Geographical variations in metal exposure and metabolic disorders in Chile using an exposome approach

Exposure to metals may disrupt metabolic pathways, contributing to metabolic disorders. Local environmental factors may modulate these effects, emphasizing the importance of territorial disaggregation. This population-based study evaluated geographic variations in exposure to four metals and their associations with obesity, diabetes, metabolic syndrome, and hypertension in Chile. Data from 3,822 participants in the National Health Survey (2016-17) were analyzed. Biomarkers included inorganic arsenic (As), cadmium (Cd), mercury (Hg) in urine, and lead (Pb) in serum. Metal exposure categories were defined according to the median (50th percentile) distribution, contrasting participants above versus below this threshold. Associations between metal exposure and comorbidities were estimated using: (i) survey-weighted models with post-stratification by sex and region, (ii) spatial autoregressive (SAR) models to account for geographical dependencies across regions, and (iii) Bayesian multilevel generalized linear models that incorporated sampling design and regional correlations. 42.4% of individuals were exposed to As, 13.6% to Pb, and 1.7% to Hg and Cd. Elevated As exposure was observed in northern areas, with lead exposure peaking at 29.9%. Adjusted models showed no associations at the national level. However, geographical disaggregation showed that As exposure was linked to obesity across most areas, and to diabetes and metabolic syndrome in the northern and central zones. Hg was associated with all conditions in the central macrozone, whereas Cd exposure was linked to diabetes in the southern. These findings underscore critical regional differences in metal exposure and metabolic disorders, highlighting the need for geographically targeted public health interventions considering an exposome-based approach.