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ELEMENTAL SPECIATION IN ENVIRONMENTAL EXPOSURE ASSESSMENT MATRICES
Citation:
Creed, J T., P A. Creed, A N. Parks, C A. Schwegel, M. Fricke, A H. Ackerman, D. T. Heitkemper, AND N. Vela. ELEMENTAL SPECIATION IN ENVIRONMENTAL EXPOSURE ASSESSMENT MATRICES. Presented at Pittcon 2004, Orlando, FL, February 27-March 4, 2005.
Impact/Purpose:
To develop an arsenic speciation protocol for the analysis of dietary components and composite diets in order to provide a more accurate assessment of human exposure to arsenicals.
Description:
Arsenic and tin are two trace metals where exposure assessments have moved towards a speciation based approach because the toxicity is very chemical form dependent. This toxicity difference can be one of many factors which influence the formulation of certain regulations. For arsenic, the drinking water maximum contaminant level is influenced by a wide variety of factors including best available treatment technology, analytical monitoring capability and risk assessments based on health data and relative exposure source estimates. The relative exposure source estimate is used to assess arsenic exposure from all possible routes. Target foods for speciation based exposure assessment can be determined by evaluating food groups high in total arsenic. Two of the key target foods are seafood and rice. Data will be presented on the analysis of these foods with an emphasis on the identification of unknowns and chromatography limitations.
A second concern in formulating drinking water regulation is treatment technology, since the removal efficiency of As(V) is greater than As(III) for most treatment options. Data will be presented using a speciation based analysis to investigate the As(III)/As(V) distribution on drinking water treatment related solids.
Organotins are a potential drinking water issue as PVC pipes (which contain organotins) are increasingly being used to replace the older pipe sections in drinking water distribution systems. Preliminary studies have indicated that PVC pipe initially releases a large percentage of its organotins immediately after being placed into service and the concentration drops off with continued use. This data raises two issues: initial exposure severity and long-term low dose exposure effects of organotins. GC-ICP-MS may provide the means to estimating the low dose exposure to organotins.