The article discusses the biomarker 8-hydroxy-2′-deoxyguanosine (8-OHdG) and its significance in assessing oxidative stress and carcinogenesis. 8-OHdG is a predominant form of free radical-induced oxidative lesions in DNA, particularly in nuclear and mitochondrial DNA. It is widely used as a biomarker for oxidative stress and carcinogenesis due to its presence in urine, which can be quantified using methods such as high-performance liquid chromatography (HPLC) with electrochemical detection (ECD), gas chromatography-mass spectrometry (GC-MS), and HPLC tandem mass spectrometry (HPLC-MS/MS). The European Standards Committee for Oxidative DNA Damage was established in 1997 to address methodological issues and improve consistency in 8-OHdG measurements. The biomarker has been used to estimate DNA damage in humans exposed to various carcinogens, including tobacco smoke, asbestos fibers, heavy metals, and polycyclic aromatic hydrocarbons. Recent studies have also shown that 8-OHdG levels are elevated in individuals with certain cancers and degenerative diseases, making it a valuable tool for risk assessment and monitoring the effects of lifestyle and environmental factors.The article discusses the biomarker 8-hydroxy-2′-deoxyguanosine (8-OHdG) and its significance in assessing oxidative stress and carcinogenesis. 8-OHdG is a predominant form of free radical-induced oxidative lesions in DNA, particularly in nuclear and mitochondrial DNA. It is widely used as a biomarker for oxidative stress and carcinogenesis due to its presence in urine, which can be quantified using methods such as high-performance liquid chromatography (HPLC) with electrochemical detection (ECD), gas chromatography-mass spectrometry (GC-MS), and HPLC tandem mass spectrometry (HPLC-MS/MS). The European Standards Committee for Oxidative DNA Damage was established in 1997 to address methodological issues and improve consistency in 8-OHdG measurements. The biomarker has been used to estimate DNA damage in humans exposed to various carcinogens, including tobacco smoke, asbestos fibers, heavy metals, and polycyclic aromatic hydrocarbons. Recent studies have also shown that 8-OHdG levels are elevated in individuals with certain cancers and degenerative diseases, making it a valuable tool for risk assessment and monitoring the effects of lifestyle and environmental factors.