Evaluation of dimethyl sulfoxide (DMSO) as a co-solvent for toxicity testing of hydrophobic organic compounds
Toxicity testing of hydrophobic compounds with low aqueous solubility remains challenging. Dimethyl sulfoxide (DMSO) is widely used as a co-solvent for toxicity testing of hydrophobic chemicals, but it may modulate chemical toxicity patterns. In this study, we critically evaluated the suitability of DMSO as a co-solvent for toxicity testing of hydrophobic organic compounds in aqueous solutions. As the toxicity measure, we used growth inhibition of a natural bacterial community, and the test toxicants included phenol, BTEX (benzene, toluene, ethylbenzene and xylene) and transformation products of polycyclic aromatic hydrocarbons (PAHs). We found that dose-response curves for phenol were unaffected by DMSO concentrations up to 10% (v/v) and that DMSO (5% v/v) did not affect the degree of bacterial growth inhibition for any of the other test compounds in short-term experiments (3.5 h). By contrast, marked co-solvent effects of DMSO were observed in the long-term assay (25 and 27 h). We therefore conclude that DMSO has excellent co-solvent properties for short-term (≤3.5 h) toxicity testing of sparingly water-soluble compounds and its application provides a simple, inexpensive approach for screening of various environmentally relevant hydrophobic chemicals. Importantly, the use of DMSO allows for generation of full dose-responses that may otherwise not be attained.
KeywordsBTEX Ecotoxicity Hydrophobic organic compounds Leucine incorporation Soil bacterial community Solubility
We acknowledge assoc. prof. Bo Markussen (University of Copenhagen) for assistance and help in statistical analysis. Funding was obtained from University of Copenhagen via the emerging elite research area ‘Environmental Chemistry and Ecotoxicology’ headed by prof. Nina Cedergreen and from the Center for Environmental and Agricultural Microbiology (CREAM) financed by the Villum Foundation.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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