category 4 based on GHS criteria
Conclusions:
In conclusion, the LD50 observed of the test item 1,3-Diethyl-2-thiourea (DETU) is equal to 2000 mg/kg body weight by dermal route in the rat.
Executive summary:

The test item 1,3-Diethyl-2-thiourea (DETU) was applied onto the intact skin of 10 Sprague Dawley rats (5 males and 5 females) at the single dose of 2000 mg/kg body weight. It is a guideline study (OECD 402) in accordance with GLP principles.

Due to the mortalities observed at the dose of 2000 mg/kg in the 5 females rats, the test item was applied in the same experimental conditions in a group of 5 females (2 in a 1st step and 3 in a second step) at the single dose of 1000 mg/kg body weight.

It was noted the death of 5 female rats treated at 2000 mg/kg b.w. (5/5). The mortalities were preceded 24 hours post dose, by several clinical signs as absence or decrease in spontaneous activity or in Preyer’s reflex. The macroscopical examination of the dead animals revealed a dark red or bright red coloration of the lungs and an important vascularisation under the treatment area.

No mortality occurred during the study in the male treated at the dose of 2000 mg/kg b.w. (0/5) or in the female treated at the dose of 1000 mg/kg b.w. (0/5). No cutaneous reactions related to the administration of the test item were observed.

In the male treated at the dose of 2000 mg/kg b.w. it was observed a decrease in the spontaneous activity (5/5) at 24 hours post dose. The animals recovered a normal activity at 48 hours post dose. In the female treated at the dose of 1000 mg/kg b.w., it was observed several clinical signs as a decrease in the spontaneous activity. The animals recovered a normal activity at 48 or 72 hours post dose. A decrease in the body weight was noted on day 2 in the male treated at 2000 mg/kg b.w. The animals recovered a normal body weight from day 7. The body weight evolution of the female treated at the dose of 1000 mg/kg b.w remained normal throughout the study.

The macroscopical examination of the animals at the end of the study did not reveal treatment-related changes.

In conclusion, the LD50 observed of the test item 1,3-Diethyl-2-thiourea (DETU) is 2000 mg/kg body weight by dermal route in the rat. The LD50 of the test item 1,3-Diethyl-2-thiourea (DETU) is higher than 1000 mg/kg body weight and lower than 2000 mg/kg body weight by dermal route in the female rat. The LD50 of the test item 1,3-Diethyl-2-thiourea (DETU) is higher than 2000 mg/kg body weight by dermal route in the male rat.