Molecular size as a limiting characteristic for bioconcentration in fish

Area of Science:

• Environmental Chemistry
• Toxicology
• Ecotoxicology

Background:

• The bioconcentration factor (BCF) predicts chemical accumulation in aquatic organisms.
• Understanding BCF is crucial for assessing environmental risk and chemical safety.
• Previous studies suggested size-based thresholds for BCF prediction.

Purpose of the Study:

• To investigate the relationship between BCF and chemical size parameters (MW, Deff, Dmax).
• To re-evaluate existing size thresholds for discriminating bioconcentrative substances.
• To refine criteria for identifying chemicals with high bioconcentration potential.

Main Methods:

• Analysis of an experimental dataset of 737 new and 441 existing chemicals.
• Statistical examination of correlations between BCF and molecular weight (MW).
• Assessment of effective cross-sectional diameter (Deff) and maximum diameter (Dmax) in relation to BCF.

Main Results:

• Chemicals with very high BCF (> or = 5000) typically have MW < 550, Deff < 1.1 nm, and Dmax < 2.0 nm.
• Chemicals with high BCF (> or = 1000) typically have MW < 550, Deff < 1.4 nm, and Dmax < 2.9 nm.
• Existing thresholds for Deff (0.95 nm) and Dmax (1.5 nm) were found to be underestimated.

Conclusions:

• The study suggests revised size parameters for predicting chemical bioconcentration in fish.
• Many substances with high BCF exceed previously established Dmax thresholds.
• Updated criteria are needed for accurate assessment of bioconcentrative potential.