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Specific investigations: other studies

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mechanistic studies
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
no data available
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: Restricted relevance of the experimental data due to intratracheal route of administration.

Data source

Reference Type:
Pulmonary reaction to barium sulfate in rats
Huston, J.; Cunningham, G.J.
Bibliographic source:
A.M.A. Arch. Pathol. 54, 430-438

Materials and methods

Test guideline
no guideline followed
Principles of method if other than guideline:
Barium sulfate was administered to 18 Sprague-Dawley rats via a tracheal catheter. Roentgenograms were taken of the animal and of the lungs (after removal from the body). Histological examinations were performed.
GLP compliance:
Type of method:
in vivo
Endpoint addressed:
respiratory irritation

Test material

Constituent 1
Chemical structure
Reference substance name:
Barium sulfate
EC Number:
EC Name:
Barium sulfate
Cas Number:
Molecular formula:
barium sulfate
Details on test material:
- Name of test material (as cited in study report): Barium sulfate (veriopaque)
- Physical state: solid
No further details are given.

Test animals

Details on test animals or test system and environmental conditions:
- Weight at study initiation: 250 and 300g
No further details are given.

Administration / exposure

Route of administration:
not specified
Details on exposure:
Rats were first anesthetised and were then tied in the supine position to a rat board by means of rubber bands on all four extremities. A fifth band, fitted over the front teeth, immobilised th ehead. The rat was held in a vertical position. The tongue was pulled of the animal as far out and to one side as possible, while the tip of the trachela catheter was placed.
Analytical verification of doses or concentrations:
not specified
Details on analytical verification of doses or concentrations:
no data
Duration of treatment / exposure:
single administration
Post exposure period:
Rats were killed at varying intervals of 30 mintes, 2, 12, 24, 48 and 72 hours, and 7, 15, 30, 94 and 126 days by lethal intraperitoneal injection of thiopental sodium.
Doses / concentrations
Doses / Concentrations:
no test concentration given

No. of animals per sex per dose:
18 animals were used in this experiment.
Control animals:
not specified
Details on study design:
No further details are given.


Roentgenograms were taken immediately prior to and after injection. Further roentgenograms were taken of the animals before killing and of the lungs after removal from the lungs. These were of value in detecting the lobs which contained barium suspension.
After killing, autopsies were performed immediately, and the lungs removed in toto. The lungs together with the spleen and portions of liver and kidney were fixed in 10% formalin. Sections were made from barium containing whole lobes and by cutting through the hilus in most cases one ore more lymph nodes were included in the sections.
Positive control:
no data

Results and discussion

Details on results:
While in general the animals survived the procedure well, 2 rats died almost immediately from tracheal or bronchial obstruction. Observations show that at first the suspension is taken up by polymorphonuclear leucocytes, which subsequently degenerate and liberate the suspension, which is then taken up by mononuclear cells. When the barium is liberated from these cells, it becomes inspissated into refractile masses. The amount od tissue reaction is slight, and giant cell reaction of the foreign body type commences after about 90 days. Finally, although barium sulfate if present in quantity cannot be completely removed, it is likely to give rise to little fibrosis ultimately.
On the basis of the observations it is concluded that barium sulfate is a relatively inert substance in the tissues and give rise to only a very mild reaction.

Applicant's summary and conclusion

An experimental study of the reaction of rat lung to the endotracheal injection of barium sulfate suspension is described. Stages of this reaction which are moderately clear-cut have been found, although the changes are mild and insidious. On the basis of the observations it is concluded that barium sulfate is a relatively inert substance in the tissues and give rise to only a very mild reaction.