Table of Contents

  • Mercury (Hg) is among our most serious health and environmental hazards. Anthropogenic emissions of Hg result in direct human exposure and a build-up in the global environment and subsequent transfer to humans via consumed fish. The supply chain from virgin mined Hg over Hgadded products to final disposal is long. While the adverse environmental impacts are globally acknowledged, the understanding and mitigation of the problem is delayed, maybe because consumers and other public and private stakeholders are not always aware of the risks, and because environmental costs are, generally, not considered in the market price for devices containing Hg. To reduce or eliminate the risks, Hg substitution is one viable option. Here we present an input to global considerations on mercury management by presenting a mercury substitution priority working list; or: An identification of the least essential mercury uses. This may be used as inspiration for reducing intentional mercury uses globally, if politically desirable, by furnishing the list to stakeholders globally as an input to constructive discussions currently undertaken under auspices of UNEP towards reducing Hg releases. The list includes all identified intentional uses of Hg, the availability of relevant alternatives, and proposed Hg substitution order, and major challenges ahead.

  • Mercury is scientifically demonstrated and politically acknowledged as a global pollutant (UNEP, 2002, 2005, 2006, 2007; The Madison Declaration on Mercury Pollution, 2007). Elemental Hg is unique when compared to other trace metals found in the atmosphere, in that it is predominantly in the gaseous elemental form (Slemr et al. , 1985; Schroeder and Munthe, 1998), where other metals, e. g. lead, are primarily spread in the atmosphere with aerosols. The characteristics of gaseous metallic Hg, such as low aqueous solubility, mean that it has relatively low reactivity and is quite stable. Therefore, gaseous elemental mercury has a long atmospheric residence time, enabling global transport. Its vapour pressure and biological processes allows it to be deposited and reemitted from land, vegetation and aquatic surfaces. All of these factors contribute to its spreading throughout the globe to areas where there are very little natural or local man-made Hg releases. Hg accumulation in aquatic food resources deserve special attention, considering that the growing world population needs increasing food supplies and cannot risk that such a nutritious food resource as fish and other sea and fresh water food turns unsuitable for human consumption due to anthropogenic emissions of Hg. In virtually all regions of the world – including such remote areas as the Arctic – fish and other aquatic foods with mercury concentrations too high for frequent human consumption have been found (UNEP, 2002). For the general population, the most critical toxic effect from mercury is damage to the central nervous system, notably the developing brain of the foetus (UNEP, 2002). In many countries women of childbearing age and small children are advised to avoid eating certain fish species often – or not at all – due to mercury contamination (NMR, 2007).

  • To serve these objectives, efforts were made to identify and list all known uses of Hg. We evaluated the state of Hg substitution for each application in developed countries (primarily OECD countries which are best described in existing literature), and listed potential major challenges for global substitution and proposed a Hg substitution order and relevant considerations.

  • Tables 1–3 below show our suggested categorization of mercury uses according to the expected time needed for global substitution, should this be desired politically. It is important to note that these suggestions are based on an overview of a limited number of reviews and the results should be taken as illustrative of the substitution potential only. It is equally important to emphasize that this categorization is primarily based on observations of the success with substituting mercury uses in developed countries. These observations can – to our opinion – be used to indicate the technical and practical possibilities for implementing mercury substitution, but do not give an adequate description of the social, economical and environmental impacts of substitution under local conditions in a developing country. No doubt, to implement substitution of mercury in developing countries worldwide, will need careful consideration of these impacts, and would probably need substantial technical and financial support in some areas. As mentioned earlier, it is important to note that the suggested time frames were considered by the authors as realistic based on a pragmatic judgment, if global mercury substitution was politically agreed on. Faster substitution could perhaps be practically possible, in case this should be backed politically and the necessary resources for implementation and assistance would be allocated.

  • Based on these findings we recommend that: A prioritised phase-out work list for intentional mercury uses is discussed and developed further in international cooperation, for example as part of the Open-ended Working Group considering legal and other initiatives on mercury established under the auspices of the United Nation's Environment Programme (UNEP).