Urinary Uranium Levels in Cancer Patients and Healthy Residents Living in Uranium Legacy-Affected Areas: A Comparative Study

Uranium is a naturally occurring radioactive heavy metal, and drinking water and food are the primary sources of non-occupational exposure for the general population. The aim of the present study was to evaluate urinary uranium concentrations among cancer patients and healthy residents living in uranium legacy-affected areas and to compare them with those of individuals residing in a region with a more favorable radiological environment, accounting for urinary creatinine levels. An observational human biomonitoring study was conducted among 80 adults divided into four groups (n = 20 each): cancer patients and healthy residents from the exposed area and cancer patients and healthy residents from the comparison area. Twenty-four-hour urine samples were analyzed for uranium using inductively coupled plasma mass spectrometry, and urinary creatinine was measured using the kinetic Jaffe method. Urinary uranium concentrations ranged from 0.01 to 1.30 µg/L, with the highest values observed in cancer patients from the exposed area. After creatinine adjustment, median uranium concentrations were 0.0974 µg/g creatinine in exposed cancer patients, 0.0888 µg/g creatinine in exposed healthy residents, 0.0515 µg/g creatinine in comparison-area cancer patients, and 0.0607 µg/g creatinine in comparison-area healthy residents. Significant differences were observed between exposed and comparison populations among both cancer patients (p = 0.0066) and healthy residents (p = 0.0499). Residence in the exposed area was positively associated with urinary uranium levels (ρ = 0.292, p = 0.012). These findings suggest higher internal uranium exposure among residents of uranium legacy-affected areas and support the use of urinary uranium as a biomarker of environmental exposure. This study contributes to the assessment of internal uranium exposure in residents of uranium legacy-affected areas, including both cancer patients and healthy residents. However, the findings should be interpreted as differences in exposure biomarkers and do not establish a causal relationship between uranium exposure and cancer.