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Repeated dose toxicity: oral

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Administrative data

sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Work carried out by recognised toxicology laboratory by qualified laboratory personnel using calibrated equipment and recognised methods of test. But the work was done in 1974 and not to GLP standards at that time

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
no guideline available
Principles of method if other than guideline:
100 rats, 50 of each gender divided into four groups, were orally dosed by intubation with a dispersion concentration of 10ml/kg of the test material in deionised water over a period of 100 consecutive days. The rats were grouped by weight and dosed according to a recorded schedule. Group 1 was the control group and had just distilled water administered. Group 2 had a low dose (5mg/kg), group 3 had a medium dose (50mg/kg) and group 4 had a high dose (500mg/kg). The rats were observed daily for signs of toxicity and mortality. All rats were weighed on day 1 and weekly thereafter and at sacrifice. Blood analysis was carried out after 6 weeks and at the end of the test period. All organs were examined after sacrifice
GLP compliance:
Limit test:

Test material

Constituent 1
Chemical structure
Reference substance name:
Silicic acid, lithium magnesium sodium salt
EC Number:
EC Name:
Silicic acid, lithium magnesium sodium salt
Cas Number:
Molecular formula:
Na0.7+ [(Si8Mg5.5Li0.3) O20(OH)4]0.7-
Silicic acid, lithium magnesium sodium salt
Details on test material:
Laponite CP is an old trade name for Laponite Type 2 i.e. silicic acid, lithium magnesium sodium salt.

Test animals

Details on test animals or test system and environmental conditions:
The rats were 28 days old when received for the start of the testing.

Administration / exposure

Route of administration:
oral: gavage
Analytical verification of doses or concentrations:
not specified


Sacrifice and pathology:
Opthalmology, blood analysis, hematology, biochemistry and urinalsysis testing were carried out
Other examinations:
Rats were weighed at day 1 and then weekly thereafter and at sacrifice

Results and discussion

Effect levels

Key result
Dose descriptor:
dose level:
Effect level:
>= 50 - <= 500 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
clinical signs
Remarks on result:
not determinable due to absence of adverse toxic effects

Target system / organ toxicity

Critical effects observed:
Lowest effective dose / conc.:
500 mg/kg bw/day (actual dose received)
gastrointestinal tract
Treatment related:
Dose response relationship:
Relevant for humans:

Applicant's summary and conclusion

Executive summary:

This study, carried out in 1973, was designed to evaluate the repeat dose oral toxicity of Laponite on rats over a period of 3 months. The material was dispersed in deionised water and the rats were fed by intubation. The rats were split into four groups, even numbers of male/female. Group 1 was the control group, (just water), group 2 was low dose (5mg/kg bw), group 3 was medium dose (50mg/kg bw) and group 4 was high dose (500mg/kg bw). The high dose group saw some premature deaths and these were found to be due to the fact that the Laponite forms a gel at high dose and this had accumulated in the animals digestive system and had not been digested. This level of dosing would not be permitted under today's controls. For surviving rats at necropsy, there were no signs of abnormalities relating to the oral dosing of the Laponite. The high dosage group resulted in half of the rats failing to survive to completion of the test but all rats in the other two groups (with the exception of 1 in the low dose group whose death was not attributed to the treatment) all survived. No systemic toxic effect as ascertained by blood analysis and histopathological examination were observed, even in the high dose rats

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