Isooctene

Developmental toxicity / teratogenicity

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, guideline study, available as published report, no restrictions, fully adequate for assessment

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: US EPA OPPTS 870.3650 combined repeated dose and reproduction / developmental screening

Deviations:

yes

Remarks:

Males and females were exposed to the test substance for 10 weeks prior to pairing.

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: OECD test guideline method 422

Deviations:

yes

Remarks:

Males and females were exposed to the test substance for 10 weeks prior to pairing.

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Isooctene

EC Number:

234-294-9

EC Name:

Isooctene

Cas Number:

11071-47-9

Molecular formula:

C8H16

IUPAC Name:

2-methylhept-1-ene

Details on test material:

- Name of test material (as cited in study report): isooctene
- Synonym: Di-n-butene
- Physical state: Clear, colourless liquid
- Analytical purity: 99.9%, 99.84% area (gas chromatography)
- Lot/batch No.: K402 distillate
- Expiration date of the lot/batch: Unlimited
- Stability under test conditions: Unlimited
- Storage condition of test material: room temperature; air sensitive, under N2

Test animals

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Research Models and Services, Germany GmbH; Sandhofer Weg 7, 97633 Sulzfeld
- Age at study initiation: Approximately 6 weeks
- Females were nulliparous and non-pregnant
- Weight at study initiation: 126.1-131.0 g
- Housing: Individually in wire cages
- Diet: Milled mouse/rat laboratory diet (Provimi Kliba SA, Kaiseraugst, Basel Switzerland) ad libitum except during exposure and motor activity measurements
- Water: tap ad libitum except during exposure and motor activity measurements
- Acclimatisation period: Approximately two weeks

ENVIRONMENTAL CONDITIONS
- Temperature: 20-24°C
- Humidity: 30-70%
- Air changes (per hr): Not reported; air-conditioned
- Photoperiod: 12 hrs dark / 12 hrs light

IN-LIFE DATES: From: 13 June 2006 To: 26 April 2007

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure (if applicable):

whole body

Vehicle:

other: air

Details on exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: glass-steel inhalation chamber, volume of about 1.4 m³ (BASF Aktiengesellschaft).
- Air flow: Approximately 20 per hour
- Air conditions: Test group 0: A positive pressure was maintained by adjusting the airflow of the exhaust air system. This ensured that no laboratory air reached the control animals.
Test groups 1 - 3: A negative pressure was maintained by adjusting the airflow of the exhaust air system. This ensured that the laboratory was not contaminated as the result of any leakage from the inhalation chamber.
- System of generating particulates/aerosols: For each concentration the test substance was supplied to a thermostated vaporizer at a constant rate by means of the metering pump.
- Temperature, humidity, pressure in air chamber: The vapour was generated with conditioned supply air (actual range 54.6-61.1% relative humidity, temperature 20.9-22.7°C) and passed into the inhalation system.

TEST ATMOSPHERE
- Brief description of analytical method used: The nominal concentration was calculated from the study means of the test pump rates and the supply airflows used during exposure to generate the respective concentrations.
The concentrations of the inhalation atmospheres were analyzed by gas chromatography in all test groups including control.
- Total hydrocarbon analyzers were used to continuously monitor the constancy of concentrations of test substance vapours in the inhalation systems.
- No surveillance of the oxygen content in the inhalation system was performed. The air change within the inhalation systems was judged to be sufficient to prevent oxygen depletion by the breathing of the animals and the concentrations of the test substance used could not have a substantial influence on oxygen partial pressure.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The vapour generation effectiveness was as expected for these high concentrations (range of 83.9-88.8%). Real time surveillance of the inhalation atmospheres with total hydrocarbon analyzers generally proved the constancy of each concentration throughout the daily exposures.

