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Repeated dose toxicity: inhalation

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sub-chronic toxicity: inhalation
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
Justification for type of information:
Laponite is a synthetically manufactured layered silicate similar to a naturally occurring smectite clay: Hecotorite. Laponite, a Silicate(2-), hexafluoro-, disodium, reaction products with lithium magnesium sodium silicate, (EC no 285-349-9) is a monoconstituent substance and is an inorganic layered silicate structure with a unit cell of the following composition: Na0.7+[(Si8Mg 5.5Li0.3)O20(OH)2.5F1.5]0.7-. Hectorite is a trioctahedral, magnesium based smectite clay with a unit cell of the following composition: H2LiMgNaO12Si4-2. The unique properties of the naturally occurring hectorite active mineral are very small platelet size, an elongated platelet structure with an inherent negative charge counterbalanced by exchangeable sodium (Na+) ions, light color with low iron content and high viscosifying ability in water.
Laux, P., et al., 2018 have published a comprehensive review on testing of aerosolized nanoforms. The formation in air of nanoform agglomerates when testing the toxicity of the aerosolization compartment limits the viability of techniques to determine aerosol exposure. The Laponite product in powder form exists only in the micron range, and is not a nanoform but may exist as a nanoform in liquid. Due to the current limitations of aerosolizing nanoforms there is insufficient justification to conduct additional testing of inhalation endpoints.
Laponite exhibited no toxicity in acute testing (oral, dermal, inhalation), mutagenicity and cytogenicity (See submitted studies) or any other toxicological relevant pathway. Laponite is a synthetic clay based on hectorite a naturally occurring clay mineral. There have been no epidemiological or toxicologically relevant studies on hectorite that found any potential risk from hectorite exposure. Laponite is a synthetic clay with the same functional chemical composition as hectorite. Any nanoform exposures from laponite would be comparable to background exposure from the nanoform compartment of hectorite (Kahn, 1957).

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Materials and methods

Results and discussion

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion