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Possible Control of EU Priority Substances in Danish Waters

7 Assessment of mercury

• 7.1 Definition of the reference state
  • 7.1.1 Introduction
  • 7.1.2 Main uses and pollution sources
  • 7.1.3 Releases to and state of the aquatic environment
  • 7.1.4 Existing legislation/regulation and their impact
  • 7.1.5 Conclusion on the need for further regulation
• 7.2 Possible reduction/elimination measures
  • 7.2.1 Technical measures to reduce/eliminate mercury
  • 7.2.2 Possible synergies with other (priority) substances
• 7.3 Economic Assessment
• 7.4 Conclusion on mercury
• 7.5 References

7.1 Definition of the reference state

7.1.1 Introduction

Mercury (CAS no. 7439-97-6) is an element, and it is therefore not degradable in nature. Besides metallic mercury there are a number of other mercury compounds to consider.

In an environmental context, mercury is a heavy metal with high toxicity. Mercury does not have a high water solubility. In soil mercury forms complexes with organic compounds. This complexing behaviour controls to a large extent the mobility of mercury in soil. Generally, mercury is assumed to have a long retention time in soil. In the environment and in particular in the aquatic environment, mercury is naturally transformed into methyl mercury, which is fat soluble and therefore has the ability of being bio-magnified in the food chain /1/.

7.1.2 Main uses and pollution sources

The dominating use of mercury is as dental amalgams. Intentionally mercury is also used in small quantities in batteries, lamps, thermometers, electrical switches and contacts and miscellaneous monitoring equipment etc. Unintentionally, mercury is consumed with coal, oil products and cement, and as an impurity in most other materials.

In 2001, the consumption of mercury in Denmark was estimated at 2.1-5.0 tonnes /2/. Intentional uses accounted for a consumption of 1.3-1.9 tonnes/year while unintentional uses accounted for about 0.8-3.1 tonnes /2/. The corresponding figures for 1982/83 were 15.1-17 tonnes and 1.1-2.9 tonnes respectively /2/, clearly illustrating that intentional uses have been reduced considerably over the last two decades while unintentional uses remain almost unchanged.

The most important pollution sources of mercury releases to the environment today may briefly be listed as follows:

Air
Air emissions from waste incineration, coal power plants, cement manufacturing, cremation as well as several other sources including scrap handling etc. The total air emissions in 2001 in Denmark were estimated at 0.8-2.0 tonnes yearly of which cremation accounted for 0.17-0.19 tonnes/year /2/.

Water
Discharges from sewage treatment plants and drilling mud (for offshore oil/gas exploration). Total annual water releases in 2001 in Denmark were estimated at 0.05-0.5 tonnes /2/.

Soil
Sewage sludge, and other waste-based residual products used for agricultural purposes and the like, burials and phosphate-based fertilizers etc. Total annual soil releases in 2001 in Denmark were estimated at 0.2-0.3 tonnes /2/.

7.1.3 Releases to and state of the aquatic environment

The most important sources of release of mercury to the aquatic environment comprise:

• Effluents from municipal sewage treatment plants and other discharges of waste and stormwater
• Use of drilling mud
• Atmospheric deposition directly to the aquatic environment.

Effluents from sewage treatment plants as well as discharge of stormwater were estimated to account for 0.03-0.36 tonnes of mercury coming from a number of sources. The most important source is dental clinics as only about 80 % of all clinics are equipped with effective mercury filters. Other significant sources include thermometers and monitoring equipment containing mercury.

As new mercury equipment is banned, the releases in these cases are assumed to originate from old equipment still in use and subject to breakage or other kinds of failure. The amount of actual releases is subject to much uncertainty.

Besides these sources, it must be anticipated that other stocks of mercury may still be present in Denmark, e.g. mercury deposits in siphon traps, and they continue to contribute to the mercury content in wastewater.

Atmospheric deposition from sources within Denmark and abroad adds to the amount of mercury emitted from sewage treatment plants and by stormwater drainage as it is washed away from ground surfaces by rain water.

Drilling liquid and mud are used to undertake and operate drillings for oil and gas in the North Sea. Mercury is a natural contaminant in some of the components (barite, BaSO₄) of the drilling liquid and mud.

