2. BIOLOGICAL MECHANISMS OF RADON TOXICITY
Radon gas itself is chemically inert, but its radioactive progeny, including polonium-218 and polonium-214, emit alpha particles during decay. These alpha particles have high LET, producing dense ionization tracks that induce significant DNA damage, including double-strand breaks, base modifications, and chromosomal aberrations [ 10,11 ]. Inhaled radon progeny deposit in the respiratory tract, where alpha radiation induces DNA damage both directly and indirectly through reactive oxygen species( ROS) generated by water radiolysis. This damage triggers cellular responses such as activation of DNA repair pathways, cell cycle arrest, or apoptosis. Failure to repair can result in mutations and carcinogenesis [ 12 ]. Due to high LET, even low doses of radon progeny can produce substantial biological effects, especially in lung stem and progenitor cells critical for tissue regeneration [ 13 ].
3. SUSCEPTIBILITY OF JUVENILE CELLS AND CHILDREN
Children’ s cells are especially vulnerable to radiation damage due to:
� High mitotic rates: Rapidly dividing cells increase the likelihood of replication of damaged DNA [ 14 ]. � Developing DNA repair systems: Immature repair mechanisms may be less efficient or error-prone [ 15 ]. � Organ development: Critical periods of organogenesis make structural and functional defects
� more likely [ 16 ]. Respiratory system differences: Smaller airway size and different airflow lead to deeper deposition of radon progeny and higher doses to sensitive lung tissues [ 17 ]. These factors collectively heighten children ' s susceptibility to radon’ s adverse effects, including increased lifetime cancer risk [ 18 ].
4. EPIDEMIOLOGICAL EVIDENCE
Multiple epidemiological studies confirm residential radon exposure is linked to increased lung cancer risk in adults. Combined analyses indicate a linear dose-response relationship with no safe threshold [ 19 ]. Although pediatric-specific data are limited due to long latency periods and lower lung cancer incidence in children, mechanistic studies and dosimetric models suggest children bear higher relative risks due to biological susceptibility and longer expected lifespan [ 20,21 ].
5. HEALTH EFFECTS BEYOND CANCER
Emerging research suggests radon exposure may also impact immune function and exacerbate respiratory diseases like asthma in children, though evidence remains preliminary and requires further investigation [ 22 ].
6. PREVENTION AND MITIGATION
Mitigating radon exposure involves testing indoor air levels, improving ventilation, sealing foundation cracks, and installing radon reduction systems, especially in homes and schools to protect vulnerable populations [ 23 ].
7. CONCLUSION
Radon gas presents a significant natural radiation hazard, particularly to children whose juvenile cells exhibit enhanced radiosensitivity. Understanding radon ' s biological impacts supports public health efforts to reduce exposure and protect children ' s health.
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