Disodium 2-hydroxyethyliminodi(acetate)

Developmental toxicity / teratogenicity

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 for cross-reference:

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

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

not specified

Principles of method if other than guideline:

Prenatal development study as part of a combined Reproduction and Teratology Studies

GLP compliance:

no

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Trisodium nitrilotriacetate

EC Number:

225-768-6

EC Name:

Trisodium nitrilotriacetate

Cas Number:

5064-31-3

Molecular formula:

C6H9NO6.3Na

IUPAC Name:

trisodium 2,2',2''-nitrilotriacetate

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:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
Rabbit study
- Virgin New Zealand Does
- Age 5-6 months old
- Source: Sweetwater Rabbitry, Hillsboro, Ohio
- Housing: caged individually
- Diet (e.g. ad libitum): Purina Chow ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimatisation period: 18 days

ENVIRONMENTAL CONDITIONS
Carefully controlled environment

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Analytical verification of doses or concentrations:

not specified

Details on mating procedure:

- Impregnation procedure: artificial insemination after an 18-day acclimatisation period.
- Semen was collected from eight bucks with an artificial vagina and used undiluted to impregnate all 120 does.
- Inseminations were done over a 10-day period with two does from each group being inseminated daily.
- The day of insemination was designated day 0.

Duration of treatment / exposure:

Daily during days 7-16 of gestation / during organogenesis

Frequency of treatment:

Daily

Duration of test:

18 days of acclimatisation
Max 10 days of insemination
Treatment during days 7-16 of gestation
On day 28, the does were sacrificed.

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 2.5, 25, 100, and 250 mg/kg bw day
Basis:
analytical conc.
All does, except the untreated controls, were weighed every 3 days during pregnancy so that dosages could be adjusted.

No. of animals per sex per dose:

120 animals in total
20 animals per dose group

Control animals:

yes, concurrent no treatment

yes, concurrent vehicle

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:no effects

Details on maternal toxic effects:
Mild diarrhea at the highest dose levels (> 25 mg7kg/d) when Na3NTA was administered by gavage or in the feed. This effect may be related to the poor absorption of NTA in the rabbit.

Effect levels (maternal animals)

Dose descriptor:

NOAEL

Effect level:

>= 250 mg/kg bw/day (nominal)

Based on:

act. ingr.

Basis for effect level:

other: no maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

>= 250 mg/kg bw/day (actual dose received)

Based on:

act. ingr.

Sex:

male/female

Basis for effect level:

other: no developmental toxicity

Overall developmental toxicity

Developmental effects observed:

no

Any other information on results incl. tables

As a result there were no significant differences in the average numbers of corpora lutea, resorptions, live and dead fetuses or in the average fetal body weights between treatment groups and controls. Also, no significant differences were seen in the number with gross abnormalities, skeletal or soft-tissue defects. For some detailed data see table 1.

Table 1: Effect of various levels of Trisodium nitrilotriacetate given by intubation on reproduction and embryogeny in the New Zealand rabbit on days 7-16 of pregnancy

Parameter	No treatment	Water treatment	2,5 mg/kg bw/day	25 mg/kg bw/day	100 mg/kg bw/day	250 mg/kg bw/day
Average no. of:
Corpora lutea	11.2	10.1	10.5	10.9	11.2	10.5
Resorptions	0.9	0.9	0.6	0.9	0.7	0.5
Live foetuses	7.1	7.4	8.0	8.0	8.5	7.7
Average foetal weight (g)	33.8	31.9	33.3	32.9	31.7	34.5
No. of dead foetuses	0	2	3	6	2	3
Incidence of soft-tissue defects and no. examined	3.2 (95)	0 (78)	0 (102)	2.2 (89)	3.0 (100)	3.0 (102)
Incidence of defects (%*):
Hydroureter	1.0	–	–	2.2	2.0	1.0
Hydronephrosis	–	–	–	1.1	–	1.0
Distended bladder	2.1	–	–	–	–	–
Umbilical hernia	1.0	–	–	–	–	1.0
Cleft palate	–	–	–	–	1.0	–
Hydrocephaly	–	–	–	–	1.0	–
Acephaly	–	–	–	–	–	1.0
Hypoplastic ovary	1.0	–	–	–	–	–
Muscle contracture	–	–	–	–	–	1.0
Incidence of skeletal defects (%) and no. examined:	8.9 (45)	5.6 (36)	2.0 (50)	8.5 (47)	5.7 (53)	6.0 (50)
Missing twelfth rib	2.2	2.8	2.0	8.5	–	–
Fusion of fourth and fifth sternebrae	6.7	2.8	–	–	5.7	2.0
Fused fourth and fifth fibs, fight side	2.2	–	–	–	–	–

*One animal may have had more than one defect.

No significant differences in the numbers of corpora lutea, resorptions or live foetuses. The number of dead foetuses in the group treated with 25 mg/kg was somewhat high, but this number was not significantly higher than the number of dead foetuses in the water-dosed control animals. Furthermore, the lack of a dose-response relationship between the levels of Trisodium nitrilotriacetate and the number of dead foetuses indicated that the deaths were due to some cause other than the Trisodium nitrilotriacetate. Similarly, no statistical differences were seen in the weights of the foetuses or in the number with congenital defects.

As with the soft-tissue defects, there were no significant differences in skeletal defects.

Some variations in the numbers of sternebrae and ribs were scattered throughout the groups, but these appeared to be within the normal range for the rabbit. Otherwise, the only abnormalities of the skeleton were a missing twelfth rib in seven foetuses, fused ribs in one foetus and vertical fusion of the fourth and fifth sternebrae in eight foetuses. These were distributed randomly throughout test and control groups.

No gross pathology was seen in the dams at laparotomy. Since no histological differences were seen in the tissues of rats in the much longer study (see Nolen et al 1971 - NTA - DevelopTox-rats, 7.8.2), no histopathology was done on these animals.

Applicant's summary and conclusion

Conclusions:

No substance-related effect on the development of the fetuses was observed in rabbits receiving Na3NTA up to 250 mg/kg/d.

Executive summary:

In a developmental toxicity study Na3NTA was administered to female New Zealand dams at dose levels of 0, 2.5, 25, 100, and 250 mg/kg/d from days 7 through 16 of gestation.

As a result there were no significant differences in the average numbers of corpora lutea, resorptions, live and dead fetuses or in the average fetal body weights between treatment groups and controls. Also, no significant differences were seen in the number with gross abnormalities, skeletal or soft-tissue defects.

The developmental toxicity study in the rabbits is sufficiently well documented and satisfies main guideline requirements for a developmental toxicity studies in rabbits.