Registration Dossier

Toxicological information

Direct observations: clinical cases, poisoning incidents and other

Administrative data

Endpoint:
direct observations: clinical cases, poisoning incidents and other
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-GLP, non-guideline human experimental study, predates implementation of GLP and/or development of study guidelines. Limitations in reporting but otherwise acceptable for assessment

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1925

Materials and methods

Study type:
study with volunteers
Endpoint addressed:
acute toxicity: inhalation
Test guideline
Qualifier:
no guideline available
Deviations:
not applicable
Principles of method if other than guideline:
Subjects were exposed to discontinuous inhalations of acetylene of various concentrations.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Source: Bon-Accord Acetylene Gas Company
- Prepared from calcium carbide and purified through a lime tower
- No further details

Method

Type of population:
not specified
Subjects:
No data
Ethical approval:
not specified
Route of exposure:
inhalation
Reason of exposure:
intentional
Exposure assessment:
measured
Details on exposure:
Mixtures of acetylene gas with oxygen were administered from a Douglas bag with the subject in a sitting position and no re-breathing. The concentrations administered were as follows:
0 % to 35 % acetylene: 100,000, 150,000, 200,000, 250,000, 300,000, 330,000 and 350,000 ppm
(50% acetylene caused an unbearable feeling of suffocation within 70 seconds and experiment was stopped)
Examinations:
- Clinical signs were monitored and the concentration that produced unconsciousness (and exposure time) was listed
- The effects of acetylene inhalation on memory, reflex times and muscular movement were also assessed
Medical treatment:
No data

Results and discussion

Clinical signs:
The lowest concentration employed, 10%, caused feelings of mild intoxication and paraesthesia. 15% caused distinct intoxication and 20% caused marked intoxication after one hour exposure.


Results of examinations:
Systemic LOAEC: 1 hour inhalation exposure at 10% (100,000 ppm or 107,000 mg/m3 equivalent) caused mild intoxication and paraesthesia. NOAEC for local irritation: 20% (200,000 ppm, equivalent to 214,000 mg/m3)

Any other information on results incl. tables

The lowest concentration employed, 10%, caused feelings of mild intoxication and paraesthesia.

15% caused distinct intoxication with talkativeness, sleepiness and inability to walk in a straight line.

20% caused marked intoxication after one hour exposure.

25% acetylene caused similar but more marked symptoms.

General uncoordination and aggressive behaviour were noted after inhalation of 30% acetylene for 13 minutes

Inhalation of 33% acetylene caused unconsciousness in 6 - 7 minutes and 35% acetylene in 5 - 5.5 minutes.

50% acetylene produced feelings of intense intoxication within 35 seconds and an unbearable feeling of suffocation in 70 seconds (after which the experiment was stopped).

Incoordination was seen after 4-5, 6, 12-13, 15 and 18 minutes at 35, 33, 30, 25 and 20% respectively.

Unconsciousness occurred at 5 – 5.5 minutes at 35% and 6 – 7 minutes at 33%.

Times of onset of other clinical observations

 

Conc of Acetylene

Effects observed

 

Initial intoxication

Marked intoxication

Talkativeness

Noisy talkativeness

Aggression

35%

25 sec

60 sec

1.5 – 2 min

2.5 – 3 min

3.5 – 4 min

33%

30 sec

70 sec

3 min

3 – 4 min

5 min

30%

30 sec

90 sec

3 – 4 min

4 – 5 min

8 – 10 min

25%

40 sec

120 sec

3.5 – 4.5 min

5 – 6 min

10 -12 min

20%

50 sec

4 min

6 min

11 min

-

 

Applicant's summary and conclusion

Conclusions:
Systemic LOAEC: 1 hour inhalation exposure at 10% (100,000 ppm or 107,000 mg/m3 equivalent) caused mild intoxication and paraesthesia. NOAEC for local irritation: 20% (200,000 ppm, equivalent to 214,000 mg/m3)
Executive summary:

A group of human volunteers was exposed to acetylene at a range of concentrations in order to assess its anaesthetic properties. The lowest concentration employed, 10%, caused feelings of mild intoxication and paraesthesia.

Systemic LOAEC: 1 hour inhalation exposure at 10% (100,000 ppm or 107,000 mg/m3 equivalent).

There was no indication of local irritation effects at 20% for 1 hour (or higher exposures but >20% were less than 1 hour).

NOAEC for local irritation: 20% (200,000 ppm, equivalent to 214,000 mg/m3)