DOI 10.1515/reveh-2014-0010 Rev Environ Health 2014; 29(1-2): 29–31
Mahmood A. Khwaja* and Maryam Shabbir Abbasi
Mercury poisoning dentistry: high-level indoor air mercury contamination at selected dental sites Abstract: Mercury (Hg), also known as quick silver, is an essential constituent of dental amalgam. It is a toxic substance of global concern. Children are more at risk from mercury poisoning which affects their neurological development and brain. In the past, a number of studies at dental sites in many countries have been carried out and reported. The present report briefly describes and discusses our recent investigations carried out at 34 dental sites (teaching institutions, hospitals and private clinics) in Pakistan. It is evident from the data that at many sites the indoor mercury vapor levels exceed far above the permissible limit recommended for safe physical and mental health. At these sites, public in general and the medical, paramedical staff and vulnerable population in particular, are at most serious risk to health resulting from exposure to toxic and hazardous mercury. To minimize such risk, some of the recommendations are, best in-house environmental practices for occupational health and safety, mercury contaminated waste reduction at source, mercury specific legislation and ratification of Minamata convention on mercury by Pakistan and other world governments at the earliest time possible Keywords: amalgams; contamination; dentistry; mercury. *Corresponding author: Mahmood A. Khwaja, Sustainable Development Policy Institute (SDPI), 38, Main Embassy Road, G-6/3, Islamabad, Pakistan, E-mail: [email protected] Maryam Shabbir Abbasi: Sustainable Development Policy Institute (SDPI), Islamabad, Pakistan
Introduction Dental mercury amalgams, also called silver and amalgam fillings, are widely used because of several advantages: they are inexpensive, easy to use, are the best settling material and, most importantly, are resin free, making them less allergenic than composite fillings. These fillings release mercury vapors. The amount released depends upon a number of factors, including cavity size, tooth characteristics, amalgam composition, age of amalgam, time taken for filling, the number of fillings, temperature
of ingested food/drinking liquids, and activities like chewing and teeth grinding (1, 2). Mercury or “quick silver”, the essential constituent of dental amalgam, is a toxic substance of global concern. A persistent pollutant, mercury is not limited to its source but can travel thousands of kilometers away from the source. Mercury poses risks to the environment and human health, especially the health of children. Last September 2012, the International Union for Conservation of Nature (IUCN) World Conservation Congress (3) adopted Sustainable Development Policy Institute (SDPI) Motion (M-169) and called upon government representatives of the Intergovernmental Negotiating Committee (INC) to support a legally binding treaty with an objective to protect human health and the environment from hazardous and toxic mercury. Early last year, in January 2013, 140 country representatives convened in Geneva and adopted a ground-breaking, legally binding treaty on mercury, called the “Minamata Convention on Mercury”, which limits the use and emission of health-hazardous mercury. A total of 92 states, including Pakistan, signed when it opened for signatures at a diplomatic conference in Japan on October 2013 (4). Scientific evidence, including those included in the United Nations Environment Program (UNEP) Global Mercury report, establishes mercury as an extremely toxic substance, making it a major threat to wildlife, ecosystems, and human health at a global scale (5, 6). It is also a major threat to fishes, which constitute an all-important nutritional component of the human diet. Children are more at risk from mercury poisoning as it affects their brain and neurological development. Mercury vapors can cause damage to the central nervous system, thyroid, kidneys, lungs, immune system, eyes, gums and skin. Neurological and behavioral disorders include tremors, insomnia, memory and vision problems, neuromuscular effects, and headaches. Fetuses and young children are more vulnerable to the mercury vapors (2, 7–9). There are few investigations on mercury contamination in air that have been carried out and reported in Pakistan (10, 11). According to a preliminary report on mercury inventory published in 2000, the main sources of mercury releases and emissions in Pakistan are dental clinics, a chlor-alkali plant, light product manufacturing units, incinerators, and other coal-based primary or
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30 Khwaja and Abbasi: Mercury contamination at dental sites secondary unit operations. Based on this reported preliminary data, the estimated values of the maximum and minimum emission and transfer of mercury in the country are about 36,900 and 10,800 kg per year, respectively. The estimated amount of mercury consumed in the dental sector in the country is reported to be 65 kg/annum (12). At present, there is no mercury-specific legislation in the country. However, the development of a mercury management action plan is currently underway. In 2010, a study evaluating the amalgam used by dentists in Pakistan and its waste management indicated that 92% of dentists often used amalgam. About 56% of the study samples disagreed that amalgam should be phased out and replaced with non-mercury fillings, 92% perceived amalgam a health risk, whereas 46% considered it an environmental hazard (13). However, in a study that monitored mercury air pollution at dental sites, very high indoor mercury contamination levels have been found at some dental sites. A similar study carried out in Karachi indicated that 94% of dentists performed dental amalgam restoration, 57% used hand mixing for dispensing, and 55% simply disposed of mercury waste in the sink (14). In the present study, mercury levels in and around mercury releasing sources and in open air are examined to identify the so-called “mercury hot spots” in five cities in Pakistan, namely, Peshawar, Rawalpindi, Islamabad, Abbottabad, and Lahore. A detailed paper with complete description and discussion of collected data is in preparation. This brief report describes and discusses results of the findings at dental clinics, hospitals, dental colleges, and teaching hospitals. The selected sampling points at these 34 sites included dentistry/treatment sections, adjacent corridors, and surrounding open air.
