Dibutyl terephthalate

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP Guideline study

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2005

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: Ministry of Health and Welfare, Japan; Guidelines for Toxicity Studies of Drugs

Principles of method if other than guideline:

Pregnant rats were given drinking water containing 1-butanol at 0.2%, 1.0% or 5.0% (316, 1454 or 5654 mg/kg/day) on days 0–20 of pregnancy. The
rats were sacrificed on day 20 of pregnancy and both the dams and fetuses were examined.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Butan-1-ol

EC Number:

200-751-6

EC Name:

Butan-1-ol

Cas Number:

71-36-3

Molecular formula:

C4H10O

IUPAC Name:

butan-1-ol

Details on test material:

- Name of test material (as cited in study report): 1-butanol
- Physical state: liquid
- Analytical purity: 99.9 %
- Stability under test conditions: the purity and stability of the chemical were verified by analysis before and after the study
- Storage condition of test material: dark place at room temperature under airtight conditions

Test animals

Species:

rat

Strain:

Crj: CD(SD)

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Tsukuba Breeding Center
- Age at study initiation: males: 10 weeks; females: 9 weeks
- Weight at study initiation: females: 217-273 g
- Housing: individually
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 7 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-25 °C
- Humidity (%): 40-70 %
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: drinking water

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
1-butanl was mixed with water to the according target concentrations. The stability of formulations in a dark and cool place under airtight conditions
has been confirmed for up to 3 days. During use, the formulations were maintained under such conditions for no more than 3 days and
were 95.7–103.5% of the target concentration.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The concentrations were determined analytically and were 95.7–103.5% of the target concentration.

Details on mating procedure:

- Impregnation procedure: [cohoused]
- If cohoused:
- M/F ratio per cage: 1/1
- Length of cohabitation: over night
- 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 0 through day 20 of pregnancy

Frequency of treatment:

continuous through drinking water

Duration of test:

until day 20 of pregnancy

No. of animals per sex per dose:

20 females per dose

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: The dosage levels were determined based on the results of our range-finding study in which administration
of 1-butanol in the drinking water on days 0–20 of pregnancy caused decreases in maternal body weight gain and food and water consumption and
tended to reduce in fetal weight at 4% and 7% in rats.
- Rationale for animal assignment (if not random): The rats were distributed using a computerized randomization procedure (TOXstaff 21 system)

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: not specified



DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: not not specified


BODY WEIGHT: Yes
- Time schedule for examinations: once daily


FOOD CONSUMPTION: Yes
- Time schedule for examinations: every 3 or 4 days


WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Time schedule for examinations: daily


POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 10
- Organs examined: not specified

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No data
- 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: Yes: [half per litter]

Statistics:

The statistical analysis of fetuses was carried out using the litter as the experimental unit. The initial body weight, body weight gain and food and water consumption of pregnant rats, numbers of corpora lutea, implantations and live fetuses per litter, fetal weight and crown-rump length and placental
weight were analyzed with Bartlett's test for homogeneity of variance at the 5% level of significance.
If it was homogeneous, the data were analyzed using Dunnett's multiple comparison test to compare the mean of the control group with that of
each dosage group, and if it was not homogeneous, the mean rank of the 1-butanol-treated groups was compared with that of the control group with the Dunnett type test. The Dunnett type test was used for the incidences of pre- and postimplantation embryonic loss and fetal anomalies and sex
ratio of fetuses to compare the mean rank of groups treated with 1-butanol and that of the control group. The incidence of dams with anomalous
fetuses was analyzed by Chi-square test or Fisher's exact test. The significance of differences from the control group was estimated at probability
levels of 1% and 5%.

Indices:

no data

Historical control data:

International Genetic Standard (Crj: CD (SD) IGS) rats were used throughout this study. This strain was chosen because it is most commonly used in
reproductive and developmental toxicity studies and historical control data are available.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Details on maternal toxic effects:
No death was found in female rats of any group. All females in all groups became pregnant. The body weight gains on days 0–7 of pregnancy
were significantly reduced at 5.0%. The body weight gain during the whole period of pregnancy was also significantly decreased at 5.0%. No significant decrease in the body weight gain was noted at 0.2 or 1.0, except for a transient decrease on days 0–2 of pregnancy at 1.0%. The food consumption on days 0–7, days 7–14, days 14–20 and days 0–20 of pregnancy was significantly lower in the 1.0% and 5.0% groups than the control group. The water
consumption on days 0–7 at 1.0 and 5.0% and on days 7–14, days 14–20 and days 0–20 at 5.0% was significantly decreased. The mean daily intakes
of 1-butanol were 316 mg/kg for the 0.2% group, 1454 mg/kg for the 1.0% group and 5654 mg/kg for the 5.0% group.

Effect levels (maternal animals)

Dose descriptor:

NOAEL

Effect level:

1 454 mg/kg bw/day (nominal)

Basis for effect level:

other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Details on embryotoxic / teratogenic effects:
No litters totally resorbed were found in any group. No effects of the administration of 1-butanol were observed on the numbers
of corpora lutea, implantations, pre- or postimplantation loss, resorptions or dead or live fetuses or sex ratio of live fetuses. The body weights of male and female fetuses were significantly lower in the 5.0% group than in the control group. There was no significant difference in the crown-rump length of male and female fetuses or placental weight between the control and groups treated with 1-butanol.
One fetus with spina bifida in the control group and one fetus with thread-like tail and anal atresia in the 0.2% group were observed. Skeletal
examination revealed one fetus with supernumerary thoracic vertebral bodies and malpositioned thoracic vertebrae at 1.0%. Although the total number of fetuses with skeletal variations was significantly increased at 5.0%, the number of fetuses with individual skeletal variations was not
significantly increased, except for fetuses with short supernumerary ribs at 5.0%. Asignifican tly lower number of forepaw proximal phalanges was
observed at 5.0%. Membranous ventricular septum defect occurred in one fetus of the control and 0.2% groups and 3 fetuses
in 3 dams of the 5.0% group. One fetus with a double aorta in the control group and one fetus with a left umbilical artery in the control and 2.0%
groups were observed. Thymic remnants in the neck were found in 4–11 fetuses of the control and groups treated with 1-butanol.
However, there was no significant difference in the incidence of fetuses with internal abnormalities between the control and groups treated with
1-butanol.

Effect levels (fetuses)

1

Dose descriptor:

NOAEL

Effect level:

5 654 mg/kg bw/day (nominal)

Basis for effect level:

other: teratogenicity

2

Dose descriptor:

NOAEL

Effect level:

1 454 mg/kg bw/day (nominal)

Basis for effect level:

other: fetotoxicity

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Any other information on results incl. tables

Summary:

A significant decrease in maternal body weight gain accompanied by reduced food and water consumption was found at 5.0%. No significant increase in the incidence of pre- and postimplantation embryonic loss was observed in any groups treated with 1-butanol. Fetal weight was significantly lowered at 5.0%. Although a significant increase in the incidence of fetuses with skeletal variations and decreased degree of ossification was found at 5.0%, no increase in the incidence of fetuses with external, skeletal and internal abnormalities was detected in any groups treated with 1-butanol. The data demonstrate that 1-butanol is developmental toxic only at maternal toxic doses. No evidence for teratogenicity of 1-butanol was noted in rats. Based on the significant decreases in maternal body weight gain and fetal weight, it is concluded that the no observed adverse effect levels (NOAELs) of 1-butanol for both dams and fetuses are 1.0% (1454 mg/kg/day) in rats.