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Toxicological information

Acute Toxicity: inhalation

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Administrative data

Endpoint:
acute toxicity: inhalation
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other: GLP compliant, guideline study, available as unpublished report, no restrictions, fully adequate for assessment

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2006
Report Date:
2006

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EPA OPPTS 870.1300 (Acute inhalation toxicity)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Test type:
standard acute method
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Diisobutylene
- Sample ID Number ID# GCRD10401R (to reference the other Lyondell DIB studies).
- Physical state: Clear light brown liquid
- Chemical composition of sample of diisobutylene: approximately 70% 2,4,4-trimethylpentene (detailed chemical composition information provided in Table 1).

Test animals

Species:
rat
Strain:
other: Crl:CD®(SD)
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Raleigh, North Carolina, USA
- Weight at study initiation: males 261-276 g; females 202-213 g
- Age at study initiation: males Approximately 8 weeks
- Fasting period before study:
- Housing: Individual suspended wire-mesh cages except during inhalation when they were placed in a wire-mesh battery containing 10 separate cages
- Diet: PMI Nutrition International, LLC, Certified Rodent Lab Diet® 5002 ad libitum except during exposure
- Water: Municipal water ad libitum except during exposure
- Acclimation period: Minimum of 7 days

ENVIRONMENTAL CONDITIONS
- Temperature: 21.2-21.7°C
- Humidity: 41.7-53.7%
- Air changes (per hr): Not reported
- Photoperiod: 12 hrs dark / 12 hrs light

IN-LIFE DATES: From: 8 November 2005 To: 22 November 2005

Administration / exposure

Route of administration:
inhalation: vapour
Type of inhalation exposure:
whole body
Vehicle:
other: air
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
Exposure apparatus: 130 L glass and stainless steel whole-body inhalation chamber operated at a minimum of 10 air changes per hour. Exposure atmosphere conditions were recorded approximately every 30 minutes during the exposure. Oxygen content was measured pre-exposure. The time required to attain 99% of the equilibrium concentration (or clearance time for the concentration to decrease from the equilibrium concentration) was calculated.
A vapour atmosphere of the test article was generated and piped to the inlet of the whole body chamber where it was mixed with the chamber supply air. Exhaust atmosphere was filtered (particulate) prior to entering the in-house exhaust system. Test article flow rate = 0.75 mL/min; supply airflow rate 26.9 L/min; chamber ventilation rate = 30.6 L/min.

TEST ATMOSPHERE
- Brief description of analytical method used: Two primary compounds of the test article, DIB-1 (2,4,4-trimethyl-1-pentene) and DIB-2 (2,4,4-trimethyl-2-pentene), were analyzed independently with each sample obtained by gas chromatography.
- Samples taken from breathing zone: yes

Analytical verification of test atmosphere concentrations:
yes
Duration of exposure:
4 h
Concentrations:
4185 ppm
No. of animals per sex per dose:
5
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Mortality - at the approximate midpoint of exposure, immediately following exposure on study day 0 and twice daily thereafter for 14 days; Clinical obs: observed for mortality at the approximate midpoint of exposure, immediately following exposure on study day 0 and twice daily thereafter for 14 days; Bodyweights: Immediately prior to exposure on day 0 and on days 7 and 14.
- Necropsy of survivors performed: yes
Statistics:
None (limit test, no mortalities)

Results and discussion

Effect levelsopen allclose all
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 19 171 mg/m³ air
Remarks on result:
other: >4185 ppm
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 4 185 ppm
Remarks on result:
other: No mortalities
Mortality:
No mortalities
Clinical signs:
Clinical observations immediately following exposure included red material around the nose, mouth and eye, white and clear material around the mouth and yellow material on the urogenital area. Yellow material on the urogenital area was noted during the 14-day post-exposure period. Animals were considered normal by study day 3.
Body weight:
There was no effect on bodyweight
Gross pathology:
There were no gross findings for any animals at the scheduled necropsy

Applicant's summary and conclusion

Interpretation of results:
not classified
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
The acute LC50 of diisobutylene was greater than 4185 ppm when male and female albino rats were exposed via whole-body to a vapour of the test
article for a single, 4-hour period.
Executive summary:

The acute inhalation toxicity of diisobutylene was evaluated in a 4-hour, single exposure study in male and female albino rats. There were no mortalities and no overt signs of toxicity. The acute LC50 of diisobutylene was greater than 4185 ppm, equivalent to 19171 mg/m3 air.

Diisobutylene does not require classification under DSD or CLP.