Comprehensive Toxicity Study Of Dechlorane Plus On The Earthworm Eisenia Fetida

Dechlorane Plus (DP), a chlorinated flame retardant, has been widely detected inenvironmental matrices, especially in sediment and soil. The results show that DP has the similar characteristics of persistent organic pollutants (POPs), such as long-distance transmission, biological enrichment nature and the refractory. However, data on potential toxicological and molecular responses to exposure are lacking, especially for terrestrial invertebrate. In this study, we use earthworms Eisenia fetida(E. fetida) as testing organisum, which were exposed to0.1,1,10, and50mg/kg DP for14days, investigated the biotoxicity of DP via the individuals, organizations, molecular and gene levels and so on. The main findings were as follows:In acute toxicity study, E. fetida was exposed to different doses of DP for14d (up to50mg/kg). No obvious dose-dependent effect was appeared. DP showed low toxicity to E.fetida.Effects of DP on E. fetida by Superoxide Dismutase (SOD) enzyme activity and contents of Glutathfone (GSH) have been studied. The results showed that the activities of SOD and GSH had been induced when E. fetida was exposed in DP in7d. The activity of SOD and GSH had been inhibited when E.fetida was exposed in DP in14d. It was implied that E.fetida was in a positive state of defense in7d, and the antioxidant system had the trend of damage in14d. But the changes were not significant. Two types of oxidative damage for lip ids and nucleic acids were characterized by the measurement of Malondialdehyde (MDA) and8-Hydroxy-2-deoxyguanosine (8-OHdG), respectively. In the high exposure group, significant increases of MDA were found after7-d and14-d exposure. For the8-OHdG, the level increased on day7, but decreased on day14. It was suggested that high concentration of DP and long exposure time can induce an obvious oxidative damage on E.fetida.The results showed that a7-day exposure of DP significantly increased Acetylcholinesterase (AChE) levels. On day14, the AChE activities were inhibited in two high-concentration groups. It is known that AChE is a key enzyme in the biological neural conduction and performs important functions in neurotrans mission. The changes of AChE activities induced by DP indicated that DP exposure could cause neurotoxicity.The results of the comet assay showed high concentration of DP and long exposure time can induce a significant genotoxic effects on E.fetida.Ultrastructure of the skin in earthworm was examined at14-day exposure of DP. The results showed that mitochondrials in the skin changed differently at different concentrations of DP. It was suggested that DP may accumulate in earthworm body through the skin and induce an obvious damage on E. fetida.Based on these results, we deduce that changes in oxidative stress and neurotoxicity might be the primary mechanisms of DP toxicity. This study provides insight into the toxicological effects of DP on earthworm model, and may be useful for risk assessment of DP on soil ecosystems.