Biological Dosimetry and Individual Susceptibility in Chronic Low-Dose Occupational Ionizing Radiation Exposure: Implications for Worker Health Surveillance

The global number of workers who are exposed to ionizing radiation through occupation is 2.3 million in the healthcare, nuclear energy, and industrial fields. In spite of regulatory annual dose limits of 20 mSv, cellular and molecular damage are measurable at lower doses than these, with chronic low-dose exposures causing damage. Current occupational surveillance relies predominantly on physical dosimetry, which does not capture individual biological susceptibility or cumulative cellular damage. This is a synthesis of peer-reviewed sources dating from 2000 to 2025 on biological damages in occupationally exposed workers. The DNA damage indicators, such as sustained gamma-H2AX foci, micronuclei, and chromosomal anomalies, report 2-7-fold increases in health workers in the field of medicine and industrial radiography below regulatory limits. The biomarkers of oxidative stress demonstrate a sustained increase of reactive oxygen species and a 25-40 percent decrease of antioxidant defenses. The data on 308,297 nuclear workers proves that leukemia has a linear dose-response dependence and an excess risk of 0.35 per sievert. Personal risk factors such as DNA repair polymorphisms, age, and smoking also have significant effects on personal risk with the same amount of occupational exposure. The biological dosimetry techniques, such as micronuclei, comet assay, and gamma-H2AX techniques, are standardized to facilitate regular occupational health monitoring. Systematic biomarker surveillance would be helpful in improving early screening of toxic exposure and allowing protective measures that are tailored to the individual. Integrating standardized biological dosimetry into routine occupational health surveillance would enable earlier detection of radiation-induced harm and support individualized risk-based protection strategies.