Determination of Acute Toxicity of the Surfactant, Sodium Lauryl Sulfate on Ostracod Stenocypris sp.

Abstract

Detergents are typical xenobiotic chemicals with polar head groups (hydrophilic) and non-polar hydrocarbonic tails that are hydrophobic. Sodium Lauryl Sulfate (SLS) has been categorized as an anionic surfactant that can be used as an emulsifying cleaning agent in household detergents such as dishwashing soaps, toothpaste and shampoo. Mechanisms related to the effects of SLS on aquatic fauna are poorly investigated, and Stenocypris sp. (Ostrocod), in particular, was not studied from this perspective. The present study was conducted to observe the behaviour, morpho-logical changes and mortality of Stenocypris sp. at different concentrations of SLS. Concentrations of 0.05 μmol/dm3, 0.1 μmol/dm3, 0.2 μmol/dm3, and 0.4 μmol/dm3 were prepared with three replicates into 6 L glass tanks along with a control tank. Fifteen individuals of Stenocypris sp. of the same size (~0.5 mm in length) were added into each tank. Water pH, temperature and conductivity were measured daily in each tank. The morphology and behaviour of individuals in the experimental series were similar to those in the control tank until 48 h. However, after 48 hrs, “attachment to the glass surface” was the only shown observable behavioural difference among individuals in the control tanks. Furthermore, discolouration of the body was observed in individuals exposed to SLS compared to the controls. The Adductor Muscle Scar, thoracopods, gut and Caudal Ramus of the organism were broken and disfigured in the concentration of 0.2 μmol/dm3 after 72 h of exposure. Based on the probit scale, the 72h lethal concentration (LC50,72 h) of SLS for Stenocypris sp. was determined as 0.101 μmol/dm3. It was concluded that the detergents containing SLS used in daily household activities have potential toxicological effects on aquatic biota by altering their behaviour, morphology and survival. Therefore, monitoring environmental concentrations of surfactants and developing management practices to mitigate potential environmental impacts are highly recommended.