Short-term effects of Dechlorane Plus on the earthworm Eisenia fetida determined by a systems biology approach

Dechlorane Plus (DP), a chlorinated flame retardant, has been widely detected in environmental matrices, especially in sediment and soil. DP has characteristics similar to persistent organic pollutants. However, no toxicity data of DP on terrestrial invertebrate are available. In this study, earthworms Eisenia fetida were exposed to 0.1, 1, 10, and 50mg/kg DP for 14 days. Lethality, oxidative stress and damage, neurotoxicity, and transcriptomic profiles of E. fetida were assessed on day 7 and day 14 of exposure. Results showed that the acute toxicity of DP was very low. However, DP exposure induced an increase in the oxidative stress markers malonaldehyde (MDA) and 8-Hydroxy-2'-deoxyguanosine (8-OHdG), and altered acetylcholinesterase (AChE) activities. High throughput sequencing-based transcriptomic analysis showed that DP exposure significantly altered gene expression and pathways related to antioxidant enzymes, stress responses, neurological dysfunctions, calcium binding, and signal transduction. The results from different toxicological endpoints indicate that DP toxicity on the earthworm is primarily through oxidative damage and neurotoxicity. 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.