Mercury

Mercury is found in the environment in the metallic form and in various inorganic and organic complexes. The sources are both natural and anthropogenic.

The natural global bio-geochemical cycling of mercury is characterized by degassing of the element from soils and surface waters, atmospheric transport, deposition of mercury back to land and surface water, sorption onto soil or sediment particles and revolatilization from land and surface water. This emission, deposition and revolatilization creates difficulties in tracing the movement of mercury to its sources. Hg can be released into the air through weathering of rock containing Hg ore, or through human activities, such as incineration and burning of fossil fuels. The life-time of mercury in the atmosphere varies between 0.8 – 2 years (Gworek, Bemowska-Kałabun, Kijeń, & Wrzosek-Jakubowska, 2016). Hg released in atmosphere is a significant indirect risk to human health, since it is the main way in which it travels around the globe and gets deposited in water bodies and on land. For this reason, mercury is global pollutant. Once in the environment, interconversion between the different forms of Hg can occur. Particulate-bound Hg can be converted to insoluble Hg sulfide and can be precipitated or bioconverted into more volatile or soluble forms that re-enter the atmosphere or are bioaccumulated in aquatic and terrestrial food chains ( National Research Council, Committee on the Toxicological Effects of Methylmercury, Board on Environmental Studies and Toxicology, 2000).

Water contamination can occur from run-off water, contaminated by either natural or anthropogenic sources or from air deposition. The biggest risk to human health is mercury in aquatic environments, because it stays there for a very long time (the lifetime of mercury in the upper oceans is 20 – 30 years and can be hundreds of years in the deep ocean) and it gets converted by microorganisms to the very toxic organic form, methylmercury (Gworek, Bemowska-Kałabun, Kijeń, & Wrzosek-Jakubowska, 2016).

Methylmercury bioaccumulates inside biological organisms, since its excretion is slower than its uptake and biomagnifies as predatory animals consume pray that already accumulated mercury (Hanna, Solomon, Poste, Buck, & Chapman, 2015), (Lavoie, Jardine, Chumchal, Kidd, & Campbell, 2013). The concentration of mercury in fish species is influenced by the position of the species in the food web (e.g. it is higher in predators, such as swordfish and lower in low-end species, such as sardines), but also on the region. In Europe, the highest concentrations are found in the Mediterranean Sea (Miklavčič Višnjevec, Kocman, & Horvat, Human mercury exposure and effects in Europe), which may be due to favourable conditions for the generation of methylmercury ( European Environment Agency , 2018), (Cossa & Coquery, 2005).

Mercury deposited on land also enters the food-chain, as for example, in the case of rice grown on contaminated soil (Rothenberg, Windham-Myers, & Creswell, 2014). Because rice is grown in water, methylmercury may be formed and absorbed in the grain (Tanner, et al.).

Mercury is a naturally occurring metal in the earth’s crust. It is ubiquitous in the global environment and occurs from both natural and anthropogenic sources. It exists in three main forms, which are not equally harmful: elemental (metallic), inorganic, and organic.

Elemental mercury (Hg, CAS number: 7439-97-6, EC number: 231-106-7) is a heavy, shiny, silver-white liquid. It is the only metal that is liquid at room temperature and for this reason, it is also known as “quicksilver” ( European Environment Agency , 2018). It is obtained primarily from the refining of mercuric sulfide in cinnabar ore. If it is not contained, mercury vaporizes easily at room temperature to an invisible, odorless toxic gas referred to as elemental mercury vapor (Agency for Toxic Substances and Disease Registry (ATSDR), U.S. Department of Health and Human Services, Public Health Service, 1999). Elemental mercury is commonly used in human activities. It has been used in electrical equipment (e.g., thermostats and switches), electrical lamps, medical and laboratory equipment (e.g. thermometers, sphygmomanometers, barometers) and dental amalgams. It has also been used industrially in the production of chlorine gas and caustic soda. The anthropogenic use of mercury results into the release of large amounts into the atmosphere and can travel long distances, presenting a significant risk to human health and environment. Elemental mercury can eventually react in the atmosphere to form inorganic mercury, which gets deposited in water bodies and on land.

Inorganic mercury compounds are formed when mercury combines with other elements such as chlorine, sulfur or oxygen. Inorganic mercury compounds exist in two oxidative states, mercurous (+1) and mercuric (+2). Mercury salts are highly toxic and corrosive. Inorganic mercury compounds, such as mercuric oxide, are used in the production of batteries, polyvinylchloride, and pigments (Agency for Toxic Substances and Disease Registry (ATSDR), U.S. Department of Health and Human Services, Public Health Service, 1999).

