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Toxicological information

Acute Toxicity: inhalation

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Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
According to the OECD SIDS document for sodium hydroxide (March 2002), a Klimisch 3 reliability score was assigned since the test conditions are described in sufficient details but no standard method is used. It is difficult to determine the exact exposure to NaOH as it reacts rapidly with CO2 in ambient air to form Na2CO3.

Data source

Reference
Reference Type:
publication
Title:
Toxicity of aerosols of sodium reaction products.
Author:
Zwicker-GM, Allen-MD, Stevens-DL
Year:
1979
Bibliographic source:
Journal of Environmental Pathology and Toxicology, 2, 1139-1150

Materials and methods

Principles of method if other than guideline:
The incidence of acute laryngitis was determined. This lesion was graded for each animal as either 0 (normal tissue), 0.5 (trace), 1 (very slight), 2 (slight), 3 (moderate) or 4 (severe). 12 animals were killed within 1 hour of removal from the exposure chamber. The other 12 animals were killed 1 day post-exposure.
GLP compliance:
no
Test type:
other: no data

Test material

Constituent 1
Chemical structure
Reference substance name:
Sodium hydroxide
EC Number:
215-185-5
EC Name:
Sodium hydroxide
Cas Number:
1310-73-2
Molecular formula:
HNaO
IUPAC Name:
sodium hydroxide
Details on test material:
no data

Test animals

Species:
rat
Strain:
Wistar
Sex:
male
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Hilltop Lab. Animals, Inc., Scottdale, PA
- Age at study initiation: juvenile rats
- Weight at study initiation: 130 +/- 29 g


Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
whole body
Vehicle:
other:
Details on inhalation exposure:
TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: 0.8 µm



Analytical verification of test atmosphere concentrations:
not specified
Duration of exposure:
2 h
Concentrations:
750 µg/l
No. of animals per sex per dose:
24
Control animals:
not specified
Details on study design:
Microscopic examinations of cross sections of nose, larynx, trachea with esophagus and lungs. Other tissues examined for some animals included stomach and eyes.

Results and discussion

Clinical signs:
other: At a NaOH aerosol concentration of 750 µg/l, 11 animals showed acute laryngitis after 1 hour and after 1 day post-exposure. the average severity of the lesions was 1.58 (1 hour post-exposure) and 1.25 (post-exposure). No rats died during the test.

Applicant's summary and conclusion