Rodent carcinogenicity bioassay: past, present, and future

Area of Science:

• Toxicology
• Carcinogenesis
• Risk Assessment

Background:

• Rodent toxicity and carcinogenicity studies are vital for identifying human health hazards.
• Nearly all known human carcinogens are also carcinogenic in rodents.
• Significant advancements in rodent study quality and mechanistic understanding have occurred over the past two decades.

Purpose of the Study:

• To highlight the established process of identifying chemical toxicity and carcinogenicity in rodents.
• To address the significant gap in extrapolating rodent data for human health risk management.
• To discuss the complexities and criticisms surrounding risk extrapolation, particularly for nongenotoxic chemicals.

Main Methods:

• Review of established rodent toxicity and carcinogenicity study protocols.
• Analysis of the challenges in extrapolating findings from rodents to humans.
• Consideration of newer molecular and cell kinetic techniques for risk assessment.

Main Results:

• The identification of toxic/carcinogenic chemicals in rodents is well-established.
• Extrapolation of rodent data to human risk management, especially for nongenotoxic chemicals, faces considerable uncertainty and criticism.
• The complexity of carcinogenesis complicates species and dose extrapolation.

Conclusions:

• A combination of well-designed rodent studies and mechanistic investigations is essential for regulatory decisions.
• Improved risk extrapolation methods are needed to bridge the gap between animal study findings and human health protection.
• Advancements in molecular biology and cell kinetics offer potential but require integration with traditional study designs.