Methodological and Environmental Impacts on Bioaccessibility Estimates Provided by Single-Point Tenax Extractions

Area of Science:

• Environmental Chemistry
• Contaminant Toxicology
• Sediment Analysis

Background:

• Single-point Tenax extractions (SPTEs) measure hydrophobic organic contaminants in sediment.
• SPTEs estimate contaminant bioaccessibility via the rapidly desorbing fraction (C_rapT0).
• The ratio C_T/C_rapT0 is expected to be constant, but environmental factors and methodology can influence it.

Purpose of the Study:

• To evaluate the impact of environmental and methodological variations on the C_24h/C_rapT0 ratio.
• To assess the consistency of SPTEs in estimating pyrethroid bioaccessibility in sediments.

Main Methods:

• Laboratory-spiked sediments with pyrethroids were used.
• Varied Tenax to organic carbon mass (Tenax:OC) ratios to simulate environmental and methodological variations.
• Multiple regression analysis examined the effects of organic carbon, pyrethroid hydrophobicity, Tenax mass, and aging time on the C_24h/C_rapT0 ratio.

Main Results:

• Aging time showed a slight, negligible decline in the C_24h/C_rapT0 ratio (-0.0027/d).
• A consistent C_24h/C_rapT0 ratio of 1.46 ± 0.03 was observed across all treatments.
• Environmental and methodological variations had minimal impact on the C_24h/C_rapT0 ratio.

Conclusions:

• SPTEs demonstrate consistency in estimating the bioaccessibility of hydrophobic contaminants in sediment.
• The findings support the utility of SPTEs for estimating contaminant exposure and subsequent bioaccumulation.
• SPTEs provide reliable bioaccessibility estimates despite variations in environmental factors and extraction methods.