Registration Dossier

Administrative data

Endpoint:
acute toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
March 20, 1980 - April 5, 1980
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1980
Report Date:
1980

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 401 (Acute Oral Toxicity)
Version / remarks:
Study performed prior to introduction of guideline
GLP compliance:
no
Test type:
standard acute method
Limit test:
no

Test material

Reference
Name:
Unnamed
Test material form:
liquid

Test animals

Species:
rat
Strain:
other: TacN(SD)fBR
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Taconic Farms (Germantown, N.Y.)
- Females (if applicable) nulliparous and non-pregnant: no information
- Age at study initiation: young adult
- Weight at study initiation: 180-280 grams
- Fasting period before study: overnight
- Housing: individually in wire cages under standard laboratory conditions
- Diet (e.g. ad libitum): ad libitum, Purina Rodent Laboratory Chow 5001
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 7 days

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
ethanol
Remarks:
SDA 39C
Details on oral exposure:
VEHICLE
- Concentration in vehicle: Appropriate for each dose level

MAXIMUM DOSE VOLUME APPLIED: 5.0 ml/kg bw

STARTING DOSE:
- Rationale for the selection of the starting dose: a preliminary dose range finding study was done to determine mortality. Two fasted rats (one male one female) were used per dose, administered the test substance and observed for the next 72 hours to determine mortality. At the initial dose of 5.0 g/kg bw, both male and female rat died. Subsequently doses of 0.1, 0.5 and 1.0 g/kg bw were used and all rats survived.
Doses:
1.0, 1.4, 1.8, 2.4, and 3.2 g/kg bw in males and females.
Additional groups of females only 0.63, 0.79, 1.0, 1.26 and 1.59 g/kg bw.
No. of animals per sex per dose:
8
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations: the animals were observed at 1, 3, 5 and 24 hours after application and thereafter twice daily (once daily on weekends).
- Necropsy of survivors performed: yes, at the end of the observation period the animals were killed by ether inhalation, necropsied and subjected to examination for gross pathological changes.
- Body weights: Individual body weights were recorded before fasting, immediately before treatment and then on the 14th day of the observation period.
Statistics:
According to J.T. Litchfield, Jr. and F. Wilcoxon, 1949, 'A Simplified Method of Evaluating Dose-Effect Experiments', J. Pharm. Exp. Therap., 96:99-115.

Results and discussion

Preliminary study:
Range finding study in 2 rats: the initial dose was 5.0 grams per kilogram body weight and both rats died. Subsequenty doses of 0.1, 0.5 and 1.0 g/kg were used and all rats survived.
Effect levelsopen allclose all
Key result
Sex:
female
Dose descriptor:
LD50
Effect level:
1 060 mg/kg bw
Based on:
test mat.
95% CL:
>= 853 - <= 1 318
Key result
Sex:
male
Dose descriptor:
LD50
Effect level:
2 000 mg/kg bw
Based on:
test mat.
95% CL:
>= 1 535 - <= 2 606
Mortality:
Mortality rate in males per dose: 1/8 (1.0 g/kg), 3/8 (1.4 g/kg), 4/8 (1.8 g/kg), 2/8 (2.4 g/kg) and 7/8 (3.2 g/kg).
Mortality rate in females per dose (first group): 4/8 (1.0 g/kg), 8/8 (1.4 g/kg), 7/8 (1.8 g/kg), 7/8 (2.4 g/kg) and 8/8 (3.2 g/kg).
Mortality rate in females per dose (second group): 1/8 (0.63 g/kg), 5/8 (0.79 g/kg), 7/8 (1.0 g/kg), 8/8 (1.26 g/kg) and 5/8 (1.59 g/kg).
Clinical signs:
At the lowest dose 1.0 g/kg in males and 0.63 g/kg in females, animals were prone or ataxic for the remainder of the day after dosing. Survivors recovered in the next day and appeared normal from day two and three, respectively, for the remainder of the study. At higher doses, similar signs occured and soft stools were relatively frequent. Less frequent signs were chromodacryorrhea, clonic convulsions and wetness of the fur around the mouth.

