Miniaturised Marine Algae Test with Polycyclic Aromatic Hydrocarbons - Comparing Equilibrium Passive Dosing and...

Area of Science:

• Environmental Toxicology
• Marine Ecotoxicology
• Chemical Risk Assessment

Background:

• Hydrophobic organic compounds (HOCs) like polycyclic aromatic hydrocarbons (PAHs) pose challenges in aquatic toxicity testing due to low solubility and sorption losses.
• Accurate risk assessment of PAHs in marine environments requires methods that maintain stable exposure concentrations.

Purpose of the Study:

• To develop and validate a miniaturised Marine Algae Test (mMAT) using passive dosing for assessing PAH toxicity.
• To compare the efficacy of passive dosing versus nominal spiking for delivering PAHs to the marine diatom Phaeodactylum tricornutum.

Main Methods:

• Development of a miniaturised Marine Algae Test (mMAT) based on ISO EN DIN10253 standards.
• Utilisation of biocompatible silicone O-rings as reservoirs for passive delivery of individual PAHs and a recreated PAH mixture.
• Comparison of passive dosing with nominal spiking for delivering PAHs to Phaeodactylum tricornutum.

Main Results:

• Passive dosing demonstrated significant growth inhibition effects of PAHs on Phaeodactylum tricornutum.
• Nominal spiking showed only slight growth inhibition, even at the highest concentrations.
• A recreated PAH mixture exhibited slight inhibition via passive dosing at 5000 times field concentration.

Conclusions:

• Passive dosing is superior to nominal spiking for assessing the toxicity of HOCs with log KOW > 4.6 in marine algae tests.
• The developed mMAT with passive dosing successfully maintains constant concentrations of HOCs, enabling reliable ecotoxicity assessments.
• This approach enhances the risk assessment of PAHs in marine ecosystems.