Low toxic herbicide Roundup induces mild oxidative stress in goldfish tissues Oleh V. Lushchak a , Olha I. Kubrak a , Janet M. Storey b , Kenneth B. Storey b , Volodymyr I. Lushchak a, * a Department of Biochemistry, Precarpathian National University named after Vassyl Stefanyk, 57 Shevchenko Str., Ivano-Frankivsk 76025, Ukraine b Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6 article info Article history: Received 14 February 2009 Received in revised form 16 April 2009 Accepted 19 April 2009 Available online 17 May 2009 Keywords: Goldfish Roundup Oxidative stress Antioxidant enzymes abstract The formulation of Roundup consists of the herbicide glyphosate as the active ingredient with polyethox- ylene amine added as a surfactant. The acute toxicity of Roundup (particularly of glyphosate) to animals is considered to be low according to the World Health Organization, but the extensive use of Roundup may still cause environmental problems with negative impact on wildlife, particularly in an aquatic envi- ronment where chemicals may persist for a long time. Therefore, we studied the effects of Roundup on markers of oxidative stress and antioxidant defense in goldfish, Carassius auratus. The fish were given 96 h exposure to Roundup at concentrations of 2.5–20 mg L 1 . Exposure to Roundup did not affect levels of lipid peroxides (LOOH) in goldfish brain or liver, and in kidney only the 10 mg L 1 treatment elevated LOOH by 3.2-fold. Herbicide exposure also had no effect on the concentrations of protein thiols or low molecular mass thiols in kidney, but selective suppression of low molecular mass thiols by 26–29% occurred at some treatment levels in brain and liver. Roundup exposure generally suppressed the activ- ities of superoxide dismutase (SOD), glutathione S-transferase (GST), glutathione reductase and glucose- 6-phosphate dehydrogenase in fish tissues. For example, SOD activities were reduced by 51–68% in brain, 58–67% in liver and 33–53% in kidney of Roundup treated fish. GST activity decreased by 29–34% in liver. However, catalase activity increased in both liver and kidney of herbicide-exposed fish. To our knowledge this is the first study to demonstrate a systematic response by the antioxidant systems of fish to Roundup exposure. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Herbicides are actively used in terrestrial and aquatic ecosys- tems to control unwanted weeds, and their use has generated seri- ous concerns about the potential adverse effects of these chemicals on the environment and human health. In many European estuar- ies, pesticide concentrations are higher than European norms which have to be lower than 0.1 lgL 1 for individual pesticide concentrations and total pesticide concentrations should be below 0.5 lgL 1 (Marchand et al., 2006). Several studies found that total pesticide concentrations were particularly high in Germany in the Rhine (2 lgL 1 ), the Elbe (0.9 lgL 1 ), the Weser (3.2 lgL 1 ), and the Ems (2.3 lgL 1 ) and were also high in France, especially in the Vilaine estuary (0.1–2.5 lgL 1 ) (cited after Marchand et al., 2006). In the United States of America 100% of all water surfaces, 33% of major aquifers, and 96% of all fish contained one or more pesticides at detectable levels (Nowell et al., 1999). Pesticides were identified as one of the leading cases of impairment for streams and one potential cause of declines and deformities among amphibians, pollinator species, and other beneficial insects. Several herbicides used including atrazine, diuron, isoproturon and the glyphosate-based herbicide, Roundup, are widely detected in Euro- pean ecosystems (Quaghebeur et al., 2004). The use of glyphosate (N-phosphoromethyl glycine) as a herbi- cide was first proposed by scientists at the Monsanto Company in 1970. It is a nonselective herbicide that inhibits plant growth through interference with the production of essential aromatic amino acids by inhibiting the enzyme enolpyruvylshikimate phos- phate synthase. This enzyme is responsible for the biosynthesis of chorismate, an intermediate in phenylalanine, tyrosine, and tryp- tophan biosynthesis (Williams et al., 2000). Glyphosate expresses its herbicidal activity most efficiently through direct contact with leaves, followed by translocation to other organs. Absorption via roots is negligible. In ecological systems glyphosate is degraded mainly by bacteria, but plants do this to small extent (Karpouzas and Singh, 2006). The Roundup formulation was proposed in 1974 and contained glyphosate as the active ingredient with polye- thoxylene amine (POEA), a non-ionic surfactant, added to increase the efficiency of the active ingredients by promoting the penetra- tion of the herbicide through plant cuticle (Brausch and Smith, 2007). The extensive use of Roundup on crops may cause environmen- tal problems with a negative impact on wildlife. The acute toxicity of Roundup (particularly glyphosate) is considered to be low, according to data from the World Health Organization (WHO, 0045-6535/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2009.04.045 * Corresponding author. Tel./fax: +38 0342 714683. E-mail address: lushchak@pu.if.ua (V.I. Lushchak). Chemosphere 76 (2009) 932–937 Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere