Age-dependent health risk assessment and excess lifetime cancer risk from radon in groundwater of northeastern Iraq

Abstract

Naturally occurring radon in groundwater represents a significant public health concern due to exposure through both ingestion and inhalation. This study investigated radon concentrations across 30 groundwater samples collected from northeastern Iraq, together with associated physicochemical parameters and radiological risk assessments. Measured radon concentrations spanned from 2.9 to 29.7 Bq L ⁻¹ , with a mean of 12.5 Bq L ⁻¹ . Approximately 43.3 % of the sampled sites exceeded the USEPA guideline, whereas all concentrations remained below the WHO and UNSCEAR limits. Radiological health risk indicators, including annual effective dose via ingestion and inhalation pathways and excess lifetime cancer risk, were evaluated across three different age groups. Although the overall total annual effective dose remained beneath the WHO recommended limit of 0.1 mSv y ⁻¹ , infants recorded higher dose values than both children and adults, with five sampling locations surpassing this threshold specifically for the infant group. Excess lifetime cancer risk estimates across all age categories fell within USEPA acceptable boundaries. Pearson correlation, skewness, kurtosis, and Shapiro-Wilk statistical tests were applied to examine relationships between radon levels and water quality indicators. Findings highlight the need for targeted mitigation interventions, continuous environmental monitoring, and community awareness initiatives to reduce long-term waterborne radon health risks.