Introduction to Biomonitoring and ADME

Biomonitoring is an approach used to measure the trace concentration of chemicals inside the human body. This approach integrates all sources and routes of exposure, including air, dust, food, water, and soil. Chemicals can be carried to the human body and may undergo chemical changes, becoming more or less toxic. Biomonitoring is an integrating measure that involves measuring chemical residues in fats, blood, bone, and urine.

The process by which chemicals react in the human body is summarized as absorption, distribution, metabolism, and excretion (ADME). For oral administration of drugs/chemicals, capsules are disintegrated in the gastrointestinal tract and absorbed through the gut wall. The drug molecules can be expelled by transporters or metabolized by enzymes in the liver, leading to increased hydrophilicity and easy excretion through the kidney. Some drugs that are not chemically modified during the metabolism process enter the systemic circulation and are delivered to target cells, while others are rapidly removed through the kidney.

Review Questions:

• What is biomonitoring, and why is it an important approach to assessing exposure?
• What are the different sources and routes of exposure that biomonitoring integrates?
• What is the ADME process, and how does it describe the way chemicals react in the human body?
• How do drugs that are not chemically modified during the metabolism process enter the systemic circulation, and what happens to them once they are delivered to target cells?