Atmospheric deposition, furthermore, is an important direct source of mercury to Danish interior waters. The contribution in 2001 was estimated at 0.08 tonnes yearly.

Table 7-1

Monitoring data for mercury (average values). The values in parenthesis are the 95% percentiles.

Sources: /4/ /5/ /6/ /7/.

*             Average value of 50% percentile values for five Danish freshwater streams /7/.
**          Average value of 50% percentile values for five Danish lakes /8/.

Based on the median values in sewage and in stormwater runoff presented in table 7-1, the total Danish releases of mercury from these sources to the aquatic environment can be estimated at about 55 kg/year and 12 kg/year, respectively.

EQS proposal

The proposed water quality criteria (EQS) for mercury is AA-EQS = 0.05 μg/l (all surface waters) and MAC-EQS = 0.07 μg/l (all surface waters).

7.1.4 Existing legislation/regulation and their impact

Statutory Order no. 627 of 1 July 2003 from the Ministry of the Environment on prohibition of import, sale and export of mercury and mercury-containing products.

The Order prohibits the import, sale and export of products, in which mercury is present in concentrations above 100 ppm in homogeneous materials. A number of exemptions to the ban have been granted, including the use of mercury for certain dental applications, for contacts and switches in certain equipment etc.

Assessment

The Order restricts most intentional uses of mercury, which should eventually result in a strong reduction of emissions to the environment covering air, water as well as soil. However, it must be emphasised, that the Order does not prohibit the use of existing equipment, for which reason existing equipment will continue to cause releases until it is being disposed of for other reasons (wear and tear or outdate technology).

This limitation is important as mercury equipment in thermometers, barometers and other types of monitoring equipment may last for many years if treated carefully, and it will generally first be replaced when it breaks. Mercury equipment in use will thus continue to be a source of release to the aquatic environment for at least the next 20 years.

It may also be noted that mercury amalgam is still allowed for molars where the filling is subject to wear. This limitation means that dental clinics will continue to be a source of release of mercury to wastewater for many years ahead as mercury fillings may well last for about 20 years, and  releases come from drilling in and replacing old fillings as well as from putting in new fillings.

Statutory Order no. 1042 of 17 December.1997 from the Ministry of the Environment on restricting the sale and use for specific purposes of certain hazardous chemical substances and products
The Order restricts the use of mercury in paint, varnish, disinfection and conservation of masonry, wood and textiles, for antifouling and similar purposes on ships and equipment used at sea and for water for industrial purposes.

Assessment
Although the use of mercury is not completely banned by the Order, the Order confirms a development towards an almost complete phase-out of mercury used in such products marketed in Denmark (reference is made to /2/). Today, the consumption of mercury for these purposes seems to be almost insignificant /2/.

Statutory Order no. 1044 of 16 December 1999 from the Ministry of the Environment on certain batteries and accumulators containing dangerous substances

The Order restricts the import and sale of batteries and accumulators with more than 0.0005 % mercury by weight. Button cells may, however, contain up to 2 % mercury by weight, but have to be labelled in case the total content exceeds 25 mg mercury.

Assessment
The Order restricts the import and sale of mercury oxide batteries and accumulators, but still allows mercury to be used in other types of button cell batteries such as alkaline, silver oxide and zinc-air batteries. Thus, the Order has reduced the amount of mercury ending up in waste and being emitted to the air etc. by waste incineration.

Statutory Order no. 998 of 12 October 2004 from the Ministry of Food, Agriculture and Fisheries on feedstuff

The Order limits the maximum content of mercury in feedstuff to between 0.1 and 0.5 mg Hg/kg feedstuff depending on the type of animal in question.

Assessment
This Order reduces the amount of mercury added to agricultural soil and thereby by time also the amount of mercury evaporated to air or leached from soil to fresh water.

Statutory Order no. 298 of 30 April 1997 from the Ministry of the Environment on certain requirements on packaging

The sum of the content of lead, cadmium, mercury and chromium (VI) present in packaging materials to be used in Denmark must not exceed 100 ppm by weight.

Assessment
Limiting the amount of mercury used in packaging materials will also limit the amount directed to waste disposal with products, which, in turn, limits the releases from waste incineration etc.

