ABSTRACT
Risk assessments are designed to calculate site, activity, or facility risks for individual chemicals and chemical mixtures. When environmental releases of chemicals or exposures are known or suspected to have occurred, environmental samples can be collected and chemically analyzed to identify and quantitate sample contaminant residue levels. Regardless of where or how an environmental sample is taken and 278its chemical composition analyzed, it must meet defined quality parameters or its usefulness is questionable. Sufficient data of known quality must be used in a risk assessment to ensure that risk assessments properly reflect site, activity, or facility risks. Environmental sample quality assurance and quality control is a major focus of chemists and risk assessors during the planning and early phases of the risk assessment process. U.S. EPA recognized the importance of data quality for risk assessment by noting that its quality assurance program goal is to ensure that all data be scientifically valid, defensible, and of known precision and accuracy to withstand scientific and legal challenge relative to the use for which the data are obtained.
