Elevated Cancer Risk from Inhaled NORM: A Quantitative Dose and Uncertainty Analysis of Rutile-Type Welding Electrode Fumes

This study conducted a comprehensive Radiological Risk Assessment of welding electrodes utilized in Shielded Metal Arc Welding (SMAW), critically establishing them as a quantifiable source of Naturally Occurring Radioactive Materials (NORM) with a focus on internal dose from inhalation. The activity concentrations of the principal radionuclides, 238U, 232Th, and 40K, were measured, with values ranging from a low of 11.92 Bq/kg for 238U to a high of 804.99 Bq/kg for 40K. Statistical analysis (one-way ANOVA) revealed a statistically significant difference in U and Th concentrations based on electrode flux type, confirming a direct link between manufacturing material (rutile-type flux) and NORM contamination. The calculated Annual Effective Dose (AEDinhalation) ranged up to 0.43 mSv/yr. Critically, the resultant Excess Lifetime Cancer Risk (ELCR) ranged up to 0.88. 10-3, a value that is 8.8 times higher than the U.S. EPA's regulatory threshold for lifetime exposure (EPA 10-4). This finding establishes that the unmanaged use of these electrodes constitutes an unacceptable occupational health risk, underscoring the urgent need for substitution and compliance with the ALARA principle.