[[(phosphonomethyl)imino]bis[ethylenenitrilobis(methylene)]]tetrakisphosphonic acid, potassium salt

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

21.05.1980 to 09.06.1980

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

2b The study was conducted according to an appropriate OECD test guideline, with acceptable restrictions. The restrictions were that there was no analytical confirmation of dosing solutions, and there was no record of gravid uterine weight or the number of corpora lutea.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1982

Report date:

1982

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

yes

Remarks:

No record of gravid uterine weight, number of corpora lutea not recorded, no analytical confirmation of dosing solutions.

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

[[(phosphonomethyl)imino]bis[(ethylenenitrilo)bis(methylene)]]tetrakisphosphonic acid, sodium salt

EC Number:

244-751-4

EC Name:

[[(phosphonomethyl)imino]bis[(ethylenenitrilo)bis(methylene)]]tetrakisphosphonic acid, sodium salt

Cas Number:

22042-96-2

IUPAC Name:

sodium hydrogen [10,10-dihydroxy-10-oxido-2,5,8-tris(phosphonomethyl)-2,5,8-triaza-10-phosphadec-1-yl]phosphonate

Constituent 2

Reference substance name:

[[(phosphonomethyl)imino]bis[(ethylenenitrilo)bis(methylene)]]tetrakisphos phonic acid, sodium salt

IUPAC Name:

[[(phosphonomethyl)imino]bis[(ethylenenitrilo)bis(methylene)]]tetrakisphos phonic acid, sodium salt

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River
- Age at study initiation: No data
- Weight at study initiation: 180-200 g
- Fasting period before study: No data
- Housing: Individually in suspended stainless steel mesh cages.
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: None, animals were recieved mated and allocated to cages.


ENVIRONMENTAL CONDITIONS
- Temperature (°F): 72 ±2
- Humidity (%): 40-60
- Air changes (per hr): No data
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: 26.05.1980 To: 09.06.1980

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: Aqueous solution

Details on exposure:

No data

Analytical verification of doses or concentrations:

no

Details on mating procedure:

No data. Animals were received on gestational day 1, having already been mated.

Duration of treatment / exposure:

GD 6 - 19

Frequency of treatment:

daily

Duration of test:

20 days

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 500, 1000 or 2000 mg/kg bw/day (active acid)
Basis:
actual ingested

No. of animals per sex per dose:

25

Control animals:

other: 0.9% (w/v) aqueous NaCl

Details on study design:

- Dose selection rationale: No data

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice daily for visible toxic effects.


DETAILED CLINICAL OBSERVATIONS: No


BODY WEIGHT: Yes
- Time schedule for examinations: Gestational days 3, 6, 8, 10, 13, 15, 17 and 20.


FOOD CONSUMPTION: No


WATER CONSUMPTION: No


POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20
- Organs examined: Gross examination of all animals that included examination of external surfaces and thoracic and abdominal cavities.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: yes
Examinations included:
- Gravid uterus weight: No
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: half per litter
- Head examinations: No data

Statistics:

Comparison of body weights between treatment and control groups was performed using Dunnett's test. Counted data (corpora lutea, implants, resorptions, live and dead fetuses) and data expressed as percentage were analysed, when appropriate with the Mann-Whitney U test. Response data (pregnancy rates, number of litters with post-implantation loss, and fetuses or litters with abnormalities and variants) were analysed, when appropriate, with Fisher's exact test and the chi-square test.

Indices:

None

Historical control data:

No data

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
No deaths occurred prior to the scheduled sacrifice. 9/25 dams had soft stools in the 2000 mg/kg bw/day group beginning on gestation day 14 (ninth day of treatment) and persisted through to gestation day 17. This finding was not observed in the other treated groups or the controls. The only statistically significant (P<0.01) effect observed was lower body weight gain (mean value approximately 68% of the control mean) between gestation day 6 and 20 for dams in the 2000 mg/kg bw/day group (33.6/27.6/27.5/22.9). However, terminal body weights were not statistically significantly affected (mean terminal body weights with uterine contents by dose: 360.1/368.1/357.0/346.1 and mean terminal bodyw eights without uterine contents: 265.8/264.5/260.1/257.2). There was no effect on pregnancy rate or the mean number of corpora lutea. There were no treatment-related findings in the gross necropsy.