Organic mercury compounds are formed when inorganic mercury is methylated or combines with organic agents. Different forms of organic mercury have different properties and toxicities. The most important organic form of mercury, with regards to human exposure and adverse effects on health, is methylmercury. Methylmercury is formed by anaerobic methylation of inorganic mercury by microorganisms in sediments. In waterbodies, methylmercury accumulates in aquatic organisms and biomagnifies up the food chain. The primary source of human exposure to mercury is through the consumption of fish and shellfish containing methylmercury.

Other organic mercury compounds have been used in fungicides, antiseptics and disinfectants, but have mostly been discontinued. Ethylmercury (thiomersal), is used in very small amounts in vaccines (as preservative) and pharmaceuticals. Ethylmercury is broken down by the body quickly and does not accumulate. The World Health Organization monitors and evaluates scientific evidence on the use of thiomersal as a vaccine preservative, and consistently concludes that there is no evidence to date that the amount of thiomersal used in vaccines poses a health risk (World Health Organization, 2012). However, concerns are still raised in the scientific community regarding the safety of the use of ethylmercury in vaccines and the lack of precise regulations at EU level (Ruggieri, Majorani, Domanico, & Alimonti, 2017).

Mercury ranks 3^rd and methylmercury 116^th (out of a total of 275 substances) on the “ATSDR 2017 Substance Priority List” of the US Agency for Toxic Substances and Disease Registry (US Agency for Toxic Substances and Disease Registry (ATSDR), 2017).

According to the harmonized classification and labelling (ATP01) approved by the European Union, elemental mercury is a hazardous substance, which is fatal if inhaled (Acute Tox.2, “H330”), may damage the unborn child (Repr. 1B, “H360”), causes damage to organs through prolonged or repeated exposure (STOT RE 1, “H372” – Central Nervous System) and is very toxic to aquatic life (Aquatic Acute 1, “H400”) and with long-lasting effects (Aquatic Chronic 1, “H410”) (European Chemicals Agency, ECHA, n.d.).

Based on a systematic review of the literature, Grandjean and Landrigan suggested in 2006 that mercury and methylmercury are suspected neurotoxicants. The same authors updated their review of the existing data and noted that methylmercury is a developmental neurotoxicant, at much lower exposures than the concentrations that affect adult brain function. Genetic polymorphisms increase the vulnerability of the developing brain (Grandjean & Landrigan, Developmental neurotoxicity of industrial chemicals., 2006), (Grandjean & Landrigan, Neurobehavioural effects of developmental toxicity, 2014).

According to the International Agency for Research on Cancer (IARC), methylmercury compounds are possibly carcinogenic to humans (Group 2B). Metallic mercury and inorganic mercury compounds are classified in Group 3 (not classifiable as to their carcinogenicity to humans) (International Agency for Research on Cancer, World Health Organization, 1993). The Commission for the Investigation of Health Hazards of Chemical Compounds of the Germany Research Foundation (DFG) placed organic and inorganic mercury compounds in Category 3B (substances that cause concern that they could be carcinogenic for man but cannot be assessed conclusively because of lack of data) (Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Germany Research Foundation, 2013).

Mercury and mercury compounds are on the Proposition 65 list (Chemicals known to the State of California to Cause Cancer or Reproductive Toxicity) because they can cause birth defects or other reproductive harm. Methylmercury compounds are also on the Proposition 65 list because they can cause cancer (The Office of Environmental Health Hazard Assessment (OEHHA), State of California, USA).

According to the IRIS database, elemental mercury is not classifiable as to human carcinogenicity (Cat D) and methylmercury is a possible human carcinogen, for which human carcinogenicity data are inadequate (Cat C).

The Japanese GHS Classification classifies mercury as causing damage to organs through prolonged or repeated exposure (STOT RE 1 – nervous system, cardiovascular system, blood, liver, gingiva), as a reproductive toxicant (Category 1A), as Category 2 for mutagenicity, and does not classify it in terms of carcinogenicity.

1.1.1.1 Knowledge gaps

The toxic effects of methylmercury at the levels of exposure found in the general population due to fish consumption are not fully understood. New developments in epidemiological studies have indicated that n-3 long-chain polyunsaturated fatty acids in fish may counteract negative effects from methylmercury exposure that could impact the safety of the tolerable weekly intake (TWI) established by EFSA (Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment, 2018). The risk associated with dental amalgams is not fully understood (Bengtsson & Lars, 2017), (Bentung Lygre , Haug , Skjærven , & Björkman, 2016). Exposure to mercury has been linked with Alzheimer’s disease, but further research is required (Mutter, Curth, Naumann, Deth, & Walach, 2010). Mercury has possible endocrine disruptive effects, which have raised public concern, but further investigation is required (Rana, 2014), (Iavicoli, Fontana , & Bergamaschi, 2009), (Rahman, Kumarathasan, & Gomes, 2016).

