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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28/10/1996 - 31/12/1997
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP, Guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997
Report date:
1997

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)
Version / remarks:
(1981)
Deviations:
no
Qualifier:
equivalent or similar to guideline
Guideline:
EU Method B.26 (Sub-Chronic Oral Toxicity Test: Repeated Dose 90-Day Oral Toxicity Study in Rodents)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPP 82-1 (90-Day Oral Toxicity)
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: JMAFF 59 NohSan no. 4200 (1985)
Deviations:
no
GLP compliance:
yes
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
1-methyl-2-nitro-3-(tetrahydrofuran-3-ylmethyl)guanidine
EC Number:
605-399-0
Cas Number:
165252-70-0
Molecular formula:
C7H14N4O3
IUPAC Name:
1-methyl-2-nitro-3-(tetrahydrofuran-3-ylmethyl)guanidine
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder

Test animals

Species:
mouse
Strain:
other: Crl:CD1® (ICR)BR VAF/Plus ®
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Age at study initiation: About 7 weeks old
- Weight at study initiation: 25.9 – 35.9 g for males. 18.8 – 32.2 g for females

Administration / exposure

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on oral exposure:
DIET PREPARATION
- Rate of preparation of diet: Diets were prepared approximately every 4 weeks [on Days -5 for Weeks 1-4], [on Day 23 for Weeks 5-8], [on Day 52 for Weeks 9-12] and [on Day 80 for Weeks 13 and 14].
- Mixing appropriate amounts with: Basal diet: Certified Rodent Diet #5002 meal
- Stability and homogeneity of the preparation: Stability of representative test diets containing 5000 or 50000ppm dinotefuran, bracketing the range of concentrations employed, was determined for 40 days at room temperature before start of the study. Stability analyses of diets containing 5000 or 50000ppm revealed dinotefuran to be stable for 40 days at room temperature. Further stability analyses on diets containing 500ppm demonstrated stability at room temperature for 40 days, at which time 100% of the initial concentration remained. The homogeneity analyses of multiple diet samples containing 500 or 50000ppm were within the ranges 101 - 106% and 96.0 - 97.4%, respectively, of theoretical concentrations.
- Achieved concentrations: Periodic analyses of all diets for achieved concentration showed dinotefuran to be present in the formulations at 91.6 to 113% nominal concentrations.
- Mean achieved dose levels: 0, 81, 844, 4442 and 10635mg/kg b.w./day (males) and 0, 102, 1064, 5414 and 11560mg/kg bw/day (females).
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Analyses for the concentration of dinotefuran in the dose preparations were conducted by Covance Laboratories Inc. using an analytical method, MP-MT25-MA, validated by Covance Laboratories Inc.
Duration of treatment / exposure:
13 weeks
Frequency of treatment:
Daily, except where mice were fasted
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
500 ppm
Basis:
nominal in diet
Remarks:
Doses / Concentrations:
5000 ppm
Basis:
nominal in diet
Remarks:
Doses / Concentrations:
25000 ppm
Basis:
nominal in diet
Remarks:
Doses / Concentrations:
50000 ppm
Basis:
nominal in diet
No. of animals per sex per dose:
10 mice per sex per dose
Control animals:
yes, concurrent no treatment
Details on study design:
- Dose selection rationale: Based on preliminary results of a previous 4-week dietary study with dinotefuran (7.5.1. Weiler (1997)/4 week diet mouse/key). Slightly lower body weights for animals given diets containing 50000 ppm dinotefuran and minimal increases in total protein and albumin in males given diets containing 50000 ppm dinotefuran in a 13-week study. It was anticipated that the low-dose level would be the no-observed-effect-level. The mid- and mid-high-dose levels were selected as fractions of the high-dose level that were expected to result in dose-related effects.
- Post exposure observation period: none
Positive control:
None

Examinations

Observations and examinations performed and frequency:
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Morbidity/mortality checks were performed twice daily and a detailed clinical examination performed weekly.

BODY WEIGHT: Yes
- Time schedule for examinations: Body weights were recorded weekly throughout the study.

FOOD CONSUMPTION:
- Time schedule for examinations: Food consumption was recorded weekly throughout the study.

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Ophthalmic examinations were conducted pre-test and in Week 14.
- Dose groups that were examined: All mice

HAEMATOLOGY: Yes / No / No data
- Time schedule for collection of blood: Hematology was performed in Week 14. Blood samples were withdrawn after a period of at least 4 hours food deprivation.
- Anaesthetic used for blood collection: Yes, sodium pentobarbital
- Animals fasted: Yes, for at least 4 hours prior to sampling
- How many animals: 5 mice/sex/group

CLINICAL CHEMISTRY: Yes / No / No data
- Time schedule for collection of blood: Hematology was performed in Week 14. Blood samples were withdrawn after a period of at least 4 hours food deprivation.
- Anaesthetic used for blood collection: Yes, sodium pentobarbital
- Animals fasted: Yes, for at least 4 hours prior to sampling
- How many animals: 5 mice/sex/group

URINALYSIS: Yes / No / No data
- Time schedule for collection of urine: Week 14
- Animals fasted: Yes, for at least 4 hours prior to sampling
- How many animals: All mice
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
Statistics:
Where appropriate, data were analysed statistically at the 5% level by one-way analysis of variance on homogeneous or transformed data followed by Dunnett’s t-test where ANOVA proved significant. Levene’s test was used to evaluate the homogeneity of variance.

