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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP-compliant OECD guideline study, available as unpublished report, no restrictions, adequate for assessment

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1986
Report Date:
1986

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
no
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Physical state: Clear, oily yellow liquid
- Analytical purity: mixture
- Concentration: Presumed to be 100% for purposes of formulating dosing solutions
- Storage condition of test material: Closed container at ambient temperature.

Test animals

Species:
rat
Strain:
Sprague-Dawley
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Breedirg Laboratories, Inc., Wilmington, Massachusetts 01887
- Age at study initiation: 66 days
- Weight at study initiation: 215.1 g (173.4-256.7)
- Housing: One per cage except during the first week of acclimation (two females/cage} and mating (one male and one female/cage).
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 23 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 66-77°F
- Humidity (%): 51-91% (R.H.)
- Photoperiod (hrs dark / hrs light): 12 hour light/dark cycle (7 am to 7 pm) via automatic timer

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
Dosing solutions were prepared fresh weekly. Appropriate amounts of the test article were weighed into labeled 500 mL volumetric flasks (one flask per group). The appropriate amounts of corn oil were added to each flask and the solutions were then swirled. The solutions were allowed to settle for several minutes and then sonicated for ten minutes. Dosing solutions were then transferred to glass storage jars with plastic screw top lids and stored refrigerated until dispensing for dosing purposes. Dosing solutions were shaken vigorously prior to dispensing into labelled beakers for dosing. Dosing solutions in the beakers were stirred while animals were being dosed. Unused portions of dosing solution for each treatment day were discarded into an appropriate waste container.

DIET PREPARATION
- Mixing appropriate amounts with (Type of food): Purina Certified Rodent Chow No. 5002

VEHICLE
- Lot/batch no. (if required): JUN 30 84A
- Storage: room temperature
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Determination of the concentration in mg/mL of Terphenyl, hydrogenated in a corn oil dosing solution with gas chromatography method. Since hydrogenated terphenyl is a mixture of similar compounds an area summation is used to produce a summed peak area. This summed peak area is used to produce a standard curve from an analytical standards using linear regression. Corn oil dose solutions are then analyzed and their summed peak areas compared to the standard curve to determine the concentration of test material in mg/mL.
Details on mating procedure:
- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: one male and one female/cage
- Length of cohabitation: nightly on 10 days
- Proof of pregnancy: vaginal plug and/or sperm in vaginal smear referred to as day 0 of pregnancy
Duration of treatment / exposure:
gestation days 6-15
Frequency of treatment:
once per day
No. of animals per sex per dose:
24 females per dose
Control animals:
yes
Details on study design:
- Dose selection rationale: Based on a range-finding study (See report BD-84-67)
- Rationale for animal assignment (if not random): Females which mated were assigned to the groups daily in such a way as to most nearly equalize the Day 0 mean group body weights.

Examinations

Maternal examinations:
PHYSICAL OBSERVATIONS: Yes
- Time schedule: Twice daily (morning and afternoon) for signs of pharmacologic or toxicologic effects and mortality. In addition, each female was given a detailed physical examination on Days 0, 6, 9, 12, 15 and 20 of gestation.

BODY WEIGHT: Yes
- Time schedule for examinations: Recorded on Days 0, 6, 9, 12, 15 and 20 of gestation.

FOOD CONSUMPTION: Yes
- Time schedule for examinations: Recorded for the following intervals during gestation: Days 0-6, 6-9, 9-12, 12-15 and 15-20.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20
- Organs examined: External surface, all orifices, the cranial cavity, carcass, the external surface of the spinal cord and sectioned surfaces of the brain, nasal cavity and paranasal sinuses, the thoracic, abdominal and pelvic cavities and their viscera and the cervical tissues and organs were examined for all animals. The carcass of each female was discarded at the completion of necropsy.
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Number of live fetuses: Yes
- Number of dead fetuses: Yes
Fetal examinations:
- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: approximately half per litter
- Skeletal examinations: Yes: the remaining fetuses in each litter
- Head examinations: Yes: approximately half per litter (same as for soft tissue examinations)
Statistics:
Results of analysis by the indicated statistical procedure were reported for the following:
Mean body weights; Mean weight change; Mean food consumption; Reproduction data (Mean number of corpora lutea; Mean number of uterine implantation sites; Mean number of live fetuses; Mean number of resorptions; Pre-implantation loss ratio; Resorption/implant ratio); Mortality rates
Pregnancy rates; Incidence of fetuses with malformations/variations and the incidence of litters containing fetuses with malformations/variations; Incidence of females with resorption sites

