Assessing toxicity of hydrophobic aliphatic and monoaromatic hydrocarbons at the solubility limit using novel dosing methods. (February 2021)

• Record Type: Journal Article
• Authors: Parkerton, Thomas F.; Letinski, Daniel J.; Febbo, Eric J.; Butler, Josh D.; Sutherland, Cary A.; Bragin, Gail E.; Hedgpeth, Bryan M.; Kelley, Barbara A.; Redman, Aaron D.; Mayer, Philipp; Camenzuli, Louise; Vaiopoulou, Eleni
• Is Part Of: Chemosphere. Volume 265(2021)
• Publication Date: 2021-02
• Subjects: Chronic effects -- Toxicity -- Hydrocarbons -- Aqueous solubility -- Chemical activity -- Cut-offs; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2020.129174
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: 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 and daphnids to evaluate the presence or absence of chronic effects at exposures corresponding to the water solubility for representative hydrocarbons from five structural classes: branched alkanes, mono, di, and polynaphthenic (cyclic) alkanes and monoaromatic naphthenic hydrocarbons (MANHs). Algal growth rate and daphnid immobilization, growth and reproduction served as the chronic endpoints investigated. Results indicated that the dosing methods applied were effective for maintaining mean measured exposure concentrations within a factor of two or higher of the measured water solubility of the substances investigated. Chronic effects were not observed for hydrocarbons with an aqueous solubility below approximately 5 μg/L. This solubility cut-off corresponds to structures consisting of 13–14 carbons for branched and cyclic alkanes and 16–18 carbons for MANHs. These data support reliable hazard and risk evaluation of hydrocarbon classes that comprise petroleum substances and the methods described have broad applicability for establishing empirical solubility cut-offs for other classes of hydrophobic substances. Future work is needed to understand the role of biotransformation on the observed presence or absence of toxicity in chronic tests. Highlights: Novel dosing methods used to evaluate chronic toxicity at water solubility limit Measured concentrations confirmed exposures maintained over test duration Data used to establish empirical chronic toxicity cut-offs for hydrocarbons Aqueous solubility serves as a useful property for delineating toxicity cut-offs