Abstract
Currently, surfactants are widely distributed in the environment. As organic pollutants, their toxicities have drawn extensive attention. In this study, the effects of anionic [sodium dodecyl sulphate (SDS) ], cationic [dodecyl dimethyl benzyl ammonium chloride (1227)] and non-ionic [fatty alcohol polyoxyethylene ether (AEO) ] surfactants on zebrafish larval behaviour were evaluated. Five behavioural parameters were recorded using a larval rest/wake assay, including rest total, number of rest bouts, rest bouts length, total activity and waking activity. The results revealed that 1227 and AEO at 1 μg/mL were toxic to larval locomotor activity and that SDS had no significant effects. Moreover, we tested the toxicities of the three surfactants in developing zebrafish embryos. AEO exposure resulted in smaller head size, smaller eye size and shorter body length relative to SDS and 1227. All three surfactants incurred concentration-dependent responses. Furthermore, in situ hybridisation indicated that smaller head size may be associated with a decreased expression of krox20. The altered expression of ntl demonstrated that the developmental retardation stemmed from inhibited cell migration and growth. These findings provide references for ecotoxicological assessments of different types of surfactants, and play a warning role in the application of surfactants.
Highlights
Water pollution is a major threat to the global ecosystem
We examined the effects of three surfactants on zebrafish embryonic development from 1.25 hours post fertilisation to 120 hpf by morphological analysis and gene expression
Our experimental protocols briefly referred to Schier’s method, in which an automatic video recording system was employed to observe the rest/wake behaviour of zebrafish larvae exposed to thousands of psychotropic drugs, followed by the assessment of the neural pathways affected by these compounds[34]
Summary
Water pollution is a major threat to the global ecosystem. The sewage from domestic washing, agriculture, and industry endangers the aquatic ecosystem and public health, and water pollution has aroused considerable public attention around the world in recent decades[1,2]. The annual global production of surfactants was approximately 13 million metric tons in 20087, and production is currently growing These chemicals are widely considered safe at low concentrations[8,9]. Vaughan et al tested the acute toxicity of anionic, cationic and non-ionic surfactants in zebrafish embryos and adults. Their study indicated that embryos are as sensitive to cationic and non-ionic surfactants as adult fish but may be more sensitive to anionic surfactants[17]. The results indicated that the toxicity of AEO in rest/wake behaviour and embryos development is much more than that of SDS and 1227 at the concentration higher than environment-related concentrations, providing references for ecotoxicological assessments of different types of surfactants with widespread application, and playing a warning role in the application of surfactants
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