Materials and methods The high precision RA-915+ mercury analyzer (Lumex instruments group, Petersburg, Russia), calibrated by the supplier, was used to Table 1 Mercury levels at visited sites in Lahore, Peshawar, Abbotabad, Rawalpindi, and Islamabad. Sr. Samples No
No. of Mercury Above samples, levels in air, standarda n ng/m3 (300 ng/m3) No, % Max Min
01 Dental teaching institutions 02 General hospitals 03 Dental clinics (private)
17 44,067 109 7 17,172 174 10 1800 333
15 (88) 5 (71) 9 (100)
ATSDR, Agency for toxic substances and disease registry, 2012.
a
measure mercury levels in air at the selected sites (15). For discussion of the results, a reference level of 300 ng/m3 from the US Environmental Protection Agency (EPA) was used (16). Overall summarized findings for mercury levels in air at dental colleges and teaching hospitals (17), general hospitals (7), and private clinics (10) are described in Table 1.
Results and discussion Among all the monitored dental sites in Lahore, Peshawar, Abbottabad, Rawalpindi and Islamabad, 11 sites have been found to be contaminated with mercury levels in the air, which is many times higher than the recommended limit of 300 ng/m3. Mercury levels in air of operative dentistry (OPD) at 15 out of 17 dental teaching institutions has also been found to be higher than the recommended limit, whereas similar higher mercury levels have been observed in 5 out of 7 general hospitals and all 10 private clinics visited (Table 1). The highest mercury levels in OPD air at teaching institutions, general hospitals, and private clinics are 44,067, 17,172 and 1800 ng/m3, respectively, while the lowest values at these sites are recorded at 109, 174 and 333 ng/ m3, respectively (Table 1). Among dental sites, mercury contamination of air has been generally found to be in the following increasing order: operative section > corridor > open air and at teaching institutions > general hospitals > private clinics. The results also show the unawareness of concerned parties regarding appropriate handling of mercury/ mercury amalgam and mercury containing wastes; improper and inadequate ventilation systems; and lack of awareness regarding health hazards of mercury to human health. The main reasons for the observed elevated levels of mercury in air at OPD, adjacent corridors, and the surrounding air at some of the visited sites are as follows: careless use of mercury/mercury amalgam and inappropriate mercury/mercury amalgam waste management.
Recommendations The recommendations presented below must be shared and discussed with all stakeholders, including officials of the Pakistan Medical and Dental Council (PMDC), ministries of health and environment, and the environmental protection agencies. Some of these have already been shared with the staff and management of the visited sites.
