Effects of exposure to soluble fraction of industrial solid waste on lipid peroxidation and DNA methylation in erythrocytes of Oreochromis niloticus, as assessed by quantification of MDA and m 5 dC rates Letı ´cia Flohr, Cristiane Funghetto Fuzinatto, Sı ´lvia Pedroso Melegari, William Gerson Matias n Laborato ´rio de Toxicologia Ambiental, LABTOX, Depto. de Engenharia Sanita ´ria e Ambiental, Universidade Federal de Santa Catarina, Campus Universita ´rio, CEP: 88040-970, Caixa Postal 476, Floriano ´polis, SC, Brasil article info Article history: Received 15 August 2011 Received in revised form 4 October 2011 Accepted 12 October 2011 Available online 1 November 2011 Keywords: Lipid peroxidation DNA methylation Industrial solid waste Oreochromis niloticus abstract In this study, lipid peroxidation and DNA methylation were observed in erythrocytes of Oreochromis niloticus exposed to soluble fractions of textile, metal–mechanic and pulp and paper industrial waste, after a period of 48 h. Lipid peroxidation was quantified by the rate of malondialdehyde (MDA) and DNA methylation was quantified by the rate of 5-methyldeoxycytosine (m 5 dC). Soluble fractions of textile industrial waste caused metabolic changes for all studied samples. In organisms exposed to samples TX1 and TX2 (textile waste) MDA rates were 132.36 and 140.28 nM MDA/mg protein, respectively, while in control organism the MDA rates were 27.5 nM MDA/mg protein. All samples from soluble fractions of textile industrial waste induced increases in m 5 dC rates, increases varied between 300 percent and 700 percent when compared to the control organism. All the organisms exposed to soluble fractions of metal–mechanic industrial waste presented increases between 360 percent and 600 percent in the rates of MDA, and one of them (sample MM3) induced an increase of 180 percent in the rate of m 5 dC, when compared to control. Although a significant increase was not observed in the MDA rate of fish exposed to the soluble fractions of pulp and paper industrial waste, there was an increase of 460 percent in the rate of m 5 dC in one of the samples (sample PP2), when compared to control. The results showed that the soluble fractions of these industrial wastes are capable of inducing oxidative damage and altering the DNA methylation of O. niloticus. Thus, the MDA and m 5 dC rates demonstrated to be effective biomarkers of exposure, which could be used to evaluate the toxicity of soluble fractions of industrial solid waste. & 2011 Elsevier Inc. All rights reserved. 1. Introduction Santa Catarina is a state in southern Brazil, which has a strong industrial activity, and sectors like textile, metal–mechanic, and pulp and paper are relevant to the local economy (FIESC, 2010). Industrial activity in these sectors generates solid waste and effluents with toxic potential. This, coupled with the lack of initiatives to protect the environment increases the risk of environmental problems, especially in water bodies that receive untreated industrial effluent or leachate from improperly dis- posed industrial waste. Effluents and industrial solid waste are complex mixtures, composed mainly of heavy metal, trace ele- ments, dioxins, furans, phenols, chlorides and cyanides (Ali and Sreekrishnan, 2001; Sisinno, 2003). The mere presence of a contaminant in the aquatic environment is not indicative of adverse effects due to the synergism between molecules and chemical interactions with the organisms, and an assessment of complex mixtures without an ecotoxicological characterization is not adequate to predict the potential effects on the environment (Van der Oost et al., 2003; Picado et al., 2008). Thus, the study of water pollution can be performed on fish, since these organisms can accumulate pollutants through contact with chemicals pre- sent in water or by eating organisms that accumulate pollutants (Al-Sabti, 1995; Hanson and Larsson, 2011). In fish, the effects of exposure to pollutants can be measured by using biomarkers such as malondialdehyde (MDA), which indicates the process of lipid peroxidation (Bacchetta et al., 2010; Garcia-Medina et al., 2010) and 5-methyldeoxycytosine (m 5 dC), which indicates changes in DNA methylation (Shugart, 1990, 2000; Aniagu et al., 2008). Lipid peroxidation can be described as a degenerative process, generated by an oxidative stress that causes damage to the function of cell membranes, such as a change in their integrity and an increase of their permeability (Storey, 1996; Girotti, 1998; Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/ecoenv Ecotoxicology and Environmental Safety 0147-6513/$ - see front matter & 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.ecoenv.2011.10.016 Abbreviations: dC, deoxycytosine; m 5 dC, 5-methyldeoxycytosine; MDA, malondialdehyde n Corresponding author. Fax: þ55 48 3721 9823. E-mail address: will@ens.ufsc.br (W.G. Matias). Ecotoxicology and Environmental Safety 76 (2012) 63–70