Statutory Order no. 1008 of 12 October 2004 from the Ministry of the Environment on import and sale of electric and electronic equipment.

Equipment containing lead, cadmium, mercury, chromium (VI), polybrominated biphenyls (PBB) or polybrominated diphenylethers (PBDE) is prohibited from 1 July 2006.

Assessment
The Order implements the EU RoHS Directive in Denmark. The effect of the Order is that the amount of mercury directed to waste incineration or steel recycling with products containing mercury is slowly reduced thereby gradually reducing the amount of mercury which could be emitted to the air or leached from residual products.

Statutory Order no. 489 of 12 June 2003 from the Ministry of the Environment on cosmetic products.

This order prohibits the use of mercury and compounds in cosmetics.

Assessment

This order has no significant impact on the aquatic environment since the consumption of mercury for cosmetics is insignificant.

Other regulation relevant for mercury includes:

• Statutory Order no. 655 of 27 June 2000 on recycling of residual products. and soil in building and construction work.
• Statutory Order no. 162 of 11 March 2003 on waste incineration plants.
• Statutory Order no. 623 of 30 June 2003 on application of waste products for agricultural purposes.

Assessment

The Orders may have a direct impact on the release to the aquatic environment depending on how the rules are actually established.

7.1.5 Conclusion on the need for further regulation

The levels of mercury in treated sewage effluents and in stormwater discharges are already today so low that only very limited dilution of these types of discharges is required to comply with the proposed AA-EQS and MAC-EQS values respectively.

Therefore, there is no need for further progressive reduction in Scenario A while additional measures could be considered in Scenario B to further reduce the lifetime of existing mercury-containing equipment in society, which is typically very long (see proposals for technical measures in Section 7.2). However, the existing statutory orders and other regulation contribute significantly to the required continued progressive reduction of mercury and could be considered sufficient in that respect.

Mercury is also classified as a priority hazardous substance for which emissions, discharges and losses must cease/be phased out within 20 years in Scenario B while Scenario A has no timeframe and only implies an obligation to consider "all technical reduction options" targeting the goal.

The regulations adopted regarding mercury in Denmark have focused on restricting the use of mercury in new products. However, the releases of mercury to the aquatic environment in Denmark today must be assumed primarily to be due to existing products already in use in society. In this context the efforts invested by municipalities in assuring that mercury waste is collected and disposed of in an environmentally safe manner is crucial with respect to releases from dental clinics as well as from other sources.

It is noted that no regulation requires dental clinics to install effective mercury filters and that no regulation prohibits the continued use of mercury products until the moment when they break where the content of mercury in many cases at least to some degree will end up with wastewater.

The gradual implementation of the proposed technical measures aimed at ceasing/phasing out mercury releases and discharges will at the same time fulfil the progressive reduction obligations in Scenario B.

In the case of mercury, the proposed options for cessation/phasing out are also relevant for Scenario A, and, apart from the timeframe, the difference between the two scenarios lies mainly in the extent to which collection of mercury-containing equipment in the Danish society is implemented.

7.2 Possible reduction/elimination measures

7.2.1 Technical measures to reduce/eliminate mercury

The following options for further reduction of releases of mercury to the aquatic environment may be considered:

• Use of mercury filters for dental clinics made mandatory.
  
  Approximately 20 % of the clinics are not equipped with mercury filters. Based on data given in /2/ it can be estimated that the installation of mercury filters at all clinics would eliminate about 80 % of the present releases from dental clinics or ~40-200 kg mercury each year.
• National collection, replacement or labelling of mercury equipment in use and other sources of mercury to wastewater.
  
  This action deals with a campaign to virtually detoxify Danish society in terms of mercury by identifying mercury equipment still in use in households, institutions, companies etc. and replacing it if feasible and otherwise by labelling it with instructions for environmentally safe disposal.
  
  Such an exercise was carried out in Sweden in the 1990's. The exercise identified and removed mercury deposits in schools and siphon traps. A rough estimate indicates that the release of 40 to 90 kg mercury annually and perhaps even more could then be avoided.
• Substitution of materials used in drilling liquid and mud that contains mercury. It is likely that other materials than barite can be used.
  
• Releases of mercury with stormwater may be reduced by op to 10 kg mercury annually by precipitation/cleaning arrangements.

