As briefly described in Slide 16, the bioconcentration factor (BCF) can be calculated from the octanol-water partition coefficient K_ow through use of the log-log quantitative structure-activity relationship (QSAR). This is necessarily the case where field and laboratory studies are not feasible. The K_ow-based QSAR approach is apparently the simplest.

Many regulatory agencies have used the K_ow-based QSAR model to estimate BCF, and hence to predict ecological effects and environmental fate of hundreds or thousands of chemicals. An extensive review of such regulatory use can be found in the paper by Cronin et al. (2002). In particular, U.S. EPA has been using the BCFWIN software developed by Syracuse Research Corporation (SRC), as well as other SRC software products, to measure the bioaccumulation factors for many chemicals submitted for marketing approval .

SRC’s BCFWIN program is designed to estimate the BCF of an organic compound using the chemical’s log K_ow. The estimation methodology for this program, which was developed by SRC in conjunction with U.S. EPA, has been described by Meylan et al. (1999). In essence, the log-transformed BCF values that were previously measured for some 694 chemicals, along with other key experimental details, were used to regress against the corresponding log K_ow. And for chemicals with significant deviations from the line of best fit, the correlation was further analyzed by chemical structure. Otherwise, the BCF for the test compound would be predicted from its K_ow by means of the log-log regression. As the name implies, the latest version of BCFWIN now runs under (later versions of) Windows, thus making the estimation of BCF values from this program more convenient and more user-friendly.