A bioassay battery for the ecotoxicity assessment of foaming agents containing anionic surfactants.

Alkylethoxysulfates (AES) surfactants are widely used in numerous industrial applications, as mechanized drill and fracking. They are present in commercial foaming products as their main components, together with different and sometimes not reported additives. In spite of their high volume utilization, very few data concerning the occurrence, fate and effects of AES on ecosystems have been published so far. The objective of this study was to evaluate the ecotoxicological effects of two commercial foaming products containing, as the main substance, the anionic surfactant sodium lauryl ether sulfate (SLES). In order to evaluate the EC50 values of the two commercial foaming products, they were initially subjected to ecotoxicological tests with aquatic and terrestrial organisms (Microtox test with Vibrio fischeri, Pseudokirchneriella subcapitata toxicity test and germination and growth test with Lepidium sativum). Then two soils with different geopedological characteristics were conditioned with the commercial foaming agents at the same concentrations used for mechanized drills and used for an experimental microcosm set-up. Soil sub-samples were collected at different times (0, 7, 14, 28 days) and soil elutriates were produced for assessing the effects of the foaming agents both on the previous tested organisms (Vibrio fischeri, Pseudokirchneriella subcapitata, Lepidium sativum) and on other two, performing the Fish Embryo Toxicity Test (FET) with Danio rerio and Daphnia magna toxicity test. The results of the five tests were then compared with SLES residual concentrations, determined by MBAS spectrophotometric method both in the elutriates and in ASE soil extracts.