Metals and metalloids are ubiquitous and persistent in urban areas and are generally released into the environment as mixtures.
The purpose of this study was to establish baseline concentrations of selected elements in meconium samples among a large urban population in the US and understand the spatial variability in concentrations. The association of metal mixtures on birth weight was also assessed.
This cross-sectional study was conducted across five public hospitals located in New York City, NY (NYC) in four boroughs. We collected meconium sample from 116 infants during the first 24 h after delivery and quantified 11 metals using ICP-MS. Principal component analysis was used to determine metal mixtures and their association with birth weight. Spatial hot spots of each metal were calculated using the Getis-Ord (GI*).
Essential elements were detected in all samples with Zn in the greatest abundance (median = 274.5 μg/g) and Mo in the least (median = 0.1845 μg/g). Pb was detected in all but two samples (median = 0.0222 μg/g), while Cd levels were detected in approximately half of the samples (median = 0.0019 μg/g). Co-located hot spots were detected for Cu, Zn, and Fe in southeast Brooklyn; Cd, Cr, and Ni in eastern Queens; and Al and Mo in south Queens. There was a significant inverse relationship between Pb concentrations (beta = -1935.7; p = 0.006) and the mixture of Cr, Cu, Mo, Zn (beta = -157.7; p = 0.045) and birth weight.
Our findings indicate that meconium is an effective biomarker for measuring metal exposures among an urban population. We were able to quantify detectable levels of ten of the eleven metals measured in the study and characterize nutritionally necessary trace elements and metals derived from anthropogenic sources without biologic need in a cohort of NYC newborns. Further research needs to establish the change point from necessary to toxic, for the essential elements.

There are many challenges to overcome in order to properly understand both the exposure to, and effects of, endocrine disruptors (EDs). This is particularly true with respect to fetal life where ED exposures are a major issue requiring toxicokinetic studies of materno-fetal exchange and identification of pathophysiological consequences. The sheep, a large, monotocous, species, is very suitable for in utero fetal catheterization allowing a modelling approach predictive of human fetal exposure. Predicting adverse effects of EDs on human health is frequently impeded by the wide interspecies differences in the regulation of endocrine functions and their effects on biological processes. Because of its similarity to humans as regards gestational and thyroid physiologies and brain ontogeny, the sheep constitutes a highly appropriate model to move one step further on thyroid disruptor hazard assessment. As a grazing animal, the sheep has also proven to be useful in the evaluation of the consequences of chronic environmental exposure to \"real-life\" complex mixtures at different stages of the reproductive life cycle.