Interspecies differences in cancer susceptibility and toxicity

Area of Science:

• Toxicology
• Comparative Metabolism
• Risk Assessment

Background:

• Extrapolation of toxicological data from laboratory animals to humans presents significant challenges.
• Understanding interspecies differences in chemical metabolism and toxicity is crucial for accurate human risk assessment.

Purpose of the Study:

• To review and analyze interspecies variations in the metabolism and toxicity of key chemical classes.
• To perform extrapolations to human toxicity and carcinogenicity where possible.

Main Methods:

• Literature review and analysis of existing toxicological data.
• Comparative assessment of metabolism and toxicity across species for selected compounds.
• Extrapolation of animal data to predict human health effects.

Main Results:

• Significant interspecies variations observed for heterocyclic amines, aflatoxin B1, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), endocrine disruptors, polycyclic aromatic hydrocarbons, tamoxifen, and digitoxin.
• Humans may be more susceptible to heterocyclic amines, while mice are resistant to aflatoxin B1 due to efficient glutathione conjugation.
• Humans appear less sensitive to TCDD and tamoxifen toxicity compared to laboratory animals like guinea pigs and rats.

Conclusions:

• Interspecies differences in metabolism and toxicity necessitate careful consideration in toxicological risk assessment.
• Human susceptibility varies greatly depending on the compound, with some posing lower risks than initially predicted from animal models.
• Further research is needed to refine extrapolation methods for more accurate human health risk predictions.