Diethyl malonate

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15/05/2003 - 22/08/2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2003

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:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Dimethyl malonate

EC Number:

203-597-8

EC Name:

Dimethyl malonate

Cas Number:

108-59-8

Molecular formula:

C5H8O4

IUPAC Name:

dimethyl malonate

Details on test material:

purity 99.8 wt%

Specific details on test material used for the study:

The stability of the test item at 5 mg/ml and 150 mg/ml was confirmed before the start of treatment and the test item was found to be stable for 8 days at both the levels of fortification in double distilled water when stored at ambient condition.

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

- Animals: HSDCpb-WU rats
- Age at study initiation: 11-12 weeks
- Weight at study initiation:
males: 377-379 g, females: 210-219 g

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The actual concentration of the test item in the solutions was analysed and documented in the study report.
The test item was found to be stable for 8 days, when fortified and stored at room temperature at both the level of fortification.

Duration of treatment / exposure:

Males:
Test groups: 39 days, male recovery group: 39 exposure days, 45 test days.
Females:
Treatment groups: 51 +/- 7 days, recovery group: 39 exposure days, 45 test days.

Frequency of treatment:

once daily, 7 days a week

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

100 mg/kg bw/day (actual dose received)

Doses / concentrations 2

Dose / conc.:

300 mg/kg bw/day (actual dose received)

Doses / concentrations 3

Dose / conc.:

1 000 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

Main group: 10 males, 10 females
Recovery groups: 5 males, 5 females

Control animals:

yes, concurrent no treatment

Details on study design:

Rats were housed under standard laboratory conditions; air conditioned with 12 - 15 filtered fresh air changes per hour; temperature: 22 - 25°C; relative humidity: 30 - 70% and 12 hour fluorescent light and 12 hour dark cycle.

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule:
Twice daily: morbidity and mortality. Daily observations for appearance, behaviour, clinical signs and preterminal deaths. Females were observed for signs of difficult and pronlonged parturition.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: once before exposure and at least once per week thereafter. Signs included were changes in skin, fur, eyes, mucous membranes, occurrence of secretions or excretions and autonomic activity, changes in gait, posture, response to handling, behavioural changes, difficult or prolonged parturition.

BODY WEIGHT: Yes
- Time schedule for examinations:
Body weights were recorded at the beginning of the study, at least weekly thereafter and at termination. All dams were weighed on gestation days 0, 7, 14 and 20 and lactation days 0 and 4.

FOOD CONSUMPTION AND COMPOUND INTAKE:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No data

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No data

OPHTHALMOSCOPIC EXAMINATION: No data

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at the end of the pre-mating period and the recovery period
- Anaesthetic used for blood collection:No data
- Animals fasted: No data
- How many animals: 5 randomly selected males and females or each group.
- Standard haematological parameters checked

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at the end of the pre-mating period and the recovery period
- Anaesthetic used for blood collection:No data
- Animals fasted: No data
- How many animals: 5 randomly selected males and females or each group.
- Standard clinical chemistry parameters checked

URINALYSIS: No data


NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: at the end of the dosing period for males and during the lactation period tor females
- Dose groups that were examined: each group
- Battery of functions tested:
handling observations, open field tests, sensory observations, neuromuscular observations and physiological observations (body temperature)

Sacrifice and pathology:

Pathology: All adult animals and pups were examined for any structural abnormalities and pathological changes.
Histopathology: The following tissues of 5 males and females of the control and high dose group as well as all animals of the recovery and recovery control groups were examined microscopically: all gross lesions, brain, spinal cord, gastrointestinal tract, liver, kidney, adrenals, spleen, heart, thymus, thyroid, trachea, lungs, testes (fixed in Bouins fluid), epididymes (fixed in Bouins fluid), ovaries, uterus, seminal vesioles, coagulating glands, prostate, urinary bladder, axillary lymph nodes, mesenteric lymph nodes, sciatic nerve, femur with marrow, bone marrow smear. Stages of spermatogenesis and interstitial testicular structure in male gonads were determined additionally. Livers of 5 males and females in the mid and low dose groups and testes of 5 males of the mid and low dose groups were also examined.

Other examinations:

LITTER DATA: All pups from each litter were examined for any external deformities, litter size and sex distribution was determined. Pup weights were recorded on day 0 and 4. All pups were examined for malformations and subject to gross pathological examination. Pup survival index up to lactation day 4 was determined.
Organ weights of liver, adrenals, kidneys, thymus spleen, brain and heart were determined of 5 males and females of each group. Testes and epididymis weights of all adult males of each group were also determined.

Statistics:

Dunnett's t-Test: body weight, body weight change, food intake, haematology, clinical chemistry, organ weight, FOB, gestation length, litter size, No. corpora lutea, No. implantation.
Z-Test/Student's t-Test: Mating performance, conception rate, fertility index, gestation index, live birth index, viability index, sex ratio, pup survival data, No. littered, No. dead pups, No. live pups, Pup survival data, Pre- and Post-implantation loss. Histopathological data.
t-Test/ANOVA: dose correlation

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

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):

no effects observed

Immunological findings:

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Neuropathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

1000 mg/kg bw: Livers of males and females showed a significantly increased incidence of hepatocellular hypertrophy. The change was considered reversible as the incidence was not significantly increased in the high dose recovery animals.
300 and 100 mg/kg bw: No treatment related changes of the liver were observed.
All other histopathological findings were not considered treatment related.

Histopathological findings: neoplastic:

no effects observed

Effect levels

1

Key result

Dose descriptor:

LOAEL

Effect level:

1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No treatment related effects have been observed.

2

Key result

Dose descriptor:

NOAEL

Effect level:

300 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Significantly increased hepatocellular hypertrophy.

Target system / organ toxicity

Key result

Critical effects observed:

no

Applicant's summary and conclusion

Conclusions:

Based on the study results a LOAEL value of 1000 mg/kg bw for both male and female can be stated for dimethyl malonate.
Based on the study results a NOAEL value of 300 mg/kg bw for both male and female can be stated for dimethyl malonate.