Methoxyammonium chloride

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

27. Apr 1993 - 24. May 1993

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

GLP compliant

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Report date:

1994

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Version / remarks:

May 1981

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Bis(hydroxylammonium) sulphate

EC Number:

233-118-8

EC Name:

Bis(hydroxylammonium) sulphate

Cas Number:

10039-54-0

Molecular formula:

H3NO.1/2H2O4S

IUPAC Name:

bis(hydroxyammonium) sulfate

Details on test material:

- Name of test material (as cited in study report): Hydroxylammoniumsulfate (solid salt)
- Physical state: solid, crystals/white
- Analytical purity: > 98.4%
- Lot/batch No.: continuous production of April 4, 1991
- Storage condition of test material: refrigerator, dry

Test animals

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Karl THOMAE, Biberach an der Riss, Germany
- Age at study initiation: 76 99 days
- Weight at study initiation: 248 g (average)
- Housing: singly in type DK III stainless steel wire mesh cages (floor area about 800 cm2) .
- Diet: ground Kliba 343 feed rat/mouse/hamster supplied by KLINGENTALMUEHLE AG, Switzerland, ad libitum
- Water: tap water quality from water bottles, ad libitum
- Acclimation period: at least 5 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24°C
- Humidity (%): 30 - 70 %
- Photoperiod: 12 hrs dark / 12 hrs light

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: Milli-Q-water

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses of the test substance:
Analytical determinations of the purity of the test substance itself were carried out before the beginning of the study (method: potentiographic titration). The stability of the test substance was proven by reanalysis.

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1/1-4
- Length of cohabitation: from about 16.00 hours to about 7.30 hours on the following day.
- Verification of same strain and source of both sexes: yes
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy

Duration of treatment / exposure:

day 6 - 15 p.c.

Frequency of treatment:

10x by gavage

Duration of test:

20 days

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

1 mg/kg bw/day (actual dose received)

Doses / concentrations 2

Dose / conc.:

3 mg/kg bw/day (actual dose received)

Doses / concentrations 3

Dose / conc.:

10 mg/kg bw/day (actual dose received)

Doses / concentrations 4

Dose / conc.:

20 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

25 (females)

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
Dose selection: In a pre-study it became obvious that the test substance caused clear signs of maternal toxicity at 30 and 15 mg/kg bw/day (hemolytic anemia).
Therefore, 20 mg was chosen as the upper dose.

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: at least once a day

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: The animals were examined for clinical symptoms at least once a day, or more often when clinical signs of toxicity were elicited.

BODY WEIGHT: Yes
- Time schedule for examinations: All animals were weighed on days 0, 1, 3, 6, 8, 10, 13, 15, 17 and 20 p.c.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 20
- Organs examined: gross pathology, weight of spleen was recorded.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
Furthermore, calculations of conception rate and preand postimplantation losses were carried out.

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:

The DUNNETT-Test was used for a simultaneous comparison of several dose groups with the control. The hypothesis of equal means was tested. This test was performed two-sided and was used for the statistical evaluation of the following parameters: Food consumption, body weight, body weight change, corrected body weight gain (net maternal body weight change), weight of the uterus before it was opened, spleen weights (absolute and relative), number of corpora lutea, number of implantations, number of resorptions and number of live fetuses; proportion of preimplantation loss, postimplantation loss, resorptions and live fetuses in each litter; litter mean fetal body weight and litter mean placental weight.

FISHER's Exact Test was used for a pairwise comparison of each dose group with the control for the hypothesis of equal proportions. This test was performed one-sided and was used for female mortality, females pregnant at terminal sacrifice and the number of litters with fetal findings.

The WILCOXON-Test was used for a comparison of each dose group with the control for the hypothesis of equal medians. This test was performed one-sided and was used for the proportion of fetuses with malformations, variations, retardations and/or unclassified observations in each litter.

