Aquatic Toxicology 140–141 (2013) 213–219 Contents lists available at SciVerse ScienceDirect Aquatic Toxicology jou rn al hom ep age: www.elsevier.com/locate/aquatox Sublethal effects of the flame retardant intermediate hexachlorocyclopentadiene (HCCPD) on the gene transcription and protein activity of Daphnia magna Magali Houde a,∗ , Barbara Carter b , Mélanie Douville a a Environment Canada, Centre Saint-Laurent, 105 McGill Street, Montreal, QC, Canada H2Y 2E7 b Applied Food Technologies, Inc., 12085 Research Drive, Alachua, FL 32615, USA a r t i c l e i n f o Article history: Received 5 April 2013 Received in revised form 7 June 2013 Accepted 8 June 2013 Keywords: Hexachlorocyclopentadiene Daphnia magna Gene transcription Enzyme activity Life-history endpoints a b s t r a c t Hexachlorocyclopentadiene (HCCPD) is a chlorinated chemical of high production volume used as an intermediate in the production of flame retardants. HCCPD may be released to the environment during production, use, and as a result of product degradation. The objectives of this study were to evalu- ate sublethal effects of HCCPD exposure to Daphnia magna at environmentally relevant concentrations (0.0138–13.8 g/L) using genomic tools (microarray and qPCR), enzyme activities, and life-history end- points (survival, reproduction, and growth). In chronic exposures, no differences were observed in life-history endpoints (survival, time of first brood, time of first molt, molt frequency, number of neonates, and body length) between exposed organisms and controls. Microarray analyses indicated significant dif- ferential genomic transcription for 46 genes (p-value ≤ 0.05 and fold-change > 2). Five identified genes were related to metabolic functions. Enzyme activities of -amylase and trypsin, selected based on transcriptional responses, were evaluated in D. magna. Although trypsin activity was similar between treatments and controls, the activity of -amylase significantly decreased with increasing HCCPD concen- trations. On the chemical level, instability of HCCPD was observed in spiked culture media, most probably due to photolysis and biodegradation. HCCPD was not detected in surface water samples collected upstream and at the point of discharge of a major wastewater treatment plant effluent. Environmen- tally, rapid degradation of HCCPD could be outdone by its continuous release into aquatic ecosystems in specific areas of concern (e.g., vicinity of industries and hazardous sites). Toxicity results from this study highlight the use of genomics in the identification of biomarkers and help advance the science, and potential use, of multi-level biological approaches for environmental risk assessment. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved. 1. Introduction Hexachlorocyclopentadiene (HCCPD) is an anthropogenic chlo- rinated hydrocarbon. It was a key intermediate in the production of chlorinated cyclodiene pesticides, including dieldrin, chlordane, heptachlor, endosulfan, and mirex before the ban or phase-out of these chemicals in North America. The decreased use of HCCPD in pesticides has been offset by the increase of its integration in flame retardants for use in the wire and cable industry. HCCPD is presently used as an intermediate in the manufacture of flame retardants such as Dechloranes (Dechlorane Plus, Dec-602, -603, -604, Chlordane Plus) (Sverko et al., 2011) and chlorendic anhy- dride used in polyester resins and plasticizers. Dechlorane Plus ∗ Corresponding author. Tel.: +1 514 496 6774; fax: +1 514 496 7398. E-mail addresses: magali.houde@ec.gc.ca (M. Houde), bcarter@appliedfoodtechnologies.com (B. Carter), melanie.douville@ec.gc.ca (M. Douville). (DP) is a high production volume flame retardant, considered as a replacement for certain regulated polybrominated biphenyl ethers. HCCPD has been identified as a chemical of concern and pre- dicted to be among the most persistent and bioaccumulative chemicals in current use at high production volume according to Muir and Howard (2006). The authors used a database approach to arrive at this conclusion, integrating physical and chemical property values estimated for thousands of chemicals includ- ing organic compounds from the Canadian Domestic Substance List and the U.S. EPA Toxic Substances Control Act Inventory Update Rule. HCCPD has been listed on the OECD (2004) list of high production volume chemicals and the EPA priority pollutant list (http://water.epa.gov/scitech/methods/cwa/pollutants.cfm). It has also been classified as a substance with long range atmo- spheric transport potential (Muir and Howard, 2006) and suggested as a chemical of consideration for further studies (Howard and Muir, 2010). The partition octanol–water coefficient (log Kow) of HCCPD is estimated between 3.99 and 5.51 (Wolfe et al., 1982; European Union, 2007) suggesting bioconcentration potential for 0166-445X/$ – see front matter. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.aquatox.2013.06.008