Results and discussion

Results of examinations

Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
See Table 1
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):
not examined
Ophthalmological findings:
no effects observed
Haematological findings:
no effects observed
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
See Table 2
Urinalysis findings:
effects observed, treatment-related
Description (incidence and severity):
See Table 2
Behaviour (functional findings):
not examined
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:
There were no deaths and no treatment-related clinical signs at any dose level during the study, but both sexes at 50000ppm lost weight during the first week of treatment and subsequently showed a treatment-related depression of body weight gain (Table 1). The overall mean weight gains of both sexes were significantly (p < 0.05) lower than control values and at termination the group mean body weights were 15.4 and 21.9% lower than the controls in males and females, respectively. The overall weight gains of males at 25000ppm and females at 500, 5000 and 25000ppm were 15.9 to 31.4% lower than, but not significantly (p > 0.05) different from, the controls. Increased food spillage occurred during the first week in the groups treated at 25000 or 50000ppm and continued throughout the study at 50000ppm. Spillage is considered to indicate reduced diet palatability at concentrations ≥ 25000ppm and any apparent increase in food consumption is considered to represent spillage. There was no evidence of an effect on food consumption or food efficiency at dose levels up to 5000ppm.

There were no treatment-related ophthalmological and hematological effects at any dose level. All group mean hematological values were similar to, and not significantly (p > 0.05) different from, the control values. Treatment-related effects on serum chemistry after 13 weeks of treatment were confined to the group treated at 50000ppm (Table 2). The serum albumin concentration of males was slightly, but significantly (p < 0.05) higher than the control value by 17.2%. Urine pH was slightly lower in both sexes, but significantly different from the controls in the female group only. These minor differences from the controls were not associated with overt histopathological alterations and are considered not to be adverse effects. With the exception of serum urea concentration in females at 25000ppm which was significantly (p < 0.05) higher than the control value, all other serum and urine clinical chemistry values were not significantly (p > 0.05) different from the control values at all dose levels.

There were no primary treatment-related effects on absolute and relative organ weights at any dose level. The absolute weights of the heart and liver in females at 50000ppm and of the kidneys in both sexes were significantly (p < 0.05) lower than control values. The differences are considered to be a consequence of growth retardation since the organ/body weight ratios were not affected. A significant (p < 0.05) increase in the brain/body weight ratios in both sexes at 50000ppm is also considered to reflect growth retardation. There were no treatment-related macroscopic findings at necropsy at any dose level. There were no treatment-related histopathological alterations and the nature, severity and incidence of microscopic findings were similar in all treated and control groups.

Effect levels

open allclose all
Dose descriptor:
NOEL
Effect level:
25 000 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: see 'Remark'
Dose descriptor:
NOAEL
Effect level:
25 000 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: see 'Remark'

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

Table 1: Summary of bodyweights, weight gains and food consumption

Interval

Males treated at (ppm):

Females treated at (ppm):

 

0

500

5000

25000

50000

0

500

5000

25000

50000

 

Group mean body weight (g)

Week 1

31.0

31.6

30.2

30.1

31.1

26.0

26.1

25.3

26.1

25.6

Week 2

32.7

33.2

32.0

31.2

30.2

27.3

27.2

26.5

26.8

24.0

Week 3

34.4

35.0

33.7

32.9

30.4*

28.9

28.5

27.6

28.0

24.7*

Week 4

34.6

34.9

34.2

32.8

30.9*

29.1

28.5

27.8

28.1

25.1*

Week 8

37.9

38.1

37.0

36.1

33.2*

31.5

30.7

30.0

30.2

26.6*

Week 14

41.7

41.9

40.3

39.1

35.3*

36.5

34.1

32.5*

33.3

28.5*

Overall gain

10.7

10.3

10.1

9.0

4.2*

10.5

8.0

7.2

7.2

2.9*

 

Group mean food consumption (g/week)**

Weeks 1 - 4

45.1

43.6

43.6

43.7

49.6

41.4

43.2

43.6

44.5

46.1

Weeks 5 - 8

45.6

44.4

45.1

45.8

51.4

45.0

46.1

45.1

45.9

42.3

Weeks 9 - 13

40.5

40.4

40.2

41.7

45.3

42.6

42.1

42.6

43.7

41.9

* p < 0.05

** food consumption of animals not showing substantial food spillage

Table 2: Treatment related serum and urine clinical chemistry findings - Week 14

Sex

 

Dose level (ppm)

Mean serum albumin concentration

±SD (g/dL)

Mean urine pH (range)

Male

0

2.9±0.14

7.3 (6.5 - 8.5)

 

500

3.1±0.31

7.5 (7.0 - 8.0)

 

5000

3.2±2.1

7.5 (7.0 - 8.0)

 

25000

3.3±0.18

6.9 (7.0 - 8.5)

 

50000

3.4±0.26*

6.3 (6.0 - 8.0)

Female

0

3.4±0.09

7.2 (6.5 - 8.0)

 

500

3.4±0.25

7.2 (6.5 - 7.5)

 

5000

3.4±0.11

7.2 (6.5 - 8.0)

 

25000

3.5±0.38

6.8 (6.5 - 7.5)

 

50000

3.6±0.29

6.6* (6.0 - 7.0)

* p < 0.05

Applicant's summary and conclusion

Conclusions:
No target organs were identified in either sex at the highest dose level employed. The no-observed-effect-level (NOEL) and no-observed-adverse-effect-level (NOAEL) were established as 25000ppm in both sexes, equivalent to dose levels of 4442mg/kg bw/day (males) and 5414mg/kg bw/day (females), based on the occurrence of reduced weight gain in both sexes at 50000ppm. In addition, non-adverse effects of increased serum albumin concentration in males and reduced urine pH in both sexes occurred at 50000ppm.