Sulphuric acid

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-guideline study

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

publication

Title:

The toxicity of H2SO4 aerosols to CD-1 mice and Fischer-344 rats.

Author:

Runkle BK & Hahn FF

Year:

1976

Bibliographic source:

Annual Report of the Inhalation Toxicology Research Institute (p435-439)

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

yes

Remarks:

Surviving animals were observed for 21 days and not the guideline required 14 days.

Principles of method if other than guideline:

The study protocol is broadly compliant with OECD 403, with the exception that exposure was for 1, 2, 4, or 8 hours and that the surviving animals were observed for 21 rather than 14 days.

GLP compliance:

no

Remarks:

: study pre-dates GLP.

Test type:

standard acute method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Sulphuric acid

EC Number:

231-639-5

EC Name:

Sulphuric acid

Cas Number:

7664-93-9

Molecular formula:

H2O4S

IUPAC Name:

sulfuric acid

Details on test material:

Aerosols of sulphuric acid were generated by mixing sulphur trioxide vapour with humid air.

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

whole body

Vehicle:

other: aerosols of sulphuric acid were generated by mixing sulphur trioxide vapour with humid air.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

>= 1 - <= 8 h

Concentrations:

250, 500, 750 and 1000 mg/m3 air; 0.25, 0.5 and 1 mg/l

No. of animals per sex per dose:

Four/sex/dose

Control animals:

no

Results and discussion

Effect levels

Sex:

male/female

Dose descriptor:

LC50

Effect level:

375 mg/m³ air

Any other information on results incl. tables

A relationship between increased mortality and higher test material concentrations (c) and also with exposure time (t) was observed in both species tested, but rat mortality increased more rapidly than mouse mortality for both variables.  Mortality was not proportional to ct; and the LC50 values are dependent on the exposure time.  The LC50 (4h) was ~375 mg/m3, while the LC50 (8h) was ~425 mg/m3.  These values are based on total deaths occurring in the 21 days after exposure.  It is suggested that the fibrosis occurring in the rat may cause malfunction of the epiglottis and subsequently result in foreign body aspiration and subsequent pneumonia. 

Applicant's summary and conclusion

Interpretation of results:

toxic

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Although the LC50 values from the inhalation toxicity study theoretically trigger Classification with (R23) 'Toxic by inhalation', classification is not proposed. The effects of sulphuric acid following inhalation are entirely due to local irritation of the respiratory tract: there is no evidence for the systemic toxicity of sulphuric acid in any study as effects are limited to the site of contact. Classification for acute inhalation toxicity is not considered to be appropriate.

Executive summary:

Groups of F344 rats (5/sex) were exposed (whole body) to aerosols of sulphuric acid (generated by combining sulphur trioxide and humid air) at a number of concentrations and exposure times between 1-8 hours. Histopathology of the respiratory tract revealed ulceration of the nasal turbinates, trachea and larynx immediately following exposure; laryngeal fibrosis and inhalation pneumonia were seen in decedents at 1 -2 weeks following exposure. A clear relationship between mortality and Ct is not apparent from the results of this study; the 4 -hour LC50 value (relevant for classification purposes) was found to be approximately 375 mg/m3 (0.375 mg/l).