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

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

There is no evidence that the substance is absorbed through ingestion, dermal contact or inhalation.

None of the ions present are known to have effects on fertility or reproduction.

Link to relevant study records

Reference

Endpoint:

extended one-generation reproductive toxicity - basic test design (Cohorts 1A, and 1B without extension)

Type of information:

other: discussion in comparison with naturally occurring structurally related hectorite

Adequacy of study:

weight of evidence

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Reason / purpose for cross-reference:

reference to other study

Reason / purpose for cross-reference:

other: see Remarks

Remarks:

general substance background and toxicokinetics summary

Qualifier:

no guideline followed

Principles of method if other than guideline:

discussion in comparison with naturally occurring structurally related hectorite

GLP compliance:

no

Justification for study design:

discussion in comparison with naturally occurring structurally related hectorite

Remarks on result:

other: see Remarks

Remarks:

see Any Other Information on Results

Remarks on result:

other: see Remarks

Remarks:

see Any Other Information on Results

Reproductive effects observed:

no

There is no evidence that the substance is absorbed through ingestion, dermal contact or inhalation None of the ions present are known to have effects on fertility or reproduction. No effects were observed in the 90-day study on a similar read-across material (Laponite type 2) to indicate effects on gonads. It is not considered justified to perform further animal testing on this class of substance.

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: Na_0.7[Mg_5.3Li_0.7Si₈O₂₀(OH)_0.0F_4.0]. 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.

Na, Mg, Li and Si are already widely found in the environment both in waters and soils / sediments. If released to the environment, the substance is expected to combine indistinguishably with the soil or sediment due to its similarity with inorganic soil/sediment matter and will be subjected to natural processes under environmental conditions (cation exchange, dissolution, sedimentation). Furthermore the potential human exposure to laponite is negligible in comparison to the release by natural deposits or alteration of naturally occurring clays with similar compositions.

Laponite is not expected to pose serious risk via the systemic absorption route. Lithium is the only metal that is less common from natural exposures. A review of publicly available information has indicated that lithium is not expected to bioaccumulate and its human and environmental toxicity are low. Large doses of lithium (up to 10 mg/L in serum) are given to patients with bipolar disorder. A provisional recommended daily intake of 14.3 μg/kg body weight lithium for an adult has been suggested. Lithium does not accumulate in the body since daily doses are required to maintain effect and has been utilized as a pharmacological treatment for over 60 years (Machado-Vieira et al. 2009). Excreted lithium from human use will find its way into the environment naturally. Accumulating evidence over the last 30 years strongly suggest that dietary silicon is beneficial to bone and connective tissue health and there are strong positive associations between dietary silica intake and bone mineral density. Dietary intake of silica is between 20-50 mg Si/day for most Western populations (Jugdaohsingh, 2007). Mg and Na are abundant minerals in the body, they are naturally present in many foods, added to other food products, available as a dietary supplement, and present in some medicines (such as antacids and laxatives). Magnesium is a cofactor in more than 300 enzyme systems that regulate diverse biochemical reactions in the body, including protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation (NIH 2019). In humans and animals, ingested fluoride occurs as hydrogen fluoride (HF) in the acidic environment of the stomach and is effectively absorbed from the gastrointestinal tract, although there is no proved absorption from the oral cavity. Once absorbed, fluoride is rapidly distributed throughout the body via the blood. Approximately 99% of the fluoride in the human body is found in bones and teeth. Renal excretion is the major route of fluoride removal from the body.

None of the ions present are known to have effects on fertility or reproduction. No effects were observed in the 90 day study to indicate effects on gonads. No significant differences we observed in the contents of magnesium, sodium in the brain, kidney, liver, or tibia from pregnant SD rats dosed with 2% sodium montmorillonite or calcium montmorillonite clay compared with animals fed the basal diet. (WHO, 2005)

Laponite exhibited no toxicity in acute testing (oral, dermal, inhalation), mutagenicity and cytogenicity (See submitted studies) or any other toxicological relevant pathway. In addition Laponite is currently being explored as a potential drug delivery mechanism for angiogenesis (Page DJ., 2019), in implantable medical devices (Hsu, 2020). 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 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).

Conclusions:

There is no evidence that the substance is absorbed through ingestion, dermal contact or inhalation.
None of the ions present are known to have effects on fertility or reproduction so further animal testing is not warranted based on animal welfare reasons..

Executive summary:

There is no evidence that the substance is absorbed through ingestion, dermal contact or inhalation.

None of the ions present are known to have effects on fertility or reproduction so further animal testing is not warranted based on animal welfare reasons.

