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Toxicological information

Acute Toxicity: inhalation

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Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study, EPA Guideline with limited documentation: comparable to OECD 403 (limit test)

Data source

Reference
Reference Type:
secondary source
Title:
Unnamed
Year:
1992

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Version / remarks:
(limit test)
Principles of method if other than guideline:
METHOD FOLLOWED: EPA/TSCA 40 CFR Part 798.1150

A group containing both sexes of experimental animals are exposed for the defined period of 4.5 hours to a single concentration of the test substance (limit test). Subsequently, observations of effects and deaths are made. Animals which die during the test are necropsied, and at the conclusion of the test surviving animals are sacrificed and necropsied as necessary.
GLP compliance:
yes
Test type:
standard acute method
Limit test:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
Sodium hydrogencarbonate
EC Number:
205-633-8
EC Name:
Sodium hydrogencarbonate
Cas Number:
144-55-8
Molecular formula:
CH2O3.Na
IUPAC Name:
sodium hydrogen carbonate
Details on test material:
- Name of test material (as cited in study report): Sodium bicarbonate
- Analytical purity > 99.5%

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS:
- Source: Hilltop Lab Animals, Scottdale, PA.
- Age: the report states that the rats were young adults, but the exact age is not given
- Weight at study initiation: ♂ 224-239 g, and ♀ 219-226 g.

ENVIRONMENTAL CONDITIONS: no data

Administration / exposure

Route of administration:
inhalation: dust
Type of inhalation exposure:
whole body
Vehicle:
other: unchanged (no vehicle)
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION:
Type or preparation of particles: the test substance was ground for 24 hours in a ball mill prior to aerosolisation. Thereafter it was sieved through a 425 micron screen to separate it from the grinding medium and any other large particles which remained.

TEST ATMOSPHERE
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): 2.8 µm (2.7 ± 1.77 and 2.9 ± 2.04 µm). 2 measurements with 2 min durations each
Analytical verification of test atmosphere concentrations:
yes
Remarks:
(gravimetric measurement)
Duration of exposure:
4.5 h
Concentrations:
4.74 ± 1.03 mg/l
No. of animals per sex per dose:
5
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Body weight was measured prior to exposure and on days 1, 7 and 14. Animals were observed before exposure commenced, every 15 min during the first exposure hour, and every 15 min thereafter through till exposure termination. The animals were individually examined on removal from the chamber. In-chamber animal observations were limited due to the accumulation of test substance on the walls of the chamber which obscured visualisation.
Statistics:
no data

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 4.74 mg/L air
Exp. duration:
4.5 h
Remarks on result:
other: No mortality occurred. Clinical signs: reduced movement, hunched posture, ocular and nasal discharge. Effects lasted 3 days
Mortality:
No mortality occurred
Clinical signs:
other: During the first hour of exposure, reduced movement and hunched posture were noted for most animals. At exposure termination test substance was observed on the fur of two animals, while the same was observed in all the remaining rats one or two days afte
Body weight:
All the animals gained body weight during the observation period (body weight males at 14 days, 311-341 g; body weight females at 14 days, 254-267 g).
Gross pathology:
The general findings at gross necropsy were unremarkable. One male and one female had moderately red lung tissue, while one male had slightly red lung tissue.

Applicant's summary and conclusion