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Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
In the OECD SIDS on sodium bicarbonate (2002) a similar reliability was assigned.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1992

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
EPA OTS 798.1150 (Acute inhalation toxicity)
GLP compliance:
yes
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:
SOURCE: Not reported.
PURITY: > 99.5%
IMPURITY/ADDITIVE/ETC.: Not reported.
ANY OTHER INFORMATION: the test substance was ground for 24 hours in a ball mill prior to testing.

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals or test system and environmental conditions:
- 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: The weight-range for males was 224-239 g, and 219-226 g for females.

Administration / exposure

Route of administration:
inhalation
Type of inhalation exposure:
whole body
Duration of exposure:
4.5 h
Concentrations:
4.74 mg/L
No. of animals per sex per dose:
5
Control animals:
no
Details on study design:
ADMINISTRATION:
- Concentrations: the measured (gravimetric) chamber concentration was 4.74 +/-1.03 mg/l.
- Particle size: MMAD in two samplings of two minutes duration, was (1) 2.9 +/- 1.77 micrometres SD and (2) 2.7 +/- 2.04 micrometres SD, respectively.
- 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.

EXAMINATIONS:
- 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 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.

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
other: limit test
Effect level:
> 4.74 mg/L air
Exp. duration:
4.5 h
Mortality:
MORTALITY:
- Time of death: there was no mortality, and the animals were sacrificed after 14 days of observation. LC50 >4.74 mg/l.
- Number of deaths at each dose: No mortality.
Clinical signs:
other: CLINICAL SIGNS: 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 on th
Gross pathology:
NECROPSY FINDINGS: 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.
POTENTIAL TARGET ORGANS: Respiratory tract, lungs.
SEX-SPECIFIC DIFFERENCES: Not reported.

Applicant's summary and conclusion

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