Toxicology and Immunotoxicology of Mercury: A Comparative Review in Fish and Humans

Abstract

This review addresses an important area of environmental and mammalian toxicology by evaluating and comparing mercury-induced effects upon the immune responses of two evolutionarily divergent yet immunologically-related species. The mechanisms of mercury toxicology and immunotoxicology are described herein, including supporting data from the following: sources of exposure; bioavailability and biodistribution; metabolism; and laboratory and field investigations. Based upon the studies presented, the relative sensitivities of fish and human immune cells to mercury exposure are compared and contrasted with regard to mercury's ability to stimulate and/or suppress host immunocompetence. In addition, results from immune assays are compared to mercury tissue burdens, as well as to toxicological threshold level estimates. Such comparisons may help to resolve gaps in our knowledge regarding sensitivity of immunological assays, standardization of immunotoxicological techniques between species, and the extent to which the vertebrate immune system possesses functional reserve and redundancy in response to xenobiotics. A review of this type begins to provide support for the potential usefulness of fish immune cells to serve as indicators for human immunotoxicology risk assessment. Analysis of the reviewed studies supports the following conclusions in both lower and higher vertebrates: a threshold for mercury-induced immunotoxicological effects is likely; multiple exposure scenarios involving high and/or chronic exposures leading to increased body burdens are linked to increased risk of immunomodulation; and highly exposed and/or susceptible subpopulations are at greater risk of toxicological impact.

Heavy metals, islet function and diabetes development

“…The mercury compounds are generally used in dry-cell batteries, fluorescent bulbs, arc lamps, mirrors, and in the extraction of gold and silver from ores, thermometers, dental amalgam fillings and vaccine preserver. [87][88][89][90][91] Thimerosal (ethylmercurithiosalicylic acid) is a mercury-containing compound and a preservative for the vaccine and biological products for more than 70 years. Thimerosal dissociates as 49.5% ethylmercury by weight and thiosalicylic acid and may possess higher cytotoxicity on renal cells.…”

Low-dose exposure to inorganic mercury accelerates disease and mortality in acquired murine lupus.

“…However, despite considerable study, no associations have been found between mercury exposure and autoimmune disease in humans, even in highly exposed workers (Moszczynski 1997;Sweet and Zelikoff 2001;Vimercati et al 2001). Experimental research in animal models of Hg-induced autoimmunity (HgIA) may suggest the reason for this.…”

Gold Mining and Mercury Bioaccumulation in a Floodplain Lake and Main Channel of the Tambopata River, Perú

“…Mercury (Hg) is a pollutant that can cause developmental and behavioral abnormalities including impaired reproduction and decreased survival in vertebrates [1]. Methylmercury (MeHg) is the form of most concern because, unlike inorganic Hg (Hg [II]) which is readily excreted from the body, MeHg bioaccumulates and can reach harmful levels in fish tissues [2].…”