Heavy metals such as mercury have led to great harm to human health and the environment, for example in the 1950s in Minamata, Japan, when the release of methylmercury in the industrial wastewater from a chemical factory poisoned many people. Even in smaller quantities, heavy metals released into the atmosphere and subsequently deposited on ecosystems, such as forests, water and vegetation, can cause significant environmental and health damage.
On 8 February, another milestone to control heavy metal pollution will be taken with the entry into force of amendments to the 1998 Aarhus Protocol on Heavy Metals, adopted in 2012. The amended protocol requires 24 Parties in Europe and North America to take measures to prevent and minimize emissions of cadmium, lead and mercury, by regulating combustion and industrial processes as predominant anthropogenic sources of their emissions, in line with the precautionary approach. Since 1990, emissions of mercury (by 60%) and lead (by 90%) have already declined in the region.
The amended Protocol, negotiated under the UNECE Convention on Long-range Transboundary Air Pollution (Air Convention), further steps up Parties’ efforts to reduce their emissions for these three heavy metals and establishes more stringent emission limit values based on best available techniques for the main stationary sources emitting these pollutants.
The Protocol on Heavy Metals, which was signed in 1998 and entered into force in 2003, was the first international treaty to regulate heavy metals on a broad regional basis. Building on the Protocol on Heavy Metals, the Minamata Convention on Mercury, a treaty negotiated under the auspices of the United Nations Environment Programme (UNEP), raised the profile of mercury to the global level in 2013.
UNECE Executive Secretary Olga Algayerova said “All amended protocols under the Air Convention are now in force, which shows the renewed efforts by Parties to work towards better air quality in the region.”
Note to editors
About the Air Convention
The UNECE Convention on Long-range Transboundary Air Pollution was adopted in 1979. Over the years, it has been extended by eight protocols that identify specific measures to be taken by Parties to cut their emissions of air pollutants. The Convention has 51 Parties, covering North America and almost the entire European continent.
The 1998 Protocol on Heavy Metals under the UNECE Convention on Long-Range Transboundary Air Pollution entered into force on 29 December 2003. It was amended in 2012.
Heavy Metals: sources, their health and environmental effects
Cadmium compounds are currently mainly found in rechargeable nickel-cadmium batteries as well as cigarette smoke. Food is the most important source of cadmium exposure. In heavily contaminated areas, dust resuspension can constitute a substantial part of the crop contamination and exposures via inhalation and digestion. The main critical effects include increased risk of osteoporosis and lung cancer.
Emissions of mercury into the air from both anthropogenic and natural sources are in inorganic forms that can be converted biologically to methylmercury in soil and water. Methylmercury bioaccumulates and enters the human body readily via the dietary route. Methylmercury is a potent neurotoxic chemical. Unborn children (i.e., fetuses) are the most susceptible population group, the exposure being mainly from fish in the diet of the mother. Methylmercury is also excreted in mothers’ milk.
Historical data, e.g., from lake sediments in Scandinavia, show a two- to fivefold increase in mercury concentrations with respect to the preindustrial era, reflecting anthropogenic emissions and long-range transport. Methylmercury in freshwater fish originates from inorganic mercury in the soil and direct atmospheric deposition.
The general population is exposed to lead from air and food. During the last century, lead emissions into the ambient air have caused considerable pollution, mainly due to lead emissions from petrol. Food is the predominant source of lead uptake in the general population. Ingestion of contaminated soil, dust and old lead-based paint due to hand- to-mouth activities may also be important regarding lead intake in infants and young children. When tap-water systems with leaded pipes are used, drinking-water can be an important source of lead intake, especially in children. Inhalation exposure may be significant when lead levels in the air are high.