Additional prospective studies, which will include speciation analysis of the different forms of mercury, are needed for the investigation of the potential links of mercury to the metabolic syndrome, immunotoxicity and cardiovascular effects (Roy, Tremblay, & Ayotte, 2017), (Maqbool, Niaz, Ismail Hassan, Khan, & Abdollahi, 2017), (Gardner & Nyland, 2016), (Genchi, Sinicropi, Carocci, Lauria, & Catalano, 2017). A recent review and meta-analysis of Environmental toxic metal contaminants and risk of cardiovascular disease was published by Chowdhury et al. (2018) found that mercury was not associated with any cardiovascular outcomes (Chowdhury, et al., 2018). In an accompanying editorial, the difficulties of taking into account fish consumption in the analyses were reported and the authors suggested that the previous findings had to be taken with caution (Tellez-Plaza, Guallar, & Navas-Acien, 2018).

Please see the link to the scoping document on Mercury at the top of the page for this information.

Humans face exposure risks to all forms of mercury from numerous sources and routes of exposure. Human exposure to mercury may occur through the following routes:

• Dermal: Mercury is a suspected skin sensitizer and allergen, but it is not significantly absorbed through the skin and so this is not a significant route.
• Inhalation: Inhalation of mercury vapours may occur in industrial processes, but for the general population, this route is not a significant route.
• Oral: This is a significant route of exposure for the general population. Human exposure occurs mainly through the consumption of contaminated fish and shellfish, with methylmercury presenting the most significant risk. Elemental mercury from ingestion is poorly absorbed with a bioavailability of less than 0.01% (Park & Zheng, 2012 ).
• Trans-placenta: This is a significant route of human exposure, since mercury crosses the placenta and results in foetal exposure.

Sources and routes of exposure vary geographically in a significant way and this complicates the development of strategies able to protect populations in specific locations. In developing nations, exposure may result from occupational activities such as artisanal and small-scale mining, religious and cultural practices and diet based almost exclusively on fish consumption. The most significant source of human exposure to mercury in Europe is through the diet. Populations consuming a lot of fish, such as in coastal regions – the Mediterranean region of Europe or Arctic regions – are the most vulnerable. Exposure levels are influenced also by the type of fish consumed (eating predatory fish entails a higher risk). On the other hand, fish consumption provides omega-3 fatty acids, which have protective health effects. To balance the health benefits provided by seafood consumption with the negative effects from possible exposure to mercury, the European and many National Food Safety Authorities developed dietary advice. A recent study by Kirk et al. in Denmark, showed that providing dietary advice to pregnant women to consume preferably non-predatory fish, was effective in lowering their exposure to methylmercury as determined by mercury analysis in hair (Kirk, Jørgensen, Nielsen, & Grandjean, 2017), ( European Environment Agency , 2018). Rise-based diets are an increasing risk factor (World Health Organization (WHO), 2010).

Mercury exposure from non-dietary sources is small for the general population. Inhaled mercury from ambient air is very efficiently absorbed, but for the general population this is not a significant risk since the levels of mercury in outdoor air are usually very low. Mercury amalgam used in dental fillings and broken mercury-containing products (e.g. thermometers) may also lead to minor exposures. Exposure to thimerosal, an ethylmercury-sulfidobenzoate used as preservative in several human vaccines, is now very limited in Europe. The European Centre for Disease Prevention and Control and the World Health Organization concluded that thimerosal is not harmful, based on assessment of the current scientific evidence ( European Environment Agency , 2018).

Local communities living near mercury-polluted sites, such as the Almaden mining area in Spain, may face increased risk of becoming exposed. One example is the former mining town of Idrija, Slovenia, where locally produced foodstuffs (fish, mushrooms, chicory) have been found to contain increased mercury concentrations (Miklavčič, Mazej, Jaćimović, Dizdareviǒ, & Horvat, 2013).

Human exposure to mercury begins at the time of conception and continuous beyond the critical time of gestation throughout infancy, childhood and into adulthood. Prenatal exposures of the foetus relate to the sources of the mother’s exposure, with the diet being very important. Another source of exposure may be Hg vapours released from dental amalgams, which contain up to 50% elemental mercury (Bentung Lygre , Haug , Skjærven , & Björkman, 2016).

During pregnancy, maternal exposure to mercury can damage the neurodevelopment of the foetus, with noticeable effects on behaviour, cognition, motor skills and the immune and reproduction systems later in life (Rice & Barone Jr., 2000). Infants are at higher risk than older children and adults. This may relate to their highly efficient gastrointestinal absorption, physiological immaturity of homeostasis and detoxification mechanisms. The most significant pathway of infant exposure is breast milk consumption, but use of specific mercury-containing products, such as teething powders, soaps, may contribute (World Health Organization, 2010). Both organic and inorganic mercury occur in breast milk, but the physiology of the mammary gland causes preferential enrichment of inorganic mercury. Inorganic mercury rapidly enters the plasma and therefore, the breast milk. Methylmercury partitions preferentially to erythrocytes (Ask Björnberg, Vahter, & Petersson-Grawé, 2003).

