Simultaneous Control of Phenanthrene and Drought by Dual Exposure System: The Degree of Synergistic Interactions in Springtails was Exposure Dependent

Stine N. Schmidt, Martin Holmstrup, Christian Damgaard, Philipp Mayer

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    Organisms in the environment are exposed to multiple stressors. However, for terrestrial invertebrates, it remains difficult to study the effects of combined stressors under well-defined exposure conditions. Thus, the current study develops a new dual exposure system for the simultaneous and independent control of chemical and drought exposure in bioassays with terrestrial organisms: Passive dosing from silicone controlled the chemical activity of phenanthrene (chemical stress), while saline solutions controlled the water activity (drought stress) in the closed exposure system. The dual exposure system was then applied in a full factorial experiment with seven exposure levels (72), which aimed at determining the combined effects of phenanthrene and drought on the survival of the terrestrial springtail Folsomia candida after 7 d exposure. Fitting an "independent action" model to the complete data set revealed statistically significant synergy between phenanthrene and drought (p <0.0001). However, the degree of synergy was exposure dependent with some synergy at higher and only minor synergy at lower exposure levels. This emphasizes the need for taking exposure levels into account when extrapolating synergy observations from (eco)toxicological studies done at high exposure levels.
    Original languageEnglish
    JournalEnvironmental Science and Technology
    Issue number16
    Pages (from-to)9737-9744
    Number of pages8
    Publication statusPublished - 2014

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