Acute and chronic effects of carrier solvents in aquatic organisms: A critical review

Recognising the scientific and regulatory need for testing relatively hydrophobic or ‘difficult substances’, the OECD currently recommends that selected organic solvents may be used in aquatic toxicity testing in order to help achieve more effective dispersion of the toxicant. The OECD recommends a maximum solvent concentration of 100 μl l−1 (with specific gravity equivalents to 100 μl l−1 in parentheses) for acetone (79 mg l−1), dimethylformamide (95 mg l−1), dimethylsulfoxide (1.10 mg l−1), ethanol (78.9 mg l−1), methanol (79.2 mg l−1) and triethylene glycol (1.12 mg l−1). While this recommendation is supported by historical data, we have recently observed evidence that some solvents may affect the reproduction of certain fish species, and also impact biomarkers of endocrine disruption. This review presents available data on the effects of solvents in aquatic organisms, supplemented by relevant information from mammalian studies (e.g. effects on liver enzyme induction potentially altering the metabolism of sex hormones). In conclusion, it is recommended that maximum effort should be given to avoiding the use of carrier solvents wherever possible, for example through the use of saturation columns or other physical methods (e.g. stirring or ultrasonification). Where solvent use is necessary, however, it is recommended that in reproduction studies with aquatic organisms, the maximum solvent concentration should not exceed 20 μl l−1 of dilution water.