Learning more about exposure to lithium in order to control the health and environmental risks
Lithium is used as a medication, in the manufacture of car and mobile phone batteries, in the production of glass and ceramics, and as an ingredient in certain cosmetics.
Given its growing uses and the emergence of plans to mine this resource in Europe, particularly in France, it seemed important to carry out a review of the potential risks associated with lithium use and their prevention. ANSES therefore examined the current state of knowledge regarding the effects of lithium and some of its salts on human health and the environment, and analysed regulatory management options for preventing potential risks.
This work focused on lithium and three of its salts: lithium carbonate, lithium chloride and lithium hydroxide.
Known effects on human health and the environment
In 2020, ANSES had proposed classifying these three lithium salts as toxic to reproduction under the European CLP Regulation on classification, labelling and packaging of substances and mixtures (Category 1A – known toxic effects on foetal development; Category 1B – presumed toxic effects on fertility). This classification is currently under review at European level. If adopted, labelling on the hazards associated with its salts will become mandatory, for example.
Data on humans and animals show that lithium also has effects on the thyroid, acting as an endocrine disruptor with implications for human health. Moreover, the data show that lithium has toxic effects on various aquatic organisms, mainly fish, invertebrates, seaweed and amphibians, including during chronic exposure. As a consequence, lithium and its salts could be classified as endocrine disruptors for human health and substances with chronic toxicity to aquatic organisms under the CLP Regulation.
Better characterisation of exposures and risks associated with lithium
The reprotoxic and endocrine-disrupting effects of lithium have mainly been demonstrated in studies conducted with lithium used as a medicine, and therefore at higher concentrations than those found in the environment. Adverse effects following environmental exposure have been observed, but only in a limited number of epidemiological studies. ANSES therefore calls for further research to be carried out to better characterise the effects of lithium at environmental doses.
The Agency also recommends that the regulatory risk assessments carried out by manufacturers, for example under the European Regulation on batteries and waste batteries, take account of the reprotoxic and endocrine-disrupting effects of lithium and its salts on human health, as well as their toxic effects on species in the environment. It calls for all data on human and environmental exposure to be made available to the public authorities.
In its work on controlling substance hazards through the European regulations, the Agency has also recommended exploring a procedure to identify lithium as a substance of very high concern, once its classification as a Category 1A reproductive toxicant has been incorporated into the CLP Regulation. The aim would be to encourage manufacturers to provide precise data on lithium uses and exposure, in order to strengthen measures to protect exposed workers, mainly by encouraging its substitution with substances of lower concern wherever possible. The Directorate General for Risk Prevention, within the Ministry for Ecological Transition, is responsible for determining the management option that France will propose at European level, based on the Agency’s work.
Definition of toxicity reference values for assessing health risks
In order to assess health risks, ANSES defines toxicity reference values (TRVs) corresponding to exposure levels with no adverse effects on the population.
Three TRVs have been established for lithium: an oral value of 0.02 mg lithium equivalent/kg body weight/day, an inhalation value of 0.05 mg lithium equivalent/m3, and an internal blood value of 0.035 mg/L. These values only concern chronic exposure lasting more than one year. Due to a lack of data, it was not possible to define TRVs applicable to all forms of lithium for shorter exposure durations, to protect against acute risks.
The TRVs will be used to interpret lithium exposure data and guide management measures, in order to protect the general population.
In addition, occupational exposure limits are currently being developed by the European Chemicals Agency (ECHA) and will supplement the risk management tools available to employers.