Mercury

Mercury is a chemical element with interesting physico-chemical properties (liquid at room temperature, formation of alloys with other metals such as tin, gold, etc., high density, high thermal expansion) that have led to its use in various products: barometers, thermometers, dental amalgams, gold washing, in the chlorine and soda industries, as a catalyser, etc.

It is also a highly toxic substance that is unique in that it can be found in different forms, depending on the environment.

Mercury hazards for humans have been particularly well described in a study of highly exposed populations: in Minamata (Japan), between 1930 and 1950, where the population was exposed to mercury through the consumption of fish contaminated by discharges from a petrochemical plant, and where neurological disorders were observed in the people exposed, along with impaired neurological development in children exposed during their mother’s pregnancies or during breastfeeding, birth defects, etc.

In view of the risks it poses to human health and the environment, in 2003 the European Commission developed a mercury strategy, containing six objectives, which were accompanied by specific actions. These elements resulted from work carried out by the EC’s Directorate-General for Enterprise and Industry, which published a report in 2003 on the “Risks to health and the environment related to the use of mercury products”. They were presented in the Communication from the Commission of 28 January 2005 “Community strategy concerning mercury” [COM(2005) 20 final – Official Journal C52 of 2 March 2005]. This strategy is aimed mainly at reducing the quantity and circulation of mercury within the European Union and throughout the world, as well as human exposure to this substance.

In this context, in July 2003 the French Ministries of Health and the Environment formally requested the Agency to prepare a brief to enable the European Commission, if necessary, to review the classification of mercury within the framework of Directive 67/548/EEC on the classification, packaging and labelling of hazardous substances.

Given the scheduled completion deadlines, the Agency elected to restrict the study to classification as a Carcinogenic, Mutagenic, Reprotoxic (CMR) substance, specifically by examining the toxic properties of mercury for reproductive organs. This classification can lead to a ban or restriction in Europe on placing mercury on the market for use by the general public, as well as increased monitoring in the workplace.

Work process

The mercury dossier was handled by the Agency’s  Expert Committee (CES) on the Assessment of risks associated with chemical substances, which prepared the preliminary versions of the briefs on elemental mercury (Hg0), inorganic mercury (particularly HgCl2) and organic mercury (CH3Hg and CH3HgCl).

Following discussions with the European authorities, data on carcinogenicity and mutagenicity were added in order to rule on these aspects concurrently with the reprotoxic aspects of mercury.

The revised dossiers were sent to the European Commission for discussion in February 2006. The proposed classifications, modifying the initial classifications for the three forms of mercury studied, are summarised in the table below.

Proposal made by France to the European Commission in March 2006 (the additional classifications proposed by the Agency’s study and adopted are shown in blue, as compared to the initial classifications of the forms of mercury; the classifications to be verified before being removed during the follow-up period are shown in green; the labelling codes corresponding to these classifications are shown in parentheses).

Following the meeting of the European classification group (Technical Committee for Classification and Labelling), the three proposals for elemental mercury, mercury dichloride and the organic forms of mercury were accepted by the Member States. 

• For elemental mercury: the following classification was adopted and inserted into the 1^st Adaptation to Technical Progress (ATP) by the European Commission: Repr 1B H360D (May damage the unborn child), Acute tox 2 H330 (Fatal if inhaled), STOT RE1 H372 (Causes damage to organs through prolonged or repeated exposure), Aquatic acute 1 H400 (Very toxic to aquatic life) and Aquatic Chronic 1 H410 (Very toxic to aquatic life with long-lasting effects).
• For mercury dichloride:  the following classification was adopted and inserted into the 1^st ATP by the European Commission: Muta 2 H341 (Suspected of causing genetic effects), Repr 2 H361f (Suspected of damaging fertility), Acute tox 2 H300 (Fatal if swallowed), STOT RE1 H372 (Causes damage to organs through prolonged or repeated exposure), Skin corr 1B H314 (Causes severe skin burns and eye damage), Aquatic acute 1 H400 (Very toxic to aquatic life) and Aquatic Chronic 1 H410 (Very toxic to aquatic life with long-lasting effects).
• For organic forms of mercury: the substance methylmercury is not on the market because it occurs naturally in the environment and is not produced in its ionic form, therefore it is not relevant to submit a classification dossier for this substance. This substance was thus removed from the classification dossier for organic forms of mercury in August 2011. However, the classification dossier for methylmercury chloride is currently being examined at the European Chemicals Agency (ECHA). It should be available shortly for public consultation on the ECHA website.