Abstract
Unitless
chemical activity, expressing the energetic level of a compound relative to its
energetic level in pure liquid [0-1], has proven useful to quantify the
effective exposure to hydrophobic organic compounds through both aerial and
aqueous media. Several studies have linked toxicity to chemical activity, as
opposed to e.g. the total concentration. Baseline toxicity (narcosis) for
neutral hydrophobic organic compounds has been shown to initiate in the narrow
chemical activity range of 0.01 to 0.1. This presentation focuses on linking
algal growth inhibition to chemical activity with the aims to (1) further
challenge the current chemical activity range for baseline toxicity, and (2)
extend the utilisation of the chemical activity concept across compounds and
species. The first part of the presentation focuses on results from a recently
published study, in which toxicity data for 39 non-polar liquids were applied
to challenge the chemical activity range for baseline toxicity. For each
compound, the effective activity (Ea50) was estimated as the ratio of the
effective concentration (EC50) and water solubility. Of these ratios, 90% were
within the expected chemical activity range of 0.01 to 0.1 for baseline
toxicity, and none of the ratios were significantly below 0.01. On a practical
level, these findings suggest EC50 values for baseline toxicity to be at or
above 1% of water solubility. On an environmental risk assessment level,
predicted no-effect concentrations (PNECs) for baseline toxicity could even be set
as a percentage of saturation, and this approach can easily be extended to
baseline toxicity of mixtures. However, EC50 values well below 1% of saturation
can still occur and indicate the potential for excess toxicity through a
specific or reactive mode of action. The second part of the presentation
focuses on extending the utilisation of the chemical activity concept. More
specifically, the chemical activity concept is applied to a much larger range
of algal toxicity data, including a wide range of solids and liquids, covering
several expected modes of action and also several algal species. High-quality
toxicity data are carefully selected from peer-reviewed scientific literature
and QSAR databases. This presentation shows how the chemical activity concept
can be used to compare and combine toxicity data across compounds and species
in order to characterize toxicity – and further how the concept can be used in
environmental risk assessment.
Original language | English |
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Publication date | 2015 |
Number of pages | 1 |
Publication status | Published - 2015 |
Event | SETAC North America 36th Annual Meeting - Salt Lake City, UT, United States Duration: 1 Nov 2015 → 5 Nov 2015 Conference number: 36 |
Conference
Conference | SETAC North America 36th Annual Meeting |
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Number | 36 |
Country/Territory | United States |
City | Salt Lake City, UT |
Period | 01/11/2015 → 05/11/2015 |
Keywords
- Algal toxicity
- Chronic toxicity
- Baseline toxicity
- QSAR
- Chemical activity