Presentation of a general algorithm to include secondary poisoning in effect assessment

Area of Science:

• Environmental Toxicology
• Ecotoxicology
• Risk Assessment

Background:

• Secondary poisoning is a significant risk to wildlife.
• Assessing this risk requires understanding chemical transfer through food chains.
• Existing models may not fully capture terrestrial and aquatic pathways.

Purpose of the Study:

• To develop a general algorithm for assessing secondary poisoning effects in birds and mammals.
• To analyze both aquatic and terrestrial food chain pathways.
• To identify chemicals posing critical secondary poisoning risks.

Main Methods:

• Developed a Maximum Permissible Concentration (MPC) algorithm using No Observed Effect Concentrations (NOECs) and Bioconcentration Factors (BCFs).
• Analyzed aquatic (water-fish-bird/mammal) and terrestrial (soil-worm-bird/mammal) food chains.
• Collected NOEC and BCF data for lindane, dieldrin, cadmium, mercury, PCB153, DDT, and PCP.

Main Results:

• Bioconcentration Factors (BCFs) were significantly higher in aquatic pathways (up to 10^4) compared to terrestrial (often < 1 to 10).
• Secondary poisoning identified as a critical pathway for methyl-mercury and PCB153 in fish-eating birds/mammals.
• Cadmium and methyl-mercury identified as critical risks in terrestrial pathways for birds/mammals.

Conclusions:

• The developed algorithm provides a robust method for evaluating secondary poisoning risks.
• Methyl-mercury, PCB153, and cadmium represent key chemical threats requiring careful management.
• Food chain transfer dynamics significantly influence secondary poisoning potential.