Inorganic mercury salts are not lipid soluble; hence, they do not readily cross the blood-brain barrier or blood-placenta barrier (Dart & Sulliva, 2004). Inhalation is a major exposure route of elemental mercury in the form of mercury vapor. Inhaled mercury vapor is readily absorbed, at a rate of approximately 80%, in the lungs, and quickly diffused into the blood and distributed into all of the organs of the body Elemental mercury can cross the blood-brain barrier and blood-placenta barrier as well as the lipid bilayers of cellular and intracellular organellar membranes (Park & Zheng, 2012 ). Elemental mercury is poorly absorbed in the gastrointestinal tract (less than 0.01%) (Von Burg, 1995).

 Establishing a quantitative dose-response relationship is particularly challenging for mercury because it can exist in different forms (elemental mercury, mono- and divalent mercury and organic mercury), each having different kinetic properties (Ha, et al., 2017).

Mercury concentrations can be measured in different human matrices: hair, urine, blood, nails, breast milk, cord tissues, cord blood and the placenta. The choice of matrix depends on the time of sampling after exposure, if chronic or acute exposure will be investigated and the type of mercury compounds, which will be assessed (Miklavčič Višnjevec, Kocman, & Horvat, Human mercury exposure and effects in Europe, 2014). Other “unconventional” matrices may be used, depending on the study objectives and design.

• Hair: is a non-invasive matrix that is easy to sample and analyze and is very useful for monitoring long-term methylmercury exposure in the general population. Methylmercury analysis in other matrices requires complicated, time-consuming and expensive methods and so has very limited use in large human biomonitoring surveys. Both inorganic and organic forms of mercury bind to the hair structure, but there is a strong preference for MeHg. Methylmercury is incorporated into the follicle during hair formation. Once transported by the blood into follicular cells, it binds to cysteines of keratin proteins and it constitutes approximately 80% or more of the total mercury in hair for fish-consuming populations ( National Research Council, Committee on the Toxicological Effects of Methylmercury, Board on Environmental Studies and Toxicology, 2000). The concentration of total mercury in scalp hair is proportional to the simultaneous concentration in blood, but in the case of exposure to methylmercury, it is ~250 times higher. Hair-to-blood concentration ratios of methylmercury can be highly variable among individuals. The error in blood Hg estimated from hair Hg using the WHO recommended hair-to-blood ratio of 250 was evaluated by Liberda et al. (2014) and it ranged -25% to +24%, with systematic underestimation for females and overestimation for males (Liberda, et al., 2014). Assuming a growth rate of 1.1 cm/month for scalp hair, an indication of temporal exposure is provided, but the uncertainty associated with this assumption must be considered (World Health Organization (WHO), 2010), (Sakamoto, et al., 2004). Hair mercury concentrations can be affected by several factors, including hair colour and variable growth rates, which can limit its usefulness as an indicator of Hg concentrations in the body (Miklavčič Višnjevec, Kocman, & Horvat, Human mercury exposure and effects in Europe, 2014). Quality assurance and control systems are required for accurate results (e.g. possible external contamination) (Grandjean, Jørgensen, & Weihe, Validity of mercury exposure biomarkers, 2002). QA/QC measures were already defined and tested in DEMOCOPHES with good results. These measures include sampling SOPs, training (including a video for hair sampling (ISCIII)) and ICI/EQUAS for mercury analysis in hair (Esteban, et al., 2015).
• Recently, the World Health Organization published standard operating procedures for the assessment of mercury in hair, cord blood and urine, with emphasis on quality control as a prerequisite for getting reliable results. This report also provides information on alternative methods that can be used for analysis of mercury (World Health Organization, 2018).

