Adverse Outcome Pathways for Chronic Copper Toxicity to Fish and Amphibians.

Area of Science:

• Environmental Toxicology
• Ecotoxicology
• Biochemistry

Background:

• Chronic copper (Cu) toxicity mechanisms in aquatic organisms are complex.
• Understanding these pathways is crucial for ecological risk assessment.

Purpose of the Study:

• To synthesize information on chronic copper toxicity mechanisms using an adverse outcome pathway framework.
• To identify and differentiate key pathways contributing to chronic Cu toxicity.

Main Methods:

• Review and synthesis of existing scientific literature.
• Application of the adverse outcome pathway (AOP) framework.
• Analysis of Cu toxicity data across multiple biological levels.

Main Results:

• Three primary chronic Cu toxicity pathways identified: sodium homeostasis disruption, bioenergetic effects, and oxidative stress.
• Oxidative stress is the principal driver of chronic Cu toxicity in aquatic vertebrates.
• While bioenergetic effects and sodium homeostasis responses contribute, oxidative stress-induced tissue damage underlies endocrine-mediated pathway alterations.

Conclusions:

• Oxidative stress is the most significant mechanism in chronic copper toxicity for aquatic vertebrates.
• Bioenergetic impacts and compensatory sodium regulation responses play secondary roles.
• Further research is needed to quantitatively link lower-level impacts to apical endpoints like growth and reproduction.