Aquatic toxicity testing of liquid hydrophobic chemicals - Passive dosing exactly at the saturation limit

作者：Stibany Felix^*; Schmidt Stine Norgaard; Schaeffer Andreas; Mayer Philipp

来源：Chemosphere, 2017, 167: 551-558.

DOI：10.1016/j.chemosphere.2016.10.014

• Highly hydrophobic liquids
• Saturation limit
• Silicone swelling
• Passive dosing
• Algal growth inhibition
• Hydrophobicity cut-off

The aims of the present study were (1) to develop a passive dosing approach for aquatic toxicity testing of liquid substances with very high K-ow values and (2) to apply this approach to the model substance dodecylbenzene (DDB, Log K-ow = 8.65). The first step was to design a new passive dosing format for testing DDB exactly at its saturation limit. Silicone O-rings were saturated by direct immersion in pure liquid DDB, which resulted in swelling of >14%. These saturated O-rings were used to establish and maintain DDB exposure exactly at the saturation limit throughout 72-h algal growth inhibition tests with green algae Raphidocelis subcapitata. Growth rate inhibition at DDB solubility was 13 +/- 5% (95% CI) in a first and 8 +/- 3% (95% CI) in a repeated test, which demonstrated that improved exposure control can lead to good precision and repeatability of toxicity tests. This moderate toxicity at chemical activity of unity was higher than expected relative to a reported hydrophobicity cut-off in toxicity, but lower than expected relative to a reported chemical activity range for baseline toxicity. The present study introduces a new effective approach for toxicity testing of an important group of challenging chemicals, while providing a basis for investigating toxicity cut-off theories.

• 出版日期2017-1