Assessment of natural radionuclides and health risk in pediatric toothpaste in Anambra State, Nigeria

Background: Pediatric toothpaste is an essential daily oral-care product and represents a potential chronic ingestion pathway for naturally occurring radionuclides, particularly in children who are biologically more sensitive to ionizing radiation. Despite widespread use, data on the radiological safety of pediatric toothpaste remain limited, especially in developing countries.

Objective: This study aims to assess the activity concentrations of naturally occurring radionuclides Potassium-40 (⁴⁰K), radium-226 (²²⁶Ra), and thorium-232 (²³²Th) in commonly consumed pediatric toothpaste brands in Anambra State, Nigeria, and to assess the associated radiological health risks to children using standard radiological hazard indices.

Methods: Five pediatric toothpaste brands were collected from retail outlets across Anambra State between December 2024 and January 2025. Gamma-ray spectrometry using a Nai(Tl) detector was employed to determine activity concentrations. Radiological hazard indices, annual effective dose equivalent (AEDE), and excess lifetime cancer risk (ELCR) were calculated using standardized equations for ingestion exposure.

Results: The activity concentrations of ⁴⁰K ranged from 55.76 ± 10.78 to 145.25 ± 22.51 Bq kg⁻¹, ²²⁶Ra from 4.27 ± 1.44 to 4.80 ± 1.79 Bq kg⁻¹, and ²³²Th from 2.44 ± 0.65 to 6.68 ± 1.69 Bq kg⁻¹. All values were below UNSCEAR reference limits. The total AEDE ranged from 0.00627 to 0.00825 mSv y⁻¹, and ELCR values ranged from 2.19 × 10⁻⁵ to 2.89 × 10⁻⁵, indicating negligible radiological health risk.

Conclusion: This study establishes baseline radiological safety data for pediatric toothpaste in Nigeria, indicating that the analyzed products do not pose significant radiological risks under normal use. While the study is limited by the number of brands analyzed and standardized ingestion assumptions, the findings provide robust, protective upper-bound dose estimates and underscore the importance of periodic radiological monitoring of child-specific consumer products.