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Toxicological information

Developmental toxicity / teratogenicity

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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:
1984-01-03 To: 1984-12-04
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Study was conducted according to OECD Guideline 414 from that time, using exposure from gestation day 6 to day 15 . However, the current guideline requires exposure from at least day 6 up to and including the day before giving birth. No data on GLP and no data on the analytical verification of the dosing solutions.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1984
Report Date:
1984

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
the current guideline requires exposure from at least gestation day 6 up to and including the day before planned delivery
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: liquid
Details on test material:
- Name of test material (as cited in study report): Triethylenetetramine
- Substance type: Active
- Physical state: Liquid
- Analytical purity: >98%
- Stability under test conditions: Determined by the Sponsor
- Storage condition of test material: Room temperature

Test animals

Species:
rat
Strain:
other: albino, Sprague-Dawley-derived [(TIf:RAIf (SPF)]
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: from a closed breeding colony (CIBA-GEIGY, WST)
- Age at study initiation: 2 months old
- Weight at study initiation: 190-200 g
- Housing: Makrolon cages equipped with a wire mesh top and water bottles, saw dust (granular form) serving as bedding material, housed 4 per cage throughout the experiment.
- Diet: Certified standard cube diet (NAFAG No. 890), ad libitum
- Water: Tap water, ad litibum
- Acclimation period: Acclimatization took place in the period of time between allocation to the corresponding group on day 0 and the first treatment on day 6 post coitum.


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21C +/- 2C
- Humidity (%): 55% +/- 10%
- Photoperiod (hrs dark / hrs light): 12/12


Administration / exposure

Route of administration:
oral: gavage
Vehicle:
other: Distilled water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: The test substance was prepared fresh daily dissolved in distilled water by magnetic stirrer, and administered at a rate of 10 ml/kg of body weight by oral intubation.

Analytical verification of doses or concentrations:
not specified
Details on mating procedure:
- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1 male/3 female
- Length of cohabitation: Overnight
- Proof of pregnancy: [sperm in vaginal smear] referred to as [day 0] of pregnancy
Duration of treatment / exposure:
Day 6 until Day 15 of pregnancy
Frequency of treatment:
Daily
Duration of test:
Duration of exposure = 10 days, Duration of test = 21 days (copulation through day 21of pregnancy)
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
0, 350, and 700 mg/kg-bw/day
Basis:
actual ingested
Preliminary dose range finding study
Remarks:
Doses / Concentrations:
0, 75, 325, and 750 mg/kg-bw/day
Basis:
actual ingested
Main study
No. of animals per sex per dose:
12 dams/dose group in preliminary study and 24 dams/dose per group in main study
Control animals:
yes, concurrent vehicle
yes, historical
Details on study design:
- Dose selection rationale: In order to determine the dose levels for the main study, a preliminary experiment was carried out on 12 fertilized rats each for the vehicle control and the dose groups (350 and 700 mg/kg). The test material was dissolved in distilled water and administered orally by intubation from day 6 until day 15 of pregnancy, inclusive. Treatment at these dose levels caused a decrease of food consumption in the mother animals of the 700 mg/kg group. No adverse effects were recorded for the progeny at sacrifice shortly before term in comparison with the vehicle control. On the basis of the foregoing results the doses for the main study were selected at 0, 75, 325 and 750 mg/kg of body weight. The test material was again mixed with distilled water and administered once daily by the oral route from day 6 until day 15 of pregnancy, inclusive.
- Rationale for animal assignment (if not random): The mated females were identified by color code, allocated to experimental and control groups (24 animals per group) by using a randomization table

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily
- Cage side observations checked: General bodily conditions and symptoms

BODY WEIGHT: Yes
- Time schedule for examinations: Daily


FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
- Time schedule for examinations: Days 6, 11, 16, and 21 of pregnancy


POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 21
- Organs examined: ovaries and uterus (including: mucosa and contents, including amniotic fluid and placentae as well as abortions and resorption sites)
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: No data
- 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: [one third per litter]
- Skeletal examinations: Yes: [two thirds per litter]
Statistics:
When feasible, statistical evaluation of data was performed. Progency abnormalities were evaluated by Student's t-test (one-tailed), Embryonic and/or foetal deaths and male to female ratios were evaluated by Chi square test with Yates correction, Average weight of live foetuses were evaluated with Student's t-test (one-tail).
Historical control data:
The current study used concurrent controls and historical data to compare the results.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
With regard to the vehicle control, food intake was slightly depressed in all dose groups during the second part of the treatment period. Body-weight gain appeared to be somewhat reduced in the experimental groups; however when corrected body weights were evaluated no differences were observed.
In the vehicle control a spontaneous litter (i.e. parturition of normally developed foetuses one or two days prior to expected delivery) was observed for one female on day 20 p.c. An early birth of the whole litter (i.e. shortly before sacrifice on day 21) was recorded for one female of the mid dose group of the main study. These animals were not taken into further consideration of data. Early birth of 5 foetuses was also noted for one female of the low-dose group in the main study, 3 of these foetuses were cannibalized, the remaining were assigned at random to a uterine location and processed as usual.

Effect levels (maternal animals)

Dose descriptor:
NOAEL
Effect level:
> 750 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
other: developmental toxicity

Results (fetuses)

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

Details on embryotoxic / teratogenic effects:
The average body-weight of the live foetuses of the low and mid dose groups from the main study were found to be slightly enhanced in comparison with the vehicle control. This, however, was not thought to be of biological relevance; a more significant increase was recorded for the high-dose group in the main study (Student's t test, one-tailed, observed p < 0.01). The gross inspection of the live foetuses did not reveal any finding either in the experimental groups or in the vehicle control. Carrying out the slicing technique for "visceral" examination, internal hydrocephaly (unilateral) was found in one foetus of the low-dose group in the main study. Encephalocele occurred in one foetus of the vehicle control. The skeletal assessment revealed instances of irregular sternebral ossification in the dose groups and in the vehicle control. Concerning the status of skeletal maturation of the foetuses shortly before term, apart from a slightly raised number of still unossified calcanei in the high-dose group in the main study, no delay of ossification could be found for the experimental groups in comparison with the vehicle control; in view of the ranges ascertained for the "historical" control, however, this finding was not thought to be of experimental significance.

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

The pregnancy rates expressed as average number of implantation sites per female were comparable for all groups. The numbers of embryonic and/or foetal deaths (resorptions) were not increased at either dose (Chi2-test, Yates' correction, observed p>0.05) in the main study. The male to female ratios of the foetuses were also comparable for all groups (Chi2-test, Yates' correction, observed p>=0.05) in the main study.

Applicant's summary and conclusion

Conclusions:
The test substance was devoid of any embryotoxic activity and did not reveal teratogenic potency in the rat under the present experimental conditions.
Executive summary:

Timed-pregnant Sprague Dawley rats were treated with triethylenetetramine by daily oral gavage on gestational days (gd) 6 up to and including day 15. Groups of 24 females each received triethylenetetramine formulated in distilled water applied at a volume of 10 ml/kg bw at dosages of 0, 75, 325 or 750 mg/kg bw per day. With regard to the vehicle control, food intake was slightly depressed in all dose groups during the second part of the treatment period. Body-weight gain appeared to be somewhat reduced in the experimental groups; however when corrected body weights were evaluated no differences were observed. No other toxic signs were observed in the mothers. A significant increase in the average body weight of the live foetuses was recorded for the high-dose group in the main study. The gross inspection of the live foetuses did not reveal any finding either in the experimental groups or in the vehicle control. The skeletal assessment revealed instances of irregular sternebral ossification in the dose groups and in the vehicle control. Concerning the status of skeletal maturation of the foetuses shortly before term, apart from a slightly raised number of still unossified calcanei in the high-dose group in the main study, no delay of ossification could be found for the experimental groups in comparison with the vehicle control.

Thus, under the conditions of this study, triethylenetetramine produced no maternal toxicity except for slightly reduced food intake and no developmental toxicity at any dosages employed.