Endosulfan affects health variables in adult zebrafish (Danio rerio) and induces alterations in larvae development Yohana M. Velasco-Santamaría a, ⁎, Richard D. Handy b , Katherine A. Sloman c a Research Group on Reproduction and Toxicology of Aquatic Organisms (GRITOX), Aquaculture Institute, University of the Llanos, Km 4 vía Puerto López, Villavicencio, Meta, Colombia b School of Biomedical and Biological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK c School of Science, University of the West of Scotland, Paisley, Scotland, PA1 2BE, United Kingdom abstract article info Article history: Received 11 August 2010 Received in revised form 16 January 2011 Accepted 17 January 2011 Available online 22 January 2011 Keywords: Blood cells Chlorinated hydrocarbon insecticide Gill and liver histology Zebrafish Larvae Latent effect Oxidative stress Reproduction Adult zebrafish (Danio rerio) were exposed to 0 (control), 0.16 or 0.48 μg/L of the insecticide, endosulfan, for 28 days. Haematology, whole body ions, thiobarbituric acid reactive substances (TBARS), Na + K + –ATPase, organ histology and reproduction were assessed in adults. The resulting offspring were examined for latent effects on development (heart rate and morphometrics). On day 14, adult fish exposed to 0.16 μg/L endosulfan showed significantly lower red blood cell counts than those exposed to 0.48 μg/L endosulfan; adult fish exposed to 0.16 ug/L also showed elevated TBARS compared to controls. Both concentrations of endosulfan caused a 4.0 fold increase in Na + K + –ATPase activity compared to controls (ANOVA, p b 0.05). On day 14, the livers of fish exposed to endosulfan had fewer, enlarged hepatocytes, with cell diameters greater than the controls (ANOVA, p b 0.05). Morphological alterations in the progeny of fish exposed to endosulfan were observed. Heart beat frequency was significantly lower in larvae from exposed adults to 0.16 μg/L compared to the control (ANOVA, p b 0.05). These findings show that sublethal exposure to endosulfan causes adverse sublethal effects in adult D. rerio, and effects on the development of their offspring. © 2011 Elsevier Inc. All rights reserved. 1. Introduction Endosulfan (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro- 6,9-methano-2,4,3-benzodioxathiepin-3-oxide) is currently the only chlorinated hydrocarbon insecticide used worldwide to treat food crops, as a wood preservative, and in pest control strategies (Capkin et al., 2006; Jonsson and Toledo, 1993a). However owing to its persistence in the environment and toxic effects, endosulfan was classified as a Persistent Organic Pollutant (POPs) during the Stockholm Convention on POPs, supporting the ban on its use and production in several countries (POPRC, 2010). Water contamination can occur through spills, drift, atmospheric transport, field runoff, individual misuse, and improper disposal (Gilliom et al., 2006). Fish are highly sensitive to low (μg/L) concentrations of endosulfan (Jonsson and Toledo, 1993a) and there are several reports of acute toxicity with LC 50 ranging from 0.5 to 20 μg/L (Capkin et al., 2006; Magesh and Kumaraguru, 2006). Endosulfan is known to bioaccumulate in fish, but is also quickly eliminated from the body. For example, after a 21 day exposure, yellow tetra (Hyphessobrycon bifasciatus) and zebrafish (Danio rerio) eliminated more than half their body burden in only 5 days (Jonsson and Toledo, 1993b; Toledo and Jonsson, 1992). The majority of studies of endosulfan toxicity in fish have been carried out using acute exposures. These acute studies have reported histopathological changes in gills leading to respiratory distress and ionoregulatory disturbances (Capkin et al., 2006; Cengiz and Ünlü, 2002; Jonsson and Toledo, 1993a). Liver necrosis (Capkin et al., 2006; Cengiz et al., 2001; Jonsson and Toledo, 1993a; Nowak and Kingsford, 2003), as well as necrosis in haematopoietic tissue and renal tubules of rainbow trout (Oncorhynchus mykiss) has also been observed (Capkin et al., 2006). Endosulfan exposure can cause haematological disturbances, although previous work has reported both reductions (Jenkins et al., 2003) and increases in red blood cell count, haemoglobin and haematocrit (Naidu et al., 1987). Reports on ionic regulation are also varied. In mrigal (Cirrhinus mrigala) exposed to 1.1 μg/L of endosulfan for 96 h, increased sodium concentration in gill and liver tissue along with increased potassium concentration in gill, liver, brain and muscle was observed (Swarup et al., 1981). In contrast to these findings, no effects on sodium, potassium or chloride have been reported in Atlantic salmon (Salmo salar) fed up to 500 μg/kg dietary endosulfan; suggesting that oral exposure may be less toxic (Petri et al., 2006). However, Atlantic salmon fed with 0.005 and 0.05 mg/kg endosulfan showed changes in spleen morphology suggesting an increased effort of the spleen to Comparative Biochemistry and Physiology, Part C 153 (2011) 372–380 ⁎ Corresponding author at: Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark. Tel.: +45 65502760; fax: +45 65502786. E-mail addresses: ymvelasco@yahoo.com, ymvelascos@gmail.com (Y.M. Velasco-Santamaría), r.handy@plymouth.ac.uk (R.D. Handy), katherine.sloman@uws.ac.uk (K.A. Sloman). 1532-0456/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.cbpc.2011.01.001 Contents lists available at ScienceDirect Comparative Biochemistry and Physiology, Part C journal homepage: www.elsevier.com/locate/cbpc