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Toxicological information

Skin irritation / corrosion

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Administrative data

Endpoint:
skin irritation: in vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1988
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Test carried out by GLP compliant laboratory to recognised validated methods by trained personnel

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1988

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
other: Draize Test Dermal Toxicity FDA 1975
Deviations:
yes
Remarks:
Modified Draize test
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
Silicic acid, lithium magnesium sodium salt
EC Number:
258-476-2
EC Name:
Silicic acid, lithium magnesium sodium salt
Cas Number:
53320-86-8
Molecular formula:
Na0.7+ [(Si8Mg5.5Li0.3) O20(OH)4]0.7-
IUPAC Name:
Silicic acid, lithium magnesium sodium salt
Details on test material:
Read-across: Laponite Type 1 (Silicate(2-), hexafluoro-, disodium, reaction products with lithium magnesium sodium silicate) and Laponite Type 2 (silicic acid, lithium magnesium sodium salt) in this case the read across substance, are essentially the same structure except that Type 1 has fluoride incorporated in the structure. They both behave in a similar way in powder form and also when dispersed in water, forming a colloidal gel. At skin pH values of essentially neutral, no hydrolysis from the clay type structure would occur and it would not be expected for there to be any difference in the dermal effect than there is for Laponite T2 .

Test animals

Species:
rabbit
Strain:
New Zealand White
Details on test animals or test system and environmental conditions:
Animals were acclimated at least 4 days prior to test. Housed in galvanised or s.s cages and kept in a 12hr day/night cycle. Room temperaturs kept between 65-75 deg F. Fed and watered. 24 hours prior to test the animals were re-examined. Any with skin problems or in poor health were not used.

Test system

Type of coverage:
occlusive
Preparation of test site:
other: two sites per animal, one shaved only, the other shaved and abraded
Vehicle:
physiological saline
Controls:
not required
Amount / concentration applied:
0.5 g of test material moistened with saline were applied to each test site
Duration of treatment / exposure:
Wrapping and test article removed after 24 hours. Remaining test article was gently washed from the skin with water and dried with paper towel.
Observation period:
Test sites were examined after 24 and 72 hours
Number of animals:
Six

Results and discussion

In vivo

Results
Irritation parameter:
primary dermal irritation index (PDII)
Basis:
mean
Time point:
other: 24 hours and 72 hous after application
Score:
0.18
Reversibility:
no data

Applicant's summary and conclusion

Interpretation of results:
not irritating
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
This substance is not a primary dermal irritant to rabbits under the consition of the test. A score in the range 0.1-0.9 is classed as "potential for slight irritation, rarely irritating to people - no warning required"
Executive summary:

Laponite Type 2 (EC 258-476-2) is not irritating to skin of rabbits under the conditions of this test. This test substance is a "read-across" for Laponite Type 1 (EC 285-349-9), their structures being essentially identical with the exception of some ionic substitution within the clay lattice. It is therefore concluded that Laponite Type 1 will not be a skin irritant to rabbits in the same way as for Laponite type 2.