Abstract
This study determined the levels and distribution patterns of Pb, Cd, Co, Cu, Ni, and Zn in indoor (n = 22) and outdoor (n = 22) dust from Basra, Iraq, and evaluated the associated human health risks. The total mean concentration of ∑ 6HMs was 247 mg/kg in the indoor dust and 285 mg/kg in the outdoor dust. Zn was the dominant metal in both environments, with mean concentrations of 155 and 161 mg/kg, contributing 63% and 56% of the total metal burden, respectively. Pb, Cd, Co, and Ni concentrations were significantly higher (p < 0.05) in outdoor dust, indicating the influence of outdoor emission sources. Human exposure assessment showed that the average daily doses (ADD) for children through ingestion, inhalation, and dermal contact were approximately 9.3-fold higher than those for adults across all metals. Zn exposure reached 1.99 × 10-3 and 2.13 × 10-4 mg kg-1 day-1 for children and adults, respectively. The non-carcinogenic hazard index (HI) for all metals remained below the acceptable threshold (HI < 1), while carcinogenic risks (CR) for Pb, Cd, and Ni were within the acceptable range (10-6–10-4). Nevertheless, Ni in outdoor dust exhibited comparatively higher carcinogenic risk values (4.03 × 10-5 for children and 1.73 × 10-5 for adults), highlighting the importance of continued environmental monitoring. These findings provide a comprehensive baseline for assessing human exposure to heavy metals in indoor and outdoor dust in Basra, Iraq.