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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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: meets generally acceptable scientific standards, well documented and accepted for assessment
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1971

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
not specified
Principles of method if other than guideline:
Developmental toxicity study in rats as part of a combined Reproduction and Teratology Studies
GLP compliance:
no
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Trisodium nitrilotriacetate
- Substance type: pure substance
- purity: not further specified

Test animals

Species:
rat
Strain:
Crj: CD(SD)
Details on test animals and environmental conditions:
TEST ANIMALS
Rat study
- Charles River CD rats
- Housing: caged individually
- Diet (e.g. ad libitum): ground Purina Chow ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 8 weeks (after weaning)

ENVIRONMENTAL CONDITIONS
carefully controlled environment

Administration / exposure

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on exposure:
DIET PREPARATION
- Mixing appropriate amounts with (Type of food): ground Purina Chow
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
NTA had been mixed to ground Purina Chow to yield the target concentrations
Details on mating procedure:
The original parent rats (F0) were bred three times to bear the generations F1a, F1b and F1c.
The F1a generation was discarded at weaning.
The F1c generation was used for teratological studies
The F1b generation were bred twice to bear the generations F2a and F2b (see chaptr 7.8.1 Toxicity to reproduction).
The F2a generation was discarded at weaning.
The F2b generation was used for teratological studies

No further specification of the mating procedure.
Day of conception (day 0) was determined by vaginal smears.
Duration of treatment / exposure:
Groups of 20 female rats each were fed two dose levels continuously during each period of organogenesis (days 6-15 of pregnancy).
Frequency of treatment:
Continously feeding
Duration of test:
10 dams sacrificed on day 13
10 dams sacrificed on day 21
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 0.1% and 0,5%
Basis:
nominal conc.
(corresponds approximately to: 90 and 450 mg/kg bw/day for the adult female rats)
No. of animals per sex per dose:
Groups of 20 pregnant rats were exposed to diet containing 0.1 respectively 0.5% Trisodium nitrilotriacetate
Control animals:
yes, plain diet
Details on study design:
- Dose selection rationale: Dose levels had been chosen from previous subacute and long-term studies, from which the lower level had been reported to be without any effect, whereas the 0.5% level had been reported to produce some mild toxicity (not further specified).

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: No data

DETAILED CLINICAL OBSERVATIONS: No data

BODY WEIGHT: Yes
- Time schedule for examinations: weekly feed consumption and body weight gain during the first 8 weeks from weaning

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes / No / No data
- Food consumption for each animal determined and mean weekly diet consumption calculated as g food and feed efficiency (%): Yes
Feed efficiency = body-weight gain/feed consumed × 10
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes

POST-MORTEM EXAMINATIONS: No data
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: No data
Examinations included:
- Gravid uterus weight: No data
- Number of corpora lutea: No data
- Number of implantations: No data
- Number of early resorptions: No data
- Number of late resorptions: No data
Fetal examinations:
Ten dams of each group were sacrificed on day 13 of gestation, respectively on day 21 of gestation:

1) In dams sacrificed on day 13 of gestation the numbers of corpora lutea, implantations and resorptions were recorded.
2) Fetuses removed from dams sacrificed on gestation day 21 were inspected for gross abnormalities, weighed and their sex determined and further investigated for skeletal and visceral defects.

Statistics:
Significance test, analysis of variance, not further specified
Indices:
Conception in %
Average no. born alive / litter
Average no. alive 4 days post partum
Average no. weaned / litter
lactation index = no. of pups weaned/no. alive at 4 days after litters reduced × 100
average weaning weight of pups per sex
Historical control data:
no data

Results and discussion

Results: maternal animals

Maternal developmental toxicity

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

Effect levels (maternal animals)

open allclose all
Dose descriptor:
NOAEL
Effect level:
450 mg/kg bw/day (nominal)
Basis for effect level:
other: developmental toxicity
Dose descriptor:
NOAEL
Effect level:
90 mg/kg bw/day (nominal)
Basis for effect level:
other: maternal toxicity
Dose descriptor:
LOAEL
Effect level:
450 mg/kg bw/day (nominal)
Basis for effect level:
other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects. Remark: oft tissue defects predominantly in the urinary system (hydroureter and /or hydronephrosis) were detected in all groups including control group and were attributed to some unknown agent, possibly a virus

Details on embryotoxic / teratogenic effects:
No differences were observed in the dams of either of the two treatment groups in comparison to controls with respect to food consumption and body weight gain. Dams sacrificed on day 13 of gestation did not differ significantly from those sacrificed at day 21 of gestation in the number of corpora lutea, implantations or resorptions. Overall, the treatment groups did not differ significantly from control groups with respect to average number of corpora lutea, resorptions, live or dead fetuses or in the average weight of male and female fetuses.
Fetal evaluation for abnormalities did not reveal any skeletal defects.
Soft tissue defects predominantly in the urinary system (hydroureter and /or hydronephrosis) were detected, however, the control groups of both generations were affected as much as any of the experimental groups. The authors therefore suggested that these effects were attributable to some unknown agent, possibly a virus.
For some detailed data see table 5.