• Blood: in children and adults, can be used to assess short-term (~1 week) exposure. It involves invasive sampling and storage / transportation require attention. Speciation analysis is preferable for a comprehensive assessment of the type and magnitude of the exposure.
• Urine: The predominant form in urine is inorganic mercury and so total urinary mercury reflects the internal dose of the inorganic form. Urine is a suitable biomarker of long-term low-exposure to both inorganic and elemental Hg, because it contains Hg which accumulated in the renal tissue (i.e., kidney is the target organ) during a chronic exposure (Ruggieri, Majorani, Domanico, & Alimonti, 2017), (Miklavčič Višnjevec, Kocman, & Horvat, Human mercury exposure and effects in Europe, 2014), (INRS).
• Cord-blood: is the most desirable biomarker for estimating pre-natal exposure. Total Hg in cord blood estimates foetal exposure over a longer period than that provided by maternal blood and provides a better indication of the risk for developmental neurotoxicity. However, it does not provide information on exposure variability during gestation and its storage and transportation are more complicated (Ruggieri, Majorani, Domanico, & Alimonti, 2017).
• Umbilical cord tissue: is a useful matrix for assessment of foetal middle-term exposure, sampling is simple and it is non-invasive. Total Hg represents exposure during the third trimester, but doesn’t provide information on sensitive short-term variation. A dry weight-based total Hg concentration is more accurate, but more labor-intensive (Ruggieri, Majorani, Domanico, & Alimonti, 2017).
• Nails: Maternal mercury concentrations in nails at parturition have also been shown to have a strong correlation with mercury concentration in cord blood and can be used as biomarker (Ha, et al., 2017). Generally, this matrix assesses long-term (chronic) exposure. Sampling is simple, non-invasive and easy to preserve. Quality assurance/quality control systems are required for accurate results. Fingernails are sometimes contaminated (Ruggieri, Majorani, Domanico, & Alimonti, 2017).
• Breast milk: is useful for investigation of long-term exposure. Total Hg is suitable for estimating maternal exposure and for predicting the potential exposure for breast-feeding in infants (Ruggieri, Majorani, Domanico, & Alimonti, 2017).
• Cerebrospinal fluid / Brain: The use of such “unconventional” matrices, in combination with speciation analysis, can be useful for the investigation of the neurotoxic effects on the target system / organs. So far, there have been only few applications of this approach, due to limited access to cerebrospinal fluid and brain samples, analytical challenges caused by matrix interferences, low concentrations and limited stability of many trace element species of interest. Modern, powerful analytical techniques, which provide advanced validity and chemical information are necessary (Michalke, Willkommen, Drobyshev, & Solovyev, 2018), (Michalke, Halbach, & Nischwitz, JEM Spotlight: Metal speciation related to neurotoxicity in humans, 2009).

The determination of mercury in biological specimens requires sensitive analytical methods, performed under good quality control conditions. The DEMOCOPHES experience proved that is possible to study the exposure to mercury in a harmonized way if common Standard Operating Procedures (SOPs) are applied and under a Quality Assurance / Quality Control (QA/QC) scheme (Esteban, et al., 2015). Various methods exist that differ in sample preparation technique and/or the detections system. Determination of total Hg concentration can be done by (1) acid digestion followed by cold vapour atomic absorption technique (CV AAS), cold vapour atomic fluorescence (CV AFS) and/or ICP MS detection; (2) thermal combustion of a sample, gold amalgamation and AAS detection.

Speciation of mercury requires complex and lengthily analytical procedures and expensive reagents and equipment, which are not routinely available in analytical laboratories. Speciation analysis is necessary to differentiate between inorganic/elemental and methyl mercury exposure. It may be possible to obtain information without the need of speciation, by using a combination of different matrices, the choice of which should depend on the type of the hypothesized exposure.

1.1.1.1 Need for new approaches

Despite the plethora of data on exposure to mercury, the results are fragmented because different studies use different approaches, which limit their usefulness. It is important to harmonize the approaches used to investigate different study populations. The DEMO/COPHES (Esteban, et al., 2015) and the pilot UNEP/WHO project on mercury biomonitoring (World Health Organization, 2018) have laid the basis for harmonization of exposure biomarkers, which needs to be further advanced (Ha, et al., 2017). HBM4EU provides a golden opportunity to improve on this basis, to test it in additional countries and to use to for answering specific policy questions.

The selection of best-suited matrices and biomarkers of exposure is crucial. For example, if hypotheses on the effects of MeHg exposure on child development will be tested, the best suited matrices and biomarkers of foetal exposure to MeHg should be selected.

The development of simple, robust and cost- effective methods for measuring total and organic mercury simultaneously is very important.

Markers of susceptibility need to be validated (Karagas, et al., 2012). These are important for understanding the human health effects of low-level MeHg exposure as a basis for future research efforts, risk assessment, and exposure remediation policies worldwide (Karagas, et al., 2012). Hg speciation in biological matrices, particularly blood, would provide characterization of species-specific exposure at levels relevant for European population. Individuals’ inherited factors seem to play a role in determining toxic effects of environmental contaminants, including those of mercury. In recent years interest in gene-environment interaction has grown substantially, because of the progress in laboratory techniques, improved understanding of genetics and realization of complex mechanisms between genetics and environment (Basu, Goodrich, & Head, Ecogenetics of mercury: from genetic polymorphisms and epigenetics to risk assessment and decision-making, 2014 ), (Andreoli & Sprovieri, 2017). Identification and validation of novel biomarkers of susceptibility is therefore an important part in investigation of exposure-health relationships.

