Determining fetal manganese exposure from mantle dentine of deciduous teeth

Studies addressing health effects of manganese (Mn) excess or deficiency during prenatal development are hampered by a lack of biomarkers that can reconstruct fetal exposure. We propose a method using the neonatal line, a histological feature in deciduous teeth, to identify regions of mantle dentine formed at different prenatal periods. Micromeasurements of Mn in these regions may be used to reconstruct exposure at specific times in fetal development. To test our hypothesis, we recruited pregnant women before 20 weeks gestation from a cohort of farmworkers exposed to Mn-containing pesticides. We collected house floor dust samples and mother's blood during the second trimester; umbilical cord blood at birth; and shed deciduous incisors when the child was ∼7 years of age. Mn levels in mantle dentine formed during the second trimester (as ⁵⁵Mn:⁴³Ca area under curve) were significantly associated with floor dust Mn loading (r_spearman = 0.40; p = 0.0005; n = 72). Furthermore, ⁵⁵Mn:⁴³Ca in sampling points immediately adjacent the neonatal line were significantly associated to Mn concentrations in cord blood (r_spearman = 0.70; p = 0.003; n = 16). Our results support that Mn levels in mantle dentine are useful in discerning perinatal Mn exposure, offering a potentially important biomarker for the study of health effects due to environmental Mn exposure.