DIETARY ACCUMULATION AND DEPURATION OF HYDROPHOBIC ORGANOCHLORINES - BIOACCUMULATION PARAMETERS AND THEIR RELATIONSHIP WITH THE OCTANOL WATER PARTITION-COEFFICIENT/

Dietary accumulation of 23 hydrophobic organochlorines (OCs) by juveni le rainbow trout (Oncorhynchus mykiss) was studied with the objective of obtaining relationships between bioaccumulation parameters and the octanol/water partition coefficient (K-ow). A wide range of OCs were u sed including 16 polychlorinated biphenyls (PCBs 18, 28, 44, 52, 66, 1 01, 105, 118, 128, 138, 153, 187, 189, 195, 206, and 209), hexachlorob enzene, mirex, tris(4-chlorophenyl)methane (TCPMe), tris(4-chloropheny l)methanol (TCPMeOH), and three toxaphene congeners (Cl-7-chlorobornan e [CHB] [Hp-sed], Cl-8-CHB [T2], and Cl-9-CHB [T12]). Tris(4-chlorophe nyl )methane (half-life [t(1/2)] = 65 d) was more persistent than TCPM eOH (t(1/2) = 20 d), and TCPMe was not blot transformed to TCPMeOH by rainbow trout. Cl-7-chlorobornane (t(1/2) = 32 d) was more rapidly eli minated, and appears to be more readily metabolized, than Cl8CHB (t(1/ 2) = 43 d) and Cl-9-CHB (t(1/2) = 42 d). With the exception of TCPMeOH , Cl-7-CHB, and PCB 18. all of the OCs had biomagnification factors (B MFs) >1, implying a potential to biomagnify. Half-lives had a signific ant curvilinear relationship with K-ow. (R-2 = 0.85, p < 0.001), with a maximum t(1/2) for OCs with log K-ow similar to 7.0. Decreasing t(1/ 2) for OCs of log K-ow > 7.0 may be related to slow kinetics of these super hydrophobic OCs and the short exposure phase, which results in i nsufficient time for the super hydrophobic OCs to reach slower clearin g compartments of the rainbow trout. Assimilation efficiency was not a s well described by K-ow as by t(1/2) and BMF, although a significant curvilinear relationship was observed (R-2 = 0.53, p = 0.004). The BMF had a significant curvilinear relationship with log K-ow (R-2 = 0.84. p < 0.001). Recalcitrant OCs with a log K-ow of similar to 7.0 would appear to have the greatest potential for food chain biomagnification in fish.