Toxicity of dodecylbenzene to algae, crustacean, and fish – Passive dosing of highly hydrophobic liquids at the solubility limit. (July 2020)

• Record Type: Journal Article
• Authors: Stibany, Felix; Schmidt, Stine Nørgaard; Mayer, Philipp; Schäffer, Andreas
• Is Part Of: Chemosphere. Volume 251(2020)
• Publication Date: 2020-07
• Subjects: Dodecylbenzene -- Highly hydrophobic -- Passive dosing -- Solubility limit -- Baseline toxicity -- Chemical activity; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2020.126396
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: In the current study, improved exposure control and measurements were applied for the aquatic toxicity testing of a highly hydrophobic organic compound. The aim was to reliably determine the ecotoxicity of the model compound dodecylbenzene (DDB, Log KOW = 8.65) by applying passive dosing for aquatic toxicity testing exactly at the solubility limit. Methodologically, silicone O-rings were saturated by immersion in pure liquid DDB (i.e., "loading by swelling") and then used as passive dosing donors. Daphnia immobilization and fish embryo toxicity tests were successfully conducted and provide, together with recently reported algal growth inhibition data, a full base-set of ecotoxicological data according to REACH. All tests were conducted in closed test systems to avoid evaporative losses, and exposure concentrations were measured throughout test durations. The Daphnia test was optimized by placing the O-rings in cages to prevent direct contact between daphnids and the passive dosing donor. Toxicologically, Daphnia magna immobilization was 19.3 ± 8% (mean ± 95% CI; 6 tests) within 72 h, whereas Danio rerio fish embryos did not show any significant lethal or sublethal toxic responses within 96 h. Growth rate inhibition for the algae Raphidocelis subcapitata was previously reported to be 13 ± 5% in a first and 8 ± 3% in a repeated test. These results for aquatic organisms, spanning three trophic levels, demonstrate toxicity of a highly hydrophobic compound and suggest that improvements of the current ecotoxicological standard tests are needed for these "difficult-to-test" chemicals. Furthermore, the obtained toxicity results significantly question the existence of a generic Log KOW cut-off in baseline toxicity. Graphical abstract: Image 1 Highlights: Aquatic toxicity testing of a highly hydrophobic liquid at its solubility limit. Constant exposure by the application of passive dosing. Suggested improvements of current standard test systems for hydrophobic chemicals. Full base-set of ecotoxicological data according to REACH (three trophic levels). Evidence against the existence of a generic Log KOW cut-off in baseline toxicity.