Dealing with Uncertainty in Chemical Risk Analysis
Abstract
For a given chemical there are usually several methods for estimating the risk. Each method is based on different assumptions. The arguments are plentiful for each method, but which method best estimates the risk? Choosing one method over another could lead to faulty risk estimates, thus the traditional methods have been very conservative to avoid underestimating the risk. With advances made in pharmacokinetics the EPA as come under pressure to re-evaluate its procedure for assigning risk. Which method or methods should be used and how much emphasis should be placed on each one? This study decomposes the various methods into their corresponding assumptions. A tree diagram is generated to describe the combinations of assumptions that make up each unit risk method. A subjective weight is assigned to each assumption (branch of the tree) to characterize its validity in estimating the risk. From this a weighted average of risk is calculated. A procedure is recommended for combining expert opinion when several experts are utilized in assigning the subjective weights. Two examples involving Methylene Chloride and 2,3,7,8-tetrachlorodibenzo-p-dioxin illustrate the decomposition method of estimating chemical risk. Keywords: Toxicology, Toxic hazards, Tree diagrams, Uncertainty, Chemical risk, Combining subjective probabilities, Carcinogens, Methylene chloride, Dioxin, Unit risk, Theses.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1988
- Accession Number
- ADA206082
Entities
People
- David S. Clement
Organizations
- Air Force Institute of Technology