Toxicological responses following short-term exposure through gavage feeding or water-borne exposure to Dechlorane Plus in zebrafish (Danio rerio).

Dechlorane Plus (DP) is a chlorinated flame retardant widely used worldwide, and has been reported in environment and humans. However, only limited information is currently available on its toxicity on aquatic organisms. In this study, we employed zebrafish to evaluate possible toxicological responses including oxidative stress and endocrine disruption following exposure to DP. DP was dissolved in corn oil and was delivered to adult male zebrafish via gavage feeding. Delivery of DP was carried out twice on days 0 and 2, at up to 3 μg/g fish wet weight. Body residue level of DP in the fish at day 6 was within a range that has been reported in hot spot areas of China. On day 6, blood, liver, testis, and brain were collected and were evaluated for oxidative damage and endocrine disruption. Following DP exposure, hepatic catalase activity significantly increased, implying its oxidative damage potential. In addition, plasma thyroxine (T4) concentrations increased along with up-regulation of corticotropin releasing hormone and thyroid stimulating hormone β genes in brain. Following DP exposure, transcriptional responses of sex hormone related genes in brain were observed, suggesting possible sex hormone disrupting potentials of DP. However, water-borne exposure to DP up to 267 μg/L among the embryo and larval fish did not show any adverse effects on hatching time and transcription of thyroid hormone related genes. Our observations indicate for the first time that DP disrupts thyroid hormone balance of zebrafish by altering regulatory pathways in the brain. Handling editor: David Volz.