Bioconcentration of organic chemicals: is a solid phase microextraction fiber a good surrogate for biota?

When organic chemicals are extracted from a water sample with solid-phase microextraction (SPME) fibers, the resulting concentrations in exposed fibers are proportional to the hydrophobicity of the compounds. This fiber accumulation is analogous to the bioconcentration of chemicals observed in aquatic organisms. The objective of this study was to investigate the prospect of measuring the total concentration in SPME fibers to estimate the total body residue in biota for the purpose of risk assessment. Using larvae of the midge, Chironomus riparius and disposable 15-μm poly(dimethylsiloxane) fibers, we studied the accumulation and accumulation kinetics of a number of narcotic compounds with a range of log Kow between 3 and 6. The fibers, which have a larger surface area-to-volume ratio, had consistently higher uptake and elimination rate constants (k1 and k2, respectively) than midge larvae and accumulated the chemicals 5 times faster. Comparison of the relationships of the partition coefficients KPDMS-wate...