Biological assessment methods biomarkers

Methods for Determining Biomarkers of Exposure and Effect. Analytical methods with satisfactory sensitivity and precision are available to determine the levels of americium in human tissues and body fluids. However, improved methods are needed to assess the biological effects of americium in tissues. 

The effects of the appropriate environmental matrices (soil, water, air, biological - for biomarker or exposure assessment studies) on assay performance must be well characterized and documented. The SOP must also include the degree of quality control necessary to ensure the satisfactory performance of the method. Quality control procedures must address the required sample preparation steps, reagent stability, instrumentation, data handling and analysis. In many immunoassay SOPs that the EPA has reviewed, quality control is totally lacking or minimally addressed particularly for the sample preparations. The Agency can provide direction on what is an appropriate degree of quality control based on the objective of the method. 

No specific biomarkers of effect have been exclusively associated with carbon disulfide exposure. Some biological parameters, e.g., decreased nerve conduction velocity and changes in lipid metabolism, have been tentatively linked to carbon disulfide exposure, but there are insufficient data with which to assess the analytical methods associated with measurement of these potential biomarkers. Further investigations into these potential biomarkers, in conjunction with improvements in their detection methods might aid in establishing reliable biomarkers of effect for carbon disulfide. 

Although several biomarkers for the effects of zinc have been identified (increased levels of serum amylases and lipase, non-iron responsive anemia, and decreased HDL cholesterol levels), these biomarkers of effect are not specific for zinc (Cotran et al. 1989 Suber 1989). Standard laboratory tests are available that can measure these biomarkers (Henry 1984). These methods are sensitive, accurate, and reliable enough to measure background levels in the population and levels at which biological effects occur. The development of methods for determining biomarkers of effect specific for zinc would be beneficial in assessing whether an individual has been exposed to zinc. 

Biological monitoring (aka biomonitoring) is another method for assessing chemical exposure. " This is not a new technique it has been around for a long time but in recent years it has become an important tool for assessing exposure to environmental chemicals. This approach involves measuring parent chemicals, their metabolites, adducts, or other biomarkers of exposure in human specimens such as blood, serum, plasma, urine, or other human tissues or fluids. 

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