Mercury is a chemical element, symbol Hg, with interesting physicochemical properties (liquid at room temperature, formation of alloys with other metals such as tin, gold, etc., high density, high thermal expansion) which have prompted it to be used in various products: barometers, thermometers, dental mixtures, for gold washing, in the chlorine and soda industries, as a catalyser, etc.
Mercury is a highly toxic substance and unique in that it can be found in different forms depending on the environment. Mercury metal can release vapours which are toxic when inhaled by humans (this is the predominant exposure for workers). This mercury metal can be oxidised in the presence of water (changes from the form Hg0 to Hg2+) and then, in the environment, bacterial activity turns the inorganic mercury Hg2+ into organic mercury in the form HgCH3, which is known to be neurotoxic and very persistent in the environment. Organic mercury therefore becomes concentrated in the food chain and humans can be exposed to it through their food (particularly by consuming highly contaminated fish).
The dangers of mercury for humans have been particularly well described by the study of highly exposed populations: in Minamata, 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 problems were observed in the people exposed, alterations in the neurological development of children during their mothers' pregnancies or during breastfeeding, malformations, etc.
Given the risks for human health and the environment associated with mercury, in 2003 the European Commission drew up a strategy on mercury, containing 6 objectives accompanied by specific measures. These elements are from work carried out by the Directorate General for Enterprise (DGE) which published a report in 2003 on "the health and environmental risks incurred by the use of mercury in products" and are presented in the Communication from the Commission of 28 January 2005 "Community Strategy concerning Mercury" [COM(2005) 20 - Official Journal C52 of 2 March 2005].
This strategy mainly seeks to reduce the quantity and circulation of mercury in the European Union and worldwide and population exposure to this substance.
Gold mining in French Guiana has massively contaminated the environment with the mercury metal used by the miners. The Guyanese population is therefore particularly exposed to mercury-related risks. For workers (miners especially), exposure occurs when mercury metal is used and concerns a neurotoxic risk. The general population is exposed by consuming foods contaminated by mercury through the food chain which leads to neurotoxic risks for the foetus and breastfed infants in particular.
Multiple studies aiming to identify the health and environmental impact of the mercury pollution in French Guiana have been conducted since the early 1990s by the CNRS , INSERM , InVS, IRD , BRGM , etc. In this context, the French Ministries of Health and Solidarities and of Ecology and Sustainable Development sent a threefold solicited request to Afsset in July 2003 concerning mercury:
Critical analysis of the report published by the DGE of the European Commission on mercury-related risks;
Organisation of a science day on the health risks associated with gold mining and mercury in French Guiana;
Preparation of facts for the European Commission with a view to revising, if this proves necessary, the classification of mercury within Directive 67/548/EEC on the classification, packaging and labelling of dangerous substances.
Given the time it took to prepare these facts, for which France had to provide scientific details to the European Commission at the beginning of 2004, Afsset chose to restrict the study to CMR classification, particularly through the study of the reprotoxic properties of mercury. This classification would lead to a Europe-wide ban or restriction to market mercury for use by the general public and reinforced surveillance in the occupational environment.
Working method (procedure):
Afsset worked with the INRS and then a committee composed of members of the INRS and INERIS , competent authorities which present classification dossiers for France and the European Commission.
The mercury dossier was managed by the Afsset "chemical substance risk assessment" committee of specialised experts (CSE) which met 3 times between July 2004 and January 2005 to draw up the preliminary versions of information on elementary mercury (Hg0), inorganic mercury (particularly HgCl2) and organic mercury (CH3Hg and CH3HgCl). A bibliographic search was conducted to identify, analyse and review data on the toxic effects (particularly reprotoxic) of mercury: effects in humans in the general and working population, effects in laboratory animals and effects on wildlife.
The dossier was then sent to the European Commission via the INRS, for putting on the agenda of the French Technical Classification and Labelling Committee.
The mercury dossier was presented to the European classification and labelling meeting in November 2005. After this meeting, Member States asked for certain protocols of toxicological studies (on monkeys) to be specified, certain data to be quantified and the justifications for existing classifications (R22, R33, etc.) to be clarified. It was also suggested that carcinogenesis and mutagenicity data be added to give an opinion on these aspects at the same time.
Afsset again called on members of its "chemical substance risk assessment" CSE between December 2005 and January 2006 to respond to the comments made on reprotoxicity data. At the same time, the INRS and INERIS worked together on carcinogenesis and mutagenicity data.
New information was sent to the European Commission via the BERPC in February 2006 for putting on the agenda of the European technical group TC C&L of 21/24 March 2006. France was represented by a committee made up of members of the two bodies, INRS and INERIS.
The classification proposals, amending the initial classifications for the three forms of mercury studied, are presented in the table below.
Proposal made by France to the European Commission in March 2006 (in blue, the additional classifications proposed by the Afsset study and adopted compared with the initial classifications of the forms of mercury, in green, the classifications to be checked before being eliminated during the follow-up period, in brackets, the labelling codes corresponding to these classifications).
Following the meeting of the European technical group, the three proposals for elementary mercury, mercury dichloride and methylmercury were accepted by the Member States, who are currently checking the data available on mercury dichloride to justify the current classification for chronic toxicity (T; R48/25) and irritation/corrosion (C; R34). Likewise, data on the cutaneous or respiratory absorption of methylmercury will confirm the elimination of the classification T+; R26/27.