Bioaccumulation, distribution and elimination of lindane in Eisenia foetida: The aging effect

Soil aging will influence the chemical speciation of pesticides, thus affecting the uptake route to be bioavailable to the organism. So far, studies on the possible effects of the uptake route on the distribution and elimination of pesticides in the organism that also considers effects of aging are limited. In our study, Eisenia fetida was exposed to 4.5 mg kg^-1 lindane aging for 0, 30 and 180 d, and the accumulation, distribution and elimination of lindane in the earthworms were analyzed. The results showed that the 6 h Tenax-extracted fraction exhibited a good linear correlation with the lindane accumulated in the earthworms. With aging time increasing, the bioaccumulation of lindane decreased and the accumulative balance was more easily reached in the earthworms. Lindane distributions were found in the whole earthworm and the proportions of lindane content at sub-organism level and the mass distribution of each fraction were similar for 0 d and 180 d aged groups. The foregut accumulated the highest content of lindane (20%) relative to its low mass distribution proportion (10%). The elimination rate of lindane in the earthworms decreased with aging time extending. Our conclusion was that the 6 h Tenax extraction could be used to assess the bioavailability of aging lindane. Although soil aging decreased the bioavailability of lindane, the soil-bound lindane entered the earthworm through dietary route would take longer to depurate from the organisms than free lindane, which implied the potential ecological risk of bound pesticide residues.