Methods used:
Bartlett’s Test; ANOVA; Dunnett’s; Kruskal-Wallis; Summed Rank Test (Dunn); Regression Analysis/Trend/Lack of Fit; Jonckheere’s Statistic; Arc Sine

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
No mortality occurred in the control, low- or mid-dose groups. At the high-dose level, a total of four females died; however, the death of one female was attributed to an intubation error. Excluding this one female, the mortality rate in the high-dose group was 12.5%.
No adverse effect of treatment was evident in pregnancy rate data. The pregnancy rate was 100% in the control, mid- and high-dose groups and, 91.7% (22/24) in the low-dose group.
At the low- and mid-dose levels, mean body weight and mean weight gain data during the treatment or post-treatment periods were not considered adversely affected by treatment. At the high-dose level, mean body weights were significantly lower than control on Days 9, 12, 15 and 20 of gestation and mean weight gain during the Day 6-15 gestation interval was significantly lower than control for this same group. No effect on food consumption data was evident at the low-dose level. In the mid-dose group, mean food consumption was significantly lower than control during the Day 8-9 and 9-12 gestation Intervals and in the high-dose group, mean food consumption was significantly lower than control only during the Day 8-9 gestation interval. A statistically significant increase in mean food consumption data for the high-dose group during the Day 15-20 gestation interval was not considered indicative of an adverse effect of treatment.
At the low-dose level, no adverse effect of treatment was evident from the detailed physical evaluations. At the mid-dose level, the incidence of females with areas of alopecia was notably increased at Days 16 and 20 of gestation; no other adverse effects of treatment at the mid-dose level were evident from the physical in-life observation data. At the high-dose level, the incidence of females with staining of the fur in the ano-genital area and/or soft stool was increased during the treatment interval of gestation. Additionally, several high-dose females were noted early in gestation (Day 9) as emaciated with red material about the snout.
No adverse effect of treatment at the low- or mid-dose level was evident from uterine implantation data. An increase in both the mean number of resorption sites and the mean ratio of resorptions to implants was seen at the high-dose level. These resorption data did not differ statistically from control data and the mean number of resorptions at the high-dose level was well within the range of historical control data for this laboratory. Thus, it is not clear if the increase in resorption data seen at the high-dose level represents an adverse effect of treatment.

Effect levels (maternal animals)

Dose descriptor:
NOAEL
Effect level:
125 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
other: maternal toxicity

Results (fetuses)

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

Details on embryotoxic / teratogenic effects:
No adverse effect of treatment was evident in fetal weight data or fetal sex distribution data at the low- and mid-dose levels. In the high-dose group, mean fetal weight was significantly lower than control; however, fetal sex distribution data were not adversely affected at this same dose level.
No increase in the incidence of malformations was seen during the external, visceral or skeletal evaluations of fetuses recovered from females treated at the low- or mid-dose levels.
At the high-dose level, no increase in malformation rate was seen during fetal external evaluations; however, the incidence of fetuses with a glassy (shiny) appearance, considered to be an external variation observation, was significantly increased. Fetuses noted as having a glassy (shiny) appearance were usually the smaller fetuses within the litters and the observation was considered related to retarded fetal development within this group. No adverse effect of treatment at the high-dose level was evident from the fetal visceral evaluations. During the skeletal evaluations, the incidence of high-dose fetuses with malformations was statistically higher than control. Skeletal malformations were seen in seven high-dose fetuses (an incidence of 5.9%) in respect to the control incidence of 0.6% (one fetus with a skeletal malformation). Two of the seven high-dose fetuses (one fetus from each of two litters) had dissimilar, relatively minor malformations which were not considered related to treatment. Five high-dose fetuses (four fetuses from one litter and one fetus from a second litter) had one or more malformations from a syndrome of observations that involved misshapen and/or fusion defects of the exoccipital bones, fused ribs, cervical vertebral defects or misaligned thoracic vertebral centre. The two females whose litters contained fetuses with one or more skeletal malformations from the above stated syndrome of observations were quite stressed during the treatment period. Both females experienced weight loss during the Day 6-9 gestation interval and at Day 9, were noted with marked staining of the fur in the ano-genital area and extreme soft stool; therefore, it is not clear if this syndrome of skeletal malformations as seen with increased frequency among the high-dose fetuses represents a response to treatment or is secondary to maternal toxicity encountered at this same dose level.

