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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
No data. Treatment days were 09.04.1980 to 13.05.1980
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

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

Materials and methods

Test guideline
Guideline:
other: FDA "Guidelines for reproductive studies for evaluation of drugs for human use", segment II (teratological study)
Deviations:
not specified
Remarks:
No analytical evaluation of exposure levels.
Principles of method if other than guideline:
The study was designed to evaluate the embryotoxic and/or teratogenic potential of the test substance. Dosing was on gestation days 6-15, no measurement of gravid uterine weights and copora lutea were not counted.
GLP compliance:
no
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Nitrilotrimethylenetris(phosphonic acid)
EC Number:
229-146-5
EC Name:
Nitrilotrimethylenetris(phosphonic acid)
Cas Number:
6419-19-8
Molecular formula:
C3H12NO9P3
IUPAC Name:
[nitrilotris(methylene)]tris(phosphonic acid)
Test material form:
liquid

Test animals

Species:
mouse
Strain:
CD-1
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratories Inc.
- Age at study initiation: Females 57 days (males stated to be sexually mature)
- Weight at study initiation: Females on gestation Day 0 were approximately 26 g.
- Fasting period before study: No data
- Housing: Individual in elevated stainless steel cages.
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: One month


ENVIRONMENTAL CONDITIONS
- Temperature (°C): No data. Monitored twice daily.
- Humidity (%): No data
- Air changes (per hr): No data
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: Day 6 of gestation: 09.04.1980 - 04.05.1980 To: Day 15 of gestation: 18.04.1980 - 13.05.1980.

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
other: Not clear, stated to be distilled water and corn oil in different parts of the report.
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: Appropriate amounts of test substance were dissolved in distilled water and administered at a constant volume of 10 ml/kg bw/day. Dosing solutions were prepared fresh daily.
Analytical verification of doses or concentrations:
no
Details on mating procedure:
- Impregnation procedure: Cohoused
- If cohoused:
- M/F ratio per cage: 1:2
- Length of cohabitation: Overnight
- Verification of same strain and source of both sexes: No data
- Proof of pregnancy: vaginal plug referred to as day 0 of pregnancy.
Duration of treatment / exposure:
GD 6 - 15
Frequency of treatment:
daily
Duration of test:
18 days
Doses / concentrationsopen allclose all
Dose / conc.:
100 mg/kg bw/day
Dose / conc.:
500 mg/kg bw/day
Dose / conc.:
1 000 mg/kg bw/day
No. of animals per sex per dose:
35 mated females
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: No data
- Rationale for animal assignment (if not random): Random

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes for mortality and gross signs of toxicological effects (no further details).
- Time schedule: Twice daily.


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Gestation days 0, 6, 9, 12, 15 and 18.


BODY WEIGHT: Yes
- Time schedule for examinations: Gestation days 0, 6, 9, 12, 15 and 18. Calculated body weight change for days 0-6, 6-15 and 15-18.


FOOD CONSUMPTION: No


WATER CONSUMPTION: No


POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 18 (all surviving dams) and Day 18 post-mating in all surviving non-pregnant females.
- Organs examined: Complete gross pathology examination.
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No
- Number of corpora lutea: No
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes, and weighed, measured and sex determined.
- Other: Live and dead fetuses. Internal sex determination of fetuses.
Fetal examinations:
- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: half per litter
- Head examinations: Yes: No data
Statistics:
Maternal body weight and reproduction data: Bartlett's test followed by one-way ANOVA (equal variance) followed by Dunnett's test or Kruskal-Wallis test (unequal variance) and summed rank test (Dunn).  Pregnancy and fetal parameters: Chi square analysis followed by Fisher Exact test with Bonferroni correction. Armitage test for linear trend.
Indices:
No data
Historical control data:
No data

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:no effects

Details on maternal toxic effects:
There were no treatment-related deaths (only deaths that occurred as a result of dosing errors and one death of a control animal on gestation day 11), no adverse clinical effects, no effects on body weights or body weight gains, and no effects on reproductive parameters (pregnancy rates, numbers of live and dead fetuses, implantations and resorptions). There were no treatment-related adverse findings during the macroscopic examination.

