Safeguarding human health from the effects of mercury

Mercury is widely considered to be among the highest priority environmental pollutants of concern on the global scale. Although occupational exposure to inorganic mercury is a continuous problem, possible effects on broader sections of the population resulting from widespread dispersal of mercury in the environment has become a major concern in recent years.

Mercury has been targeted by agencies and organisations worldwide for possible emission control. For example, the EU has called for a ban on mercury exports by 2011 1, while the United Nations Environment Programme (UNEP) coordinates intense scientific and policy debate on how best to deal with mercury on a global level. In February 2009, the Governing Council of UNEP took the decision to begin negotiations towards an international treaty on mercury that would significantly reduce the use of this dangerous chemical 2.

This thematic issue reports on research which explores the impacts of mercury emissions and contaminants, and how they may be traced, controlled and reduced.

The use of mercury in industrial processes is a key policy concern. The manufacture of chlorine in chlor-alkali plants represents one such process. A pan-European project has assessed mercury exposure levels for communities living near chlor-alkali plants and considered whether this could cause kidney damage. Read the results in the article `Impact of mercury exposure from chlor-alkali plants`.

The consequences of mercury exposure are still not fully understood. To develop effective strategies for preventing any toxic consequences, we first need a precise medical understanding of what mercury does to our bodies, and how. `Does mercury damage genes?` discusses mechanisms for DNA damage.

While dental amalgam is not widely believed to pose a health risk in itself, there is concern that it could contribute to more harmful levels of accumulated mercury in the body, by adding to deposits derived from air pollution and contaminated food. However, its exact contribution is not clear. Researchers have recently shed new light on this matter by highlighting another mechanism of exposure to mercury from dental fillings. For more details, see `Can mercury from dental fillings travel through teeth?`.

We must look for ways to control and reduce exposure to mercury, including finding alternatives to mercury in industrial processes. Artisanal gold mining can be a lifeline for many communities in the developing world, in terms of income, but the use of mercury in processing the gold ore poses a toxic threat. `Finding alternatives to mercury in small-scale gold mining` suggests `mill-leaching` with cyanide could substitute mercury.

Mercury in landfill waste must be tightly controlled to avoid potential harmful emissions. The effectiveness of several commercial forms of `activated carbon`, used to stabilise industrial mercury emissions before disposal in landfill, is evaluated in `Activated carbon`: effective at locking away mercury`.

Air pollution can be a significant source of exposure to mercury. Research can inform improved policies by revealing how mercury moves around the atmosphere and how we can track down its origin. `Understanding the movement of mercury in the atmosphere` calls for intensive global monitoring of mercury and "Chemical fingerprints` could reveal source of mercury pollution` explains how the potentially unique chemistry of coal deposits from around the world provides crucial clues as to where the pollution came from.

Although mercury pollution has received much attention and is placed high on the political agenda, it is clear that many concerning aspects of this mysterious toxic element are still not fully understood. The development of cost-effective, clean technologies for removing mercury from gaseous and liquid streams are behind current needs, particularly in fast developing economies.

The socioeconomic and health effects of mercury pollution and its effects on the world`s fisheries and wildlife are still some of the biggest concerns. However, much uncertainty still surrounds safe and recommended levels. While sound, legally binding instruments on mercury combined with voluntary approaches will reduce the extent of the problem, it will be a long time before scientists can adequately answer some key questions, particularly related to long-term, low-level mercury exposure and effects on susceptible population groups.