Is prenatal arsenic exposure associated with salivary cortisol in infants in Arica, Chile? An exploratory cohort study

Introduction. In animal models, gestational exposure to inorganic arsenic has been associated with higher corticosterone concentration and consequent impairment of stress control in offspring. An equivalent association relating cortisol, a glucocorticoid hormone, in humans has not been previously studied. Objective. The aim of the study was to explore the association between prenatal inorganic arsenic exposure and salivary cortisol in infants from Arica, Chile. Materials and method. A cohort study of 168 mother-child dyads was recruited. In the 2nd trimester of pregnancy, urinary inorganic arsenic was assessed; 18–24 months after delivery, salivary cortisol was measured in the children. Maternal cortisol, maternal depression, stress, and socio-economic status were also evaluated. Results. The adjusted association was estimated with multiple linear regression after evaluating confounding through a directed acyclic graph. Median urinary inorganic arsenic in pregnant women was 14.1 μg/L (IQR: 10.4–21.7) while salivary cortisol in the children was 0.17 μg/L (IQR: 0.11–0.38). Among children from the highest income families (> 614 USD/month), arsenic exposure was associated with salivary cortisol. Children in the third quartile of arsenic exposure had -0.769 units of the logarithm of salivary cortiso, compared with those in the first quartile (p = 0.045). Conclusions. In this sample, prenatal exposure to arsenic was associated with salivary cortisol (third quartile of inorganic arsenic), only in infants belonging the highest income strata (> 614 USD). More studies are needed to confirm these preliminary results.