Interlaboratory Comparison of Three Sediment Bioaccumulation Tests.

Area of Science:

• Environmental Toxicology
• Ecotoxicology
• Bioaccumulation Studies

Background:

• Standard bioaccumulation tests utilize Macoma nasuta (clam), Alitta virens (polychaete), and Lumbriculus variegatus (oligochaete).
• Interlaboratory variability in these standard tests was previously unknown, impacting data interpretation.

Purpose of the Study:

• To quantify interlaboratory and intralaboratory variability in standard 28-day bioaccumulation tests.
• To assess the impact of lipid normalization on variability for polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs).
• To evaluate analytical variability in tissue sample analysis.

Main Methods:

• Four laboratories conducted standard 28-day bioaccumulation tests with M. nasuta, A. virens, and L. variegatus using PCB- and PAH-contaminated sediments.
• A single laboratory performed chemical analysis of tissue samples.
• Analytical variability was assessed by multiple laboratories analyzing tissue homogenates for PCBs and lipids.

Main Results:

• Intralaboratory variance for PCB tissue concentrations was generally low (CVs 9-28%), except for one lab with L. variegatus (CV 51%).
• Intralaboratory variance exceeded interlaboratory variance for A. virens and L. variegatus (MOD 1.4-2.0).
• Lipid normalization had minimal impact on variability; analytical variability was higher than bioassay variability only for L. variegatus.

Conclusions:

• Low intralaboratory variability was observed, but the magnitude of difference (MOD) suggests limited biological significance for statistically significant findings.
• Considering MOD is crucial for interpreting bioaccumulation data and accounting for inherent test variability.
• Standardized bioaccumulation tests show manageable variability, but careful interpretation considering effect size is recommended.