Can highly hydrophobic organic substances cause aquatic baseline toxicity and can they contribute to mixture toxicity?
Article first published online: 9 DEC 2009
Copyright © 2006 SETAC
Environmental Toxicology and Chemistry
Volume 25, Issue 10, pages 2639–2644, October 2006
How to Cite
Mayer, P. and Reichenberg, F. (2006), Can highly hydrophobic organic substances cause aquatic baseline toxicity and can they contribute to mixture toxicity?. Environmental Toxicology and Chemistry, 25: 2639–2644. doi: 10.1897/06-142R.1
- Issue published online: 9 DEC 2009
- Article first published online: 9 DEC 2009
- Manuscript Accepted: 3 MAY 2006
- Manuscript Received: 24 MAR 2006
- Hydrophobic organic chemicals;
- Effective chemical activity;
- Toxicity cutoff;
- Baseline toxicity Quantitative structure-activity relationships
Effect concentrations for aquatic baseline toxicity generally decrease with increasing log octanol-water partition coefficient (Kow) values of up to 5 to 6, whereas less is known about the baseline toxicity of organic chemicals with log Kow values above 6. A physicochemical analysis of the dissolution process for organic chemicals was combined with reported baseline toxicity data, leading to the following conclusions. First, no absolute hydrophobicity cutoff exists for baseline toxicity at a log Kow value of 6, because aquatic baseline toxicity for fish and algae was observed for chemicals with log Kow values greater than 6.5 and with effect concentrations less than 10 μg/L. Second, the baseline toxicity of hydrophobic organic substances was exerted at a relatively constant chemical activity of 0.01 to 0.1. Finally, organic chemicals with high melting points cannot provide sufficient chemical activity to exert baseline toxicity when considered as individual, pure chemicals. However, such substances are still expected to contribute to baseline toxicity when part of a complex mixture.