Pollution compounds in human teeth in a Mexican metropolitan area

Environmental pollution accounts for ∼7 million deaths worldwide each year. The Monterrey metropolitan area (MMA), México-one of Latin America's most polluted regions-has seen significant increases in exposure to PM2.5 and PM10, particles that carry heavy metals such as Pb, Zn, and Sn, which can be absorbed by the body, causing neurological, renal, respiratory, metabolic, and reproductive disorders. Despite their known toxicity, there is limited research on bioaccumulation in dental tissues and its oral health implications. This observational cross-sectional study evaluated heavy metal levels in the teeth of MMA residents. Sixty-seven extracted teeth were collected and sectioned to separate the enamel and dentin. An Agilent 240FS AA atomic absorption spectrometer was used to measure heavy metal levels. The results demonstrated that heavy metal concentrations varied significantly by dental structure and geographic location. Specifically, Salinas Victoria showed the highest mean Pb levels, whereas Apodaca and General Zuazua had the highest Zn and Sn levels, respectively. Although Hg levels were too low for statistical analysis, significant differences in metal distribution were found between enamel and dentin across several municipalities. Statistical analysis revealed a strong association between heavy metal accumulation and variables such as occupation, length of residence, and, to a lesser extent, the specific municipality. This study confirms that enamel and dentin are effective biomarkers of heavy metal exposure in urban populations, such as the MMA.