Risk Characterization
In the overall scope of the reading I found the overall process by which risk is characterized to be the most fascinating. Although the Exposure Assessment is very useful it can at times be a little much due to the fact that it investigates every facet of possible exposure. This includes routes where there might be little to no risk whatsoever. The Risk Characterization looks at the big picture and illustrates where the highest risks are and the exposure channel that it follows.
According to Dow Chemical, “Risk characterization combines the results of hazard identification and exposure assessments to describe the probability and severity of adverse health or environmental effects.” (http://www.dow.com/productsafety/assess/risk_char.htm) In a sense it integrates the other three levels of the human health risk assessment, it brings all the pieces of the puzzle together.
In the overall scope of the reading I found the overall process by which risk is characterized to be the most fascinating. Although the Exposure Assessment is very useful it can at times be a little much due to the fact that it investigates every facet of possible exposure. This includes routes where there might be little to no risk whatsoever. The Risk Characterization looks at the big picture and illustrates where the highest risks are and the exposure channel that it follows.
According to Dow Chemical, “Risk characterization combines the results of hazard identification and exposure assessments to describe the probability and severity of adverse health or environmental effects.” (http://www.dow.com/productsafety/assess/risk_char.htm) In a sense it integrates the other three levels of the human health risk assessment, it brings all the pieces of the puzzle together.
Steps of Risk Characterization
1) The first step within a risk characterization is to estimate the overall risk level from both carcinogenic and non-carcinogenic materials. Carcinogenic risks are defined by LaGrega as, “the chronic daily intake dose (developed in the exposure assessment) multiplied by the carcinogenic slope factor (selected from the toxicity assessment). The result from this computation is the estimated risk for developing cancer from the chemical in question. In regards to non-carcinogenic materials there is a utilization of the hazard index which is the ratio of the estimated intake dose over the reference concentration which is measured on site. There is also an addition of a measurement of background risk which is the risk that would be left over even after remediation.
2) The second step of risk characterization, according to the EPA, is to describe the risk and in a sense provide a discussion that would logically support the estimated numbers. Numbers do not mean a whole lot on their own and as a result they need to be explained. In describing the risks it is necessary to either support or refute the quantitative evidence, very similar to a discussion on a scientific experiment. By discussing he evidence it presents a level of subjective certainty in an otherwise uncertain realm. According to the EPA there are three criteria that need to be accounted for when discussing the changes that need to be made. The first is how might the risk impact nature and what would be the intensity of the post effects. The next criteria is to view the area from a spatial point of view, as such how much area is going to be affected? The last criteria is what is the potential for an area to recover? This is extremely important in regards to remediation methods and whether or not there will be a lasting impact.
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