The toxicokinetic behavior of chlorobenzenes in earthworm (Eisenia andrei) experiments in soil

The toxicokinetic behavior of some chlorobenzenes in earthworms (Eisenia andrei) kept in soil was studied. To determine elimination kinetics, worms were exposed to chlorobenzenes for 7 d, followed by a depuration period of 15 or 35 d. Elimination of chlorobenzenes by earthworms kept in soil was best fitted using a bi-exponential elimination curve. The half-life belonging to the slow phase was in good agreement with measured elimination half-lives for the same compounds by earthworms kept in water. Accumulation of chlorobenzenes in earthworms was studied by exposure over 50 d. Equilibrium was rapidly achieved within 7 d. BAFs based on the concentration in soil and on the concentration in the interstitial water were calculated. BAFs of 1,2,3,4-tetrachlorobenzene and pentachlorobenzene in earthworms kept in soil and BCFs in earthworms kept in water were comparable, demonstrating that uptake proceeds mainly via the interstitial water. For hexachlorobenzene, the BAF was much larger than the BCF, which suggests that intestinal uptake for this compound is an important complementary route.