Indicator contaminants case study examples

A concrete example relates to the environmental levels of e.g. PCB, dioxin, pesticides or mercury, or air contamination including small particles. These have been associated with impaired perception, intelligence and mobility in children, entailing impaired earning ability and enhanced social inequity. Several case studies have indicated a loss of around 5 IQ points in a population due to hazardous chemicals, which might mean about a 10% loss of income or about the same loss of worker productivity (Trasande et al. 2005, IFCS 2003a). 

Using these examples, and the case study from the Aspo Hard Rock Laboratory, we summarize two linked principles for the redox-related performance of sub-surface repositories and the risk posed by wastes in the geosphere. Redox potentials need to be considered as critical thresholds for many controlling processes corrosion of engineered barriers, solubility and sorption of metals and attenuation of organic contaminants through biodegradation. Redox capacities, on the other hand, indicate the total amount of reductants or oxidants required to maintain redox conditions above or below these critical thresholds for performance and risk. 

Samples Obtained from Biological Fluids As illustrated in Figure 5.1, biological fluids, which also have two compartments, are placed in group I. Such fluids include blood (often classified as a tissue), urine, semen, tears, and saliva. Many of these fluids contain cells as a normal component, while in others the cells represent a contamination. Fluids like saliva that contact the outside and, when collected, often contain microbes, are examples of contaminated materials. Sometimes such microbes are the result of the collection procedure, and their numbers can often be controlled by careful technique. At other times, as is the case with urine, their presence can indicate an underlying disease process. In any case, the study of enzymes from such fluids again requires the separation of the two compartments. 

There are examples of physical and chemical indices in water quality studies, with which a sample is classified and later compared with control values/sites to establish its own quality. Even though the use of these physicochemical indices is attractive, it should be remembered that they use sets of parameters that, in many cases, may not even include the main contaminant (toxicant). The resulting value may not show any type of hazard because it does not include the substance under investigation (Pratt et al., 1971). 

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