Gases (petroleum), depropanizer dry, propene-rich

Exposure related observations in humans: other data

Administrative data

Endpoint:

exposure-related observations in humans: other data

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study predates GLP, human experimental study. Limitations in design and/or reporting but otherwise adequate for assessment

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Acute and repetitive human exposure to isobutane

Author:

Stewart RD, Herrmann AA, Baretta ED, Forster HV, Sikora JJ, Newton PE and Soto RJ

Year:

1977

Bibliographic source:

Scand. J. work. environ. & health 3 234-243

Reference 2

Reference Type:

publication

Title:

Physiological response to aerosol propellants.

Author:

Stewart RD, Newton PE, Baretta ED, Hermann AA, Forster HV, and Soto RJ

Year:

1978

Bibliographic source:

Environ. Health Perspect. 26, 275-285.

Materials and methods

Type of study / information:

Experimental results following human volunteer study

Endpoint addressed:

acute toxicity: inhalation

repeated dose toxicity: inhalation

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Adult volunteers exposed to acute & repeat concentrations of isobutane in a controlled environment chamber.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Isobutane

EC Number:

200-857-2

EC Name:

Isobutane

Cas Number:

75-28-5

Molecular formula:

C4H10

IUPAC Name:

isobutane

Details on test material:

- Name of test material (as cited in study report): isobutane and propane
- Physical state: gas
- Supplied by: Phillips Petroleum Company
Isobutane: boiling point -11.73°C, vapour pressure 3733 mm Hg, vapour density 2.068, SG 0.563
Propane: boiling point -42.49°C, vapour pressure 6612 mm Hg, vapour density 1.549, SG 0.509

Method

Ethical approval:

confirmed and informed consent free of coercion received

Details on study design:

Adult volunteers exposed to isobutane in a controlled environment chamber: Acute exposure of 250-1000 ppm for 1 min, 2 min, 1 hour, 2 hours and 8 hours, repeat exposure at 500 ppm 1, 2 or 8 hours/day, five days/week for 2 weeks. Also acute exposures to isobutane/propane mixtures for 1, 2 or 8 hours/day. All volunteers were kept under comprehensive medical surveillance including cardiac and pulmonary responses (by continuous ECG telemetry and serial computerised spirometric measurements).

Exposure assessment:

measured

Details on exposure:

TYPE OF EXPOSURE: inhalation

TYPE OF EXPOSURE MEASUREMENT: Area air sampling

EXPOSURE LEVELS:
Acute exposure: 250, 500 and 1000 ppm isobutane
Acute exposure: isobutane/propane mix (82.5%/17.5%), propane/isobutane mix (89%/11% and 87.5%/12.5%)
Repeated exposure: 500 ppm isobutane

EXPOSURE PERIOD:
Acute exposure: 1 min, 2 min, 10 min, 1 hour, 2 hour, 8 hour
Acute exposure: isobutane/propane mix 1 hour, 2 hours, 8 hours
Repeated exposure: 1, 2 and 8 hours

Results and discussion

Results:

Acute exposures to isobutane at 250, 500 and 1000 ppm for periods of 1 min to 8 hours did not produce any "untoward physiological effect". Repeat exposures to isobutane at 500 ppm for 1, 2 or 8 hours, 5 days/week for ten exposures and mixtures of isobutane/propane were also without any measurable "untoward physiological effect". 

Any other information on results incl. tables

Analysis of exposure chamber atmospheres:Actual concentrations were within a few per cent of target for each exposure..

Acute exposures: There were no "untoward responses" to the acute exposures.

Repeat exposures to isobutane and isobutane/propane mixtures: There were no untoward subjective responses or abnormal physiological responses during or after these exposures. The following serial laboratory studies were unaltered: complete blood count, urinalysis, serum alkaline phosphatise, SGOT, LDH, serum bilirubin, blood sugar, serum calcium, serum phosphorus, BUN, spontaneous electroencephalogram, visual evoked response, a battery of cognitive tests and an ACTH stimulation test.

During the final week of exposure a reduction in the amplitudes of the 3,4 and 5 waves was observed in the visual evoked response.

Applicant's summary and conclusion

Conclusions:

Acute exposures to isobutane at 250, 500 and 1000 ppm for periods of 1 min to 8 hours did not produce any "untoward physiological effect". Repeat exposures to isobutane at 500 ppm for 1, 2 or 8 hours, 5 days/week for ten exposures and mixtures of isobutane and propane were also without any measurable "untoward physiological effect". 

Executive summary:

Adult volunteers exposed to isobutane in a controlled environment chamber. Acute exposure of 250-1000 ppm (594 -2377 mg/m3 (MW 58.12) ) for 1 min, 2 min, 1 hour, 2 hours and 8 hours. Repeat exposure at 500 ppm 1, 2 or 8 hours/day, five days/week for 2 weeks. Acute exposures to mixtures of isobutane and propane for 1, 2 or 8 hours/day.

During the investigations, all volunteers were kept under comprehensive medical surveillance including cardiac and pulmonary responses (by continuous ECG telemetry and serial computerised spirometric measurements).

Acute exposures to isobutane at 250, 500 and 1000 ppm for periods of 1 min to 8 hours did not produce any "untoward physiological effect". Repeat exposures to isobutane at 500 ppm for 1, 2 or 8 hours, 5 days/week for ten exposures and mixtures of isobutane and propane were also without any measurable "untoward physiological effect".

Acute NOAEL > 1000 ppm (2377 mg/m3)

Repeat 2 week exposure NOAEL > 500 ppm (1189 mg/m3)