7.2.2 Possible synergies with other (priority) substances

Measures against suspended matter/pollutants in stormwater runoff, as described in Chapter 13, will also result in some (limited) reduction of mercury releases into the aquatic environment but it will mainly reduce the releases of most of the other PS/PHS.

7.3 Economic Assessment

It has been established above that the proposed AA-EQS and MAC-EQS values are already met today. In the technical assessment it is, however, concluded that since mercury is a priority hazardous substance, emissions, discharges and losses to the aquatic environment must cease/be phased out. In the WFD (Scenario A) there is no deadline, but in the proposed Daughter Directive (Scenario B) the deadline is 2025. To calculate the difference in cost, it is assumed that to meet the Scenario A requirement, the national deadline is 2035. The obligation to consider all technical options in Scenario A for the priority substances will be met by either of these deadlines.

The economic assessment looks at the two most realistic technical measures, i.e.

• mandatory use of mercury filters in dental clinics;
• national collection/replacement or labelling of mercury equipment in use.

With regard to filters in dental clinics, it was assessed in 2003 that approximately 20 % of the clinics did not have such mercury filters /2/. There is no data available to support this assumption, which is based on the number of municipalities in which installation of filters is not mandatory. The number may already have decreased since then, and the 20 % estimate is therefore probably a high-end estimate. The Danish Dental Association (Dansk Tandlægeforening) estimates that out of the approx. 5,000 dentists in the work force, 4,700 practice dentistry and are potential users of mercury filters /8/. If it is assumed that 20 % of these do not have a filter today, there could be 940 filters more in Denmark.

The price of the filters depends on the specific technological solution chosen, but since 80 % or more of the dentists already have filters, the market is well established. The most common types of filters are mechanical installations that do not require any electricity or incur any other running costs. These types of filters are produced by two manufacturers, one in Denmark and one in Sweden. Together they cover about 80 % of the Danish market. The cost is just under DKK 1,800 per filter, which needs to be changed one to four times a year /9/. This is equivalent to the financial cost per filter since it is the price without VAT. The welfare-economic cost per filter is just under DKK 2,400 when tax distortion and net tax factor^[15] are taken into account. As such there is no investment cost  since the lifetime is less than a year. For the purpose of this economic estimation, the average lifetime of filters is assumed to be 10 months,

To calculate the difference in cost between Scenarios A and B, it is assumed that the use of filters is gradually increased until all dentists have filters. For scenario B, the deadline is 2025, while for scenario A the deadline is set to 2035 to illustrate the possibility of adopting a more lenient strategy that still complies with the WFD. The compulsory use of filters is not assumed to take effect before 2012 according to the definition of the scenarios in Chapter 3.3. The two different time horizons are shown in the figure below, by the resulting number of new filters per year. It should be noted that the lifetime of a filter is assumed to be less than one year and that the 940 dentists without filters today will need a total of 1,128 filters per year.

Figure 7-1 Scenarios A/C and B for instalment rate of mercury filters

The two scenarios imply a gradual build-up to a yearly financial cost for the dentists of almost DKK 2 million DKK when fully implemented. The welfare-economic cost representing the cost to society would be about 2.7 million DKK/year when fully implemented.

The total financial and welfare-economic costs can also be calculated as the discounted net present value (NPV), which is the expression of the cost today of expenses over a period of time. This is done in order to be able to compare the difference in time horizon for the two scenarios. The discount rate used is 3% for the welfare-economic cost and 6 % for the financial cost. The results of the estimation can be seen in the tables below.  The total extra cost of Scenario B over Scenario A is estimated to be approximately DKK 3 million in terms of financial cost and DKK 8 million in terms of welfare-economic cost. It should be emphasized that the figures are tentative given the gaps in data on the number of filters needed. The financial unit cost of the filters is, however, well known since the filters are already on the market being manufactured by several producers.

Table 7-2 Financial and welfare-economic cost, Mercury filters at dental clinics

*             A discount rate of 3 % is used. If 6 % is used. The results for Scenarios A and B
               are DKK 10 and 14 million respectively.

It is also attempted to estimate the cost of a national collection/replacement or labelling of mercury equipment in use. This will be a very rough estimate based on Swedish experiences.

