Toxicity Evaluation of Stearamidopropyl Dimethylamine Surfactant on Embryonic Development of Zebrafish

Background: Surfactants best known for their use in the industry of detergents, household products, and cosmetics. Usually, the amount of released surfactants into the environment is diluted during secondary water treatment. However, there is always a risk of releasing untreated and polluted wastewater containing high amounts of surfactants without knowing the harmful effect on biotic and abiotic elements of the environment. SAPDMA is a surfactant that is used mostly in cosmetics, conditioning agents, and recently in corrosion inhibition. The classification of SAPDMA as a 'safe' or 'green' surfactant by different environment or chemical agencies is ambiguous, and the literature is lacking. Aim: The aim of this study is to evaluate the safety of SAPDMAusing the zebrafish embryo model. Methods: Zebrafish embryos were exposed to different concentrations of SAPDMA and the effect was assessed by different toxicity assays. This includes (i) mortality/ survival assay to assess the median lethal dose (LC50) (ii) teratogenicity assay to assess the no observed effect concentration (NOEC); and (iii) organ specific toxicity assays including cardiotoxicity, neurotoxicity (using locomotion assay), and hemoglobin synthesis (using odianisidine staining). Results: Exposure of zebrafish embryos to SAPDMA caused mortality in a dose-dependent manner with a calculated LC50 of 2.3 mg/L. Thus, based on the LC50 value and according to the Fish and Wildlife Service Acute Toxicity Rating Scale, SAPDMA is classified as 'moderately toxic'. The NOEC, the concentration that did not cause any significant teratogenicity, was 0.1mg/L. However, this concentration caused significant organ specific and cytotoxic effects, suggesting that harmless concentrations of SAPDMAare lower than 0.1 mg/L. Conclusion: Our data indicate that SAPDMA at very low concentrations causes adverse effects on zebrafish embryos. Thus, we recommend that the use of SAPDMA in industry should be re-evaluated and monitored by the environment and public health agencie