Research on the elimination and enhancement of excretion of mercury is also needed and is important for risk management options.

Following on the Advisory Board’s advice to strengthen the science-policy interface, HBM4EU developed a strategic and systematic approach to outreach and align science and policy. A legislative mapping exercise was done by RPA Consultants, providing relevant public policy processes that may benefit from the knowledge generated under HBM4EU. The documents are available for consultation here, with the tables presented here.

The European Commission adopted in 2005 the Community Strategy Concerning Mercury (European Commission, 2005), which includes a comprehensive plan to address mercury use and pollution and has resulted in the enhancement of Union law on mercury, including restrictions on the inclusion of mercury or mercury compounds in products, ban of exports of mercury from the EU and inclusion of provisions on mercury emissions in EU legislation to protect people against exposure. European legislations concerning mercury are described below.

1.1.1.1 Food Safety

Limits on the mercury content of fish for human consumption for protecting human health are defined in European Regulation (EC) No 1881/2006 (European Commission, 2006) and amended on Regulation No 629/2008 (European Commission, 2008). The maximum safe limit for most fish species for human consumption is currently 0.5 mg/kg wet body weight and for some predatory species such as swordfish and tuna, it is 1 mg/kg wet body weight. Directive 2002/32/EC sets limits in animal feedingstuff (European Commission, 2002) and Regulation (EC) No 333/207 lays down sampling methods and methods of analysis for the official control of the levels of mercury and other restricted substances in foodstuffs (European Commisssion, 2007).

The European Food Safety Authority (EFSA) and national food safety authorities provide advice on fish consumption in an attempt to minimize mercury intake. According to EFSA’s scientific opinion from 2015 (European Food Safety Authority (EFSA), 2015), limiting consumption of fish species with a high methylmercury content is the most effective way to achieve the health benefits of fish whilst minimizing the risks posed by excessive exposure to methylmercury.

EFSA recommended that individual Member States, particularly those where fish/seafood species with a high mercury content – such as swordfish, pike, tuna and hake – are consumed regularly, consider their national patterns of fish consumption and assess the risk of different population groups exceeding safe levels of methylmercury while obtaining the health benefits of fish. Earlier EFSA scientific opinions (European Food Safety Authority (EFSA), 2014), (European Food Safety Authority (EFSA), 2012), (European Food Safety Authority (EFSA), 2004) looked respectively at the risks from mercury and methylmercury in food, and the health benefits of fish/seafood. The first opinion established a TWI for methylmercury of 1.3 micrograms per kg of body weight; the second recommended weekly intakes of fish of between 1-2 servings and 3-4 servings in order to realize health benefits such as improved neurodevelopment in children and reduced risk of coronary heart disease in adults respectively, as was already proved in the DEMOCOPHES project (Castaño, et al., 2015).

In September 2018, the Standing Committee on Plants, Animals, Food and Feed of the European Commission, reported that for the time being, the review of the maximum levels (MLs) for mercury in fish will be discontinued. However, the Commission stressed the importance of consumption advice related to mercury in fish and encouraged Member States to:

• develop specific national consumption advice related to fish consumption, in order to fully achieve the beneficial effects of fish consumption, whilst limiting the risks of mercury toxicity. When developing this consumption advice, Member Sates shall especially include the frequency of fish consumption and the fish species consumed;
• communicate the specific national consumption advice to the consumers as well as to relevant health care workers, working with the consumer groups most at risk.

It further stated that possible data on the effectiveness of consumption advice can be sent to the Commission (European Commission Standing Committee on Plants, 2018).

1.1.1.2 Chemicals Regulation (EC) No 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) restricts specific uses of mercury under Annex XVII and was amended by Commission Regulation (EC) No 552/2009 to also restrict mercury in measuring devices intended for use by the general public. Annex XVII was further amended by Commission Regulation (EC) No 847/2012 to restrict mercury-containing measuring devices intended for industrial and professional uses. Commission Regulation (EU) No. 848/2012 prohibited the manufacture, use and placement on the market of five phenylmercury compounds from 10 October 2017. To date, mercury has three active registrations under REACH (European Chemicals Agency, ECHA).

Mercury has been assigned a European Union harmonized classification and labelling according to Regulation (EC) No 1272/2008 of the European Parliament and of the Council on classification, labelling and packaging of substances and mixtures (CLP) (European Chemicals Authority (ECHA), n.d.) (see §5.1.1). Mercury and its compounds are included in the “Public Activities Coordination Tool” (PACT) list, which provides up-to-date-information on the activities planned, ongoing or completed by ECHA and or Member States Competent Authorities in the frame of the REACH and CLP regulations (European Chemicals Authority (ECHA), n.d.). Mercury is subject to the “Prior Informed Consent regulation” (PIC, Regulation (EU) 649/2012) and to export notification procedure (European Commission, 2012).

