Oxidative stress in benthic oligochaete worm, Tubifex tubifex induced by sublethal exposure to a cationic surfactant cetylpyridinium chloride and an anionic surfactant sodium dodecyl sulfate

Highlights

• The potential toxic effects of a cationic surfactant, cetylpyridinium chloride (CPC), and an anionic surfactant, sodium dodecyl sulfate (SDS) were investigated in benthic oligochaete worm, Tubifex tubifex.

• Exposure to CPC and SDS altered the activities of oxidative stress biomarkers in Tubifex tubifex.

• Incongruous disposal of these surfactants in water bodies could serve as a potential threat to aquatic health.

Abstract

The present study was assessed to determine the in vivo toxic effects of a cationic surfactant, cetylpyridinium chloride (CPC), and an anionic surfactant, sodium dodecyl sulfate (SDS) in terms of oxidative stress biomarkers in benthic oligochaete worm Tubifex tubifex for 14 days. The investigation demonstrated that sublethal concentrations of CPC (0.0213, and 0.0639 mg L⁻¹) and SDS (1.094 and 3.092 mg L⁻¹)induced paramount alterations in the oxidative stress enzymes in Tubifex tubifex. Superoxide dismutase (SOD), glutathione S-transferase (GST), reduced glutathione (GSH), and glutathione peroxidase (GPx) exhibited an initial notable increase in their activities in the surfactants exposed worms at 1d and 7d of exposure period followed by consequential reduction at 14d exposure period with respect to control, while catalase (CAT) and malondialdehyde (MDA) activities markedly incremented gradually throughout the exposure periods. Through the construction of the correlation matrix and integrated biomarker response (IBR), the effects of CPC and SDS on Tubifex tubifex were distinguished. These results indicate that exposure to these cationic and anionic surfactants modulates the levels of oxidative stress enzymes in Tubifex tubifex.

Introduction

Nowadays water pollution is becoming a substantial threat to global ecosystems (Mareddy 2017). The significant and potential pollution sources for surface and groundwater in many advanced countries are household and industrial wastewaters (Jardak et al. 2016). The outrageously high utilization of detergents by households for washing and cleaning purposes and the subsequent drainage of water in localized water bodies has exacerbated imbalances in the aquatic ecosystem and has given rise to substantial public attention worldwide in recent decades (Goel and Kaur 2012). One of the chief constituents of popular household detergents, used for washing, cleaning, and bathing, are surfactants (Steber 2007). Surfactants are a diversified group of chemical compounds with hydrophobic and hydrophilic sites and are crucial for the solubilization of organic contaminants (Lechuga et al. 2016). The inordinate discharge of surfactant into the aquatic environment causes considerable damage to biological systems (Rosety-Rodríguez et al. 2002). The global consumption of surfactants increases every year and its global production is expected to reach US$ 28.8 billion until 2023, which attests to its importance in daily life (Kaczerewska et al. 2020). Though most surfactants are degradable, their consistent use and incongruous disposal in surface waters lead to persistent occurrence within the aquatic ecosystem (Mustapha and Bawa-Allah 2020). Many surfactants exert toxicity by affixing them to macromolecules in a biological system and modifying their efficacious functioning (Ivanković and Hrenović 2010). The surfactants are grouped comprehensively into anionic, nonionic, cationic, and zwitterionic surfactants (Jackson et al. 2016). Approximately 65% of total production conforms to compounds classified as anionic surfactants, while the second and third places in global production correspond to cationic and nonionic surfactants, respectively (Olkowska et al. 2014). The most frequently used active ingredients in household cleaners and laundry detergents are anionic and cationic surfactants (Ranji et al. 2019). The most commercially used anionic surfactants especially utilized as household products, cosmetics, and laundry purposes are sodium dodecyl sulfate (SDS) whereas the most abundant and widely utilized cationic surfactant is cetylpyridinium chloride (CPC) which is basically a quaternary ammonium compound explicitly utilized in mouthwashes for obviation of dental plaques and periodontitis (Bondi et al. 2015; Costa et al. 2013). Several studies have documented the toxic effects of SDS and CPC in several fish species as well as in rats, mice, and amphibians (Barbieri et al. 1998; Lin et al. 1991; Park et al. 2016; Rocha et al. 2007).

Tubifex tubifex is an aquatic oligochaete worm that mainly resides in freshwater sediments (Milbrink 1987). It is an important bioindicator species having a cosmopolitan distribution, tolerant to a diverse array of environmental variables, easily culturable in laboratory conditions and serves as a source of healthy food to fishes, especially the freshwater ornamental ones (Chapman 2001; Yildiz 2016).

Biomarkers are the biochemical designator of changes at the biochemical and physiological levels of an organism (Strimbu and Tavel 2010). The toxicity of pollutants contributes to the production of reactive oxygen species (ROS) and the induction of oxidative stress (Mittal et al. 2014). These ROS are capable of inflicting lipid peroxidation (LPO) via the formation of malondialdehyde (MDA) as well as induce substantial damage to biomolecules like DNA, protein, and membranes through oxidative stress (Monteiro et al. 2006). Oxidative stress occurs when an imbalance emerges between the production of these ROS and their neutralization process with antioxidant enzymes like catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione S-transferase (GST), and reduced glutathione (GSH) (Raibeemol and Chitra 2018). Thus, the evaluation of alterations in the activity of antioxidant enzymes is indeed a productive and effective method for the assessment of oxidative stress and therefore could serve as a potential tool in aquatic toxicology (Kumari et al. 2014). Various studies have been carried out on alterations of oxidative stress in Tubifex tubifex exposed to pesticides (Mosleh et al., 2003, Mosleh et al., 2005, Mosleh et al., 2006, Mosleh et al., 2007, Mosleh et al., 2014; Paris-Palacios et al. 2010). However, evidence regarding the toxic effect of surfactant on alterations of oxidative stress enzymes in these worms is extremely meager.

The authentic and realistic assessment of pollutant toxicity on aquatic organisms by individual biomarkers is not possible and ergo, it is prevalently recommended to use the combined biomarker study to comprehend the response of an organism to toxic substances (Sanchez et al. 2012). The integrated biomarker response (IBR) thus consequently provides a holistic approach, consolidating all biomarker responses, and plays a crucial role in evaluating pollutant toxicity. (Beliaeff and Burgeot 2002; Serafim et al. 2012).

Therefore, the study aims to evaluate the in vivo toxic effects of SDS and CPC on Tubifex tubifex during sublethal exposure by visually examining the alterations in oxidative stress biomarkers using sublethal concentrations. Moreover integrated biomarker response (IBR) is employed to gain a superior comprehension of the toxic effects of CPC and SDS on Tubifex tubifex.