Effect threshold for selenium toxicity in juvenile splittail, Pogonichthys macrolepidotus A

Area of Science:

• Environmental toxicology
• Aquatic toxicology
• Ecotoxicology

Background:

• Selenium bioaccumulation in fish can lead to adverse health effects.
• The splittail (Pogonichthys macrolepidotus) in San Francisco Bay is a species of concern for selenium exposure.
• Previous toxicity assessments using NOAEL/LOAEL methods for selenium in juvenile splittail had limitations.

Purpose of the Study:

• To re-analyze existing experimental data on selenium toxicity in juvenile splittail.
• To derive more precise threshold values for selenium toxicity using logistic regression.
• To compare derived selenium toxicity thresholds with environmental concentrations in wild splittail diets.

Main Methods:

• Re-analysis of raw experimental data using logistic regression models.
• Derivation of EC(10) values (concentration causing 10% effect) for selenium in feed, muscle, and liver tissues.
• Comparison of derived EC(10) values with reported selenium levels in the diet of wild splittail.

Main Results:

• Logistic regression analysis yielded EC(10) values of 0.9 mg/kg-dw in feed, 7.9 mg/kg-dw in muscle, and 18.6 mg/kg-dw in liver for juvenile splittail.
• Selenium concentrations found in the diet of wild splittail were observed to exceed these derived EC(10) values.
• This suggests a potential link between dietary selenium exposure and observed adverse effects.

Conclusions:

• The derived EC(10) values provide a refined understanding of selenium toxicity thresholds in juvenile splittail.
• Dietary selenium levels in wild splittail populations likely exceed critical thresholds, indicating a significant risk.
• Observed deformities in wild splittail may be attributable to elevated selenium exposure through their food chain.