Mercury: a persistent threat to the environment and people's health

Why is mercury a problem?

Mercury occurs naturally in the environment but it is generally safely contained in minerals and does not present any significant risk. The problem arises due to human activities, which result in large amounts of mercury being released into the environment, and this mercury can then remain circulating freely for thousands of years. Mercury in water and sediments is the primary concern, as it is in a highly toxic form and can easily be taken up by animals, thus finding its way into the human food chain. The World Health Organization has identified 10 chemicals of major public health concern and four of these are heavy metals: cadmium, mercury, lead and arsenic.

How much mercury is in the environment?

The legacy of the human use of mercury has resulted in hundreds of thousands of tonnes of mercury being released into the environment. The levels of mercury in the atmosphere at the moment are up to 500 % above natural levels. In the oceans, the concentrations of mercury are about 200 % above natural levels.

How is mercury used and what are the main sources of mercury emissions?

Current uses of mercury vary around the world. In Europe, the use of mercury is very limited and the main use in the coming years will actually be in dental fillings as industrial uses of mercury have been prohibited. In other parts of the world there is still higher usage of mercury in industrial activities and in small-scale gold mining.

One of the largest sources of mercury pollution in Europe and elsewhere is the burning of solids fuels — such as coal, lignite, peat and wood — both industrially and domestically. These fuels contain small quantities of mercury and when burned they release it into the environment. These releases are the main source of mercury emissions in Europe and include activities such as power generation, cement manufacture and production of metals.

How are people exposed to mercury pollution and what are the health impacts?

The most important route for human exposure to mercury is seafood. When marine animals take in mercury it tends to stay in their bodies and builds up over time. Larger predator fish tend to have higher concentrations of mercury as they consume smaller animals that already have taken up some mercury. Therefore, eating larger predatory fish, like tuna or swordfish, will typically result in greater intake of mercury compared to eating smaller fish, which are lower in the food chain.

The health impacts are dose related but the main concern is the impact of mercury on foetuses and young children. Mercury exposure can occur in the womb, due to a mother’s consumption of seafood. This can have significant and life-long impacts on the growing brain and nervous system of a baby, affecting memory, language, attention and other skills. In Europe alone, it is estimated that more than 1.8 million children are born each year with mercury levels above recommended safe limits.

What is being done in Europe and globally to address the mercury problem?

Europe has historically been a large user and emitter of mercury but significant legislative efforts over the past 40 years have substantially reduced usage and releases into the environment. In the rest of the world, the usage and emissions of mercury have been increasing over time, related to ongoing economic development and industrialisation, with key sources including coal burning and also small-scale artisanal gold mining.

In October 2013, a first global international agreement, the Minamata Convention, was adopted to tackle the mercury problem. The convention has been ratified by 98 parties and it entered into force in 2017. It is too early to assess the impact of the Convention, but it is a hugely significant step towards ensuring there are concerted global actions to reduce mercury pollution.

What are the current trends and future outlook for mercury production and emissions?

There is no longer mining of mercury in Europe, and demand in Europe will continue to decrease in the coming years. Emissions of mercury in Europe will be dominated by combustion emissions, mainly from burning solids fuels such as coal, peat, lignite and wood.

The largest global source of mercury is from small-scale gold mining. This is carried out by individuals or small groups, mining gold relatively simply and at low cost, generally in an unregulated environment. It is estimated that over one third of global emissions relate to this source, hence addressing this area by introducing alternative safer technologies could lead to substantial reductions in global usage and emissions.

Despite the past reductions in mercury usage and emissions in regions such as Europe and North America, the levels in our environment are likely to remain high for a long time, due to the long lifetime of mercury in the environment and also because mercury emissions are increasing in other global regions. These emissions also travel long distances. In fact, about half of the mercury that is deposited in Europe comes from outside of the continent.

What role does the EEA play regarding mercury?

We gather information on mercury emissions to air and water from industrial activities through the European Pollutant Release and Transfer Register (E-PRTR) and estimates of emissions to air from a broader range of sources under both EU legislation and international agreements.

The EEA also collects data on pollutant levels in water bodies under the Water Framework Directive. The latest available data that the EEA published as part of the ‘state of water’ report indicates that nearly 46 000 surface water bodies in Europe are not meeting the limits for mercury specified under the Directive.

The EEA is also a partner in the Human Biomonitoring for EU project, which aims to develop better evidence of the actual exposure of citizens to chemicals, including mercury, and their possible health effects.

All of this information helps us to monitor the achievements of existing European policies and also informs the development of new policies in areas such as industrial regulation and chemicals, as well as supporting the objectives of the Minamata Convention.

These data are presented in a new report the EEA has published, ‘Mercury in the environment’, which gives a complete overview all these health and environmental issues as well policies related to mercury.

What can individuals do to reduce their exposure to mercury?

All of us can do things to reduce our own exposure to mercury and also in preventing releases of mercury into the environment. For example, national food safety authorities often provide specific advice on how citizens can maximise the health benefits of eating fish while limiting exposure to mercury. This includes guidance on consumption of fish for pregnant women and young children.

People may also come across mercury containing equipment, such as batteries, lamps and electrical equipment. We need to make sure that we handle and dispose of these materials properly so that the mercury they contain can be safely recovered and does not end up in the environment. We can also reduce mercury emissions by not burning solids fuels for home heating, where other alternatives are available. Mercury-free fillings are also available for dental treatments and choosing to use these will further reduce the usage of mercury.

Ian Marnane
Sustainable resource use and industry expert
European Environment Agency

The interview published in the September 2018 issue of the EEA Newsletter 03/2018