W1 AM Nuts and Bolts of Logistics and Data Management for Data-Intensive Programs
Wednesday, 16 November 2005: 8:00 AM - 11:40 AM in Ballroom 1

(LIN-1117-829225) Uncertainty and variability in publicly available log Kow data: sources and consequences.

Satterstrom, F¹, Ames, M¹, Crouch, E¹, Linkov, I¹, ¹ Cambridge Environmental Inc., Cambridge, MA 02141, USA

ABSTRACT- Ecological and human health risk assessment at chemically contaminated sites requires a variety of physical and chemical properties for each compound of concern, including chemical transport, fate, and toxicity data. Small parameter differences may significantly alter estimated ecological or human health risks and also the extent and cost of recommended remediation efforts. The octanol-water partition coefficient (Kow) for hydrophobic organic compounds is a particularly important property because it is often used to estimate partitioning and bioaccumulation parameters. Unfortunately, publicly available databases of basic environmental physical-chemical properties contain considerable variability among tabulated Kow values for many compounds. We take the range of Kow values for polychlorinated biphenyls (PCBs) available from or recommended by the U.S. EPA during the spring of 2004 and estimates relative contribution of major factors to their uncertainty and variability. We found that the variation among measured Kow values due to such effects as variable congener distributions within a specific Aroclor, varying amounts of octanol and water used in the measurement, and temperature dependance are relatively insignificant (less than one log unit). The bulk of the variability among reported measurements is likely due to data quality issues (specific examples were uncovered in publicly available databases). We also assessed the implications of using various values of Kow to calculate health-protective sediment quality objectives (SQOs) in a case study using a simplified food chain model. For the site and Kow values considered in this study, the SQOs differ by as much as a factor of five, and this range of SQOs is estimated to correspond to a difference in remediation costs of $48 million. These results underscore the need for review of the quality and consistency of currently available chemical property data.

Key words: Key words: octanol-water partition coefficient, Kow, uncertainty and variability, data quality