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Khwaja and Abbasi: Mercury contamination at dental sites 31
The Minamata Convention on Mercury (2013), which has already been signed, must be ratified by the Government of Pakistan and other governments at the earliest time possible. –– Following the best preventive approach – “Waste Reduction at Source”, mercury emissions/releases streams must be identified within dental sites through an environmental waste audit so that control measures can be designed and implemented accordingly. –– Best in-house environmental practices (cross ventilation, exhaust fans) and use of best environment friendly technology must be encouraged, and standard operating procedures for mercury handling, transport, and use must be developed and implemented. –– An institutional mercury waste management plan must be established at all mercury operated sites and the same must be periodically monitored and evaluated, by the management. –– Capsulated mercury amalgam use and mechanical mixing must be be promoted because these effectively and substantially reduce mercury waste releases/ emissions to the environment. –– Non-mercury dental fillings must be advised to patients by dentists. –– At the identified highly polluted dental sites (as evidenced by the reported data of snap/spot measurements of mercury vapors in air at the time of measurements in the present study), a follow up
comprehensive survey and monitoring program must be conducted, including measurement of mercury levels for a 9-h exposure period. This program must be developed and implemented at the earliest to confirm risks to public health in general and to visitors/ medical staff in particular. –– Mercury-specific legislation, including national emissions/releases standards, standard minimum mercury levels in products and protocols for permits/ licenses issued to clinics, must be introduced for private clinics/teaching institutions. –– Curricula/syllabi used at different teaching institutions in the country must be reviewed and revised to sensitize students regarding occupational health and safety as well as impart training in best environmental practices and technologies for operative/restorative dentistry. Acknowledgments: We gratefully acknowledge the collaboration of the Zero Mercury Working Group (ZMWG) and the Institute of Chemical Sciences (ICS), Peshawar University, as well as the financial support of the Sigrid Rausing Trust and the European Commission via the European Environmental Bureau (EEB). We are also thankful to our SDPI colleagues, Fareeha Mehmood and Sehrish Jahangir, for their valuable contributions towards this study. Received January 16, 2014; accepted January 16, 2014; previously published online February 19, 2014
References 1. The Vermont Advisory Committee on Mercury Pollution. 1998. Available at: www.mercvt.org. Accessed on November 2013. 2. Intelligence Service. Study on the potential for reducing mercury pollution from dental amalgam and batteries, Final report prepared for the European Commission- DG ENV, 2012:45. 3. IUCN GCC. Legally binding global mercury treaty to protect wildlife, ecosystems and health, 2012. Available at: . Accessed on November 2013. 4. United Nations Environment Program. Advance version of the Minamata Convention on mercury, 2013. (DTTE)/Hg/INC.5/7. 5. Stortebecker P. Mercury poisoning from dental amalgam through a direct nose-brain transport. Lancet 1989;333:1207. 6. United Nations Environment Program Chemicals. Global Mercury Report. Geneva, Switzerland, 2002. 7. Pamphlett R, Coote P. Entry of low doses of mercury vapors into the nervous system, Neurotoxicol 1998;19:39–48. 8. Kirby A, Rucevska I, YemelinV, Cooke C, Simonett O, et al. Mercury – Time to Act. United Nations Environment Program 2013;23. 9. MERC Vermont. Advisory Committee on Mercury Pollution. Dental amalgam fillings. 1999. Available at: . Accessed on November 2013.
10. Khwaja MA, Umer F, Shaheen N, Sherazi A, Shaheen FH. Air pollution reduction and control in south – need for regional agreement. Sci Technol Dev 2012;31:51–68. 11. Khwaja MA, Khan SR. Air pollution: Key environmental issues in Pakistan, working paper series No.99. Sustainable Development policy Institute, Islamabad, Pakistan, 2005. 12. United Nations Environment Program. Preliminary report on Mercury Inventory in Pakistan. Chemical Branch, Ministry of Environment, Islamabad. 2000. Available at: http://www. atsdr.cdc.gov/emergency_response/Action_Levels_for_ Elemental_Mercury_Spills_2012.pdf. Accessed on November 2013. 13. Mumtaz R, Khan AA, Noor N, Humayun S. Amalgam use and waste management by Pak. dentist. EMHU 2010;16:334–9. 14. Kefi I, Maria A, Majid Z, Sana J, Afreen M, et al. Dental amalgam: effects of alloy/mercury mixing ratio, uses and waste management. J Ayub Med Coll Abbottabad 2011;23:43–5. 15. Lumex Ltd. User Manual, Mercury Analyzer RA915+. Available at: rww.Lumex.ru. Accessed on November 2013. 16. Agency for Toxic Substances and Disease Registry (ASTDR). Action Levels for Elementary Mercury Spills, Chemical-Specific Health consultation, 2012.
