http://www.healthcare.uiowa.edu/corefacilities/esr/publications/buettnerpubs/pdf/FRBM-2001-30-1191-FQS-Redox.pdf

Redox environment of the cell as viewed through the redox state of the glutathione disulfide/glutathione couple.

Aquatic chemistry is becoming both a rewarding and substantial area of inquiry and is drawing many prominent scientists to its fold. Its literature has changed from a compilation of compositional tables to studies of the chemical reactions occurring within the aquatic environments. But more than this is the recognition that human society in part is determining the nature of aquatic systems. Since rivers deliver to the world ocean most of its dissolved and particulate components, the interactions of these two sets of waters determine the vitality of our coastal waters. This significant vol ume provides not only an introduction to the dynamics of aquatic chem istries but also identifies those materials that jeopardize the resources of both the marine and fluvial domains. Its very title provides its emphasis but clearly not its breadth in considering natural processes. The book will be of great value to those environmental scientists who are dedicated to keeping the resources of the hydrosphere renewable. As the size of the world population becomes larger in the near future and as the uses of materials and energy show parallel increases, the rivers and oceans must be considered as a resource to accept some of the wastes of society. The ability of these waters and the sediments below them to accommodate wastes must be assessed continually. The key questions relate to the capacities of aqueous systems to carry one or more pollutants."

Metal pollution in the aquatic environment

Advances in metal-induced oxidative stress and human disease

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."

The Toxicology of Mercury and Its Chemical Compounds

Arsenic toxicity and potential mechanisms of action

Biomarkers for mercury (Hg) exposure have frequently been used to assess exposure and risk in various groups of the general population. We have evaluated the most frequently used biomarkers and the physiology on which they are based, to explore the inter-individual variations and their suitability for exposure assessment. Concentrations of total Hg (THg), inorganic Hg (IHg) and organic Hg (OHg, assumed to be methylmercury; MeHg) were determined in whole blood, red blood cells, plasma, hair and urine from Swedish men and women. An automated multiple injection cold vapour atomic fluorescence spectrophotometry analytical system for Hg analysis was developed, which provided high sensitivity, accuracy, and precision. The distribution of the various mercury forms in the different biological media was explored. About 90% of the mercury found in the red blood cells was in the form of MeHg with small inter-individual variations, and part of the IHg found in the red blood cells could be attributed to demethylated MeHg. THg in plasma was associated with both IHg and MeHg, with large inter-individual variations in the distribution between red blood cells and plasma. THg in hair reflects MeHg exposure at all exposure levels, and not IHg exposure. The small fraction of IHg in hair is most probably emanating from demethylated MeHg. The inter-individual variation in the blood to hair ratio was very large. The variability seemed to decrease with increasing OHg in blood, most probably due to more frequent fish consumption and thereby blood concentrations approaching steady state. THg in urine reflected IHg exposure, also at very low IHg exposure levels. The use of THg concentration in whole blood as a proxy for MeHg exposure will give rise to an overestimation of the MeHg exposure depending on the degree of IHg exposure, why speciation of mercury forms is needed. THg in RBC and hair are suitable proxies for MeHg exposure. Using THg concentration in plasma as a measure of IHg exposure can lead to significant exposure misclassification. THg in urine is a suitable proxy for IHg exposure.

/pdf/inter-individual-variations-of-human-mercury-exposure-1kl1jkxpdh.pdf

Inter-individual variations of human mercury exposure biomarkers: a cross-sectional assessment

Dithiocarbamates Induce Apoptosis in Thymocytes by Raising the Intracellular Level of Redox-active Copper

Cadmium and zinc have been analyzed in tissues from 292 persons autopsied in Stockholm. In kidney cortex, liver, and pancreas the individual cadmium levels are distributed in a lognormal way. In kidney cortex there is a continuous accumulation of cadmium with age up to 50 years, followed by a decrease. Smokers show a higher cadmium accumulation. For nonsmokers, the biological half time of cadmium in kidney cortex is estimated at 30 years, with an average concentration at age 50 of 11 mug/g wet weight. When smokers are included, the average cadmium concentration at age 50 is 22 mug/g wet weight. Based on the more pronounced cadmium accumulation among smokers than nonsmokers, the respiratory absorption rate of cadmium from tobacco smoke is estimated to be approximately 50%.

Cadmium in kidney cortex, liver, and pancreas from Swedish autopsies. Estimation of biological half time in kidney cortex, considering calorie intake and smoking habits.

Longitudinal study of methylmercury and inorganic mercury in blood and urine of pregnant and lactating women, as well as in umbilical cord blood.

Samples from the central nervous system (occipital lobe cortex, cerebellar cortex and ganglia semilunare) and kidney cortex were collected from autopsies and analysed for total mercury content using neutron activation analyses. Results from 34 individuals showed a statistically significant regression between the number of tooth surfaces containing amalgam and concentration of mercury in the occipital lobe cortex (mean 10.9, range 2.4-28.7 ng Hg/g wet weight). The regression equation y = 7.2 + 0.24x has a 95% confidence interval for the regression coefficient of 0.11-0.37. In 9 cases with suspected alcohol abuse mercury levels in the occipital lobe were, in most cases, somewhat lower than expected based on the regression line. The observations may be explained by an inhibition of oxidation of mercury vapour. The regression between amalgams and mercury levels remained after exclusion of these cases. The kidney cortex from 7 amalgam carriers (mean 433, range 48-810 ng Hg/g wet weight) showed on average a significantly higher mercury level than those of 5 amalgam-free individuals (mean 49, range 21-105 ng Hg/g wet weight). In 6 cases analysis of both inorganic and total mercury was carried out. A high proportion (mean 77% SD 17%) of inorganic mercury was found. It is concluded that the cause of the association between amalgam load and accumulation of mercury in tissues is the release of mercury vapour from amalgam fillings.

Birger Lind

Papers

Inter-individual variations of human mercury exposure biomarkers: a cross-sectional assessment

Dithiocarbamates Induce Apoptosis in Thymocytes by Raising the Intracellular Level of Redox-active Copper

Cadmium in kidney cortex, liver, and pancreas from Swedish autopsies. Estimation of biological half time in kidney cortex, considering calorie intake and smoking habits.

Longitudinal study of methylmercury and inorganic mercury in blood and urine of pregnant and lactating women, as well as in umbilical cord blood.

Mercury concentrations in the human brain and kidneys in relation to exposure from dental amalgam fillings.