Silicate(2-), hexafluoro-, disodium, reaction products with lithium magnesium sodium silicate

Skin irritation / corrosion

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

Justification for type of information:

See Document "Laponite Analog justification-BL_6_30_2020.pdf" in Section 13.2 - Toxicokinetic assessment for Synthetic fluorohectorites for justification of read-across.

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

Test material information

Constituent 1

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[Li0.3Mg5.5Si8O20(OH)4]

IUPAC Name:

Synthetic hectorite

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.