1,3-diethyl-2-thiourea

Endpoint summary

Description of key information

A reliable study on rats is available for oral route. Mortalities were observed at several doses, and the LD50 was 930 mg/kg bw in mice.
By dermal route, a guideline study (OECD 402) is available on rats. The dermal LD50 of DETU is equal to 2000 mg/kg bw. 
There are no data on acute toxicity by inhalation. 

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

The acute oral toxicity of DETU was studied in male mice. Groups of 10 -20 mice were treated with DETU by gavage. The doses used were : 500, 700, 1000, 1400, 2000, 2800 mg/kg bw. A group of 10 mice wasn't treated, it was a control group. Animals were observed three hours after administration for clinical signs, and five days for mortality.

GLP compliance:

no

Test type:

standard acute method

Limit test:

yes

Species:

mouse

Strain:

CD-1

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River
- Age at study initiation: no data
- Weight at study initiation: 19-23g
- Fasting period before study: no data
- Housing: no data
- Diet (e.g. ad libitum): no data
- Water (e.g. ad libitum): no data
- Acclimation period: no data

ENVIRONMENTAL CONDITIONS
- Temperature (°C): no data
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): no data

Route of administration:

oral: gavage

Vehicle:

other: gum arabic (10%)

Details on oral exposure:

Volume: 50 ml/kg

Doses:

500, 700, 1000, 1400, 2000, 2800 mg/kg bw

No. of animals per sex per dose:

10-20 mice/dose

Control animals:

yes

Details on study design:

Observation period: 5 days after administration

Statistics:

no

Key result

Sex:

male

Dose descriptor:

LD50

Effect level:

930 mg/kg bw

Mortality:

No mortality were observed in control group (0/10) and in 500 mg/kg group (0/10).
At 700 mg/kg bw: 5/20 mice died at 3 hours. At 1000 mg/kg bw: 5/20 mice died 3 hours after administration, then an other mouse diet at 1 day (6/20), and 4 mice at 2 days (10/20). At 1400, 2000 and 28000 : all mice died 3 hours or 1 day after administration.

Clinical signs:

other: Mice of control group did show any clinical signs. The mice treated with 500 mg/kg bw showed sedation and bradypnea. At 700 mg/kg bw, slow breathing, sedation and cyanosis were observed. At 1000, 1400, 2000 and 2800 mg/kg bw, the same symtoms that 700 mg/

Gross pathology:

no data

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

In this study, the oral LD50 of DETU was 930 mg/kg bw in male mice.

Executive summary:

The acute oral toxicity of DETU was studied in male mice. Groups of 10 -20 mice were treated with DETU by gavage. The doses used were : 500, 700, 1000, 1400, 2000, 2800 mg/kg bw. A group of 10 mice wasn't treated, it was a control group. Animals were observed three hours after administration for clinical signs, and five days for mortality.

No mortality and no clinical signs were observed at 0 and 500 mg/kg bw.

10/20 mice died at 700 mg/kg, and most of mice died at 1000, 1400, 2000 and 2800 mg/kg bw. Clinical signs observed in these animals were sedation, dyspnea, whrighting, tremor, hypothermia.

According these results, the LD50 of DETU was 930 mg/kg bw in male mice.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

930 mg/kg bw

Quality of whole database:

The key study is a reliable study and has a klimish score of 2.

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Deviations:

no

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system 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:

other: 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), bradypne

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

Value:

2 000 mg/kg bw

Quality of whole database:

The study is a GLP compliant, performed according to the OECD guideline 402, and has a klimish score of 1.

Additional information

Acute oral study (Loiseau 1972)

Groups of 10 -20 male mice were treated with DETU by gavage. The doses used were : 500, 700, 1000, 1400, 2000, 2800 mg/kg bw. A group of 10 mice wasn't treated, it was a control group. Animals were observed three hours after administration for clinical signs, and five days for mortality.

No mortality and no clinical signs were observed at 0 and 500 mg/kg bw.

10/20 mice died at 700 mg/kg, and most of mice died at 1000, 1400, 2000 and 2800 mg/kg bw. Clinical signs observed in these animals were sedation, dyspnea, whrighting, tremor, hypothermia.

According these results, the LD50 of DETU was 930 mg/kg bw in male mice.

Acute dermal study (Richeux 2011)

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 all 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 (male/female).

Justification for classification or non-classification

Proposed self-classification (Regulation (EC) No 1272/2008):

Oral acute Tox. 4, H 302 (Harmful if swallowed). Justification: LD50(oral) is between 300 and 2000 mg/kg bw.

Dermal acute Tox. 4, H 312 (Harmful if contact with skin). Justification: LD50(dermal) is between 1000 and 2000 mg/kg bw.