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Mahmood A. Khwaja* and Maryam Shabbir Abbasi
Mercury poisoning dentistry: high-level indoor air mercury contamination at selected dental sites Abstract: Mercury (Hg), also known as quick silver, is an essential constituent of dental amalgam. It is a toxic substance of global concern. Children are more at risk from mercury poisoning which affects their neurological development and brain. In the past, a number of studies at dental sites in many countries have been carried out and reported. The present report briefly describes and discusses our recent investigations carried out at 34 dental sites (teaching institutions, hospitals and private clinics) in Pakistan. It is evident from the data that at many sites the indoor mercury vapor levels exceed far above the permissible limit recommended for safe physical and mental health. At these sites, public in general and the medical, paramedical staff and vulnerable population in particular, are at most serious risk to health resulting from exposure to toxic and hazardous mercury. To minimize such risk, some of the recommendations are, best in-house environmental practices for occupational health and safety, mercury contaminated waste reduction at source, mercury specific legislation and ratification of Minamata convention on mercury by Pakistan and other world governments at the earliest time possible Keywords: amalgams; contamination; dentistry; mercury. *Corresponding author: Mahmood A. Khwaja, Sustainable Development Policy Institute (SDPI), 38, Main Embassy Road, G-6/3, Islamabad, Pakistan, E-mail: [email protected] Maryam Shabbir Abbasi: Sustainable Development Policy Institute (SDPI), Islamabad, Pakistan
Introduction Dental mercury amalgams, also called silver and amalgam fillings, are widely used because of several advantages: they are inexpensive, easy to use, are the best settling material and, most importantly, are resin free, making them less allergenic than composite fillings. These fillings release mercury vapors. The amount released depends upon a number of factors, including cavity size, tooth characteristics, amalgam composition, age of amalgam, time taken for filling, the number of fillings, temperature
of ingested food/drinking liquids, and activities like chewing and teeth grinding (1, 2). Mercury or “quick silver”, the essential constituent of dental amalgam, is a toxic substance of global concern. A persistent pollutant, mercury is not limited to its source but can travel thousands of kilometers away from the source. Mercury poses risks to the environment and human health, especially the health of children. Last September 2012, the International Union for Conservation of Nature (IUCN) World Conservation Congress (3) adopted Sustainable Development Policy Institute (SDPI) Motion (M-169) and called upon government representatives of the Intergovernmental Negotiating Committee (INC) to support a legally binding treaty with an objective to protect human health and the environment from hazardous and toxic mercury. Early last year, in January 2013, 140 country representatives convened in Geneva and adopted a ground-breaking, legally binding treaty on mercury, called the “Minamata Convention on Mercury”, which limits the use and emission of health-hazardous mercury. A total of 92 states, including Pakistan, signed when it opened for signatures at a diplomatic conference in Japan on October 2013 (4). Scientific evidence, including those included in the United Nations Environment Program (UNEP) Global Mercury report, establishes mercury as an extremely toxic substance, making it a major threat to wildlife, ecosystems, and human health at a global scale (5, 6). It is also a major threat to fishes, which constitute an all-important nutritional component of the human diet. Children are more at risk from mercury poisoning as it affects their brain and neurological development. Mercury vapors can cause damage to the central nervous system, thyroid, kidneys, lungs, immune system, eyes, gums and skin. Neurological and behavioral disorders include tremors, insomnia, memory and vision problems, neuromuscular effects, and headaches. Fetuses and young children are more vulnerable to the mercury vapors (2, 7–9). There are few investigations on mercury contamination in air that have been carried out and reported in Pakistan (10, 11). According to a preliminary report on mercury inventory published in 2000, the main sources of mercury releases and emissions in Pakistan are dental clinics, a chlor-alkali plant, light product manufacturing units, incinerators, and other coal-based primary or
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30 Khwaja and Abbasi: Mercury contamination at dental sites secondary unit operations. Based on this reported preliminary data, the estimated values of the maximum and minimum emission and transfer of mercury in the country are about 36,900 and 10,800 kg per year, respectively. The estimated amount of mercury consumed in the dental sector in the country is reported to be 65 kg/annum (12). At present, there is no mercury-specific legislation in the country. However, the development of a mercury management action plan is currently underway. In 2010, a study evaluating the amalgam used by dentists in Pakistan and its waste management indicated that 92% of dentists often used amalgam. About 56% of the study samples disagreed that amalgam should be phased out and replaced with non-mercury fillings, 92% perceived amalgam a health risk, whereas 46% considered it an environmental hazard (13). However, in a study that monitored mercury air pollution at dental sites, very high indoor mercury contamination levels have been found at some dental sites. A similar study carried out in Karachi indicated that 94% of dentists performed dental amalgam restoration, 57% used hand mixing for dispensing, and 55% simply disposed of mercury waste in the sink (14). In the present study, mercury levels in and around mercury releasing sources and in open air are examined to identify the so-called “mercury hot spots” in five cities in Pakistan, namely, Peshawar, Rawalpindi, Islamabad, Abbottabad, and Lahore. A detailed paper with complete description and discussion of collected data is in preparation. This brief report describes and discusses results of the findings at dental clinics, hospitals, dental colleges, and teaching hospitals. The selected sampling points at these 34 sites included dentistry/treatment sections, adjacent corridors, and surrounding open air.