There is no doubt that a significant quantity of mercury is present in Denmark. The stocks include mercury in electrical and technical equipment and instruments in use in society (e.g. in thermometers, thermostats, blood pressure gauges, level switches). To this may be added intentional stocks in educational institutions and private companies.

The stock of mercury will slowly be disposed as mercury-containing instruments or equipment are outdated or broken. The actual lifetime is difficult to predict as the mercury-containing instruments are simple in construction (e.g. mercury contained in a closed glass tube) and in principle may last for decades. To the extent that mercury-containing instruments are not collected and disposed of in a controlled manner, there is a risk that the mercury will eventually be released into wastewater, the air etc. when the instruments are broken.

While no significant organised effort has been made in Denmark to collect waste mercury in instruments, huge efforts were made in Sweden in the years from 1994 to 1999. The effort was directed towards:

• Intentional stocks of mercury in educational and training institutions and private companies;
• Mercury contained in electrical/technical equipment and instruments in use in Sweden;
• Residues of mercury in e.g. siphon traps in schools and training institu-tions where mercury was used for educational or scientific purposes.

In the years from 1995 to 1998, the Swedish EPA used approximately SEK 15 million partly as contributions (SEK 10 million) to local authorities (counties and municipalities) undertaking collection and labelling efforts, and partly to finance projects directly carried out by the Swedish EPA (collection in schools inclusive of siphon traps - collection directly from major industries) /10/. By this effort about 9-11 tonnes of mercury was identified while about 6-7 tonnes were collected /10/.

It was roughly estimated that the collection/labelling effort undertaken by the local authorities reached approximately 1/3 of the Swedish population /12/, while the coverage rate regarding other projects was assumed to be higher.

Apart from the direct contribution from the Swedish EPA, local authorities made an effort to carry out the projects. In the case of the project collecting mercury from schools and training institutions, the institutions financed at least 1/4 of the total project costs /11/.

The project activities carried out generally had the following elements:

• Training of personnel to identify and handle mercury instruments;
• Preparation and publishing of information material, labels etc.;
• Visits to private companies, institutions and households and collection, labelling, and disposal of equipment and instruments;
• Administration.

Based on the Swedish experience presented above it is estimated that the total costs of an almost complete collection of mercury equipment and instruments in Denmark are likely to be in the range of DKK 40-50 million. This investment would be a one-time investment with no additional administrative costs or running costs in the years following the campaign. The outcome of the investment would eliminate the annual release of mercury into wastewater (estimated to be 40-90 kg /3/) in the years following the investment.

For the purpose of assigning the cost in the scenarios to the Daughter Directive implementation in Denmark, it is assumed that a national campaign similar to the Swedish one is conducted in Denmark. This would entail national collection, replacement or labelling of mercury equipment in use and similar initiatives. The campaign in Sweden did produce quite rapid results and the campaign could therefore be postponed to for instance five years prior to the deadlines in the two scenarios. It is therefore assumed that the campaign is initiated in either 2020 (Scenario B) or 2030 (Scenario A). The financial cost of such a campaign is set to DKK 40-50 million as a one-time investment and to DKK 100,000 annually in running costs, mainly being administration.^[16] This corresponds to a welfare-economic cost to society of DKK 55-68.5 million in investment and DKK 137,000 DKK/year in running costs.

As above, the total financial and welfare-economic cost can be calculated as the discounted net present value (NPV). The results of the estimation can be seen in the table below.

Table 7-3 Financial and welfare economic cost, National collection

*             A discount rate of 3 % is used. If 6 % is used the results for Scenarios A and B
               are DKK 13-16 million and DKK 23-29 million respectively.

The financial cost of Scenario B would be DKK 17-21 million compared to Scenario A estimated at DKK 9-12 million. The corresponding welfare-economic cost is DKK 26-33 million in Scenario A and DKK 35-44 million in Scenario B. Again, it must be emphasized that these are only very rough estimates.

7.4 Conclusion on mercury

According to the monitoring data available, the concentrations of mercury in various discharges as well as in surface waters do not pose a problem in relation to compliance with the proposed EQS values. There is no need for further progressive reduction in Scenario A. For the progressive reduction of discharges, emission and losses in Scenario B, additional measures are needed to shorten the present very long lifetime of existing mercury-containing equipment in society. However, the existing regulation already contributes to some extent  to the progressive reduction beyond the EQS.

