Spatial variability of heavy metals in pregnant women: linking urinary biomarkers, indoor dust contamination, and air quality in Isfahan, Iran.

Pregnant women are particularly vulnerable to environmental stressors, including heavy metals from indoor dust and ambient air. This study evaluated chromium (Cr), lead (Pb), cadmium (Cd), and nickel (Ni) in paired urine and indoor vacuum dust samples from 80 pregnant women in Isfahan, Iran. Metal concentrations were quantified using inductively coupled plasma optical emission spectrometry (ICP-OES). Significant spatial variability across urban zones was observed for urinary metal concentrations and the Air Quality Index (both p < 0.001), whereas dust metal concentrations showed no significant spatial differences, including dust Pb (p = 0.514). In indoor dust, metal concentrations followed the order Pb > Cr > Ni > Cd, with Pb showing the highest mean concentration (111.10 μg/g). Urinary concentrations followed the order Pb > Cr > Ni, with mean concentrations of 10.52, 8.30, and 4.14 μg/L, respectively. Building age was strongly correlated with dust Pb levels (ρ = 0.788, p < 0.001). However, dust and urinary metal profiles were not significantly correlated, indicating that environmental contamination does not translate linearly into maternal internal exposure. These findings highlight diverse environmental, dietary, and behavioral pathways influencing maternal metal burden. Integrated multi-matrix assessments are therefore essential to accurately characterize pregnant women's environmental risks.