Maternal stress modifies the effect of exposure to lead during pregnancy and 24-month old children's neurodevelopment. (January 2017)

• Record Type: Journal Article
• Authors: Tamayo y Ortiz, Marcela; Téllez-Rojo, Martha María; Trejo-Valdivia, Belem; Schnaas, Lourdes; Osorio-Valencia, Erika; Coull, Brent; Bellinger, David; Wright, Rosalind J.; Wright, Robert O.
• Is Part Of: Environment international. Volume 98(2017:Jan.)
• Page Start: 191
• Page End: 197
• Publication Date: 2017-01
• Subjects: Prenatal -- Neurodevelopment -- Lead -- Stress -- Effect modification; Environmental protection -- Periodicals; Environmental health -- Periodicals; Environmental monitoring -- Periodicals; Environmental Monitoring -- Periodicals; Environnement -- Protection -- Périodiques; Hygiène du milieu -- Périodiques; Environnement -- Surveillance -- Périodiques; Environmental health; Environmental monitoring; Environmental protection; Periodicals; 333.705
• DOI: 10.1016/j.envint.2016.11.005
• Languages: English
• ISSNs: 0160-4120

Abstract

Abstract: Background: Lead and psychosocial stress disrupt similar but not completely overlapping mechanisms. Exposure during the prenatal period to each of these insults singularly has been found to alter normal neurodevelopment; however, longitudinal associations with stress modifying the effect of lead have not been sufficiently analyzed in epidemiologic studies. Objective: To evaluate prenatal stress as an effect modifier of gestational lead neurotoxicity. Methods: We used a structural equations modeling approach with a trivariate response to evaluate cognitive, language and motor scores of the Bayley Scales of Infant Development-III in 24 month-old children ( n = 360). Maternal blood lead levels were measured at the 2nd and 3rd trimester and psychosocial stress during pregnancy was assessed using a negative life events (NLE) scale derived from the CRYSIS questionnaire. Results: 3rd trimester lead (mean 3.9 ± 3.0 SD μg/dL) and stress (median = 3 NLE) were negatively associated with Bayley III scores. Using the model's results we generated profiles for 0, 2, 4 and 6 NLE across lead levels (up to 10 μg/dL) and observed a dose–response for the developmental scores when lead levels were below 2 μg/dL. Each NLE curve had a different shape across increasing lead levels. Higher stress (NLE = 6) resulted in lower cognitive scores for both sexes, in lower language scores in girls but not boys. In the absence of stress we saw a negative association with lead for all scores, however for language and motor scores, higher stress seemed to mask this association. Conclusions: Our work examined and confirmed prenatal stress exposure as a modifier of the well-known neurotoxic effects of prenatal lead. It adds to the existing evidence pointing at the importance of studying the co-exposure of chemical and non-chemical exposures, specifically of considering the emotional environment of children at early developmental stages of life. Highlights: Lead and stress were negatively associated with Bayley III neurodevelopment scores. For lead levels < 2 μg/dL there was a dose–response for stress with both scores. Prenatal stress exposure modified the neurotoxic effects of prenatal lead. Higher prenatal stress resulted in lower cognitive scores. Further modification by sex was seen for language scores.