Are biomarkers of exposure and biomarkers of effect the same?

• A. Yes, they are the same.
• B. No, biomarkers of exposure measure internal dose while biomarkers of effect indicate early biological changes.
• C. They are unrelated to toxicology.
• D. Biomarkers of exposure measure early effects; biomarkers of effect measure dose.

Answer: (B)

Biomarkers come in two distinct roles in toxicology: exposure biomarkers quantify how much chemical or its metabolites are present inside the body, reflecting the internal dose from the exposure. They help answer “how much exposure did the body experience?” Biomarkers of effect detect early biological changes triggered by the exposure, such as changes in enzyme activity or cellular processes, indicating that biology is responding to the chemical. They answer “has exposure altered biology, and in what way?” Because these two types measure different things, they are not the same. The other statements mischaracterize their relationship: exposure biomarkers do not measure early effects, and effect biomarkers do not measure dose.