Effects on developmental toxicity

Description of key information

There is no evidence that the substance is absorbed through ingrestion, dermal contact or inhalation 
None of the ions present are known to have effects on fertility or reproduction.

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

other: discussion in comparison with naturally occurring structurally related hectorite

Adequacy of study:

weight of evidence

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Reason / purpose for cross-reference:

reference to other study

Reason / purpose for cross-reference:

other: see Remarks

Remarks:

general substance background and toxicokinetics summary

Qualifier:

no guideline followed

Principles of method if other than guideline:

discussion in comparison with naturally occurring structurally related hectorite

GLP compliance:

no

Species:

rat

Remarks on result:

other: see Remarks

Remarks:

see Any Other Information on Results

Remarks on result:

other: see Remarks

Remarks:

see Any Other Information on Results

Developmental effects observed:

no

There is no evidence that the substance is absorbed through ingestion, dermal contact or inhalation None of the ions present are known to have effects on fertility or reproduction.No effects were observed in the 90-day study on a similar read-across material (Laponite type 2) to indicate effects on gonads. It is not considered justified to perform further animal testing on this class of substance.

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: Na_0.7[Mg_5.3Li_0.7Si₈O₂₀(OH)_0.0F_4.0]. 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.

Na, Mg, Li and Si are already widely found in the environment both in waters and soils / sediments. If released to the environment, the substance is expected to combine indistinguishably with the soil or sediment due to its similarity with inorganic soil/sediment matter and will be subjected to natural processes under environmental conditions (cation exchange, dissolution, sedimentation). Furthermore the potential human exposure to laponite is negligible in comparison to the release by natural deposits or alteration of naturally occurring clays with similar compositions.

Laponite is not expected to pose serious risk via the systemic absorption route. Lithium is the only metal that is less common from natural exposures. A review of publicly available information has indicated that lithium is not expected to bioaccumulate and its human and environmental toxicity are low. Large doses of lithium (up to 10 mg/L in serum) are given to patients with bipolar disorder. A provisional recommended daily intake of 14.3 μg/kg body weight lithium for an adult has been suggested. Lithium does not accumulate in the body since daily doses are required to maintain effect and has been utilized as a pharmacological treatment for over 60 years (Machado-Vieira et al. 2009). Excreted lithium from human use will find its way into the environment naturally. Accumulating evidence over the last 30 years strongly suggest that dietary silicon is beneficial to bone and connective tissue health and there are strong positive associations between dietary silica intake and bone mineral density. Dietary intake of silica is between 20-50 mg Si/day for most Western populations (Jugdaohsingh, 2007). Mg and Na are abundant minerals in the body, they are naturally present in many foods, added to other food products, available as a dietary supplement, and present in some medicines (such as antacids and laxatives). Magnesium is a cofactor in more than 300 enzyme systems that regulate diverse biochemical reactions in the body, including protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation (NIH 2019). In humans and animals, ingested fluoride occurs as hydrogen fluoride (HF) in the acidic environment of the stomach and is effectively absorbed from the gastrointestinal tract, although there is no proved absorption from the oral cavity. Once absorbed, fluoride is rapidly distributed throughout the body via the blood. Approximately 99% of the fluoride in the human body is found in bones and teeth. Renal excretion is the major route of fluoride removal from the body.

None of the ions present are known to have effects on fertility or reproduction. No effects were observed in the 90 day study to indicate effects on gonads. No significant differences we observed in the contents of magnesium, sodium in the brain, kidney, liver, or tibia from pregnant SD rats dosed with 2% sodium montmorillonite or calcium montmorillonite clay compared with animals fed the basal diet. (WHO, 2005)

Laponite exhibited no toxicity in acute testing (oral, dermal, inhalation), mutagenicity and cytogenicity (See submitted studies) or any other toxicological relevant pathway. In addition Laponite is currently being explored as a potential drug delivery mechanism for angiogenesis (Page DJ., 2019), in implantable medical devices (Hsu, 2020). 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 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).

Conclusions:

There is no evidence that the substance is absorbed through ingestion, dermal contact or inhalation
None of the ions present are known to have effects on fertility or reproduction so further animal testing is not warranted based on animal welfare reasons.

Executive summary:

There is no evidence that the substance is absorbed through ingestion, dermal contact or inhalation

None of the ions present are known to have effects on fertility or reproduction so further animal testing is not warranted based on animal welfare reasons.

Justification for classification or non-classification

There is no evidence that the substance is absorbed through ingestion, dermal contact or inhalation.

None of the ions present are known to have effects on fertility or reproduction.