Monitoring statistics site specificity

From the above example, it is apparent that the statistical approach is not generally practical for exposure assessment of new chemicals due to the site-specific nature of the analysis and the time and money required for monitoring. This is not to detract from the value of this approach for the detailed study of selected existing chemicals and validation of kinetics/rates models and model ecosystem studies. 

Since temporary relocation may involve large numbers of individuals and substantial time periods as well as large zones, large sets of results from environmental monitoring that yield adequate statistics should be obtained. Such large sets of data and the use of realistic site specific models rather than conservative generic models would enable the overall uncertainties in the dose assessment to be substantially reduced. 

Principal Component Analysis (PCA) is performed on a human monitoring data base to assess its ability to identify relationships between variables and to assess the overall quality of the data. The analysis uncovers two unusual events that led to further investigation of the data. One, unusually high levels of chlordane related compounds were observed at one specific collection site. Two, a programming error is uncovered. Both events had gone unnoticed after conventional univariate statistical techniques were applied. These results Illustrate the usefulness of PCA in the reduction of multi-dimensioned data bases to allow for the visual inspection of data in a two dimensional plot. 

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