Materials and methods The high precision RA-915+ mercury analyzer (Lumex instruments group, Petersburg, Russia), calibrated by the supplier, was used to Table 1 Mercury levels at visited sites in Lahore, Peshawar, Abbotabad, Rawalpindi, and Islamabad. Sr. Samples No
No. of Mercury Above samples, levels in air, standarda n ng/m3 (300 ng/m3) No, % Max Min
01 Dental teaching institutions 02 General hospitals 03 Dental clinics (private)
17 44,067 109 7 17,172 174 10 1800 333
15 (88) 5 (71) 9 (100)
ATSDR, Agency for toxic substances and disease registry, 2012.
a
measure mercury levels in air at the selected sites (15). For discussion of the results, a reference level of 300 ng/m3 from the US Environmental Protection Agency (EPA) was used (16). Overall summarized findings for mercury levels in air at dental colleges and teaching hospitals (17), general hospitals (7), and private clinics (10) are described in Table 1.
Results and discussion Among all the monitored dental sites in Lahore, Peshawar, Abbottabad, Rawalpindi and Islamabad, 11 sites have been found to be contaminated with mercury levels in the air, which is many times higher than the recommended limit of 300 ng/m3. Mercury levels in air of operative dentistry (OPD) at 15 out of 17 dental teaching institutions has also been found to be higher than the recommended limit, whereas similar higher mercury levels have been observed in 5 out of 7 general hospitals and all 10 private clinics visited (Table 1). The highest mercury levels in OPD air at teaching institutions, general hospitals, and private clinics are 44,067, 17,172 and 1800 ng/m3, respectively, while the lowest values at these sites are recorded at 109, 174 and 333 ng/ m3, respectively (Table 1). Among dental sites, mercury contamination of air has been generally found to be in the following increasing order: operative section > corridor > open air and at teaching institutions > general hospitals > private clinics. The results also show the unawareness of concerned parties regarding appropriate handling of mercury/ mercury amalgam and mercury containing wastes; improper and inadequate ventilation systems; and lack of awareness regarding health hazards of mercury to human health. The main reasons for the observed elevated levels of mercury in air at OPD, adjacent corridors, and the surrounding air at some of the visited sites are as follows: careless use of mercury/mercury amalgam and inappropriate mercury/mercury amalgam waste management.
Recommendations The recommendations presented below must be shared and discussed with all stakeholders, including officials of the Pakistan Medical and Dental Council (PMDC), ministries of health and environment, and the environmental protection agencies. Some of these have already been shared with the staff and management of the visited sites.
