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Acute Toxicity: inhalation

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Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1980
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1987

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Deviations:
yes
Remarks:
No necropsy performed
GLP compliance:
not specified
Test type:
fixed concentration procedure
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Ethylene oxide
EC Number:
200-849-9
EC Name:
Ethylene oxide
Cas Number:
75-21-8
Molecular formula:
C2H4O
IUPAC Name:
oxirane
Test material form:
gas under pressure: liquefied gas
Details on test material:
Lot: 0018-1
Supplier: Union Carbide, lnc. (Torrance, CA, USA)

The liquefied ethylene oxide was stored at room temperature in its original cylinder and was analyzed periodically at the study laboratory by infrared spectroscopy and gas chromatography with a flame ionization detector and Porapak QS 80/100 mesh column.
Specific details on test material used for the study:
purity: >99%

Test animals

Species:
mouse
Strain:
B6C3F1
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratories, USA
- Females (if applicable) nulliparous and non-pregnant: [yes/no]
- Age at study initiation: 8 - 10 weeks
- Housing: Single
- Diet: ad libitum
- Water: ad libitum)
- Acclimation period: 28 days

ENVIRONMENTAL CONDITIONS
- Temperature (Fahrenheit): 70 - 72
- Humidity (%): 40 - 60%
- Air changes (per hr): 10 during exposure, 20 at all other times
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: February 2, 1980 To February 21, 1980

Administration / exposure

Route of administration:
inhalation: vapour
Type of inhalation exposure:
whole body
Vehicle:
air
Details on inhalation exposure:
Liquefied ethylene oxide was dispensed through an eductor tube from the 175-pound cylinder to a coiled-tube hot water boiler by pressurizing the tankhead space with nitrogen (regulated at 20 psi). The vapor was generated in a stainless steel coiled tube boiler located in a 55° ± 10° C water bath. From the boiler, ethylene oxide vapor was routed through a manifold to dual gas metering valves that controlled the gas flow to each chamber. The manifold and valves were heated to about 55° C with a heat tape and a small heater.

Vapor to each chamber was routed through a three-way purge/expose valve into a pipe at the chamber inlet, where the gas was mixed with 0.28 ± 0.04 m3/min of diluent air.
Analytical verification of test atmosphere concentrations:
yes
Duration of exposure:
4 h
Concentrations:
Target: 100, 200, 400, 800 and 1600 ppm (measured: 96, 201, 409, 816 and 1542 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: Mice were observed continuously during the exposure period and three times per day during nonexposure periods. They were weighed only before exposure.
- Necropsy of survivors performed: no

Results and discussion

Effect levelsopen allclose all
Sex:
female
Dose descriptor:
LC50
Effect level:
660 ppm
Based on:
test mat.
95% CL:
> 509 - < 856
Exp. duration:
4 h
Remarks on result:
other: corresponds to 1189 mg/m3 air)
Sex:
male
Dose descriptor:
LC50
Effect level:
ca. 660 ppm
Based on:
test mat.
Exp. duration:
4 h
Mortality:
All mice exposed at 1,600 ppm and 5/5 males and 4/5 females exposed at 800 ppm died before the end of the studies.
Clinical signs:
other: At 800 ppm, lacrimation was observed after 3 hours; dyspnea was observed after 4 hours. At 1,600 ppm, dyspnea, lacrimation, and incoordination were observed after 3 hours; semiconsciousness, severe dyspnea, and diarrhea were observed after 3.5 hours.
Body weight:
not determined
Gross pathology:
not performed

Applicant's summary and conclusion

Interpretation of results:
Category 3 based on GHS criteria
Conclusions:
The LC50 for 4h whole body exposure of mice is ca 660 ppm (1189 mg/m3 air).

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