Historical control data:

yes

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

no effects observed

Dermal irritation (if dermal study):

not examined

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Endocrine findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Absolute and relative spleen weights were statistically significantly higher in the 10 and 20 mg/kg bw groups than in the control group. In the 10 mg/kg bw group the spleen weights were approx. 60% higher than the respective control values, whereas the spleen weights of the high dose group dams were nearly twice as high as in the control group. The increased spleen weights are well known substance induced effects. At the lower dose levels (1 or 3 mg/kg body weight) absolute and relative spleen weights were similar to the control weights.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

At necropsy the enlargement of the spleens of all dams of test groups 10 and 20 mg/kg body weight/day is in-line with the distinct increases in absolute and relative spleen weights in these groups.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Maternal developmental toxicity

Number of abortions:

no effects observed

Pre- and post-implantation loss:

no effects observed

Total litter losses by resorption:

no effects observed

Early or late resorptions:

no effects observed

Dead fetuses:

no effects observed

Changes in number of pregnant:

not examined

Details on maternal toxic effects:

In the dams an enlargement of the spleens and a dose related statistically significant increase in absolute and relative spleen weights was revealed at dosages of 10 and 20 mg/kg bw/day. No substance-related effects on dams were reported for the lower dose groups. There were no substance-related differences between the groups in conception rate, the mean number of corpora lutea and implantation sites or in the values calculated for the pre- and the postimplantation losses, the number of resorptions and of viable foetuses.

Effect levels (maternal animals)

Dose descriptor:

NOAEL

Remarks:

general maternal toxicity

Effect level:

3 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

organ weights and organ / body weight ratios

Results (fetuses)

Fetal body weight changes:

no effects observed

Reduction in number of live offspring:

no effects observed

Changes in sex ratio:

no effects observed

Changes in litter size and weights:

no effects observed

Anogenital distance of all rodent fetuses:

not examined

Changes in postnatal survival:

not examined

External malformations:

no effects observed

Skeletal malformations:

no effects observed

Visceral malformations:

no effects observed

Details on embryotoxic / teratogenic effects:

Mean fetal body weight of the dosed groups did not differ from that of the control. Examination of foetuses did not reveal any signs for substance related abnormalities.

All signs of embryo-/ fetotoxicity and substance-related teratogenicity, malformations recorded, appeared without a clear dose-response relationship, can be found in a similar frequency in the historical control data and/or the differences between the groups are without biological relevance.

Effect levels (fetuses)

Dose descriptor:

NOAEL

Remarks:

teratogenicity

Effect level:

>= 20 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Remarks on result:

not determinable due to absence of adverse toxic effects

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

From this study a NOAEL for maternal toxicity of 3 mg/kg bw/d and a NOAEL for embryo-/fetotoxicity of >= 20 mg/kg bw/d can be derived.

Executive summary:

An OECD 414 guideline study (GLP, reliability 1)is available for the assessment of the developmental toxicity potential. In this study the test material was investigated for its prenatal toxicity in Wistar rats by the oral (gavage) route of administration. Groups of 22 - 24 pregnant rats had been treated with hydroxylammonium sulfate at dosages of 1, 3, 10, and 20 mg/kg bw on day 6 through day 15 post coitum. The test substance (purity > 98.4%) had been administered as an aqueous solution and at a standard dose volume of 5 ml/kg bw. The control group, consisting of 20 dams, was dosed with the vehicle (Milli-Q-water) only. Food consumption and body weights of the animals were recorded regularly throughout the study period. The state of health of the animals was checked each day. At sacrifice on day 20 post coitum dams were assessed by gross pathology (including weight determinations of the spleen), and numbers of corpora lutea and numbers and distributions of implantation sites were recorded. Foetuses were sexed, weighed and further investigated for any external, soft tissue and/or skeletal findings. In the dams an enlargement of the spleens and a dose related statistically significant increase in absolute and relative spleen weights was revealed at dosages of 10 and 20 mg/kg bw/d. No substance-related effects on dams were reported for the lower dose groups. There were no substance-related differences between the groups in conception rate, the mean number of corpora lutea and implantation sites or in the values calculated for the pre- and the postimplantation losses, the number of resorptions and of viable foetuses. Mean fetal body weight of the dosed groups did not differ from that of the control. Examination of foetuses did not reveal any signs for substance related abnormalities. From this study a NOAEL for maternal toxicity of 3 mg/kg bw/d and a NOAEL for embryo-/fetotoxicity of >= 20 mg/kg bw/d can be derived.