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

Table 1: Effect of feeding 0.1 and 0.5% dietary Na3NTA on the growth, feed consumption and feed efficiency of first- and second-generation rats

Gain in body weight (g) by wk 8  Total feed consumed (g) by wk 8  Feed efficiency (%)
Generation
male female male female male female
Treatment  F0 F1b   F0 F1b   F0 F1b   F0 F1b   F0 F1b   F0 F1b  
Control  359 322 205 137 1261 1463 943 956 28,5 22,3 21,7 14,5
0.1 % NTA 356 311 200 141 1285 1405 926 1003 27,7 22,3 21,5 14,2
0.5 % NTA  335  284* 188*  133 1191 t  1398 891 1018 28,2 20,7 21,2 13,4

Values are means of groups of 20 rats. Those marked with an asterisk differ significantly (Analysis of Variance) from those of controls: *P >= 0,05. That marked with a dagger differs significantly from the group fed 0,1% NTA: t P <= 0,05

Table 3. Effect of 0.1 and 0.5 % dietary NTA on the reproductive performance and lactation of first- and second-generation rats (Feeding on days 6-15 of each pregnancy)

Control 0,1% 0,5%
Parameter  Generation and litters   F1a+ F1b  F2a   F1a+ F1b  F2a   F1a+ F1b  F2a
Conception (%)    95,0 92,0 82,0 100,0 93,0 92,0
No. of stillborn    15,0 13,0 15,0 5,0 17,0 5,0
Average no. born alive/litter    11,3 12,3 11,9 12,2 11,7 13,4
Average no. alive 4 days post partum   11,1 11,1 11,4 11,4 10,9 10,8
Average no. weaned/litter+ +    7,2 7,0 7,5 7,5 7,6 7,9
Lactation index§    96,3 96,3 96,2 98,3 97,9 99,3
Average weaning weight of pups:               
Male    54,3  55,4 49,9 52,9  53,0 53,2 51,4  51,3 52,2
Female    52,4  55,3 47,5 50,8  51,0 5,3 49,6  48,2 49,5

++Litters containing more than eight pups were reduced to that number on day 4.

§No. of pups weaned/no, alive at 4 days after litters reduced × 100.

Values marked with an asterisk are significantly less (Analysis of Variance) than those of controls (*P <= 0,05) and that marked with a dagger is significantly less than that for the group fed 0.1 % NTA on days 6-15 of gestation (t P <= 0,05).

Table 5: Incidence and distribution or foetal abnormalities observed in rats fed 0.1 and 0.5% Trisodium nitrilotriacetate in dietry on

days 6 -15 of each pregnancy

  Control 0.1 % 0.5 %
   
Parameter         F1c F2b F1c F2b F1c F2b
No. of foetuses examined for skeletal defects*  17 45 22 27 34 35
No. of foetuses examined for soft-tissue defects  36 98 42 64 74 79
No. of abnormal foetuses  9 16 8 8 10 7
Incidence of soft-tissue defects t:             
Total  25 16 19 13 12 9
Hydroureter  17 16 17 13 10 9
Hydronephrosis  3
Distended bladder  6 2 3
Folded retina 
Umbilical hernia  1,0
Cleft lip 2
Cleft palate 

* No skeletal defects found.

t A foetus may have had more than one defect, thus the percentages of the individual anomalies may not equal the total incidence.

 

Applicant's summary and conclusion

Conclusions:
No significant effects on embryonic development at dose levels up to 450 mg/kg/d.
Executive summary:

In a developmental toxicity study Na3NTA was administered to female Charles River CD rats in dietary concentrations of 0, 0.1% and 0.5% (resp. daily intake for the adult female rats approximately 90 and 450 mg/kg bw / day) from days 6 through 15 of gestation.

No differences were observed in the dams of either of the two treatment groups in comparison to controls with respect to food consumption and body weight gain. Dams sacrificed on day 13 of gestation did not differ significantly from those sacrificed at day 21 of gestation in the number of corpora lutea, implantations or resorptions. Overall, the treatment groups did not differ significantly from control groups with respect to average number of corpora lutea, resorptions, live or dead fetuses or in the average weight of male and female fetuses. Fetal evaluation for abnormalities did not reveal any skeletal defects. Soft tissue defects predominantly in the urinary system (hydroureter and /or hydronephrosis) were detected, however, the control groups of both generations were affected as much as any of the experimental groups. The effects must be attributable to some unknown agent, possibly a virus.

The only effect of Na3NTA on rats was some growth depression in both adult and weanling animals fed the 0-5% level continuously. This effect was probably due mostly to a reduced palatability of the feed, since no such depression was seen in the weights of foetuses removed by Caesarean-section or in the weights of 4-day-old liveborn animals.

Thus the study shows that Na3NTA, even at highly exaggerated levels, causes no deleterious effects on embryonic development in rats.

The developmental toxicity study in the rat is classified acceptable, sufficienty documented and satisfies main guideline requirements for a developmental toxicity studies in rats.