DNA adduct

Overview
A DNA adduct is an abnormal piece of DNA covalently-bonded to a cancer-causing chemical. This has shown to be the start of a cancerous cell, or carcinogenesis. DNA adducts in scientific experiments are used as bio-markers and as such are themselves measured to reflect quantitatively, for comparison, the amount of cancer in the subject, i.e. rats or other living animals. Under experimental conditions for study, such DNA adducts are induced by known carcinogens, of which commonly used is DMBA, chemically structured and named as 7,12-Dimethyl-benz[a] Anthracene. For example, a scientific journal that writes "DMBA - DNA adduct" is referring to a piece of DNA that has the chemical DMBA attached to it. The presence of such adduct indicates the presence of cancer in the subject animal.

Other examples : - acetaldehyde DNA Adducts. Note: acetaldehyde is a major component of cigarette smoke.

DNA Damage
When a chemical bonds to DNA, the DNA becomes damaged, and proper and complete replication cannot occur to make the normal intended cell. This would be the start of a mutation, or mutagenesis, and without proper DNA repair (DNA repair happens naturally under normal circumstances), this can lead to carcinogenesis, the beginnings of cancer.