Content area
Full Text
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 fish 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
I. INTRODUCTION
Mercury and its compounds have long presented a dilemma to those interested in making use of its many and varied properties. On the one hand, mercury has many attractive and useful properties, but on the other hand it presents a risk of toxic effects. The challenge we face today is to take advantage of these useful applications while at the same time assuring no adverse health effects occur. A key role for the toxicologist is to develop an understanding of its toxic properties so as to give advice to users and regulatory agencies to ensure that safe levels of exposure are not exceeded. This review focuses on the toxic properties of this metal and discusses current knowledge of the mechanisms of toxic action.
A. The Major Physical and Chemical Forms of Mercury
Table 1 summarizes the major chemical and physical forms of mercury. In its zero oxidation state, Hg^sup 0^, it exists in its silvery liquid form as the only metal that is a liquid at ambient temperatures. The liquid is volatile and releases a monatomic gas usually referred to as mercury vapor. It is stable in ambient air and can remain in the atmosphere for months perhaps years. It plays a key role in the global cycling of mercury. It can undergo oxidation to form the two major oxidation states of mercury.
The first oxidation state, where the mercury atom has...