John Wiley & Sons, Ltd.

Acute toxicity of the cationic surfactant C12‐benzalkonium in different bioassays: How test design affects bioavailability and effect concentrations

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Using an ion‐exchange based solid phase micro‐extraction (SPME) method, the freely dissolved concentrations of C12‐benzalkonium were measured in different toxicity assays, including i) immobilization of Daphnia magna in the presence/absence of dissolved humic acid; ii) mortality of Lumbriculus variegatus in the presence/absence of a suspension of OECD sediment iii) photosystem II inhibition of green algae Chlorella vulgaris; and iv) viability of in vitro rainbow trout gill cell line (RT‐gill W1) in the presence/absence of serum proteins. Furthermore, the loss due to chemical adsorption to the different test vessels applied in these tests was also determined. The C12‐benzalkonium sorption isotherms to the different sorbent phases were established as well. Our result shows the freely dissolved concentration is a better indicator of the actual exposure concentration than the nominal or total concentration in most test assays. Daphnia was the most sensitive species to C12‐benzalkonium. Both the acute Daphnia and Lumbriculus tests showed no enhanced toxicity due to possible ingestion of sorbed C12‐benzalkonium, in comparison with water‐only exposure, which is in accordance with the equilibrium partitioning theory. Moreover, the present study demonstrated that commonly used sorbent phases can strongly affect bioavailability and observed effect concentrations for C12‐benzalkonium. Even stronger effects of decreased actual exposure concentrations due to sorption to test vessels, cells and sorbent phases can be expected for more hydrophobic cationic surfactants. Environ Toxicol Chem © 2013 SETAC

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