RAIS: Lithium (7439-93-2)The Risk Assessment Information SystemNOTE: Although the toxicity values presented in these toxicity profiles were correct at the time they were produced, these values are subject to change. Users should always refer to the Toxicity Value Database for the current toxicity values.Lithium is an alkali metal similar to magnesium and sodium in its properties (Birch, 1988; Arena, 1986) and has a molecular weight of 6.941 (Beliles, 1994). It does not occur in nature in its free form but is found in minerals such as spodumene, petalite, and eucryptite (Beliles, 1994). Lithium compounds are found in natural waters and in some foods. The average dietary intake is estimated to be about 2 mg per day (Beliles, 1994). The nervous system is the primary target organ of lithium toxicity. Neurologic effects occurring during prolonged therapy often include minor effects on memory, motor activity, and associative productivity (Kocsis et al., 1993). Movement disorders (myoclonus, choreoathetosis), proximal muscle weakness, fasciculations, gait disturbances, incontinence, corticospinal tract signs, and a Parkinsonian syndrome (cogwheel rigidity, tremor) have been reported (Sansone and Ziegler, 1985). Cases of severe lithium neurotoxicity, which may occur during chronic therapy as a result of increased lithium retention, may be characterized by disorientation, incoherence, paralysis, stupor, seizure, and coma (Hall et al., 1979). Permanent brain damage has occurred in several patients on long-term lithium therapy (Gosselin et al., 1984).
