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Administrative data

Description of key information

An oral acute study was performed on 1,3-dibutyl thiourea in rat. One animal died at 2000 mg/kg bw, so the LD50 is higher than 2000 mg/kg bw in rat by oral route.

An acute dermal study is available on an analogue of 1,3-dibutyl thiourea in rat : 1,3-diethyl thiourea. In this study, the LD50 is equal to 2000 mg/kg bw.

No data by inhalation is available.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records
Reference
Endpoint:
acute toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 12 Oct 2004 to 3 Nov 2004
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 423 (Acute Oral toxicity - Acute Toxic Class Method)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.1 tris (Acute Oral Toxicity - Acute Toxic Class Method)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Test type:
acute toxic class method
Limit test:
yes
Test material information:
Composition 1
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Breeder: Janvier, Le Genest-Saint-Isle, France
- Age at study initiation: on the day of treatment, the females were approximately 8-week old
- Mean body weight at study initiation: 280 ± 15 g for the males and 199 ± 2 g for the females.
- Fasting period before study: yes, during the night before treatment
- Housing: polycarbonate cages with stainless steel lids
- Diet: SSNIFF R/M-H pelleted diet (free access)
- Water: tap water filtered with a 0.22 µm filter (free access)
- Acclimation period: at least 5 days before the beginning of the study.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 2°C
- Humidity (%): 30 to 70%
- Air changes (per hr): approximately 12 cycles/hour of filtered, non-recycled air
- Photoperiod (hrs dark / hrs light): 12 h/12 h.
Route of administration:
oral: gavage
Vehicle:
other: 0.5% methylcellulose aqueous solution
Details on oral exposure:
Three animals of one sex were used for each step. Males were used in the initial step.
As no information on the toxic potential of the test item was available, for animal welfare reasons, the starting dose of 200 mg/kg was chosen.
After the first assay, as 0/3 animals died, another assay was carried out on three males at the next After the second assay, as 1/3 animals died, the results were confirmed in three females at 2000 mg/kg.

The dosage form preparations were administered to the animals under a volume of 10 mL/kg.
The administration was performed in a single dose by oral route using a metal gavage tube fitted to a 5 mL glass syringe (0.05 mL graduations).
The volume administered to each animal was adjusted according to body weight determined on the day of treatment.
Doses:
200 and 2000 mg/kg.
No. of animals per sex per dose:
200 mg/kg: 3 males
2000 mg/kg : 3 males and 3 females
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Clinical observations: frequently during the hours following treatment; then, at least once a day.
- Body weight: just before treatment on day 1; then on days 8 and 15.
- Necropsy of survivors performed: All study animals were subjected to a macroscopic examination as soon as possible after death.
After opening the thoracic and abdominal cavities, a macroscopic examination of the main organs (digestive tract, heart, kidneys, liver, lungs, pancreas, spleen and any other organs with obvious abnormalities) was performed.
Statistics:
no
Key result
Sex:
male/female
Dose descriptor:
LD50
Effect level:
> 2 000 mg/kg bw
Based on:
test mat.
Remarks on result:
other: 1/6 died at 2000 mg/kg/d
Mortality:
At 200 mg/kg: No mortality occurred.
At 2000 mg/kg : In males, 1/3 animals were found dead on day 2; hypoactivity or sedation, piloerection and dyspnea were recorded prior to death. In females, no mortality occurred.
Clinical signs:
At 200 mg/kg: Only hypoactivity, piloerection and dyspnea were observed in all animals on day 1.
At 2000 mg/kg : In all male surviving animals, hypoactivity, piloerection and dyspnea were noted from day 1 up to day 4. Hypoactivity and piloerection were observed in all females on day 1; then hypoactivity, piloerection and dyspnea were recorded in 1/3 females on day 2. No clinical signs were noted thereafter in females and males.
Body weight:
The overall body weight gain of the animals treated at 200 mg/kg was not affected by treatment with the test item.
At the 2000 mg/kg dose-level, a slightly reduced body weight gain was seen in all surviving animals during the first week of the study, when compared to historical control animals.
Gross pathology:
Macroscopic examination of the main organs of the animals revealed no apparent abnormalities.
Other findings:
no
Interpretation of results:
Category 5 based on GHS criteria
Conclusions:
Under these experimental conditions, the oral LD50 of the test item Dibutyl thiourea is higher than 2000 mg/kg in rats.
Executive summary:

The acute oral toxicity of the test item Dibutyl thiourea was evaluated in rats according to OECD (No. 423, 22 March 1996) and EC (96/54/EC, B.1 tris, 30 July 1996) guidelines. The study was conducted in compliance with the principles of Good Laboratory Practice Regulations.

