Sodium carbonate

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1983

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable, well documented publication which meets basic scientific principles. Comparable to guideline study with acceptable restrictions. Reported as the key study with this level of reliability in the OECD SIDS Sodium Carbonate publication

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1983

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

yes

Remarks:

2h exposure instead of 4h exposure; only males used; reporting less elaborate and complete; assays of cellular immunity were included.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Sodium carbonate

EC Number:

207-838-8

EC Name:

Sodium carbonate

Cas Number:

497-19-8

Molecular formula:

CH2O3.2Na

IUPAC Name:

disodium carbonate

Test material form:

aerosol dispenser: not specified

Remarks:

migrated information: aerosol

Details on test material:

Test substance: sodium carbonate (purity 91%). (The OECD considered the study result reliable/acceptable.)
SOURCE: sodium combustion products, formed by sodium in combination with oxygen.
IMPURITY/ADDITIVE/ETC.: 9.0% NaOH and 0.0% NaHCO3

Test animals

Species:

rat

Strain:

other: Wistar and Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

60 animals in total
Source: Not reported.
- Age: Adult
- Weight at study initiation: Average weight 365 g.
- Number of animals: 6 trials of each 10 animals.
- Controls: Not reported

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

whole body

Vehicle:

air

Details on inhalation exposure:

- Particle size: median aerodynamic diametre ± GSD: 1.04±1.97 micrometre
- Type or preparation of particles: Sodium combines with oxygen to form combustion products. These react subsequently and rapidly with
atmospheric components. In a typical atmosphere the predominant reactions proceed rapidly from the oxide forms to NaOH, then to Na2CO3.
They all form in the atmosphere without appreciable settling and produce an aerosol in the order of 1 micrometre aerodynamic equivalent diameter.

Duration of exposure:

2 h

Concentrations:

Concentrations: 17 concentrations between 800-4600 mg/m3.

No. of animals per sex per dose:

10 animals per trial. Six trials in total = 60 animals for the complete testing.

Control animals:

not specified

Details on study design:

METHOD FOLLOWED: More or less comparable to OECD guideline 403.
In addition cellular immunity was assessed using mitogen-induced lymphocyte activation assays and T-cell distribution assays in rats killed at
3-4 days and at 12-13 days after inhalation. The mitogens used were concanavalin A, phytohemagglutinin, pokeweed mitogen, and
lipopolysaccharide. T-cell distribution was based on uptake of [3H]uridine.

DEVIATIONS FROM OECD GUIDELINE 403: 2h exposure instead of 4h exposure; only males used; reporting less elaborate and complete; assays of cellular immunity were included.

METHOD OF CALCULATION: LC50 were calculated from acute death (those occurring from beginning of the exposure to 2 hr after exposure) data from three trials. In other trials, acute deaths were scattered over all dose ranges. In no trial was LC50 calculable from overall death data (i.e., from beginning of exposure to 14 days after exposure).

Statistics:

Not reported

Results and discussion

Effect levels

Sex:

male

Dose descriptor:

LC50

Effect level:

2 300 mg/m³ air

Based on:

other: sodium combustion products, formed by sodium in combination with oxygen.

Exp. duration:

2 h

Mortality:

- Time of death: During and within 1-2 hr after exposure, or beginning at 1 day after exposure, peaking at 5-7 days, and continuing to 9-10 days after exposure.
- Number of deaths at each dose: Not reported.

Clinical signs:

other: Signs of respiratory impairment immediately after exposure. Dyspnea, wheezing, excessive salivation, and distention of the abdomen. In many animals, excessive salivation and repeated swallowing continued during the first 2 h r following exposure. Signs su

Gross pathology:

Lesions in respiratory tract in animals that died limited to the posterior pharynx, larynx, anterior trachea, and in approximately 3% of the animals, lungs.

Other findings:

A transitory immunologic repression. This may be, at least in part, contributory to bacteremia

Any other information on results incl. tables

In an attempt to establish a LC50 for sodium carbonate, a series of whole -body inhalation exposures of male rats (Sprague-Dawley and Wistar strains), male mice (Swiss-Webster) and male guinea pigs (Hartley-albino) to varying concentrations were performed (Busch et al., 1983).

The animals exhibited respiratory impairment when exposed for 2 hours to aerosols of sodium combustion products (1 μm aerodynamic equivalent diameter), the major constituent of which was shown to be sodium carbonate (rats 91% Na2CO3, dose range 800-4600 mg/m3, mice 95% Na2CO3, dose range 600-3000 mg/m3, guinea pigs 95% Na2CO3, dose range 500-3000 mg/m3). Clinical signs included dyspnoea, wheezing, excessive salivation and distention of abdomen. Mortality occurred mainly in

two periods, namely during exposure and within 1-2 hours afterwards or beginning at 1 day after exposure peaking at 5-7 days and continuing to 9-10 days after exposure. Lesions in animals that died during or shortly after exposure were present in the posterior pharynx and larynx and included accumulation of mucus, vesiculation, and mucosal oedema. Other lesions included oedema and

vesiculation of the anterior trachea, haemorrhage in the lungs, and severe gastric tympany. For animals that survived, lesions in the respiratory tract were limited to the laryngeal mucosa.

The LC50s for guinea pigs, mice and rats were calculated to be 800, 1200 and 2300 mg/m3, respectively

Applicant's summary and conclusion

Interpretation of results:

relatively harmless

Remarks:

Migrated information Criteria used for interpretation of results: EU