The use of the bivalve Mytilus edulis as a test organism for bioconcentration studies. I. Designing a continuous-flow system and its application to some organochlorine compounds

Abstract Most bioconcentration studies have previously been carried out using fish as a test organism. Equally important is the use of bivalves for this purpose, from both an ecological and an economic point of view. A continuous-flow system has thus been designed for use also with extremely hydrophobic substances and evaluated using 2,4′,5-trichlorobiphenyl, methoxychlor, pentachlorobenzene, and lindane. The variation of the uptake in the individuals after 3 weeks' exposure was quite small (relative standard errors varied from 10.1 to 15.3% depending on the test substance), indicating a high degree of reproducibility. The bivalves, however, are known to close their valves under unfavorable conditions, which occasionally may bias the results. To overcome this disadvantage, it is suggested that an internal standard—i.e., a chemically defined compound—be added to the water simultaneously with the test substances. Although there is a principal risk for interactive effects, unexpected variations in the uptake can thus be compensated for by relating the concentration of the test substance to the concentration of the internal standard in the organisms. Comparisons between continuous-flow systems and static systems have also been made. It is concluded that continuous-flow systems are more suitable for studying hydrophobic compounds than static systems.