Oxirane, 2-methyl-, (2R)-

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Cited experiments were summarized in the European Chemicals Bureau Methyloxirane (Propylene Oxide) Risk Assessment Report. The original studies were not reviewed.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

review article or handbook

Title:

Unnamed

Year:

2002

Materials and methods

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

propylene oxide

IUPAC Name:

propylene oxide

Constituent 2

Reference substance name:

Methyloxirane

EC Number:

200-879-2

EC Name:

Methyloxirane

Cas Number:

75-56-9

IUPAC Name:

2-methyloxirane

Applicant's summary and conclusion

Conclusions:

The 4 -hr inhalation LC50 of propylene oxide vapour is reported to be 1,740 ppm (4,124 mg/m3) for mice. Values of 4,000 ppm (9,480 mg/m3) and 4,197 ppm have been reported for rats.

Results were reported of a single 4 -hr exposure to propylene oxide vapour in F344/N rats and B6C3F1 mice. Rats (5 per sex per group) were
exposed to 1,277, 2,970, 3,794 and 3,900 ppm (3,033, 7,055, 9,012 and 9,204 mg/m3). Mortalities were 0, 1, 4 and 3 males, and 0, 2,4 and 3 females, respectively. Clinical observations at the 3 higher concentrations included dyspnoea and red nasal discharge. Mice (5 per sex per group) were
exposed to 387, 859, 1,102, 1,277 and 2,970 ppm (919, 2,041, 2,618, 3,033 and 7,054 mg/m3). Mortalities were 0, 0, 2, 2 and 5 males and 1, 0, 4, 5 and 5 females, respectively. Dyspnoea occurred in all groups. Lachrymation occurred in animals exposed to the highest doses.

Groups of rats exposed to propylene oxide vapour for 30 minutes. Mortality was 100% with 14,400 ppm (34,128 mg/m3) and 50% with 7,200 ppm (17,064 mg/m3). Exposure to 3,600 ppm (8,532 mg/m3) for 2 hrs killed 4/10 animals.

Groups of 10 rats and 5 guinea ppigs were exposed to propylene oxide vapour at concentrations of 2,000, 4,000, 8,000 and 16,000 ppm (4,740,
9,480, 18,960 and 37,920 mg/m3) and for periods from 0.25 -7 hrs. Exposure to 4,000 ppm for 4 hrs caused 4/10 deaths among rats and 1/5
deaths among guinea pigs. Exposure to 2,000 ppm for 7 hrs caused no deaths in either species. During the exposures, rats and guinea pigs
exhibited irritation of the eyes and nasal passages, difficulty breathing, drowsiness, weakness and occacional incoordination. The severity of
response was dependent on the concentration and duration of exposure. Survivors showed temporary loss of body weight gain, but recovered
weight gain within 14 days of exposure.

Mice inhaling 20 ppm of propylene oxide for 3 hrs showed no statistically significant changes in mortality from experimentally-induced
Streptococcal pneumonia and pulmonary bactericidal activity.