Effect levels (maternal animals)

Key result
Dose descriptor:
NOAEL
Effect level:
> 1 000 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
other: maternal toxicity

Maternal abnormalities

Abnormalities:
no effects observed

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
No effects on mean fetal body w eights, crown-rump length and fetal sex distribution. During the fetal skeletal evaluations, the incidence of fetuses with at least one ossification variation was slightly higher than the concurrent control in the mid and high dose groups. However, incidences for these groups were within the range of historical values for the laboratory and strain of mouse. The type and incidence of ossification variations during the skeletal evaluations were similar to the controls. However there was a slight increase in the incidence of fetuses with rudimentary structures observed in the mid and high dose groups. The incidence of fetal external and soft tissue malformations were comparable between control and treated groups. No malformations were noted in the treated groups during the gross evisceration examinations. During the skeletal evaluations the incidence of malformations was low in the low (no malformations observed) and high dose groups. The incidence of skeletal malformations in the mid-dose group was significantly increased. However, this increase was attributed to a high number of malformed fetuses from a single mid-dose litter. Six fetuses from this litter had skeletal malformations that included misshapen tibia and fibula, angulated ribs and defective sternebrae. Since these effects were not observed in the highest and lowest dose groups they were not considered to be related to treatment.

Effect levels (fetuses)

open allclose all
Key result
Dose descriptor:
NOAEL
Effect level:
> 1 000 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: teratogenicity
Key result
Dose descriptor:
NOAEL
Effect level:
> 1 000 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: fetotoxicity

Fetal abnormalities

Abnormalities:
no effects observed

Overall developmental toxicity

Developmental effects observed:
no

Any other information on results incl. tables

Table 1 Summary of Malformations found during the fetal skeletal examination.

 Group (mg/kg bw/day)  Malformation     Fetuses     Litter
     No. with malf./total examined  %  No. with malf fetuses/total examined  %
 0  None  0/138    0/24  
 100  Cervical vertebral defect 1/156   0.6  1/28  3.6
 500  Tibia misshapened - alone  1/203  0.5  1/34 2.9 
  - with misshapened fibula and angulated ribs  2/203   1.0  1/34  2.9
   - with misshapened fibula, angulated ribs and sternebrae defects   1/203  0.5  1/34  2.9
  - with angulated ribs  1/203  0.5  1/34  2.9
   Angulated ribs and scrambled sternebrae  1/203  0.5  1/34  2.9
   Cervical rib  1/203  0.5  1/34 2.9 
   5 lumbar vertebrae  2/203  1.0  1/34  2.9
   Total  9/203  4.4*  3/34  8.8
 1000  Scrambled sternebrae  1/183  0.5 1/32   3.1
   Vertebral defects  1/183  0.5  1/32  3.1

*Difference from the control group statistically significant p<0.05 (Fisher Exact test).

Applicant's summary and conclusion

Conclusions:
In a well conducted teratogenicity study (FDA segment II: teratological study; reliability score 2) conducted prior to the adoption of OECD test guidelines and GLP, it was concluded that Dequest 2000 was not embryotoxic or teratogenic when administered to mice at 100, 500 or 1000 mg/kg bw/d by gavage on GD6-15.
Executive summary:

In a well conducted teratogenicity study (FDA segment II: teratological study; reliability score 2) conducted prior to the adoption of OECD test guidelines and GLP, Dequest 2000 was administered by oral gavage to pregnant CD-1 mice (35 mated females/dose) on gestation days 6 -15. The doses tested were 100, 500 and 1000 mg/kg bw/day. The control group received the vehicle only. Parameters evaluated were mortality, body weight, clinical signs, uterine implantation data, ossification variation data and teratological evaluation. There were no treatment-related deaths (only deaths that occurred as a result of dosing errors and one death of a control animal on gestation day 11), no adverse clinical effects, no effects on body weights or body weight gains, and no effects on reproductive parameters (pregnancy rates, numbers of live and dead fetuses, implantations and resorptions). There were no treatment-related adverse findings during the macroscopic examination. No effects on mean fetal body weights, crown-rump length and fetal sex distribution. During the fetal skeletal evaluations, the incidence of fetuses with at least one ossification variation was slightly higher than the concurrent control in the mid and high dose groups. However, incidences for these groups were within the range of historical values for the laboratory and strain of mouse. The type and incidence of ossification variations during the skeletal evaluations were similar to the controls. However there was a slight increase in the incidence of fetuses with rudimentary structures observed in the mid and high dose groups. The incidence of fetal external and soft tissue malformations were comparable between control and treated groups. No malformations were noted in the treated groups during the gross evisceration examinations. During the skeletal evaluations the incidence of malformations was low in the low (no malformations observed) and high dose groups. The incidence of skeletal malformations in the mid-dose group was significantly increased. However, this increase was attributed to a high number of malformed fetuses from a single mid-dose litter. Six fetuses from this litter had skeletal malformations that included misshapen tibia and fibula, angulated ribs and defective sternebrae. Since these effects were not observed in the highest and lowest dose groups they were not considered to be related to treatment. The NOAEL for maternal toxicity, fetal toxicity and teratogenicity was greater than 1000 mg/kg bw/day.