The test item was prepared as a suspension in 0.5% methylcellulose and was administered by oral route (gavage), under a volume of 10 mL/kg, to groups of three fasted Sprague-Dawley rats. At first, three males were treated with 200 mg/kg bw; then after, three males and three females were treated with 2000 mg/kg bw. Clinical signs, mortality and body weight gain were checked for a period of up to 14 days following the single administration of the test item. All animals were subjected to necropsy.

At 200 mg/kg bw: No mortality occurred. Only hypoactivity, piloerection and dyspnea were observed in all animals on day 1.

At 2000 mg/kg bw : In males, 1/3 animals were found dead on day 2; hypoactivity or sedation, piloerection and dyspnea were recorded prior to death. In all surviving animals, hypoactivity, piloerection and dyspnea were noted from day 1 up to day 4.

In females, no mortality occurred. Hypoactivity and piloerection were observed in all animals on day 1; then hypoactivity, piloerection and dyspnea were recorded in 1/3 females on day 2. No clinical signs were noted thereafter.

The overall body weight gain of the animals treated at 200 mg/kg was not affected by treatment with the test item. At the 2000 mg/kg dose-level, a slightly reduced body weight gain was seen in all surviving animals during the first week of the study, when compared to historical control animals. At necropsy, no apparent abnormalities were observed.

Under these experimental conditions, the oral LD50 of the test item Dibutyl thiourea is higher than 2000 mg/kg in rats.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
discriminating dose
2 000 mg/kg bw
Quality of whole database:
The study is considered to be reliable with a klimisch score of 1.

Acute toxicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no study available

Acute toxicity: via dermal route

Link to relevant study records
Reference
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
Reference:
Composition 0
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 information:
Composition 1
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
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
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

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

 

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.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
LD50
2 000 mg/kg bw
Quality of whole database:
The study is considered to be reliable with a klimisch score of 1.

Additional information

Acute toxicity: oral (OECD 423, Ollivier 2006)

The test item was prepared as a suspension in 0.5% methylcellulose and was administered by oral route (gavage), under a volume of 10 mL/kg, to groups of three fasted Sprague-Dawley rats. At first, three males were treated with 200 mg/kg bw; then after, three males and three females were treated with 2000 mg/kg bw. Clinical signs, mortality and body weight gain were checked for a period of up to 14 days following the single administration of the test item. All animals were subjected to necropsy.

At 200 mg/kg bw: No mortality occurred. Only hypoactivity, piloerection and dyspnea were observed in all animals on day 1.

At 2000 mg/kg bw : In males, 1/3 animals were found dead on day 2; hypoactivity or sedation, piloerection and dyspnea were recorded prior to death. In all surviving animals, hypoactivity, piloerection and dyspnea were noted from day 1 up to day 4.

In females, no mortality occurred. Hypoactivity and piloerection were observed in all animals on day 1; then hypoactivity, piloerection and dyspnea were recorded in 1/3 females on day 2. No clinical signs were noted thereafter.

The overall body weight gain of the animals treated at 200 mg/kg was not affected by treatment with the test item. At the 2000 mg/kg dose-level, a slightly reduced body weight gain was seen in all surviving animals during the first week of the study, when compared to historical control animals. At necropsy, no apparent abnormalities were observed.

Under these experimental conditions, the oral LD50 of the test item Dibutyl thiourea is higher than 2000 mg/kg in rats.

Acute toxicity: dermal (OECD 402, Richeux 2011) on analogue substance:

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.

Justification for classification or non-classification

Based on the available data, 1,3-dibutyl thiourea should be classified as Harmful if contact with skin (Acute tox 4, H312) according to the Regulation EC 1272/2008.

Justification: the dermal LD50 = 2000 mg/kg in rats.

No CLP classification is required by oral and inhalation route.