Carbonic acid, ethyl methyl ester

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study performed under GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.7 (Repeated Dose (28 Days) Toxicity (Oral))

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

433-480-9

EC Name:

-

Cas Number:

623-53-0

Molecular formula:

C4 H8 O3

IUPAC Name:

ethyl methyl carbonate

Details on test material:

Lot number: 009141

Test animals

Species:

rat

Strain:

other: Sprague-Dawley Crl:CD (SD) IGS BR

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River (UK) Limited, Margate, Kent.
- Age at study initiation: 5-6 weeks old
- Weight at study initiation: males: 125 - 163g; females: 126 - 150 g
- Housing: housed in groups of 5 (by sex) in polypropylene grid-floor cages.
- Diet: Rat and Mouse SQC Expanded Diet No.1, ad libitum
- Water: mains drinking water, ad libitum (supplied in polycarbonate bottles attached to the cage).
- Acclimation period: 8 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 +/- 2
- Humidity (%): 55 +/- 15
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12 hours light / 12 hours dark

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

arachis oil

Details on oral exposure:

Test material was administered on a daily basis for 28 consecutive days using a stainless steel cannula attached to a plastic syringe. Control animals were treated in a similar fashion except instead of receiving test material they received 2 ml/kg/day of arachis oil BP.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Test material concentrations were analysed using the following gas chromatography parameters:
- GC system: Hewlett-Packard 5890A, incorporating autosampler and workstation.
- Column: ZB 624 (60 m x 0.32 mm id x 1.8 um film)
- Oven temperature program: initial 50 degrees C for 1 minute; rate: 10 degrees C/min; final: 200 degrees C for 5 minutes.
- Injection temperature: 250 degrees C
- Flame ionisation detector temperature: 250 degrees C
- Injection volume: 1 µl
- Retention time: approximately 14 minutes

Duration of treatment / exposure:

28 days (consecutive)

Frequency of treatment:

Once daily

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 15, 150 and 1000 mg/kg/day
Basis:
actual ingested

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

A range-finding study was initially conducted to determine the doses used for the definitive study (see below in 'Any other information on materials and methods incl. tables' field). In the definitive study, test animals were administered doses daily for 28 consecutive days. Test animals were observed for signs of toxicity or behavioural changes immediately before dosing and 1-5 hours after dosing during the working week. At weekends, animals were observed immediately before dosing and 1 hour after dosing. Before treatment on days 7, 14, 18 and 25, all animals were observed for signs of functional/behavioural toxicity. Functional performance tests (to assess motor activity, forelimb/hindlimb grip strength and sensory reactivity) were conducted on all animals during week 4 along with an assessment of sensory reactivity to different stimuli. Observations were carried out 2 hours after dosing.

Individual body weights were measured on days 0, 7, 14, 21 and 28 and also prior to termination. Food consumption was recorded at weekly intervals and water intake was observed on a daily basis (visual inspection of water bottles).

Haematological and blood chemical investigations were performed on all animals at the end of the study. After the dosing period all animals were killed and subjected to a full external and internal examination, any macroscopic abnormalities were recorded.

Examinations

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Prior to dosing, then at 1 and 5 hours after dosing (during weekdays) or 1 hours after dosing (during weekends).

BODY WEIGHT: Yes
- Time schedule for examinations: Days 0, 7, 14, 21 and 28.

FOOD CONSUMPTION:
- Food consumption and food efficiency: Yes

HAEMATOLOGY: Yes
- Time schedule for collection of blood: end of study (day 28)
- Anaesthetic used for blood collection: No
- Animals fasted: No
- How many animals: all animals
- Parameters checked: Haemoglobin, erythrocyte count, haemocrit, erythrocyte indices (mean corpuscular haemoglobin, mean corpuscular volume, mean corpuscular haemoglobin concentration), total leucocyte count, differential leucocyte count (neutrophils, lymphocytes, monocytes, eosinophils, basophils), platelet count, reticulocyte count (cresyl blue stained slides were prepared but reticulocytes were not assessed), prothrombin time and activated partial thromboplastin time.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: end of study (day 28)
- Animals fasted: No
- How many animals: all animals
- Parameters checked: urea, glucose, total protein, albumin, albumin/globulin ratio, sodium, potassium, chloride, calcium, inorganic phosphorous, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, creatinine, total cholesterol, total bilirubin.

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: week 4
- Dose groups that were examined: all
- Battery of functions tested: sensory activity, grip strength and motor activity.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

no effects observed

Water consumption and compound intake (if drinking water study):

no effects observed

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Behaviour (functional findings):

effects observed, treatment-related

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
No treatment related mortality was observed in this study. Females of the 1000 mg/kg treatment groups displayed isolated cases of increased salivation after dosing on day 5 and hunched posture from day 14 onwards. No treatment related signs of toxicity were observed in males of the 1000 mg/kg dose group or animals of the 150 mg/kg and 15 mg/kg dose groups.

BODY WEIGHT AND WEIGHT GAIN
No treatment related effect on bodyweight development was observed. Although males of the 150 mg/kg dose group showed a slight but significantly reduction in bodyweight gain during week 4 - in absence of a dose-response relationship this was not considered to be of toxicological importance.

FOOD CONSUMPTION AND FOOD EFFICIENCY:
No significant effects on food consumption or food efficiency.

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study)
Daily inspection of water bottles revealed no significant changes in water consumption.

HAEMATOLOGY
No significant treatment related effects.

CLINICAL CHEMISTRY
No significant treatment related effects.

NEUROBEHAVIOUR
No treatment related effects were observed in the sensory reactivity and functional performance tests. In the behavioural assessment, females of the 1000 mg/kg dose group displayed a hunched posture from week 2 onwards. No behavioural effects were observed in males of the 1000 mg/kg treatment group or animals of the 150 mg/kg and 15 mg/kg treatment group.

ORGAN WEIGHTS
No significant treatment related effects on organ weights were observed. Females of the 1000 mg/kg treatment group did show a slight but statistically significant increase in relative heart weight compared to the control animals - this was not considered to be toxicologically important given the absence of microscopic evidence.

GROSS PATHOLOGY
No significant treatment related macroscopic abnormalities were observed. One male rat of the 15 mg/kg group showed small testes and one female of the 15 mg/kg group showed hydronephrosis of the right kidney. These are considered to be sporadic findings and are not considered to be of toxicological significance.

HISTOPATHOLOGY: NON-NEOPLASTIC
No significant treatment related effects were observed.

HISTOPATHOLOGY: NEOPLASTIC
No significant treatment related effects were observed.

Effect levels

1

Dose descriptor:

NOEL

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

2

Dose descriptor:

NOEL

Effect level:

150 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

other: Hunched posture

3

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Range-finding study: No mortality or signs of toxicity were observed at any dose group. During the 1st week of the study, bodyweight gain of test material treated animals was comparable to the controls however a possible slight reduction in bodyweight was observed in week 2. The necropsy revealed no macroscopic abnormalities. Based on these results the following doses were selected for the definitive study:

- High dose: 1000 mg/kg/day

- Intermediate dose: 150 mg/kg/day

- Low dose: 15 mg/kg/day

Applicant's summary and conclusion

Conclusions:

Under the conditions of this study, the subacute toxicity of ethyl methyl carbonate was assessed and gave a NOEL of 1000 mg/kg for male rats and a NOEL of 150 mg/kg for female rats.
The NOAEL for male animals is >= 1000 mg/kg bw and for female animals 1000 mg/kg bw.