Effect levels (fetuses)

Dose descriptor:
NOAEL
Effect level:
500 mg/kg bw/day
Basis for effect level:
other: fetotoxicity and embryotoxicity

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
No relevant effects were observed at 125 mg/kg bw/day. NOAEL for maternal toxicity was 125 mg/kg bw/day; NOAEL for fetotoxicity was 500 mg/kg bw/day.
Executive summary:

A developmental toxicity / teratogenicity was performed in a teratology study with hydrogenated terphenyl in Sprague-Dawley rats (24/group) from day 6-15 of pregnancy. No mortality occurred in the control, low- or mid-dose groups. At the high-dose level, 4 females died, however, the death of one female was attributed to an intubation error. Excluding this one female, the mortality rate in the high-dose group was 12.5%. No adverse effect of treatment was evident in pregnancy rate data. At the high-dose level, mean body weights were significantly lower than control. In the mid-dose and high group, mean food consumption was significantly lower than control. At the mid-dose level, the incidence of females with areas of alopecia was notably increased. At the high-dose level, the incidence of females with staining of the fur in the ano-genital area and/ or soft stool was increased during the treatment interval of gestation. Additionally, several high-dose females were noted early in gestation (Day 9) as emaciated with red material about the snout. No adverse effect of treatment at the low- or mid-dose level was evident from uterine implantation data. An increase in both the mean number of resorption sites and the mean ratio of resorptions to implants was seen at the high-dose level, however it was not clear if the increase represents an adverse effect of treatment. No increase in the incidence of malformations was seen during the external, visceral or skeletal evaluations of fetuses recovered from females treated at the low- or mid-dose levels. At the high-dose level, no increase in malformation rate was seen during fetal external evaluations; however, the incidence of fetuses with a glassy (shiny) appearance, considered to be an external variation observation, was significantly increased. Fetuses noted as having a glassy (shiny) appearance were usually the smaller fetuses within the litters and the observation was considered related to retarded fetal development within this group. No adverse effect of treatment at the high-dose level was evident from the fetal visceral evaluations. During the skeletal evaluations, the incidence of high-dose fetuses with malformations was statistically higher than control. Skeletal malformations were seen in seven high-dose fetuses (an incidence of 5.9%) in respect to the control incidence of 0.6% (one fetus with a skeletal malformation). Two of the seven high-dose fetuses (one fetus from each of two litters) had dissimilar, relatively minor malformations which were not considered related to treatment. Five high-dose fetuses (four fetuses from one litter and one fetus from a second litter) had one or more malformations from a syndrome of observations that involved misshapen and/or fusion defects of the exoccipital bones, fused ribs, cervical vertebral defects or misaligned thoracic vertebral centre. The two females whose litters contained fetuses with one or more skeletal malformations from the above stated syndrome of observations were quite stressed during the treatment period. Both females experienced weight loss during the Day 6-9 gestation interval and at Day 9, were noted with marked staining of the fur in the ano-genital area and extreme soft stool; therefore, it is not clear if this syndrome of skeletal malformations as seen with increased frequency among the high-dose fetuses represents a response to treatment or is secondary to maternal toxicity encountered at this same dose level.

In conclusion, NOAELfor maternal toxicity was 125 mg/kg bw/day; NOAEL for fetotoxicity was 500 mg/kg bw/day.