Application of the Sea Urchin Embryo Test in Toxicity Evaluation and Effect-Directed Analysis of Wastewater Treatment Plant Effluents

Sea urchin embryo assay was used
to assess general toxicity at
four wastewater treatment plant effluents of Biscay (Gorliz, Mungia,
Gernika, and Galindo), and within the tested range, all the extracts
showed embryo growth inhibition and skeleton malformation activities
with EC50 values, in relative enrichment factor units,
between 1.1–16.8 and 1.1–8.8, respectively. To identify
the causative compounds, effect-directed analysis was successfully
applied for the first time using a sea urchin embryo test to the secondary
treatment of the Galindo effluent. To this end, two subsequent fractionation
steps were performed using C18 (21 fractions) and aminopropyl columns
(15 fractions). By this fractionation, the number of features detected
by LC–HRMS in the raw sample was drastically reduced from 1500
to 9, and among them, two pesticides (mexacarbate, 17 ng/L, and fenpropidin,
23 ng/L), two antidepressants (amitriptyline, 304 ng/L, and paroxetine,
26 ng/L), and two anthelmintic agents (mebendazole, 65 ng/L, and albendazole,
48 ng/L) could be identified in the two toxic fractions. The artificial
mixture of the identified six compounds could explain 79% of the observed
effect, with albendazole and paroxetine as the predominant contributors
(49% and 49%, respectively) affecting the sea urchin embryogenesis
activity.