Lithium bis(trifluoromethylsulfonyl)imide

Endpoint summary

Description of key information

No data on toxicokinetics, metabolism and distribution are available for Bis trifluoromethanesulfonimide Lithium. Based on its high water-solubility, moderate molecular weight and the effects observed in rats upon (sub)acute oral exposure and acute dermal exposure, the substance is expected to be well absorbed by the gastro-intestinal and respiratory tracts and through the skin. 

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Absorption rate - oral (%):

100

Absorption rate - dermal (%):

100

Absorption rate - inhalation (%):

100

Additional information

No studies on toxicokinetics are available for Bis trifluoromethanesulfonimide Lithium (TFSILi). Physico-chemical properties and the results of acute and repeated dose toxicity studies with TFSILi were used to assess the toxicokinetic profile. The substance is a white solid with a molecular weight of 287.08 g/mol. It is highly water soluble (>1000 g/L at 20°C) with a low log Pow of between -1.46 and -1.19. TFSILi is hydrolytically stable at pH 4, 7 and 9.

Absorption

Oral route:

The physicochemical characteristics of TFSILi and the molecular weight mass are in a range suggestive of absorption as such from the gastro-intestinal tract subsequent to oral ingestion. The assumption of oral adsorption is supported by the mortality and clinical signs observed in the available acute oral toxicity studies in rats (Pelcot, 2002a; Prinsen, 1997a; Glaza, 1988a). Autopsy of the rats that died as a result of treatment revealed dark red discoloration of the glandular mucosa of the stomach. Clinical signs consisted of hypoactivity then sedation, hypersensitivity to touch, dyspnea, tonic-clonic convulsions, hypersalivation and piloerection and were mainly indicative of effects on the central and peripheral nervous system. In the available sub-acute oral toxicity studies in which rats were exposed to resp. 1.67, 10 and 60 mg/kg/day and 15, 45, 90 mg/kg/day, no treatment related mortality was observed among the animals. The observed effects in rats treated at 60 and 90 mg/kg/day consisted of findings in the liver and kidneys.

In the absence of substance specific quantitative data on absorption, a default (worst case) absorption value of 100% is assumed for the oral route.

Inhalation route:

TFSILi is a solid with a negligible vapour pressure of 4x 10E-06 Pa at 25°C. About 83% of the particles are below the size of 100 µm and about 13% of the particles are below 10 µm. Therefore, inhalation exposure should result primarily in deposition of the material in the head and the tracheobronchial regions with less exposure of the alveolar region. The fate and uptake of deposited particles depends on the clearance mechanisms present in the different parts of the airway. Due to the high water solubility, the material deposited in the head and tracheobronchial regions will be transferred to the digestive system via the mucociliary cleansing mechanism. Once translocated to the gastrointestinal tract, the uptake will be in accordance with oral uptake kinetics. The material that is deposited in the pulmonary region may be assumed by default to be absorbed to 100%.

To provide a most conservative estimate and for risk assessment purposes, a 100% absorption by the inhalation route is assumed.

Dermal route:

Dermal absorption studies are not available for TFSILi. Compounds most readily absorbed through the relatively impervious stratum corneum skin layer are those of moderate lipophilicity and having both some water and fat solubility. Molecular weights below 500 are favorable for absorption.

TFSILi has a molecular weight of 287.08 g/mol and is highly soluble in water. Although the Log Pow is low (< -1), the solubility of the substance in fat is high. For this reason, it may be assumed that TFSILi penetrates the skin readily. This assumption is supported by the mortality observed in the acute dermal toxicity study in rabbits (Perkins, 1991). The substance is highly irritating to skin and damage to the skin surface may therefore enhance skin penetration.

To provide a most conservative estimate and for risk assessment purposes, a 100% absorption of the subject material by the dermal route is assumed.

 

Distribution

Any TFSILi that is absorbed will be distributed via the blood to the liver and other organs and tissues. Due to its high water solubility and hydrophilic nature, it will tend to remain in the circulating blood and will not distribute into fatty tissues. The changes in organ weights (including those of the liver and kidneys) at the top dose level in the 28-day rat studies provide evidence that the substance is distributed to several limited tissues, and changes to haematological and clinical chemistry parameters are also evidence of distribution.

Metabolism

No information is available on the metabolism of TFSILi.

Elimination

TFSILi is of low molecular weight and is highly water soluble, therefore it is expected that the absorbed TFSILi will be primarily eliminated unchanged via the urine.