Comparing sensitivity of ecotoxicological effect endpoints between laboratory and field

Area of Science:

• Environmental toxicology
• Ecotoxicology
• Marine ecology

Background:

• Extrapolating toxicant effects from single-species to ecosystem levels is crucial for environmental risk assessment.
• Fixed application factor (AF) and species sensitivity distribution (SSD) models are commonly used for this extrapolation.
• Assessing the reliability of these models requires comparison with field data.

Purpose of the Study:

• To compare the effectiveness of AF and SSD models in predicting ecosystem-level effects of tributyltin (TBT) and linear alkylbenzene sulfonates (LAS).
• To evaluate whether laboratory-derived effect concentrations accurately reflect field-measured effects.
• To determine if current extrapolation methods provide protective predicted no-effect concentrations (PNECs).

Main Methods:

• Measured effect concentrations from multispecies plankton field tests with TBT and LAS were compared to laboratory single-species test results.
• Predicted no-effect concentrations (PNECs) were calculated using both AF and SSD models.
• PNECs were compared with No Observed Effect Concentrations (NOECs) and Effect Concentrations (EC50s) from field studies.

Main Results:

• Effect concentrations from laboratory and field experiments were comparable.
• Both AF and SSD approaches yielded PNECs that appear protective for ecosystems.
• The AF approach is simpler to implement and yields PNECs that are as conservative as those from SSD models.
• Calculated PNECs and lowest field effect concentrations were below measured environmental concentrations for both TBT and LAS.

Conclusions:

• Both AF and SSD models are valuable tools for estimating ecosystem-level risks of toxicants.
• The AF approach offers a simpler, equally conservative alternative to SSD models.
• Measured environmental concentrations of TBT and LAS may pose a risk to marine ecosystems, necessitating careful risk management.