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Khwaja and Abbasi: Mercury contamination at dental sites 31
The Minamata Convention on Mercury (2013), which has already been signed, must be ratified by the Government of Pakistan and other governments at the earliest time possible. –– Following the best preventive approach – “Waste Reduction at Source”, mercury emissions/releases streams must be identified within dental sites through an environmental waste audit so that control measures can be designed and implemented accordingly. –– Best in-house environmental practices (cross ventilation, exhaust fans) and use of best environment friendly technology must be encouraged, and standard operating procedures for mercury handling, transport, and use must be developed and implemented. –– An institutional mercury waste management plan must be established at all mercury operated sites and the same must be periodically monitored and evaluated, by the management. –– Capsulated mercury amalgam use and mechanical mixing must be be promoted because these effectively and substantially reduce mercury waste releases/ emissions to the environment. –– Non-mercury dental fillings must be advised to patients by dentists. –– At the identified highly polluted dental sites (as evidenced by the reported data of snap/spot measurements of mercury vapors in air at the time of measurements in the present study), a follow up
comprehensive survey and monitoring program must be conducted, including measurement of mercury levels for a 9-h exposure period. This program must be developed and implemented at the earliest to confirm risks to public health in general and to visitors/ medical staff in particular. –– Mercury-specific legislation, including national emissions/releases standards, standard minimum mercury levels in products and protocols for permits/ licenses issued to clinics, must be introduced for private clinics/teaching institutions. –– Curricula/syllabi used at different teaching institutions in the country must be reviewed and revised to sensitize students regarding occupational health and safety as well as impart training in best environmental practices and technologies for operative/restorative dentistry. Acknowledgments: We gratefully acknowledge the collaboration of the Zero Mercury Working Group (ZMWG) and the Institute of Chemical Sciences (ICS), Peshawar University, as well as the financial support of the Sigrid Rausing Trust and the European Commission via the European Environmental Bureau (EEB). We are also thankful to our SDPI colleagues, Fareeha Mehmood and Sehrish Jahangir, for their valuable contributions towards this study. Received January 16, 2014; accepted January 16, 2014; previously published online February 19, 2014
References 1. The Vermont Advisory Committee on Mercury Pollution. 1998. Available at: www.mercvt.org. Accessed on November 2013. 2. Intelligence Service. Study on the potential for reducing mercury pollution from dental amalgam and batteries, Final report prepared for the European Commission- DG ENV, 2012:45. 3. IUCN GCC. Legally binding global mercury treaty to protect wildlife, ecosystems and health, 2012. Available at: . Accessed on November 2013. 4. United Nations Environment Program. Advance version of the Minamata Convention on mercury, 2013. (DTTE)/Hg/INC.5/7. 5. Stortebecker P. Mercury poisoning from dental amalgam through a direct nose-brain transport. Lancet 1989;333:1207. 6. United Nations Environment Program Chemicals. Global Mercury Report. Geneva, Switzerland, 2002. 7. Pamphlett R, Coote P. Entry of low doses of mercury vapors into the nervous system, Neurotoxicol 1998;19:39–48. 8. Kirby A, Rucevska I, YemelinV, Cooke C, Simonett O, et al. Mercury – Time to Act. United Nations Environment Program 2013;23. 9. MERC Vermont. Advisory Committee on Mercury Pollution. Dental amalgam fillings. 1999. Available at: . Accessed on November 2013.
10. Khwaja MA, Umer F, Shaheen N, Sherazi A, Shaheen FH. Air pollution reduction and control in south – need for regional agreement. Sci Technol Dev 2012;31:51–68. 11. Khwaja MA, Khan SR. Air pollution: Key environmental issues in Pakistan, working paper series No.99. Sustainable Development policy Institute, Islamabad, Pakistan, 2005. 12. United Nations Environment Program. Preliminary report on Mercury Inventory in Pakistan. Chemical Branch, Ministry of Environment, Islamabad. 2000. Available at: http://www. atsdr.cdc.gov/emergency_response/Action_Levels_for_ Elemental_Mercury_Spills_2012.pdf. Accessed on November 2013. 13. Mumtaz R, Khan AA, Noor N, Humayun S. Amalgam use and waste management by Pak. dentist. EMHU 2010;16:334–9. 14. Kefi I, Maria A, Majid Z, Sana J, Afreen M, et al. Dental amalgam: effects of alloy/mercury mixing ratio, uses and waste management. J Ayub Med Coll Abbottabad 2011;23:43–5. 15. Lumex Ltd. User Manual, Mercury Analyzer RA915+. Available at: rww.Lumex.ru. Accessed on November 2013. 16. Agency for Toxic Substances and Disease Registry (ASTDR). Action Levels for Elementary Mercury Spills, Chemical-Specific Health consultation, 2012.
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