Details on mating procedure:

- M/F ratio per cage: 1:1
- Length of cohabitation: 16 days
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 post coitum

Duration of treatment / exposure:

Males were treated for approx. 13 weeks (10 weeks premating, 3 weeks mating and post mating). In females treatment was performed during premating (10 weeks), mating and gestation through day 4 after delivery (approx. 15 weeks).

Frequency of treatment:

6 hours per day / 5 days per week

Duration of test:

Until offspring were 4 days old

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0, 1000, 5000 and 15000 mg/m3
Basis:
other: target concentrations

Doses / concentrations 2

Remarks:

Doses / Concentrations:
0, 1200, 5600 and 16900 mg/m3
Basis:
nominal conc.

Doses / concentrations 3

Remarks:

Doses / Concentrations:
0, 1000±100, 5000±200 and 14900±700 mg/m3
Basis:
analytical conc.

No. of animals per sex per dose:

10

Control animals:

yes, sham-exposed

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: The clinical conditions of the test animals were recorded at least 3 times (before, during and after exposure) on exposure days and once during the preflow period, on the day of neurofunctional test and prior to gross necropsy. During exposure only a group wise examination was possible.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Detailed clinical observations were performed in all animals prior to the exposure period and thereafter in weekly intervals.

BODY WEIGHT: Yes
- Time schedule for examinations: The body weight of all parental animals was determined on day -5 (start preflow period), on day 0 (start exposure period) and then in weekly intervals as well as prior to gross necropsy. Female parental animals were weighed on days 0, 7, 14 and 20 post coitum and on days 1 and 4 post partum. Parental females without litters were not weighed.

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes, with the following exceptions; Food consumption was not determined during the mating period, food consumption of the parental females with evidence of sperm was determined for days 0-7, 7-14 and 14-20 post coitum, food consumption of parental females, which gave birth to a litter was determined for days 1-4 post partum.

FOOD EFFICIENCY:
- Food efficiency (group means) was calculated based upon individual values for body weight and food consumption.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day #: Not applicable - females allowed to litter
- Females and pups killed on day 4 post partum
- Organs weighed/examined: adrenals, brain, heart, kidneys, liver, lungs, ovaries, spleen, thymus, uterus

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: No. Not applicable - females were allowed to litter.

Fetal examinations:

Not applicable - females were allowed to litter.

Statistics:

Means and standard deviations of each test group were calculated for parameters measured. Further statistical analyses were performed as appropriate, according to the methods of Dunnett’s t-test (two-sided), Fisher’s Exact test, Wilcoxon test (one-sided), and/or Kruskal-Wallis test (two-sided).

Indices:

Mating and fertility indices (%) and female gestation index (%)

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
Slight ataxia (from day 9 onward) and salivation (from day 8 onward) were observed at 15000 mg/m3 indicating marginal irritation and systemic toxicity of Isooctene.

Effect levels (maternal animals)

Dose descriptor:

NOAEC

Effect level:

15 000 other: mg/m3 (target concentration)

Basis for effect level:

other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:not examined

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Under the conditions of this test, isooctene did not influence pre/postnatal development at dose levels as high as 15000 mg/m3.
The NOAEC for developmental toxicity was 15000 mg/m3.

Executive summary:

Wistar rats were exposed, whole body, to 0, 1000, 5000 and 15000 mg/m³ isooctene vapour for 6 hours/day, 5 days/week. Males were exposed for approximately 13 weeks (10 weeks pre-mating, 3 weeks mating and post mating). Females were exposed during pre-mating (10 weeks), mating and gestation through day 4 after delivery (approximately 15 weeks). The parental animals were examined for their mating and reproductive performances. The pups were sexed and were weighed on the day after birth and on day 4 post partum. Their viability was recorded. All pups underwent necropsy on day 4 post partum and were examined macroscopically for external and visceral findings.

There were no adverse effects on the development of offspring in the litters of all exposed groups.

 

Under the conditions of this test, isooctene did not influence pre/postnatal development at dose levels as high as 15000 mg/m³.