Assessing toxicity of hydrophobic aliphatic and monoaromatic hydrocarbons at the solubility limit using novel dosing methods

Reliable delineation of aquatic toxicity cut-offs for poorly soluble hydrocarbons is lacking. In this study, vapor and passive dosing methods were applied in limit tests with algae daphnids to evaluate the presence or absence chronic effects at exposures corresponding water solubility representative from five structural classes: branched alkanes, mono, di, polynaphthenic (cyclic) alkanes monoaromatic naphthenic (MANHs). Algal growth rate daphnid immobilization, reproduction served as endpoints investigated. Results indicated that effective maintaining mean measured exposure concentrations within a factor two higher substances Chronic not observed an aqueous below approximately 5 ?g/L. This cut-off corresponds structures consisting 13–14 carbons cyclic 16–18 MANHs. These data support reliable hazard risk evaluation hydrocarbon classes comprise petroleum described have broad applicability establishing empirical other hydrophobic substances. Future work needed understand role biotransformation on tests.