Study of Radon Concentration in Well Water in the Districts of Kirkuk Governorate

This study evaluates the radon ²²²Rn concentrations in well water from seven districts (Qara Hanjir, Yaychi, Taza, Laylan, Altun Kupri, Dibis and Hawija) of Kirkuk Governorate, Northern Iraq, using the RAD7–H₂O dosimeter. A total of 21 samples were collected (three from each district): Qara Hanjir, Yaychi, Taza, Laylan, Altun Kupri, Dibis, and Hawija. This study is motivated by the fact that radon in groundwater is a significant source of natural radiation exposure, with potential health effects such as lung and stomach cancer if concentrations exceed the international safety limits. The measured radon concentrations ranged from 7.93 Bq\l in Altun Kupri to 18.7 Bq\l in Dibis District. According to the United States Environmental Protection Agency (USEPA) guideline of 11 Bq. l^-1, only Taza and Altun Kupri were within the permissible limit, while the other districts exceeded it. The annual effective dose of inhalation ranged from 0.020 mSv.y^-1 in Altun Kupri to 0.047 mSv.y^-1 in Dibis, whereas the ingestion dose varied from 1.67 mSv.y^-1 in Altun Kupri to 3.92 mSv.y^-1 in Dibis. Compared with the international standards, inhalation doses remained well below the permissible limits, while ingestion doses in some districts (Dibis and Laylan) slightly exceeded the ICRP lower threshold (3 mSv.y^-1), just above the UNSCEAR global average (1.15 mSv.y^-1). The calculated excess lifetime cancer risk (ELCR) values are within acceptable ranges, indicating a limited long-term risk from inhalation exposure, but ingestion exposure requires continuous monitoring.