Effect levels (maternal animals)

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day

Basis for effect level:

other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
There were no significant differences between any of the treatment groups and the control group in the number of pre- or postimplantation losses, rresorptions or mean number of live fetuses. There were no effects on fetal body weight, sex ratios (males/litter: 5.6/5.8/5.9/4.8. Females/litter:  5.9/6.5/5.4/6.4). There were no treatment-related gross external malformations present. Subcutaneous haematomas were present in controls and all treated groups, however the incidence increased at 500 mg/kg bw/day (P<0.05) and was considered unrelated to treatment by the study authors (no dose relationship was present). The occurence of one female fetus that was hydrocephalic and one female with gastroschisis in the 1000 mg/kg bw/day group was considered by the study authors to be spontaneous. The hydrocephalic female also exhibited a developmental variation (underdeveloped renal papilla) that was not considered to be related to treatment.
Skeletal examination revealed single incidences of dwarfism (one female fetus of 500 mg/kg bw/day group) and fused sternebrae (one female fetus of the 2000 mg/kg bw/day group), which were considered spontaneous. Two fetuses from different litters in the 2000 mg/kg bw/day group and one fetus of the 1000 mg/kg bw/day group had vertebral anomalies (missing, reduced or fused vertebral arches). Although the incidence of these anomalies was not statistically significant compared with the control group, the rare spontaneous occurrence of such anomalies and the pattern of incidence indicated that they might have been treatment-related. Various skeletal variations occurred, but none showed a clear dose-response and so were considered spontaneous. Review of these results for the REACH assessment concluded that the effects should not be considered adverse as they were not statistically significant and were only observed in the presence of maternal toxicity.

Effect levels (fetuses)

1

Dose descriptor:

NOAEL

Effect level:

2 000 mg/kg bw/day

Basis for effect level:

other: teratogenicity

2

Dose descriptor:

NOAEL

Effect level:

2 000 mg/kg bw/day

Basis for effect level:

other: fetotoxicity

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

In a good quality prenatal developmental toxicity screening study (reliability score 2) conducted using a protocol similar to OECD 414, and to GLP, clear maternal toxicity (approx. 30% decrease in body weight gain, soft stools) was noted in pregnant SD rats given 2000 mg/kg bw/day DTPMP (Dequest 2061; expressed as active acid) on GD 6-19 (NOAEL 1000 mg/kg bwt/d). The NOAEL for developmental toxicity was 2000 mg/kg bw/day (active acid).

Executive summary:

In a good quality prenatal developmental toxicity screening study (reliability score 2) conducted using a protocol similar to OECD 414, and to GLP, mated female Sprague-Dawley rats (25/dose) were dosed by gavage at doses of 500, 1000, 2000 mg/kg bw/day (neutral sodium salt; expressed as active acid). They were dosed on gestation days 6 to 19. Control animals were given 0.9% sodium chloride solution. On day 20 all surviving animals were sacrificed. There were no deaths prior to scheduled sacrifice. The highest dose produced marginal toxic effects in the dams, as evidenced by lower mean body weight gain between gestational days 6 and 20, and soft stools in some animals. No treatment-related lesions were detected at gross necropsy of the dams of any treatment group.

There were no statistically significant treatment-related effects on postimplantation loss or fetal weight at any dose. Vertebral anomalies were observed in single fetuses in two litters of the 2000 mg/kg bw/day group and one of the 1000 mg/kg bw/day group. The incidence was not statistically significant, but the rare spontaneous occurrence of this type of malformation and the pattern of incidence was suggestive of a treatment-related effect. Review of these results for the REACH assessment concluded that the effects should not be considered adverse as they were not statistically significant and were only observed in the presence of maternal toxicity.

Overall, the NOAEL for maternal toxicity was 1000 mg/kg bw/day, and for developmental toxicity was 2000 mg/kg bw/day (active acid).