1.1.1.3 Environment Regulation (EU) 2017/852 transposes in the European Union the obligations under the Minamata Convention on Mercury (see §10.1.3.7). It covers the full life cycle of mercury and complements existing EU environmental law on mercury and repeals regulation (EC) No 1102/2008 (European Commission, 2017).

It prohibits the export of mercury and mercury compounds, and the manufacture, export and import of a large range of mercury-added products, restricts all uses of mercury catalysts and large electrodes in industrial processes and future new uses of mercury in industry and in products and requires that all mercury waste is safely taken out of the economic sphere, stabilized in a less toxic form and stored permanently in environmentally sound conditions.

It also sets restrictions on the use of dental amalgam, which is the last large use of mercury in the EU, and sets out a process to assess the feasibility of a complete phase out of the use of mercury in dentistry. As from 1/7/2018, the use of dental amalgam is prohibited for dental treatment of (i) deciduous teeth, (ii) of children under 15 years and (iii) of pregnant or breastfeeding women, unless deemed strictly necessary by the dental practitioner on the ground of specific medical needs of the patient. By 1/7/2019, each Member State must set out and publish on the Internet a national plan on measures to phase down the use of dental amalgam. As from 1/1/2019, dental practitioners are no longer allowed to use dental amalgam in bulk, but only in pre-dosed encapsulated form and all dental facilities using amalgam and/or removing dental amalgam fillings must be equipped with amalgam separators ensuring the retention and collection of amalgam particles with a view to preventing their release into wastewater systems. Dental practitioners must ensure that their amalgam waste is handled and collected by authorized waste management establishments or undertakings (no direct or indirect release into the environment). The Commission shall report by 30/6/2020 on the feasibility of a phase out of the use of dental amalgam in the long term, and preferably by 2030, and present concomitantly, if deemed appropriate, a legislative proposal.

The EU Water Framework Directive (“WFD”, Directive 2000/60/EC) requires EU Member States to ensure that water bodies achieve good chemical and ecological status. Directive 2013/39/EU sets environmental quality standards for mercury in surface waters and fish to protect higher level predators from secondary poisoning through bioaccumulation. The Groundwater Directive 2006/118/EC, the Environmental Quality Standards Directive 2008/105/EC and the Dangerous substances Directive 2006/11/EC complement the overall framework for integrated management. In particular Decision 2455/2001/EC (which forms Annex X of the Water Framework Directive) establishes the list of priority substances and priority hazardous substances for which measures must be adopted. Directive 2006/118/EC also complements the provisions preventing or limiting inputs of pollutants into groundwater already contained in the WFD. According to the European Environment Agency ( European Environment Agency , 2018), ~41% of surface water bodies in the EU exceed the mercury concentration for protecting fish-eating birds and mammals.

Directive 2010/74/EU lays down rules on integrated prevention and control of pollution arising from industrial activities and rules designed to prevent or, where that is not practicable, to reduce emissions into air, water and land and to prevent the generation of waste, in order to achieve a high level of protection of the environment taken as a whole. This includes mercury and its compounds, expressed as mercury (Hg).

The Waste Incineration Directive 2000/76/EC aims to prevent or to limit pollution from the incineration and co-incineration of waste requiring operators of plants with a nominal capacity of 2 tonnes or more per hour to provide the competent authority with an annual report including emissions into air and water, but there is no specific requirement for an emission inventory. Member States provide reports to the Commission on implementation progress based on questionnaire sent by the Commission to Member States every three years. Periodic measurement is required but no obligation for an annual inventory is specified.

1.1.1.4 Consumer products

Regulation (EC) No 1223/2009 of the European Parliament and of the Council of 30 November 2009 on cosmetic products prohibits mercury in cosmetic products (Annex II). Limited exemptions for mercury compounds used as preservatives in cosmetics are provided in Annex V.

The Restriction of Hazardous Substances Directive 2002/95/EC bans the use of mercury in Electrical and electronic equipment.

Directive 2008/12/EC in conjunction with Directive 2006/66/EC restricts mercury in batteries and accumulators.

Chemical Agents Directive 98/24/EC lays down minimum requirements for the protection of workers from risks to their safety and health arising, or likely to arise, from the effects of chemical agents that are present at the workplace or as a result of any work activity involving chemical agents. Directive 2009/161/EU26 established a third list of indicative occupational exposure limit values (IOELVs), which includes an IOELV for mercury and divalent inorganic mercury compounds for the protection of workers who may be exposed to mercury.

Member States may have regulated the exposure limit value for alkyl compounds of mercury (e.g. Spain, 0.01 mg/m³).