In general, clinical signs observed included ataxia, lacrimation, prone position, tremors, lethargy, chromodacryorrhea, twitches/jerks, unkempt fur, chromorinhorrhea, piloerection, abdominal gripping, diarrhea, moribund, hyperresponsiveness to external stimuli, hematuria and oral discharge.
Body weight:
All surviving animals gained weight in a normal pattern.
Gross pathology:
No signs of systemic toxicity were found in any animal necropsied at termination. Common signs in animals that died were yellow fluid in the stomach (probably test article) and reddish fluid in the intestines. In two animals red lining of the intestines is observed from which one animal also showed red lining of the stomach. Furthermore in one animal black fluid in the intestines was observed and in one animal autolysis of tissue in other than standard examined tissues.

Any other information on results incl. tables

Dosage (g/kg)

Mortality males

Mortality females (first group)

Mortality females (second group)

All surviving animals were normal by day

0.63

 

 

1/8

3

0.79

 

 

5/8

5

1.0

1/8

4/8

7/8

All but one on day 2, one on day 5

1.26

 

 

8/8

 

1.4

3/8

8/8

 

2

1.59

 

 

5/8

4

1.8

4/8

7/8

 

3

2.4

2/8

7/8

 

All but one on day 2, one on day 3

3.2

7/8

8/8

 

2

Applicant's summary and conclusion

Interpretation of results:
other: Acute Oral Toxicity, Category 4
Remarks:
in accordance with EU CLP (EC 1272/2008 and its updates)
Conclusions:
The calculated acute oral LD50 for males was 2000 (95% Cl 1535-2606) mg/kg bw, and the calculated acute oral LD50 for females was 1060 (95% Cl 853-1318) mg/kg bw. Based on the results of this study it is concluded that Dimeth Cyclormol should be classified as harmful if swallowed.
Executive summary:

An acute oral toxicity study was performed according to a method similar to OECD TG 401, not under GLP and therefore receives Kl. 2. In this study, 80 rats (40 males and 40 females) were administered Dimeth Cyclormol at dose levels of 1.0, 1.4, 1.8, 2.4, and 3.2 g/kg bw resulting in mortality rates of 1/8, 3/8, 4/8, 2/8, and 7/8 for males and 4/8, 8/8, 7/8, 7/8 and 8/8, respectively.The calculated acute oral LD50 for males was 2000 (95% Cl 1535-2606) mg/kg bw, and the calculated acute oral LD50 for females was 1060 (95% Cl 853-1318) mg/kg bw.

Clinical signs: At the lowest dose 1.0 g/kg in males and 0.63 g/kg in females, animals were prone or ataxic for the remainder of the day after dosing. Survivors recovered in the next day and appeared normal from day two and three, respectively, for the remainder of the study. At higher doses similar signs occurred and soft stools were relatively frequent. Other signs that occurred sporadically were e.g. chromodacryorrhea, clonic convulsions, and wetness of the fur around the mouth. All surviving animals gained weight in a normal pattern.

Necropsy: No signs of systemic toxicity were found in animals necropsied at termination. Common signs in animals that died were yellow fluid in the stomach (probably test article) and reddish fluid in the intestines. In two animals red lining of the intestines is observed from which one animal also showed red lining of the stomach. Furthermore in one animal black fluid in the intestines was observed and in one animal autolysis of tissue in other than standard examined tissues.

Supporting 2nd study (which is part of the report in which the key study is presented) An additional groups of 8 females were dosed 0.63, 0.79, 1.0, 1.26 and 1.59 g/kg bw and a mortality rate of 1/8, 5/8, 7/8, 8/8 and 5/8 animals was found, respectively.The LD50 in the additional females was not calculated in absence of a clear dose response. A new study in females was performed.