Assessing bioavailability and toxicity of permethrin and DDT in sediment using matrix solid phase microextraction.

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Analytical Chemistry

Background:

• Assessing bioavailability and toxicity of hydrophobic pesticides in sediments is crucial for environmental risk assessment.
• Sediment aging significantly impacts contaminant bioavailability and toxicity.
• Traditional methods for measuring absorbed doses in organisms can be complex and time-consuming.

Purpose of the Study:

• To evaluate matrix solid phase microextraction (SPME) as a surrogate for absorbed dose in organisms.
• To estimate the bioavailability and toxicity of permethrin and dichlorodiphenyltrichloroethane (DDT) in aged sediments.
• To investigate the effect of sediment aging on pesticide bioavailability and toxicity.

Main Methods:

• Laboratory-spiked sediments were aged for 7, 28, and 90 days.
• Matrix-SPME with polydimethylsiloxane fibers was used to estimate absorbed doses.
• Toxicity was assessed using freshwater invertebrates: Chironomus dilutus and Hyalella azteca.
• Median lethal fiber concentrations (LC50) were determined.

Main Results:

• Equilibrium fiber concentrations decreased with sediment aging, indicating reduced bioavailability.
• Permethrin toxicity remained consistent across aging times.
• DDT degradation to DDD altered toxicity differently for C. dilutus and H. azteca.
• Linear relationships were observed between organism body residues and fiber concentrations.

Conclusions:

• Matrix-SPME effectively mimicked organism bioaccumulation and enabled estimation of body residues.
• SPME can be a valuable tool for assessing bioavailability and toxicity of hydrophobic pesticides in environmental risk assessments.
• The method shows potential for application across different matrices, including sediment and water.