Registration Dossier

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:
1976-1978
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Comparable guideline study, tested with the source substance Nitroglycerin. According to the ECHA guidance document “Practical guide 6: How to report read-across and categories (March 2010)”, the reliability was changed to RL2 to reflect the fact that this study was conducted on a read-across substance.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1978
Report Date:
1978

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
other: FDA Guidelines (1966)
Deviations:
no
Principles of method if other than guideline:
Sexually mature virgin females were mated with experienced young adult male rats. The dams' F1c litter was used for this study. The dams were placed on test or control diets for gestation days 6-15, incl., and were sacrificed (CO2 inhalation) on gestation day 20.
GLP compliance:
no
Remarks:
Unlikely. Study pre-dated even USFDA GLPs
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Nitroglycerin, TNG
- Molecular formula (if other than submission substance): C3H5N3O9
- Molecular weight (if other than submission substance): 227.08
- Smiles notation (if other than submission substance): [O-][N+](=O)OCC(CO[N+](=O)[O-])O[N+](=O)[O-]
- InChl (if other than submission substance): InChI=1/C3H5N3O9/c7-4(8)13-1-3(15-6(11)12)2-14-5(9)10/h3H,1-2H2
- Structural formula attached as image file (if other than submission substance): see Fig.1
- Substance type: technical product
- Physical state: a 10 % mixture on lactose
- Analytical purity: 9.72% +/- 0.09%
- Lot/batch No.: D17-H3 (Source: Atlas Chemical Division, ICI America Inc., Wilmington, DE)

Test animals

Species:
rat
Strain:
other: Charles River CD
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratory, Wilmington, Massachusetts, USA
- Age at study initiation: All animals were maturing
- Fasting period before study: no data
- Housing: plastic cages with metal lids, filter tops, 4 male or 5 female in each cage, some groups were subdivided to prevent fighting.
- Identification of animals: ear-punches
- Bedding: with hardwood chip
- Diet: ad libitum, Diets were prepared weekly
- Water: ad libitum
- Acclimation period: 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°F): 75+/-5
- Humidity (%): 50+/-10%
- Air changes (per hr): 10 air changes per hour
- Photoperiod (hrs dark / hrs light):12 hour light/12 hour dark

Administration / exposure

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Test levels of diet were prepared fresh weekly by dilution of the concentrate with unheated feed and were analyzed after preparation. Control analyses were carried out over eight-day periods to measure evaporation of NG from the diet under cage conditions during the week. GC also was used for these analyses, but with a 63Ni detector. This information was used to calculate actual dosage received by the rats.
Duration of treatment / exposure:
24 hours/day for 10 days (gestation days 6-15, incl.)
Doses / concentrations
Remarks:
Doses / Concentrations:
0.9, 6.4 and 59.3 mg/kg/day for females
Basis:
actual ingested

Examinations

Maternal examinations:
During pregnancy the dams were observed daily. Females were weighted day 0 and day 20 of pregnancy. The females were sacrificed (CO2 inhl.) on gestation day 20.
Ovaries and uterine content:
After necropsy the weight of uterus was recorded. The number of corpora lutea and number and position of live, dead and resorbed fetuses is recorded.
Fetal examinations:
Fetuses were then removed from the uterus, weighed, and examined for any external anomalies. Half the fetuses from each litter were then fixed in
Bouin's fluid, manually sectioned, and examined for soft tissue /internal organ anomalies by Wilson's method (Wilson, 1965). The remaining fetuses were fixed in 70% ethanol followed by 1% potassium hydroxide and then stained with alizarin red (Staples and Schnell, 1964). This was followed by differential decolorization and examination for skeletal anomalies

Results and discussion

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
See attached document, Table-No. 1.

Effect levels (fetuses)

Dose descriptor:
NOEL
Effect level:
6.4 mg/kg bw/day
Basis for effect level:
other: teratogenicity

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
The weights of the high-dose females at termination and their weight changes (excluding the uterus and contents) were significantly less than those of the control group and less than those of the two groups tested at lower doses, as indicated in the summary table above. In addition, their liver weights were significantly increased relative to their corrected body weight and increased relative to those of the two lower dose test groups. Diaphragmatic hernias occurred only in the high dose group and were believed, by the investigators, to be due to the test material. Their incidence was not significant (two-sample rank test), but they occurred in 4 / 19 of the high dose litters from this study. The incidences of unossified and incompletely ossified hyoid bones also were significantly increased compared to the controls and were increased compared to the two lower dose test groups. However, sternabrae, centra, and skull bones were not similarly affected.