Identification Of Land Potentially Contaminated With Mercury

An exercise to identify land in Northern Ireland potentially contaminated by mercury due to historic practices and industry has been undertaken to meet this requirement.  This was conducted by means of a desk-based review, using the NIEA Historical Land Use Database and the DOE Industry Profiles. The Historical Land Use Database is a list of approximately 14,000 sites with information on the types of industry that might have been undertaken at the sites. The DOE Industry profile lists different types of industry and the contaminants that may be associated with them. This exercise cross referenced the two sources of information to assess where mercury contamination was possible. 

It is important to stress that no site visits or field work were undertaken during this exercise and no conclusions or inferences can be drawn as to actual mercury contamination at these sites.

A report detailing the methodologies employed and a summary of the findings is available at DAERA Open Data .

The report found that there were 25 sites which were ‘highly likely’ to have some mercury contamination.  The historical records for those sites suggest that the industrial activity undertaken may have given rise to mercury contamination, according to the DOE Industry Profiles. The NIEA completed a further, more detailed analysis of the 25 sites, using historical maps, aerial photographs and records of current use. The NIEA found that, in all cases, either mercury contamination was unlikely or that the risk of exposure to mercury was low.

 

Frequently Asked Questions

Q.  What is Mercury and how toxic is it?

Mercury is a metal element, highly toxic to humans, that is found both naturally and as an introduced contaminant in the environment.  The risk is determined by the likelihood of exposure, the form of mercury present (some forms are more toxic than others), and the geochemical and ecological factors that influence how mercury moves and changes form in the environment.  Methylmercury is the most toxic and bioavailable mercury compound.  

Q. How likely am I to be exposed to Mercury contamination?

On all land there are background levels of substances, including substances that are naturally present because of the varied geology in Northern Ireland (e.g. Metals) and substances resulting from diffuse human pollution (e.g. Road Traffic pollution).  However, there are greater concentrations in some areas, often associated with historic industrial use and waste disposal, and in a minority of cases these may be sufficient to pose a risk to public health or the environment. 

Human exposure to methylmercury is almost exclusively through consumption of contaminated fish and shellfish.  However, a 2022/23 survey by the Food Standards Agency in Northern Ireland found that only 1.6% of fish sampled had Mercury levels above the EU Regulatory Limit. 

Q.  Will any further action be taken? 

Mercury is just one of a wide range of contaminants that may be present in the soil.  The Contaminated Land Regime, which is set out in Part III of the Waste and Contaminated Land (Northern Ireland) Order 1997 has been enacted but is not yet in force.  Work is currently underway to determine the cost of introducing a Contaminated Land Regime in Northern Ireland to inform a decision on commencement of Part III.

Planning Laws and Regulations require site owners who propose to significantly alter a site or its use (for example to excavate a site that was previously covered by hardstanding) to apply for permission and approval to do so.  As part of the Planning Process, operators may be required to investigate any possible contamination and, if necessary, carry out remediation work to mitigate unacceptable risk to human health or the environment.

Q. Is mercury still being used in Northern Ireland?

The use of mercury has declined significantly in recent decades as it has been replaced by safer and more sustainable elements for a number of its applications. It can be found in some older bulb thermometers, dental amalgams, fluorescent light bulbs, and some electric switches.

Q. How is mercury waste dealt with in Northern Ireland?

The main sources of mercury waste in Northern Ireland are:   

• Fluorescent tubes - the amount of mercury in a tube is very small but large quantities of them are consigned (114.8 tonnes in 2023, the year for which the most recent figures are available);
• Mercury-containing batteries, whilst less common than other types, still get consigned as hazardous waste and the figure for 2023 was 0 tonnes plus 101.4 tonnes of mixed waste batteries (which may include mercury-containing batteries);
• Dental amalgam containing mercury - dental practices are required to have amalgam separators in place to prevent water contamination (7.1 tonnes in 2023);
• Construction and demolition waste containing mercury will arise infrequently and the amount of waste of this type consigned in 2023 was 0 tonnes; and
• Elemental mercury may be disposed of occasionally (0 tonnes in 2023).

Mercury waste in Northern Ireland is collected by authorised registered carriers of waste and transported to regulated facilities authorised to accept such waste.  Most of this waste is either “bulked up” within Northern Ireland for onward transport to GB or transported directly to GB for disposal.

Q. Is mercury used in mining here?

Mine developments will require an Environmental Impact Assessment, Mine Waste Management Plan and Habitats Regulation Assessment to be carried out as part of the consideration of the planning application and environmental authorizations.

Q. What do I do if I find that I live near one of the sites listed in your report?

For contamination to be a risk, there needs to be a pathway between the verified contaminant and a receptor (human or environmental). The 25 sites listed are considered to have a low risk of contamination. They are either highly regulated due to current usage, not accessible or built over with hard standing with no exposed ground.  These factors, and others, account for the revised Low-Risk status of these sites,  

In many cases, the sites listed may have been the subject of Planning Applications owing to redevelopment of the area in question.  As part of this process, developers will have been required to assess and remediate any areas found to be contaminated by material deemed to pose an adverse environmental risk. Similarly, any changes to sites that may be proposed that could pose a risk, would, as stated above, come under Planning Regulations, where conditions may apply to mitigate any contamination risk.