The Minamata Convention on Mercury

The Minamata Convention on Mercury is a global treaty, effective as of 16 August 2017, which aims to protect human health and the environment from anthropogenic emissions and releases of mercury and mercury compounds. It has been ratified by 99 parties, including the European Union. The obligations under the Convention are transposed in the EU by Regulation (EU) 2017/852 on mercury.

Some issues covered by the Convention, which relate to the scope of HBM4EU, are:

Capacity-building, technical assistance and technology transfer

It calls for cooperation between Parties for timely and appropriate capacity-building and technical assistance to developing country Parties.

Health aspects

It encourages Parties to promote the development and implementation of strategies and programmes to identify and protect populations at risk, to promote appropriate health-care services for prevention, treatment and care for populations affected by the exposure to mercury or mercury compounds and to establish and strengthen institutional and health professional capacities.

Information exchange

It calls for exchange of information concerning mercury and mercury compounds, including toxicological and safety information, and of epidemiological information concerning health impacts associated with exposure to mercury and mercury compounds, in close cooperation with the World Health Organization and other relevant organizations, as appropriate.

Public information, awareness and education

It calls for the provision to the public of available information, awareness and education about the effects of exposure to mercury/mercury compounds on human health/environment, about alternatives and about results from research & monitoring activities

Research, development and monitoring

It calls for Parties to cooperate to develop harmonized methodologies and to use them within their capacity, for modelling and geographically representative monitoring of levels of mercury and mercury compounds in vulnerable populations, for collaboration in the collection and exchange of relevant and appropriate samples and for assessments of the impact of mercury and mercury compounds on human health and the environment.

Reporting

Each Party shall report to the Conference of the Parties (COP) on the measures it has taken to implement the provisions of the Convention, on the effectiveness of such measures and of possible challenges in meeting the obligations of the Convention.

Effectiveness evaluation

The effectiveness of the Convention will be evaluated by COP within six years from the date of entry into force of the Convention and periodically thereafter, using comparable monitoring data on the presence and movement of mercury and mercury compounds in the environment as well as trends in levels of mercury and mercury compounds observed in biotic media and vulnerable populations.

Section §10.1.3 presents an overview of current EU policies related to mercury, including the Minamata Convention, a global treaty to address mercury pollution, which was ratified by the EU.

The following policy-related questions relate to commitments under this frame.

1. What biomonitoring and exposure data on mercury (and its species), relevant to the European population, are currently available and what new data are needed to address policy-related questions?
2. What toxicological data on mercury (and its species) are available and what new data are needed to answer policy-related questions?
3. How can harmonized, validated and comparable information be collected to support and evaluate current policies?
4. How can information be exchanged regarding mercury / mercury compounds?
5. How can transfer of knowledge & technology be facilitated to support current policies?
6. Which populations remain vulnerable to health impacts from mercury exposure and how can they be protected?
7. ‘What is the geographic spread of the current exposure and how does it relate to different exposure sources (environmental; contaminated sites; dental amalgams; dietary, including different species of sea-food)?
8. How effective are current policies (including the EU’s Strategy on Mercury and the Minamata Convention, which was ratified by the EU and Member States) in reducing human exposure to mercury in Europe? Are these policies implemented effectively?
9. At what level of exposure to different mercury species and to total mercury are health effects likely to occur?
10. What are the safe levels of mercury species in fish and other food?
11. What are possible health effects resulting from chronic low exposure to mercury and its organic compounds (such as from food consumption and dental amalgams)?
12. What is the safe intake level for methyl and inorganic mercury that is without any appreciable health risk in the general European population?
13. What factors make people more susceptible to the development of health effects due to mercury exposure?
14. What are cumulative risks from concurrent exposure to other chemicals (mainly other metals and other reprotoxic substances)?
15. How can the public be informed and how can public awareness and education be raised regarding the effects of mercury on health and the environment and about management options (also see below)?
16. What advice should be given regarding dietary recommendations to vulnerable Europeans (e.g. pregnant women, infants, high sea-food consumers) and other stakeholders (e.g. health practitioners, policy makers) to reduce exposure to mercury while in keeping with nutritional requirements and cultural dietary preferences?
17. How can HBM4EU results support policy decisions at EFSA and ECHA?
18. How can occupational exposure policy and other policy initiatives be better coordinated?
19. How should occupational exposure be assessed when there is a previous exposure of the worker from other sources and since birth or childhood?

Please find answers to the updated (2020) Policy-related questions on Mercury here 

In the interest of transparency and accountability, HBM4EU invites interested stakeholders to submit comments on the scoping document on acrylamide.

All submitted comments will be made available for download on this webpage and will be taken into consideration by the HBM4EU consortium, where possible.

Please click here to submit your comments.

Please click here to access the Substance Report.

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