clarkson 06 mercury toxicology

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Critical Reviews in Toxicology, 36:609662, 2006 Copyright c Informa Healthcare ISSN: 1040-8444 print / 1547-6898 online DOI: 10.1080/10408440600845619

The Toxicology of Mercury and Its Chemical CompoundsThomas W. ClarksonDepartment of Environmental Medicine, University of Rochester School of Medicine, Rochester, New York, USA

Laszlo MagosRetired from Medical Research Council, Toxicology Unit, Surrey, United Kingdom

This review covers the toxicology of mercury and its compounds. Special attention is paid to those forms of mercury of current public health concern. Human exposure to the vapor of metallic mercury dates back to antiquity but continues today in occupational settings and from dental amalgam. Health risks from methylmercury in edible tissues of sh have been the subject of several large epidemiological investigations and continue to be the subject of intense debate. Ethylmercury in the form of a preservative, thimerosal, added to certain vaccines, is the most recent form of mercury that has become a public health concern. The review leads to general discussion of evolutionary aspects of mercury, protective and toxic mechanisms, and ends on a note that mercury is still an element of mystery. Keywords: Dental Amalgam, Ethylmercury, Inorganic Mercury, Mercury, Mercury Vapor, Methylmercury, Phenylmercury, Thimerosal

ContentsI. INTRODUCTION ................................................................................................................................................................610 A. The Major Physical and Chemical Forms of Mercury ..........................................................................................................610 B. Ancient and Modern Uses of Mercury ...............................................................................................................................611 INORGANIC MERCURY ...................................................................................................................................................612 A. An Overview ...................................................................................................................................................................612 B. Pathways of Human Exposures .........................................................................................................................................613 C. Quicksilver ......................................................................................................................................................................613 1. Disposition in the Body ..............................................................................................................................................613 2. Toxic Effects .............................................................................................................................................................613 D. Mercurous Mercury .........................................................................................................................................................613 1. Disposition in the Body ..............................................................................................................................................613 2. Toxic Effects .............................................................................................................................................................614 E. Mercuric Mercury ............................................................................................................................................................614 1. Disposition in the Body ..............................................................................................................................................614 2. Toxic Effects .............................................................................................................................................................616 F. Inhaled Mercury Vapor .....................................................................................................................................................616 1. Disposition in the Body ..............................................................................................................................................616 2. Metabolism ...............................................................................................................................................................618 3. Biological Indicators ..................................................................................................................................................618 4. Toxic Effects .............................................................................................................................................................619 a. Acute Toxicity .....................................................................................................................................................619 b. Chronic Toxicity: Effects on Humans .....................................................................................................................619 c. Studies on Animals ..............................................................................................................................................621 G. Dental Amalgam ..............................................................................................................................................................621

II.

Address correspondence to Thomas Clarkson, Department of Environmental Medicine University of Rochester School of Medicine, Rochester, NY. E-mail: Twc30@aol.com

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T. W. CLARKSON AND L. MAGOS 1. Disposition in the Body ..............................................................................................................................................622 2. Toxic Effects .............................................................................................................................................................623

III.

ORGANIC MERCURY .......................................................................................................................................................624 A. An Overview ...................................................................................................................................................................624 B. Methylmercury ................................................................................................................................................................625 1. Pathways of Human Exposures ...................................................................................................................................625 2. Disposition in the Body ..............................................................................................................................................627 3. Metabolism ...............................................................................................................................................................628 4. Biological Indicators ..................................................................................................................................................629 5. Toxic Effects .............................................................................................................................................................630 a. Adult Exposures ..................................................................................................................................................630 b. Prenatal Exposures ...............................................................................................................................................635 i. Consumption of contaminated loaves ...............................................................................................................635 ii. Populations consuming sh or sea mammals ....................................................................................................636 (a). New Zealand Study ................................................................................................................................637 (b). The Faroes Study ...................................................................................................................................637 (c). The Seychelles Study ..............................................................................................................................639 c. Comparison of Outcomes of the Three Major Studies with Iraq ................................................................................641 d. Exposure in Childhood and Adolescence ................................................................................................................644 e. Effects in Pregnant Subjects ..................................................................................................................................644 6. The Role of Nutrition .................................................................................................................................................645 C. Ethylmercury ..................................................................................................................................................................645 1. Pathways of Human Exposures ...................................................................................................................................645 2. Disposition in the Body ..............................................................................................................................................645 3. Toxic Effects ........................................................................................................................