Prenatal Metal Exposures and Infants’ Developmental Outcomes in a Navajo Population

Abstract

Early-life exposure to environmental toxicants can have detrimental effects on children’s neurodevelopment. In the current study, we employed a causal modeling framework to examine the direct effect of specific maternal prenatal exposures on infants’ neurodevelopment in the context of co-occurring metals. Maternal metal exposure and select micronutrients’ concentrations were assessed using samples collected at the time of delivery from mothers living across Navajo Nation with community exposure to metal mixtures originating from abandoned uranium mines. Infants’ development across five domains was measured at ages 10 to 13 months using the Ages and Stages Questionnaire Inventory (ASQ:I), an early developmental screener. After adjusting for effects of other confounding metals and demographic variables, prenatal exposure to lead, arsenic, antimony, barium, copper, and molybdenum predicted deficits in at least one of the ASQ:I domain scores. Strontium, tungsten, and thallium were positively associated with several aspects of infants’ development. Mothers with lower socioeconomic status (SES) had higher lead, cesium, and thallium exposures compared to mothers from high SES backgrounds. These mothers also had infants with lower scores across various developmental domains. The current study has many strengths including its focus on neurodevelopmental outcomes during infancy, an understudied developmental period, and the use of a novel analytical method to control for the effects of co-occurring metals while examining the effect of each metal on neurodevelopmental outcomes. Yet, future examination of how the effects of prenatal exposure on neurodevelopmental outcomes unfold over time while considering all potential interactions among metals and micronutrients is warranted.

“Know Your Children, Who They Are, Their Weakness, and Their Strongest Point”: A Qualitative Study on Diné Parent Experiences Accessing Autism Services for Their Children

“…Many Diné families struggle economically (e.g., the Navajo Nation median household income = 25,963 USD, and 41 percent of households are below the federal poverty level) [ 25 ]. Diné children living in these communities may also be at an increased risk for developmental delays given the elevated environmental exposures to heavy metals including arsenic, uranium, and lead [ 26 ].…”

Urinary biomarkers of exposure to toxic and essential elements: A comparison of infants fed with human milk or formula

“… 1 – 3 For example, prenatal exposure to nonessential elements like arsenic, 1 , 2 nickel, 3 and uranium 4 , 5 is associated with altered birth outcomes, neurodevelopmental effects, and health complications in adulthood. Similarly, early-life exposure to low levels of arsenic, 6 , 7 cadmium, 8 , 9 nickel, 4 , 8 and uranium 10 , 11 is associated with adverse neurodevelopmental effects. Micronutrients involved in essential physiological processes—including cobalt, 4 , 12 molybdenum, 4 , 6 and selenium 13 —can also be toxic at high doses.…”

“…Similarly, early-life exposure to low levels of arsenic, 6 , 7 cadmium, 8 , 9 nickel, 4 , 8 and uranium 10 , 11 is associated with adverse neurodevelopmental effects. Micronutrients involved in essential physiological processes—including cobalt, 4 , 12 molybdenum, 4 , 6 and selenium 13 —can also be toxic at high doses. While prenatal exposure is relatively well-studied, less is known about exposure to potentially toxic nonessential and essential elements during the immediate postnatal period.…”

Uranium in Waters of The Southern Colorado Plateau: Implications for the Navajo Nation

“…Surface water is scarce on the Colorado Plateau, and elevated uranium (U) in groundwater further complicates water access. Water scarcity is driven by a low annual rainfall that is below 20-30 cm per year (Credo et al, 2019;Jones et al, 2020;Ingram et al, 2020), and enrichments of U in these waters pose health concerns for people and animals (USDHHS 2013;Hund et al, 2015;Rock et al, 2019;Hoover et al, 2020;Ingram et al, 2020;Lister et al, 2021;Nozadi et al, 2022). The southern Colorado Plateau is the ancestral land of the Navajo (Diné) people and the current boundaries of the Navajo Nation are located entirely in the region (Figure 1A).…”