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Activity Number:
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353
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Type:
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Contributed
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Date/Time:
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Wednesday, August 14, 2002 : 2:00 PM to 3:50 PM
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Sponsor:
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Section on Statistics & the Environment*
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| Abstract - #301511 |
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Title:
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Cumulative Risk Assessment for Quantitative Response Data
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Author(s):
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James Chen*+
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Affiliation(s):
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National Center for Toxicological Research
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Address:
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3900 NCTR Road, Jefferson, Arkansas, 72079, United States of America
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Keywords:
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Chemical mixtures ; Classification tree ; Point of departure ; Relative potency factor ; Similar action
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Abstract:
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The Relative Potency Factor approach (RPF) is used to normalize and combine different toxic potencies among a group of chemicals selected for cumulative risk assessment. The RPF method assumes that the slopes of the dose response functions are all equal; but this method depends on the choice of the index chemical, i.e., different index chemicals will give different predicted mean estimates. This paper proposes a procedure for cumulative risk assessment from exposure to multiple chemicals that have a common mechanism of toxicity. We propose two classification algorithms to cluster the chemicals into subclasses such that the chemicals in the same subclass have a common slope. The joint response is estimated by fitting the dose response model of the mixture under dose addition. The proposed method will give the same predicted mean response regardless of the selection of the index chemical for the chemicals in the same subclass. The proposed method also allows one to estimate the joint response for chemicals having different slopes. An example data set of six hypothetical pesticide chemicals is used to illustrate the proposed procedure.
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