Mercury is classified as a priority hazardous substance for which emissions, discharges and losses eventually (Scenario A) or within 20 years (Scenario B) must cease/be phased out. The gradual implementation of the proposed technical measures aimed at ceasing emissions and discharges will also cover the progressive reduction obligation in Scenario B.

Mercury is one of the few substances included in this study for which the total load on surface waters from sewage effluent is larger than that from discharge of stormwater. The two main sources affecting the mercury level in urban sewage are dental clinics and the variety of mercury-containing equipment (e.g. thermometers), currently in use in Denmark.

The most realistic technical measures reducing the level of mercury in sewage target the mentioned two sources. Mandatory use of mercury filters at dental clinics and national collection/replacement or labelling of mercury equipment in use. A cost assessment was made for these two measures for Scenarios A and B.

Today, around 80 % of all dentists in Denmark use mercury filters though the data supporting the figure are uncertain. If the remaining 20 % also used filters, it is assessed that around 40-200 kg of mercury could be collected each year.

The result of the cost estimation of such a policy, adopted in 2025 (Scenario B) instead of 2035 (Scenario A), is a net present value of approximately DKK 3 million in financial costs (for the dentists). The cost of Scenario A is DKK 7 million and the cost of Scenario B is DKK 10 million. In welfare-economic terms, the difference is DKK 8 million as the costs related to Scenarios A and B are DKK 17 and DKK 25 million respectively..

A rough estimate of the cost of a campaign to enhance national collection of mercury equipment in use is also given. Based on Swedish experiences, the extra economic cost of such a campaign initiated in 2020 (Scenario B) instead of 2030 (Scenario A) is estimated to approximately DKK 8-9 million in financial cost as the cost of the two Scenarios are 9-12 and 17-21 million DKK, respectively. The welfare-economic estimates are DKK 26-33 and DKK 35-44 million for Scenarios B and A respectively, and the difference is thus DKK 7-9 million. For this amount, an estimated annual release of 40-90 kg mercury (and perhaps more) could be eliminated.

7.5 References

/1/ UNEP 2002. Global Mercury Assessment. UNEP Chemicals. Geneva, Switzerland.

/2/ Massestrømsanalyse for kviksølv 2001. Miljøprojekt 808, 2003. Udført for Miljøstyrelsen af S. Skårup, C.L. Christensen, J. Maag og S. H. Jensen, COWI A/S.

/3/ GEUS (2004). Grundvandsovervågningen 2003.

/4/ Miljøstyrelsen (2004). Punktkilder 2003.

/5/ Miljøstyrelsen (1997). Miljøfremmede stoffer i overfladeafstrømning fra   befæstede arealer. Miljøprojekt nr. 355.

/6/  Bøgestrand, J. (red.) (2002): Vandløb 2001. NOVA 2003. Danmarks       Miljøundersøgelser. - Faglig rapport fra DMU 422: 39 s. (elektronisk).

/7/  DMU (2004). Søer 2003. Faglig rapport fra DMU nr. 516 (elektronisk).

/8/ Based on personal communication with Danish Dental Association   (Dansk Tandlægeforening; Claus Jørgensen) December 2005

/9/ Based on personal communication with Rectus Aps (Ole Gunderson) and        Den-Tec Aps (Claus Møller), December 2005

/10/       Naturvårdsverket 2005. Kviksilver. Information available on the homepage  http://www.naturvardsverket.se/dokument/teknik/kemikali/hg.html   (opdated 2005-01-24 by Petra Hagström).

/11/       Naturvårdsverket 1999. Skolprojekt Mercurius 98. Naturvårdsverkets   projekt för insamling av och information om kvicksilver (Hg) på skoler och         gymnasier. Slutrapport. Mars 1999.

/12/       Rein, Kristina von, 1998. Mer pengar til kvicksilverinsamling. Pressmeddelande. Naturvårdsverket 1998-02-18, Stockholm.

Footnotes

^[15] See the methodology chapter 3.1.

^[16] COWI expert assessment based on proposal for a similar, small-scale municipal campaign in 2005.

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